Arthroplasty/Joint Replacement

The introduction of extended reality (XR) to the operating room (OR) has proved promising for enhancing surgical precision and improving patient outcomes. In the field of orthopedic surgery, precise alignment of implants is integral to maintaining functional range of motion and preventing impingement of adjacent neurovascular structures. XR systems have shown promise in arthroplasty including by improving precision and streamlining surgery by allowing surgeons to create 3D preoperative plans that are accessible intraoperatively. This article explores the current applications of XR in arthroplasty, highlights recent advancements and benefits, and describes limitations in comparison to traditional techniques.

Methods

A literature search identified studies involving the use of XR in arthroplasty and current US Food and Drug Administration (FDA)-approved XR systems. Multiple electronic databases were used, including PubMed, Google Scholar, and IEEE Xplore. Search terms included: extended reality, augmented reality, virtual reality, arthroplasty, joint replacement, total knee arthroplasty, total shoulder arthroplasty, and total hip arthroplasty. The study design, intervention details, outcomes, and comparisons with traditional surgical techniques were thematically analyzed, with identification of common ideas associated with XR use in arthroplasty. This narrative report highlights the integration of XR in arthroplasty.

Extended Reality Fundamentals

XR encompasses augmented reality (AR), virtual reality (VR), and mixed reality (MR). AR involves superimposing digitally rendered information and images onto the surgeon’s view of the real world, typically through the use of a headset and smart glasses.¹ AR allows the surgeon to move and interact freely within the OR, removing the need for additional screens or devices to display patient information or imaging. VR is a fully immersive simulation using a headset that obstructs the view of the real world but allows the user to move freely within this virtual setting, often with audio or other sensory stimuli. MR combines AR and VR to create a digital model that allows for real-world interaction, with the advantage of adapting information and models in real time.² Whereas in AR the surgeon can view the data projected from the headset, MR provides the ability to interact with and manipulate the digital content (Figure). Both AR and MR have been adapted for use in the OR, while VR has been adapted for use in surgical planning and training.

Extended Reality Use in Orthopedics

The HipNav system was introduced in 1995 to create preoperative plans that assist surgeons in accurately implanting the acetabular cup during total hip arthroplasty (THA).³ Although not commercially successful, this system spurred surgeons to experiment with XR to improve the accuracy and alignment of orthopedic implants. Systems capable of displaying the desired intraoperative implant placement have flourished, with applications in fracture reduction, arthroplasty, solid tumor resection, and hardware placement.^4-7 Accurate alignment has been linked to improvements in patient outcomes.^8-10 XR has great potential within the field of arthroplasty, with multiple new systems approved by the FDA and currently available in the US (Table).

Hip Arthroplasty

Orientation of the acetabular cup is a technically challenging part of THA. Accuracy in the anteversion and inclination angles of the acetabular cup is required to maintain implant stability, preserve functional range of motion (ROM), and prevent precocious wear.^11,12 Despite preoperative planning, surgeons often overestimate the inclination angle and underestimate anteversion.¹³ Improper implantation of the acetabular cup can lead to joint instability caused by aseptic loosening, increasing the risk of dislocation and the need for revision surgery.^14,15 Dislocations typically present to the emergency department, but primary care practitioners may encounter patients with pain or diminished sensation due to impingement or instability.¹⁶

The introduction of XR into the OR has provided the opportunity for real-time navigation and adjustment of the acetabular cup to maximize anteversion and inclination angles. Currently, 2 FDA-approved systems are available for THA: the Zimmer and Surgical Planning Associates HipInsight system, and the Insight Augmented Reality Visualization and Information System (ARVIS). The HipInsight system consists of a hologram projection using the Microsoft HoloLens2 device and optimizes preoperative planning, producing accuracy of anteversion and inclination angles within 3°.¹⁷ ARVIS employs existing surgical helmets and 2 mounted tracking cameras to provide navigation intraoperatively. ARVIS has also been approved for use in total knee arthroplasty (TKA) and unicompartmental knee arthroplasty.¹⁸

HipInsight has shown utility in increasing the accuracy of acetabular cup placement along with the use of biplanar radiographic scans.¹⁹ However, there are no studies validating the efficacy of ARVIS and HipInsight and assessing long-term disease-oriented or patient-oriented outcomes.

Knee Arthroplasty

In the setting of TKA, XR is most effective in ensuring accurate resection of the tibial and femoral components. Achieving the planned femoral coronal, axial, and sagittal angles allows the prosthesis to be on the femoral axis of rotation, improving functional outcomes. XR systems for TKA have been shown to increase the accuracy of distal femoral resection with a limited increase in surgery duration.^20,21 For TKA in particular, patients are often less satisfied with the result than surgeons expect.²² Accurate alignment can improve patient satisfaction and reduce return-to-clinic rates for postoperative pain management, a factor that primary care practitioners should consider when recommending a patient for TKA.²³

Along with ARVIS, 3 additional XR systems are FDA-approved for use in TKA. The Pixee Medical Knee+ system uses smart glasses and trackers to aid in the positioning of instruments for improved accuracy while allowing real-time navigation.²⁴ The Medacta NextAR Knee’s single-use tracking system allows for intraoperative navigation with the use of AR glasses.²⁵ The Polaris STELLAR Knee uses MR and avoids the need for preoperative imaging by capturing real-time anatomic data.²⁶

The Pixee Medical Knee+ system was commercially available in Europe for several years prior to FDA approval, so more research exists on its efficacy. One study found that the Pixee Medical Knee+ system initially demonstrated an inferior clinical outcome, attributed to the learning curve associated with using the system.²⁷ However, more recent studies have shown its utility in improving alignment, regardless of implant specifications.^28,29 The Medacta NextAR Knee system has been shown to improve accuracy of tibial rotation and soft tissue balance and even increase OR efficiency.^30,31 The Polaris STELLAR Knee system received FDA approval in 2023; no published research exists on its accuracy and outcomes.²⁶

Shoulder Arthroplasty

Minimally invasive techniques are favored in total shoulder arthroplasty (TSA) due to the vitality of maintaining the surrounding soft tissue to maximize preservation of motility and strength.³² However, this complicates the procedure by decreasing the ability to effectively access and visualize key structures of the shoulder. Accordingly, issues with implant positioning and alignment are more common with TSA than other joint arthroplasties, making XR particularly promising.³³ Some studies report that up to 67% of patients experience glenohumeral instability, which can clinically present as weakness, decreased range of motion, and persistent shoulder pain.^34,35 The use of preoperative computed tomography to improve understanding of glenoid anatomy and glenohumeral subluxation is becoming increasingly common, and it can be combined with XR to improve accuracy.^36,37

Two FDA-approved systems are available. The Stryker Blueprint MR system is used for intraoperative guidance and integration for patient imaging used for preoperative planning. The Medacta NextAR Shoulder system is a parallel of the company’s TKA system. The Stryker Blueprint MR system combines the Microsoft HoloLens 2 headset to display preoperative plans with a secondary display for coordination with the rest of the surgical team.³⁸ Similar to the Medacta NextAR Knee, the Medacta NextAR Shoulder system uses the same single-use tracking system and AR glasses for intraoperative guidance.³⁹

Data on the long-term outcomes of using these systems are still limited, but the Stryker Blueprint MR system has not been shown to accurately predict postoperative ROM.⁴⁰ Cadaveric studies have demonstrated that the Medacta NextAR Shoulder system can provide accurate inclination, retroversion, entry point, depth, and rotation values based on the preoperative planned values.^41,42 However, this accuracy has yet to be confirmed in vivo, and the impact of using XR in TSA on long-term outcomes is still unknown.

Challenges and Limitations

Though XR has proven to be promising in arthroplasty, several limitations regarding widespread implementation exist. In particular, there is a steep learning curve associated with the use of XR systems, which can cause increased operative time and even initial inferior outcomes, as demonstrated with the Pixee Medical Knee+ system. The need for extensive practice and training prior to use could delay widespread adoption and may cause discrepancies in surgical outcomes. Unfamiliarity with the system and technological difficulties that may require troubleshooting can also increase operative time, particularly for surgeons new to using the XR system. Though intraoperative navigation is expected to improve accuracy of implant alignment, its added complexity may also result in longer surgeries.

In addition to the steep learning curve and increased operative time, there is a high upfront cost associated with XR systems. Exact costs of XR systems are not typically disclosed, but available estimates suggest an average sales price of about $1000 per case. Given the proprietary nature of these technologies, publicly available cost data are limited, making it challenging to fully assess the financial burden on health care institutions. Though some systems, such as ARVIS, can be integrated with existing surgical helmets, many require the purchase of AR glasses and secondary displays. This can cause further variation in the total expense for each system. In low-resource settings, this represents a significant challenge to widespread implementation. To justify this cost, additional research on long-term patient outcomes is needed to ensure the benefits of XR systems outweigh the cost. 

Although early studies on XR systems in arthroplasty have shown improvements in precision and short-term outcomes, long-term data regarding effectiveness remains. Even systems such as ARVIS and HipInsight have limited long-term follow-up, making it difficult to assess whether the improved accuracy with these XR systems translates into improved patient outcomes compared with traditional arthroplasty.

CONCLUSIONS

XR technologies have shown significant potential in enhancing precision and patient outcomes. Through the integration of XR in the OR, surgeons can visualize preoperative plans and even make intraoperative changes, with the benefit of improving implant alignment.

There are some disadvantages to its use, however, including high cost and increased operative time. Despite this, the integration of XR into surgical practice can deliver more precise implant alignment and address other challenges faced with conventional techniques. As these technologies evolve and studies on long-term outcomes validate their utility, XR has the potential to transform the field of arthroplasty.

The introduction of extended reality (XR) to the operating room (OR) has proved promising for enhancing surgical precision and improving patient outcomes. In the field of orthopedic surgery, precise alignment of implants is integral to maintaining functional range of motion and preventing impingement of adjacent neurovascular structures. XR systems have shown promise in arthroplasty including by improving precision and streamlining surgery by allowing surgeons to create 3D preoperative plans that are accessible intraoperatively. This article explores the current applications of XR in arthroplasty, highlights recent advancements and benefits, and describes limitations in comparison to traditional techniques.

Methods

A literature search identified studies involving the use of XR in arthroplasty and current US Food and Drug Administration (FDA)-approved XR systems. Multiple electronic databases were used, including PubMed, Google Scholar, and IEEE Xplore. Search terms included: extended reality, augmented reality, virtual reality, arthroplasty, joint replacement, total knee arthroplasty, total shoulder arthroplasty, and total hip arthroplasty. The study design, intervention details, outcomes, and comparisons with traditional surgical techniques were thematically analyzed, with identification of common ideas associated with XR use in arthroplasty. This narrative report highlights the integration of XR in arthroplasty.

Extended Reality Fundamentals

XR encompasses augmented reality (AR), virtual reality (VR), and mixed reality (MR). AR involves superimposing digitally rendered information and images onto the surgeon’s view of the real world, typically through the use of a headset and smart glasses.¹ AR allows the surgeon to move and interact freely within the OR, removing the need for additional screens or devices to display patient information or imaging. VR is a fully immersive simulation using a headset that obstructs the view of the real world but allows the user to move freely within this virtual setting, often with audio or other sensory stimuli. MR combines AR and VR to create a digital model that allows for real-world interaction, with the advantage of adapting information and models in real time.² Whereas in AR the surgeon can view the data projected from the headset, MR provides the ability to interact with and manipulate the digital content (Figure). Both AR and MR have been adapted for use in the OR, while VR has been adapted for use in surgical planning and training.

Extended Reality Use in Orthopedics

The HipNav system was introduced in 1995 to create preoperative plans that assist surgeons in accurately implanting the acetabular cup during total hip arthroplasty (THA).³ Although not commercially successful, this system spurred surgeons to experiment with XR to improve the accuracy and alignment of orthopedic implants. Systems capable of displaying the desired intraoperative implant placement have flourished, with applications in fracture reduction, arthroplasty, solid tumor resection, and hardware placement.^4-7 Accurate alignment has been linked to improvements in patient outcomes.^8-10 XR has great potential within the field of arthroplasty, with multiple new systems approved by the FDA and currently available in the US (Table).

Hip Arthroplasty

Orientation of the acetabular cup is a technically challenging part of THA. Accuracy in the anteversion and inclination angles of the acetabular cup is required to maintain implant stability, preserve functional range of motion (ROM), and prevent precocious wear.^11,12 Despite preoperative planning, surgeons often overestimate the inclination angle and underestimate anteversion.¹³ Improper implantation of the acetabular cup can lead to joint instability caused by aseptic loosening, increasing the risk of dislocation and the need for revision surgery.^14,15 Dislocations typically present to the emergency department, but primary care practitioners may encounter patients with pain or diminished sensation due to impingement or instability.¹⁶

The introduction of XR into the OR has provided the opportunity for real-time navigation and adjustment of the acetabular cup to maximize anteversion and inclination angles. Currently, 2 FDA-approved systems are available for THA: the Zimmer and Surgical Planning Associates HipInsight system, and the Insight Augmented Reality Visualization and Information System (ARVIS). The HipInsight system consists of a hologram projection using the Microsoft HoloLens2 device and optimizes preoperative planning, producing accuracy of anteversion and inclination angles within 3°.¹⁷ ARVIS employs existing surgical helmets and 2 mounted tracking cameras to provide navigation intraoperatively. ARVIS has also been approved for use in total knee arthroplasty (TKA) and unicompartmental knee arthroplasty.¹⁸

HipInsight has shown utility in increasing the accuracy of acetabular cup placement along with the use of biplanar radiographic scans.¹⁹ However, there are no studies validating the efficacy of ARVIS and HipInsight and assessing long-term disease-oriented or patient-oriented outcomes.

Knee Arthroplasty

In the setting of TKA, XR is most effective in ensuring accurate resection of the tibial and femoral components. Achieving the planned femoral coronal, axial, and sagittal angles allows the prosthesis to be on the femoral axis of rotation, improving functional outcomes. XR systems for TKA have been shown to increase the accuracy of distal femoral resection with a limited increase in surgery duration.^20,21 For TKA in particular, patients are often less satisfied with the result than surgeons expect.²² Accurate alignment can improve patient satisfaction and reduce return-to-clinic rates for postoperative pain management, a factor that primary care practitioners should consider when recommending a patient for TKA.²³

Along with ARVIS, 3 additional XR systems are FDA-approved for use in TKA. The Pixee Medical Knee+ system uses smart glasses and trackers to aid in the positioning of instruments for improved accuracy while allowing real-time navigation.²⁴ The Medacta NextAR Knee’s single-use tracking system allows for intraoperative navigation with the use of AR glasses.²⁵ The Polaris STELLAR Knee uses MR and avoids the need for preoperative imaging by capturing real-time anatomic data.²⁶

The Pixee Medical Knee+ system was commercially available in Europe for several years prior to FDA approval, so more research exists on its efficacy. One study found that the Pixee Medical Knee+ system initially demonstrated an inferior clinical outcome, attributed to the learning curve associated with using the system.²⁷ However, more recent studies have shown its utility in improving alignment, regardless of implant specifications.^28,29 The Medacta NextAR Knee system has been shown to improve accuracy of tibial rotation and soft tissue balance and even increase OR efficiency.^30,31 The Polaris STELLAR Knee system received FDA approval in 2023; no published research exists on its accuracy and outcomes.²⁶

Shoulder Arthroplasty

Minimally invasive techniques are favored in total shoulder arthroplasty (TSA) due to the vitality of maintaining the surrounding soft tissue to maximize preservation of motility and strength.³² However, this complicates the procedure by decreasing the ability to effectively access and visualize key structures of the shoulder. Accordingly, issues with implant positioning and alignment are more common with TSA than other joint arthroplasties, making XR particularly promising.³³ Some studies report that up to 67% of patients experience glenohumeral instability, which can clinically present as weakness, decreased range of motion, and persistent shoulder pain.^34,35 The use of preoperative computed tomography to improve understanding of glenoid anatomy and glenohumeral subluxation is becoming increasingly common, and it can be combined with XR to improve accuracy.^36,37

Two FDA-approved systems are available. The Stryker Blueprint MR system is used for intraoperative guidance and integration for patient imaging used for preoperative planning. The Medacta NextAR Shoulder system is a parallel of the company’s TKA system. The Stryker Blueprint MR system combines the Microsoft HoloLens 2 headset to display preoperative plans with a secondary display for coordination with the rest of the surgical team.³⁸ Similar to the Medacta NextAR Knee, the Medacta NextAR Shoulder system uses the same single-use tracking system and AR glasses for intraoperative guidance.³⁹

Data on the long-term outcomes of using these systems are still limited, but the Stryker Blueprint MR system has not been shown to accurately predict postoperative ROM.⁴⁰ Cadaveric studies have demonstrated that the Medacta NextAR Shoulder system can provide accurate inclination, retroversion, entry point, depth, and rotation values based on the preoperative planned values.^41,42 However, this accuracy has yet to be confirmed in vivo, and the impact of using XR in TSA on long-term outcomes is still unknown.

Challenges and Limitations

Though XR has proven to be promising in arthroplasty, several limitations regarding widespread implementation exist. In particular, there is a steep learning curve associated with the use of XR systems, which can cause increased operative time and even initial inferior outcomes, as demonstrated with the Pixee Medical Knee+ system. The need for extensive practice and training prior to use could delay widespread adoption and may cause discrepancies in surgical outcomes. Unfamiliarity with the system and technological difficulties that may require troubleshooting can also increase operative time, particularly for surgeons new to using the XR system. Though intraoperative navigation is expected to improve accuracy of implant alignment, its added complexity may also result in longer surgeries.

In addition to the steep learning curve and increased operative time, there is a high upfront cost associated with XR systems. Exact costs of XR systems are not typically disclosed, but available estimates suggest an average sales price of about $1000 per case. Given the proprietary nature of these technologies, publicly available cost data are limited, making it challenging to fully assess the financial burden on health care institutions. Though some systems, such as ARVIS, can be integrated with existing surgical helmets, many require the purchase of AR glasses and secondary displays. This can cause further variation in the total expense for each system. In low-resource settings, this represents a significant challenge to widespread implementation. To justify this cost, additional research on long-term patient outcomes is needed to ensure the benefits of XR systems outweigh the cost. 

Although early studies on XR systems in arthroplasty have shown improvements in precision and short-term outcomes, long-term data regarding effectiveness remains. Even systems such as ARVIS and HipInsight have limited long-term follow-up, making it difficult to assess whether the improved accuracy with these XR systems translates into improved patient outcomes compared with traditional arthroplasty.

CONCLUSIONS

XR technologies have shown significant potential in enhancing precision and patient outcomes. Through the integration of XR in the OR, surgeons can visualize preoperative plans and even make intraoperative changes, with the benefit of improving implant alignment.

There are some disadvantages to its use, however, including high cost and increased operative time. Despite this, the integration of XR into surgical practice can deliver more precise implant alignment and address other challenges faced with conventional techniques. As these technologies evolve and studies on long-term outcomes validate their utility, XR has the potential to transform the field of arthroplasty.

The introduction of extended reality (XR) to the operating room (OR) has proved promising for enhancing surgical precision and improving patient outcomes. In the field of orthopedic surgery, precise alignment of implants is integral to maintaining functional range of motion and preventing impingement of adjacent neurovascular structures. XR systems have shown promise in arthroplasty including by improving precision and streamlining surgery by allowing surgeons to create 3D preoperative plans that are accessible intraoperatively. This article explores the current applications of XR in arthroplasty, highlights recent advancements and benefits, and describes limitations in comparison to traditional techniques.

Methods

A literature search identified studies involving the use of XR in arthroplasty and current US Food and Drug Administration (FDA)-approved XR systems. Multiple electronic databases were used, including PubMed, Google Scholar, and IEEE Xplore. Search terms included: extended reality, augmented reality, virtual reality, arthroplasty, joint replacement, total knee arthroplasty, total shoulder arthroplasty, and total hip arthroplasty. The study design, intervention details, outcomes, and comparisons with traditional surgical techniques were thematically analyzed, with identification of common ideas associated with XR use in arthroplasty. This narrative report highlights the integration of XR in arthroplasty.

Extended Reality Fundamentals

XR encompasses augmented reality (AR), virtual reality (VR), and mixed reality (MR). AR involves superimposing digitally rendered information and images onto the surgeon’s view of the real world, typically through the use of a headset and smart glasses.¹ AR allows the surgeon to move and interact freely within the OR, removing the need for additional screens or devices to display patient information or imaging. VR is a fully immersive simulation using a headset that obstructs the view of the real world but allows the user to move freely within this virtual setting, often with audio or other sensory stimuli. MR combines AR and VR to create a digital model that allows for real-world interaction, with the advantage of adapting information and models in real time.² Whereas in AR the surgeon can view the data projected from the headset, MR provides the ability to interact with and manipulate the digital content (Figure). Both AR and MR have been adapted for use in the OR, while VR has been adapted for use in surgical planning and training.

Extended Reality Use in Orthopedics

The HipNav system was introduced in 1995 to create preoperative plans that assist surgeons in accurately implanting the acetabular cup during total hip arthroplasty (THA).³ Although not commercially successful, this system spurred surgeons to experiment with XR to improve the accuracy and alignment of orthopedic implants. Systems capable of displaying the desired intraoperative implant placement have flourished, with applications in fracture reduction, arthroplasty, solid tumor resection, and hardware placement.^4-7 Accurate alignment has been linked to improvements in patient outcomes.^8-10 XR has great potential within the field of arthroplasty, with multiple new systems approved by the FDA and currently available in the US (Table).

Hip Arthroplasty

Orientation of the acetabular cup is a technically challenging part of THA. Accuracy in the anteversion and inclination angles of the acetabular cup is required to maintain implant stability, preserve functional range of motion (ROM), and prevent precocious wear.^11,12 Despite preoperative planning, surgeons often overestimate the inclination angle and underestimate anteversion.¹³ Improper implantation of the acetabular cup can lead to joint instability caused by aseptic loosening, increasing the risk of dislocation and the need for revision surgery.^14,15 Dislocations typically present to the emergency department, but primary care practitioners may encounter patients with pain or diminished sensation due to impingement or instability.¹⁶

The introduction of XR into the OR has provided the opportunity for real-time navigation and adjustment of the acetabular cup to maximize anteversion and inclination angles. Currently, 2 FDA-approved systems are available for THA: the Zimmer and Surgical Planning Associates HipInsight system, and the Insight Augmented Reality Visualization and Information System (ARVIS). The HipInsight system consists of a hologram projection using the Microsoft HoloLens2 device and optimizes preoperative planning, producing accuracy of anteversion and inclination angles within 3°.¹⁷ ARVIS employs existing surgical helmets and 2 mounted tracking cameras to provide navigation intraoperatively. ARVIS has also been approved for use in total knee arthroplasty (TKA) and unicompartmental knee arthroplasty.¹⁸

HipInsight has shown utility in increasing the accuracy of acetabular cup placement along with the use of biplanar radiographic scans.¹⁹ However, there are no studies validating the efficacy of ARVIS and HipInsight and assessing long-term disease-oriented or patient-oriented outcomes.

Knee Arthroplasty

In the setting of TKA, XR is most effective in ensuring accurate resection of the tibial and femoral components. Achieving the planned femoral coronal, axial, and sagittal angles allows the prosthesis to be on the femoral axis of rotation, improving functional outcomes. XR systems for TKA have been shown to increase the accuracy of distal femoral resection with a limited increase in surgery duration.^20,21 For TKA in particular, patients are often less satisfied with the result than surgeons expect.²² Accurate alignment can improve patient satisfaction and reduce return-to-clinic rates for postoperative pain management, a factor that primary care practitioners should consider when recommending a patient for TKA.²³

Along with ARVIS, 3 additional XR systems are FDA-approved for use in TKA. The Pixee Medical Knee+ system uses smart glasses and trackers to aid in the positioning of instruments for improved accuracy while allowing real-time navigation.²⁴ The Medacta NextAR Knee’s single-use tracking system allows for intraoperative navigation with the use of AR glasses.²⁵ The Polaris STELLAR Knee uses MR and avoids the need for preoperative imaging by capturing real-time anatomic data.²⁶

The Pixee Medical Knee+ system was commercially available in Europe for several years prior to FDA approval, so more research exists on its efficacy. One study found that the Pixee Medical Knee+ system initially demonstrated an inferior clinical outcome, attributed to the learning curve associated with using the system.²⁷ However, more recent studies have shown its utility in improving alignment, regardless of implant specifications.^28,29 The Medacta NextAR Knee system has been shown to improve accuracy of tibial rotation and soft tissue balance and even increase OR efficiency.^30,31 The Polaris STELLAR Knee system received FDA approval in 2023; no published research exists on its accuracy and outcomes.²⁶

Shoulder Arthroplasty

Minimally invasive techniques are favored in total shoulder arthroplasty (TSA) due to the vitality of maintaining the surrounding soft tissue to maximize preservation of motility and strength.³² However, this complicates the procedure by decreasing the ability to effectively access and visualize key structures of the shoulder. Accordingly, issues with implant positioning and alignment are more common with TSA than other joint arthroplasties, making XR particularly promising.³³ Some studies report that up to 67% of patients experience glenohumeral instability, which can clinically present as weakness, decreased range of motion, and persistent shoulder pain.^34,35 The use of preoperative computed tomography to improve understanding of glenoid anatomy and glenohumeral subluxation is becoming increasingly common, and it can be combined with XR to improve accuracy.^36,37

Two FDA-approved systems are available. The Stryker Blueprint MR system is used for intraoperative guidance and integration for patient imaging used for preoperative planning. The Medacta NextAR Shoulder system is a parallel of the company’s TKA system. The Stryker Blueprint MR system combines the Microsoft HoloLens 2 headset to display preoperative plans with a secondary display for coordination with the rest of the surgical team.³⁸ Similar to the Medacta NextAR Knee, the Medacta NextAR Shoulder system uses the same single-use tracking system and AR glasses for intraoperative guidance.³⁹

Data on the long-term outcomes of using these systems are still limited, but the Stryker Blueprint MR system has not been shown to accurately predict postoperative ROM.⁴⁰ Cadaveric studies have demonstrated that the Medacta NextAR Shoulder system can provide accurate inclination, retroversion, entry point, depth, and rotation values based on the preoperative planned values.^41,42 However, this accuracy has yet to be confirmed in vivo, and the impact of using XR in TSA on long-term outcomes is still unknown.

Challenges and Limitations

Though XR has proven to be promising in arthroplasty, several limitations regarding widespread implementation exist. In particular, there is a steep learning curve associated with the use of XR systems, which can cause increased operative time and even initial inferior outcomes, as demonstrated with the Pixee Medical Knee+ system. The need for extensive practice and training prior to use could delay widespread adoption and may cause discrepancies in surgical outcomes. Unfamiliarity with the system and technological difficulties that may require troubleshooting can also increase operative time, particularly for surgeons new to using the XR system. Though intraoperative navigation is expected to improve accuracy of implant alignment, its added complexity may also result in longer surgeries.

In addition to the steep learning curve and increased operative time, there is a high upfront cost associated with XR systems. Exact costs of XR systems are not typically disclosed, but available estimates suggest an average sales price of about $1000 per case. Given the proprietary nature of these technologies, publicly available cost data are limited, making it challenging to fully assess the financial burden on health care institutions. Though some systems, such as ARVIS, can be integrated with existing surgical helmets, many require the purchase of AR glasses and secondary displays. This can cause further variation in the total expense for each system. In low-resource settings, this represents a significant challenge to widespread implementation. To justify this cost, additional research on long-term patient outcomes is needed to ensure the benefits of XR systems outweigh the cost. 

Although early studies on XR systems in arthroplasty have shown improvements in precision and short-term outcomes, long-term data regarding effectiveness remains. Even systems such as ARVIS and HipInsight have limited long-term follow-up, making it difficult to assess whether the improved accuracy with these XR systems translates into improved patient outcomes compared with traditional arthroplasty.

CONCLUSIONS

XR technologies have shown significant potential in enhancing precision and patient outcomes. Through the integration of XR in the OR, surgeons can visualize preoperative plans and even make intraoperative changes, with the benefit of improving implant alignment.

There are some disadvantages to its use, however, including high cost and increased operative time. Despite this, the integration of XR into surgical practice can deliver more precise implant alignment and address other challenges faced with conventional techniques. As these technologies evolve and studies on long-term outcomes validate their utility, XR has the potential to transform the field of arthroplasty.

TOPLINE:

After Staphylococcus aureus bacteremia, patients with rheumatoid arthritis (RA) face nearly double the risk for osteoarticular infections compared with those without RA, with similar mortality risks in both groups.

METHODOLOGY:

• The contraction of S aureus bacteremia is linked to poor clinical outcomes in patients with RA; however, no well-sized studies have evaluated the risk for osteoarticular infections and mortality outcomes in patients with RA following S aureus bacteremia.
• This Danish nationwide cohort study aimed to explore whether the cumulative incidence of osteoarticular infections and death would be higher in patients with RA than in those without RA after contracting S aureus bacteremia.
• The study cohort included 18,274 patients with a first episode of S aureus bacteremia between 2006 and 2018, of whom 367 had been diagnosed with RA before contracting S aureus bacteremia.
• The RA cohort had more women (62%) and a higher median age of participants (73 years) than the non-RA cohort (37% women; median age of participants, 70 years).

TAKEAWAY:

• The 90-day cumulative incidence of osteoarticular infections (septic arthritis, spondylitis, osteomyelitis, psoas muscle abscess, or prosthetic joint infection) was nearly double in patients with RA compared with in those without RA (23.1% vs 12.5%; hazard ratio [HR], 1.93; 95% CI, 1.54-2.41).
• In patients with RA, the risk for osteoarticular infections increased with tumor necrosis factor inhibitor use (HR, 2.27; 95% CI, 1.29-3.98) and orthopedic implants (HR, 1.75; 95% CI, 1.08-2.85).
• Moreover, 90-day all-cause mortality was comparable in the RA (35.4%) and non-RA cohorts (33.9%).

IN PRACTICE:

“Our findings stress the need for vigilance in patients with RA who present with S aureus bacteremia to ensure timely identification and treatment of osteoarticular infections, especially in current TNFi [tumor necrosis factor inhibitor] users and patients with orthopedic implants,” the authors wrote.

SOURCE:

This study, led by Sabine S. Dieperink, MD, of the Centre of Head and Orthopaedics, Copenhagen University Rigshospitalet Glostrup, Denmark, was published online March 9 in Rheumatology (Oxford).

LIMITATIONS:

There might have been chances of misclassification of metastatic S aureus infections owing to the lack of specificity in diagnoses or procedure codes. This study relied on administrative data to record osteoarticular infections, which might have led investigators to underestimate the true cumulative incidence of osteoarticular infections. Also, some patients might have passed away before being diagnosed with osteoarticular infection owing to the high mortality.

DISCLOSURES:

This work was supported by grants from The Danish Rheumatism Association and Beckett Fonden. Some of the authors, including the lead author, declared receiving grants from various funding agencies and other sources, including pharmaceutical companies.

A version of this article appeared on Medscape.com.

TOPLINE:

After Staphylococcus aureus bacteremia, patients with rheumatoid arthritis (RA) face nearly double the risk for osteoarticular infections compared with those without RA, with similar mortality risks in both groups.

METHODOLOGY:

• The contraction of S aureus bacteremia is linked to poor clinical outcomes in patients with RA; however, no well-sized studies have evaluated the risk for osteoarticular infections and mortality outcomes in patients with RA following S aureus bacteremia.
• This Danish nationwide cohort study aimed to explore whether the cumulative incidence of osteoarticular infections and death would be higher in patients with RA than in those without RA after contracting S aureus bacteremia.
• The study cohort included 18,274 patients with a first episode of S aureus bacteremia between 2006 and 2018, of whom 367 had been diagnosed with RA before contracting S aureus bacteremia.
• The RA cohort had more women (62%) and a higher median age of participants (73 years) than the non-RA cohort (37% women; median age of participants, 70 years).

TAKEAWAY:

• The 90-day cumulative incidence of osteoarticular infections (septic arthritis, spondylitis, osteomyelitis, psoas muscle abscess, or prosthetic joint infection) was nearly double in patients with RA compared with in those without RA (23.1% vs 12.5%; hazard ratio [HR], 1.93; 95% CI, 1.54-2.41).
• In patients with RA, the risk for osteoarticular infections increased with tumor necrosis factor inhibitor use (HR, 2.27; 95% CI, 1.29-3.98) and orthopedic implants (HR, 1.75; 95% CI, 1.08-2.85).
• Moreover, 90-day all-cause mortality was comparable in the RA (35.4%) and non-RA cohorts (33.9%).

IN PRACTICE:

“Our findings stress the need for vigilance in patients with RA who present with S aureus bacteremia to ensure timely identification and treatment of osteoarticular infections, especially in current TNFi [tumor necrosis factor inhibitor] users and patients with orthopedic implants,” the authors wrote.

SOURCE:

This study, led by Sabine S. Dieperink, MD, of the Centre of Head and Orthopaedics, Copenhagen University Rigshospitalet Glostrup, Denmark, was published online March 9 in Rheumatology (Oxford).

LIMITATIONS:

There might have been chances of misclassification of metastatic S aureus infections owing to the lack of specificity in diagnoses or procedure codes. This study relied on administrative data to record osteoarticular infections, which might have led investigators to underestimate the true cumulative incidence of osteoarticular infections. Also, some patients might have passed away before being diagnosed with osteoarticular infection owing to the high mortality.

DISCLOSURES:

This work was supported by grants from The Danish Rheumatism Association and Beckett Fonden. Some of the authors, including the lead author, declared receiving grants from various funding agencies and other sources, including pharmaceutical companies.

A version of this article appeared on Medscape.com.

TOPLINE:

After Staphylococcus aureus bacteremia, patients with rheumatoid arthritis (RA) face nearly double the risk for osteoarticular infections compared with those without RA, with similar mortality risks in both groups.

METHODOLOGY:

• The contraction of S aureus bacteremia is linked to poor clinical outcomes in patients with RA; however, no well-sized studies have evaluated the risk for osteoarticular infections and mortality outcomes in patients with RA following S aureus bacteremia.
• This Danish nationwide cohort study aimed to explore whether the cumulative incidence of osteoarticular infections and death would be higher in patients with RA than in those without RA after contracting S aureus bacteremia.
• The study cohort included 18,274 patients with a first episode of S aureus bacteremia between 2006 and 2018, of whom 367 had been diagnosed with RA before contracting S aureus bacteremia.
• The RA cohort had more women (62%) and a higher median age of participants (73 years) than the non-RA cohort (37% women; median age of participants, 70 years).

TAKEAWAY:

• The 90-day cumulative incidence of osteoarticular infections (septic arthritis, spondylitis, osteomyelitis, psoas muscle abscess, or prosthetic joint infection) was nearly double in patients with RA compared with in those without RA (23.1% vs 12.5%; hazard ratio [HR], 1.93; 95% CI, 1.54-2.41).
• In patients with RA, the risk for osteoarticular infections increased with tumor necrosis factor inhibitor use (HR, 2.27; 95% CI, 1.29-3.98) and orthopedic implants (HR, 1.75; 95% CI, 1.08-2.85).
• Moreover, 90-day all-cause mortality was comparable in the RA (35.4%) and non-RA cohorts (33.9%).

IN PRACTICE:

“Our findings stress the need for vigilance in patients with RA who present with S aureus bacteremia to ensure timely identification and treatment of osteoarticular infections, especially in current TNFi [tumor necrosis factor inhibitor] users and patients with orthopedic implants,” the authors wrote.

SOURCE:

This study, led by Sabine S. Dieperink, MD, of the Centre of Head and Orthopaedics, Copenhagen University Rigshospitalet Glostrup, Denmark, was published online March 9 in Rheumatology (Oxford).

LIMITATIONS:

There might have been chances of misclassification of metastatic S aureus infections owing to the lack of specificity in diagnoses or procedure codes. This study relied on administrative data to record osteoarticular infections, which might have led investigators to underestimate the true cumulative incidence of osteoarticular infections. Also, some patients might have passed away before being diagnosed with osteoarticular infection owing to the high mortality.

DISCLOSURES:

This work was supported by grants from The Danish Rheumatism Association and Beckett Fonden. Some of the authors, including the lead author, declared receiving grants from various funding agencies and other sources, including pharmaceutical companies.

A version of this article appeared on Medscape.com.

The European Society of Cardiology guidelines on cardiovascular assessment and management of patients undergoing noncardiac surgery have seen extensive revision since the 2014 version.

They still have the same aim – to prevent surgery-related bleeding complications, perioperative myocardial infarction/injury (PMI), stent thrombosis, acute heart failure, arrhythmias, pulmonary embolism, ischemic stroke, and cardiovascular (CV) death.

lyosha_nazarenko/Thinkstock

Cochairpersons Sigrun Halvorsen, MD, PhD, and Julinda Mehilli, MD, presented highlights from the guidelines at the annual congress of the European Society of Cardiology and the document was simultaneously published online in the European Heart Journal.

The document classifies noncardiac surgery into three levels of 30-day risk of CV death, MI, or stroke. Low (< 1%) risk includes eye or thyroid surgery; intermediate (1%-5%) risk includes knee or hip replacement or renal transplant; and high (> 5%) risk includes aortic aneurysm, lung transplant, or pancreatic or bladder cancer surgery (see more examples below).

It classifies patients as low risk if they are younger than 65 without CV disease or CV risk factors (smoking, hypertension, diabetes, dyslipidemia, family history); intermediate risk if they are 65 or older or have CV risk factors; and high risk if they have CVD.  

In an interview, Dr. Halvorsen, professor in cardiology, University of Oslo, zeroed in on three important revisions:

First, recommendations for preoperative ECG and biomarkers are more specific, he noted.

The guidelines advise that before intermediate- or high-risk noncardiac surgery, in patients who have known CVD, CV risk factors (including age 65 or older), or symptoms suggestive of CVD:

• It is recommended to obtain a preoperative 12-lead ECG (class I).
• It is recommended to measure high-sensitivity cardiac troponin T (hs-cTn T) or high-sensitivity cardiac troponin I (hs-cTn I). It is also recommended to measure these biomarkers at 24 hours and 48 hours post surgery (class I).
• It should be considered to measure B-type natriuretic peptide or N-terminal of the prohormone BNP (NT-proBNP).

However, for low-risk patients undergoing low- and intermediate-risk noncardiac surgery, it is not recommended to routinely obtain preoperative ECG, hs-cTn T/I, or BNP/NT-proBNP concentrations (class III).

Troponins have a stronger class I recommendation, compared with the IIA recommendation for BNP, because they are useful for preoperative risk stratification and for diagnosis of PMI, Dr. Halvorsen explained. “Patients receive painkillers after surgery and may have no pain,” she noted, but they may have PMI, which has a bad prognosis.

Second, the guidelines recommend that “all patients should stop smoking 4 weeks before noncardiac surgery [class I],” she noted. Clinicians should also “measure hemoglobin, and if the patient is anemic, treat the anemia.”

Third, the sections on antithrombotic treatment have been significantly revised. “Bridging – stopping an oral antithrombotic drug and switching to a subcutaneous or IV drug – has been common,” Dr. Halvorsen said, “but recently we have new evidence that in most cases that increases the risk of bleeding.”

“We are [now] much more restrictive with respect to bridging” with unfractionated heparin or low-molecular-weight heparin, she said. “We recommend against bridging in patients with low to moderate thrombotic risk,” and bridging should only be considered in patients with mechanical prosthetic heart valves or with very high thrombotic risk.
 

More preoperative recommendations

In the guideline overview session at the congress, Dr. Halverson highlighted some of the new recommendations for preoperative risk assessment.  

If time allows, it is recommended to optimize guideline-recommended treatment of CVD and control of CV risk factors including blood pressure, dyslipidemia, and diabetes, before noncardiac surgery (class I).

Patients commonly have “murmurs, chest pain, dyspnea, and edema that may suggest severe CVD, but may also be caused by noncardiac disease,” she noted. The guidelines state that “for patients with a newly detected murmur and symptoms or signs of CVD, transthoracic echocardiography is recommended before noncardiac surgery (class I).

“Many studies have been performed to try to find out if initiation of specific drugs before surgery could reduce the risk of complications,” Dr. Halvorsen noted. However, few have shown any benefit and “the question of presurgery initiation of beta-blockers has been greatly debated,” she said. “We have again reviewed the literature and concluded ‘Routine initiation of beta-blockers perioperatively is not recommended (class IIIA).’ “

“We adhere to the guidelines on acute and chronic coronary syndrome recommending 6-12 months of dual antiplatelet treatment as a standard before elective surgery,” she said. “However, in case of time-sensitive surgery, the duration of that treatment can be shortened down to a minimum of 1 month after elective PCI and a minimum of 3 months after PCI and ACS.”
 

Patients with specific types of CVD

Dr. Mehilli, a professor at Landshut-Achdorf (Germany) Hospital, highlighted some new guideline recommendations for patients who have specific types of cardiovascular disease.

Coronary artery disease (CAD). “For chronic coronary syndrome, a cardiac workup is recommended only for patients undergoing intermediate risk or high-risk noncardiac surgery.”

“Stress imaging should be considered before any high risk, noncardiac surgery in asymptomatic patients with poor functional capacity and prior PCI or coronary artery bypass graft (new recommendation, class IIa).”

Mitral valve regurgitation. For patients undergoing scheduled noncardiac surgery, who remain symptomatic despite guideline-directed medical treatment for mitral valve regurgitation (including resynchronization and myocardial revascularization), consider a valve intervention – either transcatheter or surgical – before noncardiac surgery in eligible patients with acceptable procedural risk (new recommendation).

Cardiac implantable electronic devices (CIED). For high-risk patients with CIEDs undergoing noncardiac surgery with high probability of electromagnetic interference, a CIED checkup and necessary reprogramming immediately before the procedure should be considered (new recommendation).

Arrhythmias. “I want only to stress,” Dr. Mehilli said, “in patients with atrial fibrillation with acute or worsening hemodynamic instability undergoing noncardiac surgery, an emergency electrical cardioversion is recommended (class I).”

Peripheral artery disease (PAD) and abdominal aortic aneurysm. For these patients “we do not recommend a routine referral for a cardiac workup. But we recommend it for patients with poor functional capacity or with significant risk factors or symptoms (new recommendations).”

Chronic arterial hypertension. “We have modified the recommendation, recommending avoidance of large perioperative fluctuations in blood pressure, and we do not recommend deferring noncardiac surgery in patients with stage 1 or 2 hypertension,” she said.
 

Postoperative cardiovascular complications

The most frequent postoperative cardiovascular complication is PMI, Dr. Mehilli noted.

“In the BASEL-PMI registry, the incidence of this complication around intermediate or high-risk noncardiac surgery was up to 15% among patients older than 65 years or with a history of CAD or PAD, which makes this kind of complication really important to prevent, to assess, and to know how to treat.”

“It is recommended to have a high awareness for perioperative cardiovascular complications, combined with surveillance for PMI in patients undergoing intermediate- or high-risk noncardiac surgery” based on serial measurements of high-sensitivity cardiac troponin.

The guidelines define PMI as “an increase in the delta of high-sensitivity troponin more than the upper level of normal,” Dr. Mehilli said. “It’s different from the one used in a rule-in algorithm for non-STEMI acute coronary syndrome.”

Postoperative atrial fibrillation (AFib) is observed in 2%-30% of noncardiac surgery patients in different registries, particularly in patients undergoing intermediate or high-risk noncardiac surgery, she noted.

“We propose an algorithm on how to prevent and treat this complication. I want to highlight that in patients with hemodynamic unstable postoperative AF[ib], an emergency cardioversion is indicated. For the others, a rate control with the target heart rate of less than 110 beats per minute is indicated.”

In patients with postoperative AFib, long-term oral anticoagulation therapy should be considered in all patients at risk for stroke, considering the anticipated net clinical benefit of oral anticoagulation therapy as well as informed patient preference (new recommendations).

Routine use of beta-blockers to prevent postoperative AFib in patients undergoing noncardiac surgery is not recommended.

The document also covers the management of patients with kidney disease, diabetes, cancer, obesity, and COVID-19. In general, elective noncardiac surgery should be postponed after a patient has COVID-19, until he or she recovers completely, and coexisting conditions are optimized.

The guidelines are available from the ESC website in several formats: pocket guidelines, pocket guidelines smartphone app, guidelines slide set, essential messages, and the European Heart Journal article.
 

Noncardiac surgery risk categories

The guideline includes a table that classifies noncardiac surgeries into three groups, based on the associated 30-day risk of death, MI, or stroke:

• Low (< 1%): breast, dental, eye, thyroid, and minor gynecologic, orthopedic, and urologic surgery.
• Intermediate (1%-5%): carotid surgery, endovascular aortic aneurysm repair, gallbladder surgery, head or neck surgery, hernia repair, peripheral arterial angioplasty, renal transplant, major gynecologic, orthopedic, or neurologic (hip or spine) surgery, or urologic surgery
• High (> 5%): aortic and major vascular surgery (including aortic aneurysm), bladder removal (usually as a result of cancer), limb amputation, lung or liver transplant, pancreatic surgery, or perforated bowel repair.

The guidelines were endorsed by the European Society of Anaesthesiology and Intensive Care. The guideline authors reported numerous disclosures.

A version of this article first appeared on Medscape.com.

The European Society of Cardiology guidelines on cardiovascular assessment and management of patients undergoing noncardiac surgery have seen extensive revision since the 2014 version.

They still have the same aim – to prevent surgery-related bleeding complications, perioperative myocardial infarction/injury (PMI), stent thrombosis, acute heart failure, arrhythmias, pulmonary embolism, ischemic stroke, and cardiovascular (CV) death.

lyosha_nazarenko/Thinkstock

Cochairpersons Sigrun Halvorsen, MD, PhD, and Julinda Mehilli, MD, presented highlights from the guidelines at the annual congress of the European Society of Cardiology and the document was simultaneously published online in the European Heart Journal.

The document classifies noncardiac surgery into three levels of 30-day risk of CV death, MI, or stroke. Low (< 1%) risk includes eye or thyroid surgery; intermediate (1%-5%) risk includes knee or hip replacement or renal transplant; and high (> 5%) risk includes aortic aneurysm, lung transplant, or pancreatic or bladder cancer surgery (see more examples below).

It classifies patients as low risk if they are younger than 65 without CV disease or CV risk factors (smoking, hypertension, diabetes, dyslipidemia, family history); intermediate risk if they are 65 or older or have CV risk factors; and high risk if they have CVD.  

In an interview, Dr. Halvorsen, professor in cardiology, University of Oslo, zeroed in on three important revisions:

First, recommendations for preoperative ECG and biomarkers are more specific, he noted.

The guidelines advise that before intermediate- or high-risk noncardiac surgery, in patients who have known CVD, CV risk factors (including age 65 or older), or symptoms suggestive of CVD:

• It is recommended to obtain a preoperative 12-lead ECG (class I).
• It is recommended to measure high-sensitivity cardiac troponin T (hs-cTn T) or high-sensitivity cardiac troponin I (hs-cTn I). It is also recommended to measure these biomarkers at 24 hours and 48 hours post surgery (class I).
• It should be considered to measure B-type natriuretic peptide or N-terminal of the prohormone BNP (NT-proBNP).

However, for low-risk patients undergoing low- and intermediate-risk noncardiac surgery, it is not recommended to routinely obtain preoperative ECG, hs-cTn T/I, or BNP/NT-proBNP concentrations (class III).

Troponins have a stronger class I recommendation, compared with the IIA recommendation for BNP, because they are useful for preoperative risk stratification and for diagnosis of PMI, Dr. Halvorsen explained. “Patients receive painkillers after surgery and may have no pain,” she noted, but they may have PMI, which has a bad prognosis.

Second, the guidelines recommend that “all patients should stop smoking 4 weeks before noncardiac surgery [class I],” she noted. Clinicians should also “measure hemoglobin, and if the patient is anemic, treat the anemia.”

Third, the sections on antithrombotic treatment have been significantly revised. “Bridging – stopping an oral antithrombotic drug and switching to a subcutaneous or IV drug – has been common,” Dr. Halvorsen said, “but recently we have new evidence that in most cases that increases the risk of bleeding.”

“We are [now] much more restrictive with respect to bridging” with unfractionated heparin or low-molecular-weight heparin, she said. “We recommend against bridging in patients with low to moderate thrombotic risk,” and bridging should only be considered in patients with mechanical prosthetic heart valves or with very high thrombotic risk.
 

More preoperative recommendations

In the guideline overview session at the congress, Dr. Halverson highlighted some of the new recommendations for preoperative risk assessment.  

If time allows, it is recommended to optimize guideline-recommended treatment of CVD and control of CV risk factors including blood pressure, dyslipidemia, and diabetes, before noncardiac surgery (class I).

Patients commonly have “murmurs, chest pain, dyspnea, and edema that may suggest severe CVD, but may also be caused by noncardiac disease,” she noted. The guidelines state that “for patients with a newly detected murmur and symptoms or signs of CVD, transthoracic echocardiography is recommended before noncardiac surgery (class I).

“Many studies have been performed to try to find out if initiation of specific drugs before surgery could reduce the risk of complications,” Dr. Halvorsen noted. However, few have shown any benefit and “the question of presurgery initiation of beta-blockers has been greatly debated,” she said. “We have again reviewed the literature and concluded ‘Routine initiation of beta-blockers perioperatively is not recommended (class IIIA).’ “

“We adhere to the guidelines on acute and chronic coronary syndrome recommending 6-12 months of dual antiplatelet treatment as a standard before elective surgery,” she said. “However, in case of time-sensitive surgery, the duration of that treatment can be shortened down to a minimum of 1 month after elective PCI and a minimum of 3 months after PCI and ACS.”
 

Patients with specific types of CVD

Dr. Mehilli, a professor at Landshut-Achdorf (Germany) Hospital, highlighted some new guideline recommendations for patients who have specific types of cardiovascular disease.

Coronary artery disease (CAD). “For chronic coronary syndrome, a cardiac workup is recommended only for patients undergoing intermediate risk or high-risk noncardiac surgery.”

“Stress imaging should be considered before any high risk, noncardiac surgery in asymptomatic patients with poor functional capacity and prior PCI or coronary artery bypass graft (new recommendation, class IIa).”

Mitral valve regurgitation. For patients undergoing scheduled noncardiac surgery, who remain symptomatic despite guideline-directed medical treatment for mitral valve regurgitation (including resynchronization and myocardial revascularization), consider a valve intervention – either transcatheter or surgical – before noncardiac surgery in eligible patients with acceptable procedural risk (new recommendation).

Cardiac implantable electronic devices (CIED). For high-risk patients with CIEDs undergoing noncardiac surgery with high probability of electromagnetic interference, a CIED checkup and necessary reprogramming immediately before the procedure should be considered (new recommendation).

Arrhythmias. “I want only to stress,” Dr. Mehilli said, “in patients with atrial fibrillation with acute or worsening hemodynamic instability undergoing noncardiac surgery, an emergency electrical cardioversion is recommended (class I).”

Peripheral artery disease (PAD) and abdominal aortic aneurysm. For these patients “we do not recommend a routine referral for a cardiac workup. But we recommend it for patients with poor functional capacity or with significant risk factors or symptoms (new recommendations).”

Chronic arterial hypertension. “We have modified the recommendation, recommending avoidance of large perioperative fluctuations in blood pressure, and we do not recommend deferring noncardiac surgery in patients with stage 1 or 2 hypertension,” she said.
 

Postoperative cardiovascular complications

The most frequent postoperative cardiovascular complication is PMI, Dr. Mehilli noted.

“In the BASEL-PMI registry, the incidence of this complication around intermediate or high-risk noncardiac surgery was up to 15% among patients older than 65 years or with a history of CAD or PAD, which makes this kind of complication really important to prevent, to assess, and to know how to treat.”

“It is recommended to have a high awareness for perioperative cardiovascular complications, combined with surveillance for PMI in patients undergoing intermediate- or high-risk noncardiac surgery” based on serial measurements of high-sensitivity cardiac troponin.

The guidelines define PMI as “an increase in the delta of high-sensitivity troponin more than the upper level of normal,” Dr. Mehilli said. “It’s different from the one used in a rule-in algorithm for non-STEMI acute coronary syndrome.”

Postoperative atrial fibrillation (AFib) is observed in 2%-30% of noncardiac surgery patients in different registries, particularly in patients undergoing intermediate or high-risk noncardiac surgery, she noted.

“We propose an algorithm on how to prevent and treat this complication. I want to highlight that in patients with hemodynamic unstable postoperative AF[ib], an emergency cardioversion is indicated. For the others, a rate control with the target heart rate of less than 110 beats per minute is indicated.”

In patients with postoperative AFib, long-term oral anticoagulation therapy should be considered in all patients at risk for stroke, considering the anticipated net clinical benefit of oral anticoagulation therapy as well as informed patient preference (new recommendations).

Routine use of beta-blockers to prevent postoperative AFib in patients undergoing noncardiac surgery is not recommended.

The document also covers the management of patients with kidney disease, diabetes, cancer, obesity, and COVID-19. In general, elective noncardiac surgery should be postponed after a patient has COVID-19, until he or she recovers completely, and coexisting conditions are optimized.

The guidelines are available from the ESC website in several formats: pocket guidelines, pocket guidelines smartphone app, guidelines slide set, essential messages, and the European Heart Journal article.
 

Noncardiac surgery risk categories

The guideline includes a table that classifies noncardiac surgeries into three groups, based on the associated 30-day risk of death, MI, or stroke:

• Low (< 1%): breast, dental, eye, thyroid, and minor gynecologic, orthopedic, and urologic surgery.
• Intermediate (1%-5%): carotid surgery, endovascular aortic aneurysm repair, gallbladder surgery, head or neck surgery, hernia repair, peripheral arterial angioplasty, renal transplant, major gynecologic, orthopedic, or neurologic (hip or spine) surgery, or urologic surgery
• High (> 5%): aortic and major vascular surgery (including aortic aneurysm), bladder removal (usually as a result of cancer), limb amputation, lung or liver transplant, pancreatic surgery, or perforated bowel repair.

The guidelines were endorsed by the European Society of Anaesthesiology and Intensive Care. The guideline authors reported numerous disclosures.

A version of this article first appeared on Medscape.com.

The European Society of Cardiology guidelines on cardiovascular assessment and management of patients undergoing noncardiac surgery have seen extensive revision since the 2014 version.

They still have the same aim – to prevent surgery-related bleeding complications, perioperative myocardial infarction/injury (PMI), stent thrombosis, acute heart failure, arrhythmias, pulmonary embolism, ischemic stroke, and cardiovascular (CV) death.

lyosha_nazarenko/Thinkstock

Cochairpersons Sigrun Halvorsen, MD, PhD, and Julinda Mehilli, MD, presented highlights from the guidelines at the annual congress of the European Society of Cardiology and the document was simultaneously published online in the European Heart Journal.

The document classifies noncardiac surgery into three levels of 30-day risk of CV death, MI, or stroke. Low (< 1%) risk includes eye or thyroid surgery; intermediate (1%-5%) risk includes knee or hip replacement or renal transplant; and high (> 5%) risk includes aortic aneurysm, lung transplant, or pancreatic or bladder cancer surgery (see more examples below).

It classifies patients as low risk if they are younger than 65 without CV disease or CV risk factors (smoking, hypertension, diabetes, dyslipidemia, family history); intermediate risk if they are 65 or older or have CV risk factors; and high risk if they have CVD.  

In an interview, Dr. Halvorsen, professor in cardiology, University of Oslo, zeroed in on three important revisions:

First, recommendations for preoperative ECG and biomarkers are more specific, he noted.

The guidelines advise that before intermediate- or high-risk noncardiac surgery, in patients who have known CVD, CV risk factors (including age 65 or older), or symptoms suggestive of CVD:

• It is recommended to obtain a preoperative 12-lead ECG (class I).
• It is recommended to measure high-sensitivity cardiac troponin T (hs-cTn T) or high-sensitivity cardiac troponin I (hs-cTn I). It is also recommended to measure these biomarkers at 24 hours and 48 hours post surgery (class I).
• It should be considered to measure B-type natriuretic peptide or N-terminal of the prohormone BNP (NT-proBNP).

However, for low-risk patients undergoing low- and intermediate-risk noncardiac surgery, it is not recommended to routinely obtain preoperative ECG, hs-cTn T/I, or BNP/NT-proBNP concentrations (class III).

Troponins have a stronger class I recommendation, compared with the IIA recommendation for BNP, because they are useful for preoperative risk stratification and for diagnosis of PMI, Dr. Halvorsen explained. “Patients receive painkillers after surgery and may have no pain,” she noted, but they may have PMI, which has a bad prognosis.

Second, the guidelines recommend that “all patients should stop smoking 4 weeks before noncardiac surgery [class I],” she noted. Clinicians should also “measure hemoglobin, and if the patient is anemic, treat the anemia.”

Third, the sections on antithrombotic treatment have been significantly revised. “Bridging – stopping an oral antithrombotic drug and switching to a subcutaneous or IV drug – has been common,” Dr. Halvorsen said, “but recently we have new evidence that in most cases that increases the risk of bleeding.”

“We are [now] much more restrictive with respect to bridging” with unfractionated heparin or low-molecular-weight heparin, she said. “We recommend against bridging in patients with low to moderate thrombotic risk,” and bridging should only be considered in patients with mechanical prosthetic heart valves or with very high thrombotic risk.
 

More preoperative recommendations

In the guideline overview session at the congress, Dr. Halverson highlighted some of the new recommendations for preoperative risk assessment.  

If time allows, it is recommended to optimize guideline-recommended treatment of CVD and control of CV risk factors including blood pressure, dyslipidemia, and diabetes, before noncardiac surgery (class I).

Patients commonly have “murmurs, chest pain, dyspnea, and edema that may suggest severe CVD, but may also be caused by noncardiac disease,” she noted. The guidelines state that “for patients with a newly detected murmur and symptoms or signs of CVD, transthoracic echocardiography is recommended before noncardiac surgery (class I).

“Many studies have been performed to try to find out if initiation of specific drugs before surgery could reduce the risk of complications,” Dr. Halvorsen noted. However, few have shown any benefit and “the question of presurgery initiation of beta-blockers has been greatly debated,” she said. “We have again reviewed the literature and concluded ‘Routine initiation of beta-blockers perioperatively is not recommended (class IIIA).’ “

“We adhere to the guidelines on acute and chronic coronary syndrome recommending 6-12 months of dual antiplatelet treatment as a standard before elective surgery,” she said. “However, in case of time-sensitive surgery, the duration of that treatment can be shortened down to a minimum of 1 month after elective PCI and a minimum of 3 months after PCI and ACS.”
 

Patients with specific types of CVD

Dr. Mehilli, a professor at Landshut-Achdorf (Germany) Hospital, highlighted some new guideline recommendations for patients who have specific types of cardiovascular disease.

Coronary artery disease (CAD). “For chronic coronary syndrome, a cardiac workup is recommended only for patients undergoing intermediate risk or high-risk noncardiac surgery.”

“Stress imaging should be considered before any high risk, noncardiac surgery in asymptomatic patients with poor functional capacity and prior PCI or coronary artery bypass graft (new recommendation, class IIa).”

Mitral valve regurgitation. For patients undergoing scheduled noncardiac surgery, who remain symptomatic despite guideline-directed medical treatment for mitral valve regurgitation (including resynchronization and myocardial revascularization), consider a valve intervention – either transcatheter or surgical – before noncardiac surgery in eligible patients with acceptable procedural risk (new recommendation).

Cardiac implantable electronic devices (CIED). For high-risk patients with CIEDs undergoing noncardiac surgery with high probability of electromagnetic interference, a CIED checkup and necessary reprogramming immediately before the procedure should be considered (new recommendation).

Arrhythmias. “I want only to stress,” Dr. Mehilli said, “in patients with atrial fibrillation with acute or worsening hemodynamic instability undergoing noncardiac surgery, an emergency electrical cardioversion is recommended (class I).”

Peripheral artery disease (PAD) and abdominal aortic aneurysm. For these patients “we do not recommend a routine referral for a cardiac workup. But we recommend it for patients with poor functional capacity or with significant risk factors or symptoms (new recommendations).”

Chronic arterial hypertension. “We have modified the recommendation, recommending avoidance of large perioperative fluctuations in blood pressure, and we do not recommend deferring noncardiac surgery in patients with stage 1 or 2 hypertension,” she said.
 

Postoperative cardiovascular complications

The most frequent postoperative cardiovascular complication is PMI, Dr. Mehilli noted.

“In the BASEL-PMI registry, the incidence of this complication around intermediate or high-risk noncardiac surgery was up to 15% among patients older than 65 years or with a history of CAD or PAD, which makes this kind of complication really important to prevent, to assess, and to know how to treat.”

“It is recommended to have a high awareness for perioperative cardiovascular complications, combined with surveillance for PMI in patients undergoing intermediate- or high-risk noncardiac surgery” based on serial measurements of high-sensitivity cardiac troponin.

The guidelines define PMI as “an increase in the delta of high-sensitivity troponin more than the upper level of normal,” Dr. Mehilli said. “It’s different from the one used in a rule-in algorithm for non-STEMI acute coronary syndrome.”

Postoperative atrial fibrillation (AFib) is observed in 2%-30% of noncardiac surgery patients in different registries, particularly in patients undergoing intermediate or high-risk noncardiac surgery, she noted.

“We propose an algorithm on how to prevent and treat this complication. I want to highlight that in patients with hemodynamic unstable postoperative AF[ib], an emergency cardioversion is indicated. For the others, a rate control with the target heart rate of less than 110 beats per minute is indicated.”

In patients with postoperative AFib, long-term oral anticoagulation therapy should be considered in all patients at risk for stroke, considering the anticipated net clinical benefit of oral anticoagulation therapy as well as informed patient preference (new recommendations).

Routine use of beta-blockers to prevent postoperative AFib in patients undergoing noncardiac surgery is not recommended.

The document also covers the management of patients with kidney disease, diabetes, cancer, obesity, and COVID-19. In general, elective noncardiac surgery should be postponed after a patient has COVID-19, until he or she recovers completely, and coexisting conditions are optimized.

The guidelines are available from the ESC website in several formats: pocket guidelines, pocket guidelines smartphone app, guidelines slide set, essential messages, and the European Heart Journal article.
 

Noncardiac surgery risk categories

The guideline includes a table that classifies noncardiac surgeries into three groups, based on the associated 30-day risk of death, MI, or stroke:

• Low (< 1%): breast, dental, eye, thyroid, and minor gynecologic, orthopedic, and urologic surgery.
• Intermediate (1%-5%): carotid surgery, endovascular aortic aneurysm repair, gallbladder surgery, head or neck surgery, hernia repair, peripheral arterial angioplasty, renal transplant, major gynecologic, orthopedic, or neurologic (hip or spine) surgery, or urologic surgery
• High (> 5%): aortic and major vascular surgery (including aortic aneurysm), bladder removal (usually as a result of cancer), limb amputation, lung or liver transplant, pancreatic surgery, or perforated bowel repair.

The guidelines were endorsed by the European Society of Anaesthesiology and Intensive Care. The guideline authors reported numerous disclosures.

A version of this article first appeared on Medscape.com.

Practice has gone back and forth on whether atrial fibrillation (AFib) should be considered in the preoperative cardiovascular risk (CV) evaluation of patients slated for noncardiac surgery, and the Revised Cardiac Risk Index (RCRI), currently widely used as an assessment tool, doesn’t include the arrhythmia.

But consideration of preexisting AFib along with the RCRI predicted 30-day mortality more sharply than the RCRI alone in an analysis of data covering several million patients slated for such procedures.

enot-poloskun/Getty Images

• 1.31 (95% CI, 1.30-1.33) for heart failure
• 1.40 (95% CI, 1.37-1.43) for stroke
• 1.59 (95% CI, 1.43-1.75) for systemic embolism
• 1.14 (95% CI, 1.13-1.16) for major bleeding  
• 0.81 (95% CI, 0.79-0.82) for MI

Those with preexisting AFib also had longer hospitalizations at a median 5 days, compared with 4 days for those without such AFib (P < .001).

The study has the limitations of most any retrospective cohort analysis. Other limitations, the report notes, include lack of information on any antiarrhythmic meds given during hospitalization or type of AFib.

For example, AFib that is permanent – compared with paroxysmal or persistent – may be associated with more atrial fibrosis, greater atrial dilatation, “and probably higher pressures inside the heart,” Dr. Mentias observed.

“That’s not always the case, but that’s the notion. So presumably people with persistent or permanent atrial fib would have more advanced heart disease, and that could imply more risk. But we did not have that kind of data.”

Dr. Mentias and Dr. Prasada report no relevant financial relationships; disclosures for the other authors are in the report. Dr. Curtis discloses serving on advisory boards for Abbott, Janssen Pharmaceuticals, Sanofi, and Milestone Pharmaceuticals; receiving honoraria for speaking from Medtronic and Zoll; and serving on a data-monitoring board for Medtronic. Dr. Korada reports he has no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Practice has gone back and forth on whether atrial fibrillation (AFib) should be considered in the preoperative cardiovascular risk (CV) evaluation of patients slated for noncardiac surgery, and the Revised Cardiac Risk Index (RCRI), currently widely used as an assessment tool, doesn’t include the arrhythmia.

But consideration of preexisting AFib along with the RCRI predicted 30-day mortality more sharply than the RCRI alone in an analysis of data covering several million patients slated for such procedures.

enot-poloskun/Getty Images

• 1.31 (95% CI, 1.30-1.33) for heart failure
• 1.40 (95% CI, 1.37-1.43) for stroke
• 1.59 (95% CI, 1.43-1.75) for systemic embolism
• 1.14 (95% CI, 1.13-1.16) for major bleeding  
• 0.81 (95% CI, 0.79-0.82) for MI

Those with preexisting AFib also had longer hospitalizations at a median 5 days, compared with 4 days for those without such AFib (P < .001).

The study has the limitations of most any retrospective cohort analysis. Other limitations, the report notes, include lack of information on any antiarrhythmic meds given during hospitalization or type of AFib.

For example, AFib that is permanent – compared with paroxysmal or persistent – may be associated with more atrial fibrosis, greater atrial dilatation, “and probably higher pressures inside the heart,” Dr. Mentias observed.

“That’s not always the case, but that’s the notion. So presumably people with persistent or permanent atrial fib would have more advanced heart disease, and that could imply more risk. But we did not have that kind of data.”

Dr. Mentias and Dr. Prasada report no relevant financial relationships; disclosures for the other authors are in the report. Dr. Curtis discloses serving on advisory boards for Abbott, Janssen Pharmaceuticals, Sanofi, and Milestone Pharmaceuticals; receiving honoraria for speaking from Medtronic and Zoll; and serving on a data-monitoring board for Medtronic. Dr. Korada reports he has no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Practice has gone back and forth on whether atrial fibrillation (AFib) should be considered in the preoperative cardiovascular risk (CV) evaluation of patients slated for noncardiac surgery, and the Revised Cardiac Risk Index (RCRI), currently widely used as an assessment tool, doesn’t include the arrhythmia.

But consideration of preexisting AFib along with the RCRI predicted 30-day mortality more sharply than the RCRI alone in an analysis of data covering several million patients slated for such procedures.

enot-poloskun/Getty Images

• 1.31 (95% CI, 1.30-1.33) for heart failure
• 1.40 (95% CI, 1.37-1.43) for stroke
• 1.59 (95% CI, 1.43-1.75) for systemic embolism
• 1.14 (95% CI, 1.13-1.16) for major bleeding  
• 0.81 (95% CI, 0.79-0.82) for MI

Those with preexisting AFib also had longer hospitalizations at a median 5 days, compared with 4 days for those without such AFib (P < .001).

The study has the limitations of most any retrospective cohort analysis. Other limitations, the report notes, include lack of information on any antiarrhythmic meds given during hospitalization or type of AFib.

For example, AFib that is permanent – compared with paroxysmal or persistent – may be associated with more atrial fibrosis, greater atrial dilatation, “and probably higher pressures inside the heart,” Dr. Mentias observed.

“That’s not always the case, but that’s the notion. So presumably people with persistent or permanent atrial fib would have more advanced heart disease, and that could imply more risk. But we did not have that kind of data.”

Dr. Mentias and Dr. Prasada report no relevant financial relationships; disclosures for the other authors are in the report. Dr. Curtis discloses serving on advisory boards for Abbott, Janssen Pharmaceuticals, Sanofi, and Milestone Pharmaceuticals; receiving honoraria for speaking from Medtronic and Zoll; and serving on a data-monitoring board for Medtronic. Dr. Korada reports he has no relevant financial relationships.

A version of this article first appeared on Medscape.com.

CHICAGO – Patients discharged to facilities rather than to home after total hip arthroplasty (THA) or total knee arthroplasty (TKA) may need more potent chemoprophylaxis than aspirin to prevent blood clots, new data suggest.

Researchers led by Stefano Muscatelli, MD, an orthopedist at Michigan Medicine, Ann Arbor, first aimed to determine whether there was an increase in risk of venous thromboembolism (VTE) in patients who were discharged to facilities such as a skilled nursing facility or inpatient rehabilitation facility, compared with those discharged to home after THA or TKA.

The second aim was to determine whether VTE risk differed between home- and non–home-discharge patients when stratified by the chemoprophylaxis prescribed to prevent VTE.

Findings were presented at the annual meeting of the American Academy of Orthopaedic Surgeons by coauthor Michael McHugh, MD, also an orthopedist at Michigan Medicine in Ann Arbor.

The agents were categorized in three groups: aspirin only; more aggressive anticoagulants, including warfarin, factor Xa inhibitor, direct thrombin inhibitor, low-molecular-weight heparin, pentasaccharide, or antiplatelet agents, with or without concurrent aspirin; and other regimens.

The researchers found that rates of VTE were higher among patients discharged to facilities.

Of 6,411 patients included in the study, the overall rate of VTE was 1.05%. Among home-discharge patients (n = 5445), rates of VTE were significantly lower than among patients discharged to facilities (n = 966) (0.83% vs. 2.26%; P < .001).

However, the researchers found there was no difference in VTE rates between non-home and home discharge in patients who received more aggressive chemoprophylaxis.

Among discharged patients who received only aspirin, rates of VTE among those discharged to home were significantly lower compared to those discharged to facilities (0.76% vs. 3.83%; P < .001).

“Smoking, BMI [body mass index], procedure type, and preoperative anticoagulation were not associated with the outcome of VTE,” Dr. McHugh said.

“Although we found VTE to continue to be an uncommon complication, non-home discharge is independently associated with higher rates of VTE. Patients should be encouraged to discharge home, but those discharged to non-home facilities after total joint arthroplasty should be considered for more potent chemoprophylaxis than aspirin,” he concluded.

Stuart J. Fischer, MD, with Summit (N.J.) Orthopaedics and Sports Medicine, who was not part of the study, told this news organization that he found the results inconclusive.

He said there is the potential for confounding because “the people who are sent to a facility after total hip or total knee are inherently less mobile and less able to take care of themselves, so they are at a higher risk for VTE. They are going to be more static.”

Dr. Fischer noted that over the past few years, there has been a movement away from anticoagulation with more aggressive agents toward aspirin, for several reasons. Providers don’t have to monitor aspirin use and can instruct patients to take it once or twice a day. Initial data seem to show that it protects well against VTE.

“The question is, in certain population of patients, is it enough? And that’s where the data are unclear,” Dr. Fischer said.

“It’s certainly a useful study, and we need to find out which methods of anticoagulation are most effective in each setting,” he said.

Limitations include that it was a retrospective review and that adverse events from more aggressive chemoprophylaxis agents were not assessed. Prophylactic regimens were chosen at the discretion of the treating surgeon.

The researchers excluded bilateral cases, conversion arthroplasty, hip hemiarthroplasty, unicompartmental knee arthroplasty, and deaths.

Dr. Muscatelli and Dr. McHugh reported no relevant financial relationships. A coauthor reported being a paid consultant for DePuy and Zimmer. Dr. Fischer reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

CHICAGO – Patients discharged to facilities rather than to home after total hip arthroplasty (THA) or total knee arthroplasty (TKA) may need more potent chemoprophylaxis than aspirin to prevent blood clots, new data suggest.

Researchers led by Stefano Muscatelli, MD, an orthopedist at Michigan Medicine, Ann Arbor, first aimed to determine whether there was an increase in risk of venous thromboembolism (VTE) in patients who were discharged to facilities such as a skilled nursing facility or inpatient rehabilitation facility, compared with those discharged to home after THA or TKA.

The second aim was to determine whether VTE risk differed between home- and non–home-discharge patients when stratified by the chemoprophylaxis prescribed to prevent VTE.

Findings were presented at the annual meeting of the American Academy of Orthopaedic Surgeons by coauthor Michael McHugh, MD, also an orthopedist at Michigan Medicine in Ann Arbor.

The agents were categorized in three groups: aspirin only; more aggressive anticoagulants, including warfarin, factor Xa inhibitor, direct thrombin inhibitor, low-molecular-weight heparin, pentasaccharide, or antiplatelet agents, with or without concurrent aspirin; and other regimens.

The researchers found that rates of VTE were higher among patients discharged to facilities.

Of 6,411 patients included in the study, the overall rate of VTE was 1.05%. Among home-discharge patients (n = 5445), rates of VTE were significantly lower than among patients discharged to facilities (n = 966) (0.83% vs. 2.26%; P < .001).

However, the researchers found there was no difference in VTE rates between non-home and home discharge in patients who received more aggressive chemoprophylaxis.

Among discharged patients who received only aspirin, rates of VTE among those discharged to home were significantly lower compared to those discharged to facilities (0.76% vs. 3.83%; P < .001).

“Smoking, BMI [body mass index], procedure type, and preoperative anticoagulation were not associated with the outcome of VTE,” Dr. McHugh said.

“Although we found VTE to continue to be an uncommon complication, non-home discharge is independently associated with higher rates of VTE. Patients should be encouraged to discharge home, but those discharged to non-home facilities after total joint arthroplasty should be considered for more potent chemoprophylaxis than aspirin,” he concluded.

Stuart J. Fischer, MD, with Summit (N.J.) Orthopaedics and Sports Medicine, who was not part of the study, told this news organization that he found the results inconclusive.

He said there is the potential for confounding because “the people who are sent to a facility after total hip or total knee are inherently less mobile and less able to take care of themselves, so they are at a higher risk for VTE. They are going to be more static.”

Dr. Fischer noted that over the past few years, there has been a movement away from anticoagulation with more aggressive agents toward aspirin, for several reasons. Providers don’t have to monitor aspirin use and can instruct patients to take it once or twice a day. Initial data seem to show that it protects well against VTE.

“The question is, in certain population of patients, is it enough? And that’s where the data are unclear,” Dr. Fischer said.

“It’s certainly a useful study, and we need to find out which methods of anticoagulation are most effective in each setting,” he said.

Limitations include that it was a retrospective review and that adverse events from more aggressive chemoprophylaxis agents were not assessed. Prophylactic regimens were chosen at the discretion of the treating surgeon.

The researchers excluded bilateral cases, conversion arthroplasty, hip hemiarthroplasty, unicompartmental knee arthroplasty, and deaths.

Dr. Muscatelli and Dr. McHugh reported no relevant financial relationships. A coauthor reported being a paid consultant for DePuy and Zimmer. Dr. Fischer reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

CHICAGO – Patients discharged to facilities rather than to home after total hip arthroplasty (THA) or total knee arthroplasty (TKA) may need more potent chemoprophylaxis than aspirin to prevent blood clots, new data suggest.

Researchers led by Stefano Muscatelli, MD, an orthopedist at Michigan Medicine, Ann Arbor, first aimed to determine whether there was an increase in risk of venous thromboembolism (VTE) in patients who were discharged to facilities such as a skilled nursing facility or inpatient rehabilitation facility, compared with those discharged to home after THA or TKA.

The second aim was to determine whether VTE risk differed between home- and non–home-discharge patients when stratified by the chemoprophylaxis prescribed to prevent VTE.

Findings were presented at the annual meeting of the American Academy of Orthopaedic Surgeons by coauthor Michael McHugh, MD, also an orthopedist at Michigan Medicine in Ann Arbor.

The agents were categorized in three groups: aspirin only; more aggressive anticoagulants, including warfarin, factor Xa inhibitor, direct thrombin inhibitor, low-molecular-weight heparin, pentasaccharide, or antiplatelet agents, with or without concurrent aspirin; and other regimens.

The researchers found that rates of VTE were higher among patients discharged to facilities.

Of 6,411 patients included in the study, the overall rate of VTE was 1.05%. Among home-discharge patients (n = 5445), rates of VTE were significantly lower than among patients discharged to facilities (n = 966) (0.83% vs. 2.26%; P < .001).

However, the researchers found there was no difference in VTE rates between non-home and home discharge in patients who received more aggressive chemoprophylaxis.

Among discharged patients who received only aspirin, rates of VTE among those discharged to home were significantly lower compared to those discharged to facilities (0.76% vs. 3.83%; P < .001).

“Smoking, BMI [body mass index], procedure type, and preoperative anticoagulation were not associated with the outcome of VTE,” Dr. McHugh said.

“Although we found VTE to continue to be an uncommon complication, non-home discharge is independently associated with higher rates of VTE. Patients should be encouraged to discharge home, but those discharged to non-home facilities after total joint arthroplasty should be considered for more potent chemoprophylaxis than aspirin,” he concluded.

Stuart J. Fischer, MD, with Summit (N.J.) Orthopaedics and Sports Medicine, who was not part of the study, told this news organization that he found the results inconclusive.

He said there is the potential for confounding because “the people who are sent to a facility after total hip or total knee are inherently less mobile and less able to take care of themselves, so they are at a higher risk for VTE. They are going to be more static.”

Dr. Fischer noted that over the past few years, there has been a movement away from anticoagulation with more aggressive agents toward aspirin, for several reasons. Providers don’t have to monitor aspirin use and can instruct patients to take it once or twice a day. Initial data seem to show that it protects well against VTE.

“The question is, in certain population of patients, is it enough? And that’s where the data are unclear,” Dr. Fischer said.

“It’s certainly a useful study, and we need to find out which methods of anticoagulation are most effective in each setting,” he said.

Limitations include that it was a retrospective review and that adverse events from more aggressive chemoprophylaxis agents were not assessed. Prophylactic regimens were chosen at the discretion of the treating surgeon.

The researchers excluded bilateral cases, conversion arthroplasty, hip hemiarthroplasty, unicompartmental knee arthroplasty, and deaths.

Dr. Muscatelli and Dr. McHugh reported no relevant financial relationships. A coauthor reported being a paid consultant for DePuy and Zimmer. Dr. Fischer reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

A new study has found that a simple screening tool can identify patients at risk of postoperative delirium (POD) after orthopedic surgery, and a prevention program can help improve staff education and outcomes.

Spotmatik/Thinkstock

“In an aging society, it is very important to develop and implement a strategy for POD prevention to ensure that aging patients are treated as safely and effectively as possible,” wrote Jung-Yeon Choi of Seoul (South Korea) National University Bundang Hospital and coauthors. The study was published in BMC Geriatrics.

To determine how to better identify and treat high-risk patients for POD after orthopedic surgery, the researchers led a retrospective cohort study that included an intervention group of participants who were aged at least 65 years (n = 275) and a control group from a year prior (n = 274). Patients in the intervention group had their risk of delirium assessed and categorized using a simple screening tool, and those deemed at risk were entered into a multicomponent delirium prevention program.

Of the 275 patients in the intervention group, 144 required screening for delirium. Ninety-nine were classified as low risk, 29 were classified as high risk, and 16 missed the screening. Fifty-three additional patients were classified as high risk because they were aged 80 years or older. During the study, 17 participants experienced POD, 16 of whom were classified as high risk. In regard to estimating POD risk, the sensitivity and specificity of the delirium screening tool were 94.1% and 72.7%, respectively. Incidence rates of POD were 10.2% in the control group and 6.2% in the intervention group.

The authors noted their study’s limitations, including its design as a retrospective review of medical records rather than a prospective randomized controlled trial. In addition, because it was conducted in just one teaching hospital, they deemed it “not possible to determine the generalizability and long-term effect of our findings.”

The authors reported no conflicts of interest.

SOURCE: Choi JY et al. BMC Geriatr. 2019 Oct 26. doi: 10.1186/s12877-019-1303-z.

A new study has found that a simple screening tool can identify patients at risk of postoperative delirium (POD) after orthopedic surgery, and a prevention program can help improve staff education and outcomes.

Spotmatik/Thinkstock

“In an aging society, it is very important to develop and implement a strategy for POD prevention to ensure that aging patients are treated as safely and effectively as possible,” wrote Jung-Yeon Choi of Seoul (South Korea) National University Bundang Hospital and coauthors. The study was published in BMC Geriatrics.

To determine how to better identify and treat high-risk patients for POD after orthopedic surgery, the researchers led a retrospective cohort study that included an intervention group of participants who were aged at least 65 years (n = 275) and a control group from a year prior (n = 274). Patients in the intervention group had their risk of delirium assessed and categorized using a simple screening tool, and those deemed at risk were entered into a multicomponent delirium prevention program.

Of the 275 patients in the intervention group, 144 required screening for delirium. Ninety-nine were classified as low risk, 29 were classified as high risk, and 16 missed the screening. Fifty-three additional patients were classified as high risk because they were aged 80 years or older. During the study, 17 participants experienced POD, 16 of whom were classified as high risk. In regard to estimating POD risk, the sensitivity and specificity of the delirium screening tool were 94.1% and 72.7%, respectively. Incidence rates of POD were 10.2% in the control group and 6.2% in the intervention group.

The authors noted their study’s limitations, including its design as a retrospective review of medical records rather than a prospective randomized controlled trial. In addition, because it was conducted in just one teaching hospital, they deemed it “not possible to determine the generalizability and long-term effect of our findings.”

The authors reported no conflicts of interest.

SOURCE: Choi JY et al. BMC Geriatr. 2019 Oct 26. doi: 10.1186/s12877-019-1303-z.

A new study has found that a simple screening tool can identify patients at risk of postoperative delirium (POD) after orthopedic surgery, and a prevention program can help improve staff education and outcomes.

Spotmatik/Thinkstock

“In an aging society, it is very important to develop and implement a strategy for POD prevention to ensure that aging patients are treated as safely and effectively as possible,” wrote Jung-Yeon Choi of Seoul (South Korea) National University Bundang Hospital and coauthors. The study was published in BMC Geriatrics.

To determine how to better identify and treat high-risk patients for POD after orthopedic surgery, the researchers led a retrospective cohort study that included an intervention group of participants who were aged at least 65 years (n = 275) and a control group from a year prior (n = 274). Patients in the intervention group had their risk of delirium assessed and categorized using a simple screening tool, and those deemed at risk were entered into a multicomponent delirium prevention program.

Of the 275 patients in the intervention group, 144 required screening for delirium. Ninety-nine were classified as low risk, 29 were classified as high risk, and 16 missed the screening. Fifty-three additional patients were classified as high risk because they were aged 80 years or older. During the study, 17 participants experienced POD, 16 of whom were classified as high risk. In regard to estimating POD risk, the sensitivity and specificity of the delirium screening tool were 94.1% and 72.7%, respectively. Incidence rates of POD were 10.2% in the control group and 6.2% in the intervention group.

The authors noted their study’s limitations, including its design as a retrospective review of medical records rather than a prospective randomized controlled trial. In addition, because it was conducted in just one teaching hospital, they deemed it “not possible to determine the generalizability and long-term effect of our findings.”

The authors reported no conflicts of interest.

SOURCE: Choi JY et al. BMC Geriatr. 2019 Oct 26. doi: 10.1186/s12877-019-1303-z.

MELBOURNE – A majority of minor surgeries can be performed in hemophilia A patients receiving emicizumab therapy without requiring prophylactic treatment with coagulation factors, according to data presented at the International Society on Thrombosis and Haemostasis congress.

Bianca Nogrady/MDedge News

Elena Santagostino, MD, PhD, from the Hemophilia and Thrombosis Center at Ospedale Maggiore Policlinico in Milan presented data from 399 patients involved in the four HAVEN trials of the humanized bispecific monoclonal antibody emicizumab (Hemlibra), which is Food and Drug Administration–approved for the prevention of bleeding episodes in individuals with hemophilia A, with or without inhibitors.

The analysis focused on the 126 patients (31.6%) who underwent at least one surgical procedure during the studies. Of the 233 surgeries, there were 215 minor procedures performed in 115 patients, and 18 major surgeries in 18 patients. All patients were receiving ongoing treatment with emicizumab, and there was no change to that treatment regimen during surgery.

“It is clear that surgery is a challenge for hemophilia,” Dr. Santagostino said. “It is a challenge for bleeding, it is a challenge for thrombosis, it is a challenge for any new drug, and this is why there is a lot of interest around this topic.”

Overall, 65.6% of minor surgeries were performed without any prophylactic coagulation factor treatment, and 90.8% of minor surgeries were conducted without postoperative bleeds requiring treatment. There were no cases of thrombosis reported.

The surgeries that did not require prophylactic coagulation factor included 42 dental procedures, 25 central venous access devices, 17 endoscopic procedures, and 12 joint procedures.

While the HAVEN studies did not allow for elective major surgery, there were still 18 unplanned major surgical situations that arose during the course of the studies. These included three hip, one knee, and one ankle arthroplasties; three synovectomies; and some dental, central venous line, and endoscopic biopsy procedures.

Of these, 15 involved prophylactic coagulant factor administration, but three procedures – including one synovectomy – were performed without prophylaxis and none resulted in a bleed.

There was one complicated bleed that occurred in a patient undergoing multiple procedures including a synovectomy, joint debridement and chondroplasty, who received prolonged treatment with recombinant Factor VIIa.

Dr. Santagostino said the findings showed surgery could be safely performed in patients who were being treated with emicizumab, both with and without inhibitors.

“A large number of minor procedures can be done without adding coagulation factors,” she said in an interview. “This is true for less invasive surgeries, such as catheter-related central venous line procedures. Even several endoscopic procedures, like a single biopsy, can be done reasonably safely.”

However she said there was still a lack of experience in dealing with hemophilia A patients who were undergoing cancer surgery, or who had significant comorbidities that might put them at higher risk of thrombosis.

“These are special patients populations that are still not investigated in the trial setting,” she said.

Commenting on the data, session cochair Liane Khoo, MD, from the Haemophilia Treatment Centre at Royal Prince Alfred Hospital in Sydney, said the results showed surgery could be performed in hemophilia A patients with and without inhibitors.

“The more we have the medication and the more experience we have, then we become more confident in using it,” she said.

The study was funded by F. Hoffman-La Roche and Chugai Pharmaceutical. Dr. Santagostino reported consultancies and speakers bureau engagements with the pharmaceutical sector.

SOURCE: Santagostino E et al. 2019 ISTH Congress, Abstract OC 60.1.

MELBOURNE – A majority of minor surgeries can be performed in hemophilia A patients receiving emicizumab therapy without requiring prophylactic treatment with coagulation factors, according to data presented at the International Society on Thrombosis and Haemostasis congress.

Bianca Nogrady/MDedge News

Elena Santagostino, MD, PhD, from the Hemophilia and Thrombosis Center at Ospedale Maggiore Policlinico in Milan presented data from 399 patients involved in the four HAVEN trials of the humanized bispecific monoclonal antibody emicizumab (Hemlibra), which is Food and Drug Administration–approved for the prevention of bleeding episodes in individuals with hemophilia A, with or without inhibitors.

The analysis focused on the 126 patients (31.6%) who underwent at least one surgical procedure during the studies. Of the 233 surgeries, there were 215 minor procedures performed in 115 patients, and 18 major surgeries in 18 patients. All patients were receiving ongoing treatment with emicizumab, and there was no change to that treatment regimen during surgery.

“It is clear that surgery is a challenge for hemophilia,” Dr. Santagostino said. “It is a challenge for bleeding, it is a challenge for thrombosis, it is a challenge for any new drug, and this is why there is a lot of interest around this topic.”

Overall, 65.6% of minor surgeries were performed without any prophylactic coagulation factor treatment, and 90.8% of minor surgeries were conducted without postoperative bleeds requiring treatment. There were no cases of thrombosis reported.

The surgeries that did not require prophylactic coagulation factor included 42 dental procedures, 25 central venous access devices, 17 endoscopic procedures, and 12 joint procedures.

While the HAVEN studies did not allow for elective major surgery, there were still 18 unplanned major surgical situations that arose during the course of the studies. These included three hip, one knee, and one ankle arthroplasties; three synovectomies; and some dental, central venous line, and endoscopic biopsy procedures.

Of these, 15 involved prophylactic coagulant factor administration, but three procedures – including one synovectomy – were performed without prophylaxis and none resulted in a bleed.

There was one complicated bleed that occurred in a patient undergoing multiple procedures including a synovectomy, joint debridement and chondroplasty, who received prolonged treatment with recombinant Factor VIIa.

Dr. Santagostino said the findings showed surgery could be safely performed in patients who were being treated with emicizumab, both with and without inhibitors.

“A large number of minor procedures can be done without adding coagulation factors,” she said in an interview. “This is true for less invasive surgeries, such as catheter-related central venous line procedures. Even several endoscopic procedures, like a single biopsy, can be done reasonably safely.”

However she said there was still a lack of experience in dealing with hemophilia A patients who were undergoing cancer surgery, or who had significant comorbidities that might put them at higher risk of thrombosis.

“These are special patients populations that are still not investigated in the trial setting,” she said.

Commenting on the data, session cochair Liane Khoo, MD, from the Haemophilia Treatment Centre at Royal Prince Alfred Hospital in Sydney, said the results showed surgery could be performed in hemophilia A patients with and without inhibitors.

“The more we have the medication and the more experience we have, then we become more confident in using it,” she said.

The study was funded by F. Hoffman-La Roche and Chugai Pharmaceutical. Dr. Santagostino reported consultancies and speakers bureau engagements with the pharmaceutical sector.

SOURCE: Santagostino E et al. 2019 ISTH Congress, Abstract OC 60.1.

MELBOURNE – A majority of minor surgeries can be performed in hemophilia A patients receiving emicizumab therapy without requiring prophylactic treatment with coagulation factors, according to data presented at the International Society on Thrombosis and Haemostasis congress.

Bianca Nogrady/MDedge News

Elena Santagostino, MD, PhD, from the Hemophilia and Thrombosis Center at Ospedale Maggiore Policlinico in Milan presented data from 399 patients involved in the four HAVEN trials of the humanized bispecific monoclonal antibody emicizumab (Hemlibra), which is Food and Drug Administration–approved for the prevention of bleeding episodes in individuals with hemophilia A, with or without inhibitors.

The analysis focused on the 126 patients (31.6%) who underwent at least one surgical procedure during the studies. Of the 233 surgeries, there were 215 minor procedures performed in 115 patients, and 18 major surgeries in 18 patients. All patients were receiving ongoing treatment with emicizumab, and there was no change to that treatment regimen during surgery.

“It is clear that surgery is a challenge for hemophilia,” Dr. Santagostino said. “It is a challenge for bleeding, it is a challenge for thrombosis, it is a challenge for any new drug, and this is why there is a lot of interest around this topic.”

Overall, 65.6% of minor surgeries were performed without any prophylactic coagulation factor treatment, and 90.8% of minor surgeries were conducted without postoperative bleeds requiring treatment. There were no cases of thrombosis reported.

The surgeries that did not require prophylactic coagulation factor included 42 dental procedures, 25 central venous access devices, 17 endoscopic procedures, and 12 joint procedures.

While the HAVEN studies did not allow for elective major surgery, there were still 18 unplanned major surgical situations that arose during the course of the studies. These included three hip, one knee, and one ankle arthroplasties; three synovectomies; and some dental, central venous line, and endoscopic biopsy procedures.

Of these, 15 involved prophylactic coagulant factor administration, but three procedures – including one synovectomy – were performed without prophylaxis and none resulted in a bleed.

There was one complicated bleed that occurred in a patient undergoing multiple procedures including a synovectomy, joint debridement and chondroplasty, who received prolonged treatment with recombinant Factor VIIa.

Dr. Santagostino said the findings showed surgery could be safely performed in patients who were being treated with emicizumab, both with and without inhibitors.

“A large number of minor procedures can be done without adding coagulation factors,” she said in an interview. “This is true for less invasive surgeries, such as catheter-related central venous line procedures. Even several endoscopic procedures, like a single biopsy, can be done reasonably safely.”

However she said there was still a lack of experience in dealing with hemophilia A patients who were undergoing cancer surgery, or who had significant comorbidities that might put them at higher risk of thrombosis.

“These are special patients populations that are still not investigated in the trial setting,” she said.

Commenting on the data, session cochair Liane Khoo, MD, from the Haemophilia Treatment Centre at Royal Prince Alfred Hospital in Sydney, said the results showed surgery could be performed in hemophilia A patients with and without inhibitors.

“The more we have the medication and the more experience we have, then we become more confident in using it,” she said.

The study was funded by F. Hoffman-La Roche and Chugai Pharmaceutical. Dr. Santagostino reported consultancies and speakers bureau engagements with the pharmaceutical sector.

SOURCE: Santagostino E et al. 2019 ISTH Congress, Abstract OC 60.1.

Knee osteoarthritis (OA) affects almost 9.3 million adults in the US and accounts for $27 billion in annual health care expenses.^1,2 Due to the increasing cost of health care and an aging population, there has been renewed interest in establishing criteria for nonarthroplasty treatment of knee OA.

In 2013, using the RAND/UCLA Appropriateness method, the American Academy of Orthopaedic Surgeons (AAOS) developed an appropriate use criteria (AUC) for nonarthroplasty management of primary OA of the knee, based on orthopaedic literature and expert opinion.³ Interventions such as activity modification, weight loss, prescribed physical therapy, nonsteroidal anti-inflammatory drugs, tramadol, prescribed oral or transcutaneous opioids, acetaminophen, intra-articular corticosteroids, hinged or unloading knee braces, arthroscopic partial menisectomy or loose body removal, and realignment osteotomy were assessed. An algorithm was developed for 576 patients scenarios that incorporated patient-specific, prognostic/predictor variables to assign designations of “appropriate,” “may be appropriate,” or “rarely appropriate,” to treatment interventions.^4,5 An online version of the algorithm (orthoguidelines.org) is available for physicians and surgeons to judge appropriateness of nonarthroplasty treatments; however, it is not intended to mandate candidacy for treatment or intervention.

Clinical evaluation of the AAOS AUC is necessary to determine how treatment recommendations correlate with current practice. A recent examination of the AAOS Appropriateness System for Surgical Management of Knee OA found that prognostic/predictor variables, such as patient age, OA severity, and pattern of knee OA involvement were more heavily weighted when determining arthroplasty appropriateness than was pain severity or functional loss.⁶ Furthermore, non-AAOS AUC prognostic/predictor variables, such as race and gender, have been linked to disparities in utilization of knee OA interventions.^7-9 Such disparities can be costly not just from a patient perceptive, but also employer and societal perspectives.¹⁰

The Department of Veterans Affairs (VA) health care system represents a model of equal-access-to care system in the US that is ideal for examination of issues about health care utilization and any disparities within the AAOS AUC model and has previously been used to assess utilization of total knee arthroplasty.⁹ The aim of this study was to characterize utilization of the AAOS AUC for nonarthroplasty treatment of knee OA in a VA patient population. We asked the following questions: (1) What variables are predictive of receiving a greater number of AAOS AUC evaluated nonarthroplasty treatments? (2) What variables are predictive of receiving “rarely appropriate” AAOS AUC evaluated nonarthroplasty treatment? (3) What factors are predictive of duration of nonarthroplasty care until total knee arthroplasty (TKA)?

Methods

The institutional review board at the Louis Stokes Cleveland VA Medical Center in Ohio approved a retrospective chart review of nonarthroplasty treatments utilized by patients presenting to its orthopaedic section who subsequently underwent knee arthroplasty between 2013 and 2016. Eligibility criteria included patients aged ≥ 30 years with a diagnosis of unilateral or bilateral primary knee OA. Patients with posttraumatic OA, inflammatory arthritis, and a history of infectious arthritis or Charcot arthropathy of the knee were excluded. Patients with a body mass index (BMI) > 40 or a hemoglobin A_1c > 8.0 at presentation were excluded as nonarthroplasty care was the recommended course of treatment above these thresholds.

Data collected included race, gender, duration of nonarthroplasty treatment, BMI, and Kellgren-Lawrence classification of knee OA at time of presentation for symptomatic knee OA.¹¹ All AAOS AUC-evaluated nonarthroplasty treatments utilized prior to arthroplasty intervention also were recorded (Table 1). 

Statistical Analysis

Statistical analysis was completed with GraphPad Software Prism 7.0a (La Jolla, CA) and Mathworks MatLab R2016b software (Natick, MA). Univariate analysis with Student t tests with Welch corrections in the setting of unequal variance, Mann-Whitney nonparametric tests, and Fisher exact test were generated in the appropriate setting. Multivariable analyses also were conducted. For continuous outcomes, stepwise multiple linear regression was used to generate predictive models; for binary outcomes, binomial logistic regression was used.

Factors analyzed in regression modeling for the total number of AAOS AUC evaluated nonarthroplasty treatments utilized and the likelihood of receiving a rarely appropriate treatment included gender, race, function-limiting pain, range of motion (ROM), ligamentous instability, arthritis pattern, limb alignment, mechanical symptoms, BMI, age, and Kellgren-Lawrence grade. Factors analyzed in timing of TKA included the above variables plus the total number of AUC interventions, whether the patient received an inappropriate intervention, and average appropriateness of the interventions received. Residual analysis with Cook’s distance was used to identify outliers in regression. Observations with Cook’s distance > 3 times the mean Cook’s distance were identified as potential outliers, and models were adjusted accordingly. All statistical analyses were 2-tailed. Statistical significance was set to P ≤ .05 for all outputs.

Results

In the study, 97.8% of participants identified as male, and the mean age was 62.8 years (Table 3). 

Appropriate Use Criteria Interventions

Patients received a mean of 5.2 AAOS AUC evaluated interventions before undergoing arthroplasty management at a mean of 32.3 months (range 2-181 months) from initial presentation. The majority of these interventions were classified as either appropriate or may be appropriate, according to the AUC definitions (95.1%). Self-management and physical therapy programs were widely utilized (100% and 90.1%, respectively), with all use of these interventions classified as appropriate.

Hinged or unloader knee braces were utilized in about half the study patients; this intervention was classified as rarely appropriate in 4.4% of these patients. Medical therapy was also widely used, with all use of NSAIDs, acetaminophen, and tramadol classified as appropriate or may be appropriate. Oral or transcutaneous opioid medications were prescribed in 14.3% of patients, with 92.3% of this use classified as rarely appropriate. Although the opioid medication prescribing provider was not specifically evaluated, there were no instances in which the orthopaedic service provided an oral or transcutaneous opioid prescriptions. Procedural interventions, with the exception of corticosteroid injections, were uncommon; no patient received realignment osteotomy, and only 12.1% of patients underwent arthroscopy. The use of arthroscopy was deemed rarely appropriate in 72.7% of these cases.

Factors Associated With AAOS AUC Intervention Use

There was no difference in the number of AAOS AUC evaluated interventions received based on BMI (mean [SD] BMI < 35, 5.2 [1.0] vs BMI ≥ 35, 5.3 [1.1], P = .49), age (mean [SD] aged < 60 years, 5.4 [1.0] vs aged ≥ 60 years, 5.1 [1.2], P = .23), or Kellgren-Lawrence arthritic grade (mean [SD] grade ≤ 2, 5.5 [1.0] vs grade > 2, 5.1 [1.1], P = .06). These variables also were not associated with receiving a rarely appropriate intervention (mean [SD] BMI < 35, 0.27 [0.5] vs BMI > 35, 0.2 [0.4], P = .81; aged > 60 years, 0.3 [0.5] vs aged < 60 years, 0.2 [0.4], P = .26; Kellgren-Lawrence grade < 2, 0.4 [0.6] vs grade > 2, 0.2 [0.4], P = .1).

Regression modeling to predict total number of AAOS AUC evaluated interventions received produced a significant model (R² = 0.111, P = .006). The presence of ligamentous instability (β coefficient, -1.61) and the absence of mechanical symptoms (β coefficient, -0.67) were negative predictors of number of AUC interventions received. Variance inflation factors were 1.014 and 1.012, respectively. Likewise, regression modeling to identify factors predictive of receiving a rarely appropriate intervention also produced a significant model (pseudo R²= 0.06, P = .025), with lower Kellgren-Lawrence grade the only significant predictor of receiving a rarely appropriate intervention (odds ratio [OR] 0.54; 95% CI, 0.42 -0.72, per unit increase).

Timing from presentation to arthroplasty intervention was also evaluated. Age was a negative predictor (β coefficient -1.61), while positive predictors were reduced ROM (β coefficient 15.72) and having more AUC interventions (β coefficient 7.31) (model R²= 0.29, P = < .001). Age was the most significant predictor. Variance inflations factors were 1.02, 1.01, and 1.03, respectively. Receiving a rarely appropriate intervention was not associated with TKA timing.

Discussion

This single-center retrospective study examined the utilization of AAOS AUC-evaluated nonarthroplasty interventions for symptomatic knee OA prior to TKA. The aims of this study were to validate the AAOS AUC in a clinical setting and identify predictors of AAOS AUC utilization. In particular, this study focused on the number of interventions utilized prior to knee arthroplasty, whether interventions receiving a designation of rarely appropriate were used, and the duration of nonarthroplasty treatment.

Patients with knee instability used fewer total AAOS AUC evaluated interventions prior to TKA. Subjective instability has been reported as high as 27% in patients with OA and has been associated with fear of falling, poor balance confidence, activity limitations, and lower Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function scores.¹² However, it has not been found to correlate with knee laxity.¹³ Nevertheless, significant functional impairment with the risk of falling may reduce the number of nonarthroplasty interventions attempted. On the other hand, the presence of mechanical symptoms resulted in greater utilization of nonarthroplasty interventions. This is likely due to the greater utilization of arthroscopic partial menisectomy or loose body removal in this group of patients. Despite its inclusion as an AAOS AUC evaluated intervention, arthroscopy remains a contentious treatment for symptomatic knee pain in the setting of OA.^14,15

For every unit decrease in Kellgren-Lawrence OA grade, patients were 54% more likely to receive a rarely appropriate intervention prior to knee arthroplasty. This is supported by the recent literature examining the AAOS AUC for surgical management of knee OA. Riddle and colleagues developed a classification tree to determine the contributions of various prognostic variables in final classifications of the 864 clinical vignettes used to develop the appropriateness algorithm and found that OA severity was strongly favored, with only 4 of the 432 vignettes with severe knee OA judged as rarely appropriate for surgical intervention.⁶

Our findings, too, may be explained by an AAOS AUC system that too heavily weighs radiographic severity of knee OA, resulting in more frequent rarely appropriate interventions in patients with less severe arthritis, including nonarthroplasty treatments. It is likely that rarely appropriate interventions were attempted in this subset of our study cohort based on patient’s subjective symptoms and functional status, both of which have been shown to be discordant with radiographic severity of knee OA.¹⁶

Oral or transcutaneous prescribed opioid medications were the most frequent intervention that received a rarely appropriate designation. Patients with preoperative opioid use undergoing TKA have been shown to have a greater risk for postoperative complications and longer hospital stay, particularly those patients aged < 75 years. Younger age, use of more interventions, and decreased knee ROM at presentation were predictive of longer duration of nonarthroplasty treatment. The use of more AAOS AUC evaluated interventions in these patients suggests that the AAOS AUC model may effectively be used to manage symptomatic OA, increasing the time from presentation to knee arthroplasty.

Interestingly, the use of rarely appropriate interventions did not affect TKA timing, as would be expected in a clinically effective nonarthroplasty treatment model. The reasons for rarely appropriate nonsurgical interventions are complex and require further investigation. One possible explanation is that decreased ROM was a marker for mechanical symptoms that necessitated additional intervention in the form of knee arthroscopy, delaying time to TKA.

Limitations

There are several limitations of this study. First, the small sample size (N = 90) requires acknowledgment; however, this limitation reflects the difficulty in following patients for years prior to an operative intervention. Second, the study population consists of veterans using the VA system and may not be reflective of the general population, differing with respect to gender, racial, and socioeconomic factors. Nevertheless, studies examining TKA utilization found, aside from racial and ethnic variability, patient gender and age do not affect arthroplasty utilization rate in the VA system.¹⁷

Additional limitations stem from the retrospective nature of this study. While the Computerized Patient Record System and centralized care of the VA system allows for review of all physical therapy consultations, orthotic consultations, and medications within the VA system, any treatments and intervention delivered by non-VA providers were not captured. Furthermore, the ability to assess for confounding variables limiting the prescription of certain medications, such as chronic kidney disease with NSAIDs or liver disease with acetaminophen, was limited by our study design.

Although our study suffers from selection bias with respect to examination of nonarthroplasty treatment in patients who have ultimately undergone TKA, we feel that this subset of patients with symptomatic knee OA represents the majority of patients evaluated for knee OA by orthopaedic surgeons in the clinic setting. It should be noted that although realignment osteotomies were sometimes indicated as appropriate by AAOS AUC model in our study population, this intervention was never performed due to patient and surgeon preference. Additionally, although it is not an AAOS AUC evaluated intervention, viscosupplementation was sporadically used during the study period; however, it is now off formulary at the investigation institution.

Conclusion

Our study suggests that patients without knee instability use more nonarthroplasty treatments over a longer period before TKA, and those patients with less severe knee OA are at risk of receiving an intervention judged to be rarely appropriate by the AAOS AUC. Such interventions do not affect timing of TKA. Nonarthroplasty care should be individualized to patients’ needs, and the decision to proceed with arthroplasty should be considered only after exhausting appropriate conservative measures. We recommend that providers use the AAOS AUC, especially when treating younger patients with less severe knee OA, particularly if considering opiate therapy or knee arthroscopy.

Acknowledgments
The authors would like to acknowledge Patrick Getty, MD, for his surgical care of some of the study patients. This material is the result of work supported with resources and the use of facilities at the Louis Stokes Cleveland VA Medical Center in Ohio.

Knee osteoarthritis (OA) affects almost 9.3 million adults in the US and accounts for $27 billion in annual health care expenses.^1,2 Due to the increasing cost of health care and an aging population, there has been renewed interest in establishing criteria for nonarthroplasty treatment of knee OA.

In 2013, using the RAND/UCLA Appropriateness method, the American Academy of Orthopaedic Surgeons (AAOS) developed an appropriate use criteria (AUC) for nonarthroplasty management of primary OA of the knee, based on orthopaedic literature and expert opinion.³ Interventions such as activity modification, weight loss, prescribed physical therapy, nonsteroidal anti-inflammatory drugs, tramadol, prescribed oral or transcutaneous opioids, acetaminophen, intra-articular corticosteroids, hinged or unloading knee braces, arthroscopic partial menisectomy or loose body removal, and realignment osteotomy were assessed. An algorithm was developed for 576 patients scenarios that incorporated patient-specific, prognostic/predictor variables to assign designations of “appropriate,” “may be appropriate,” or “rarely appropriate,” to treatment interventions.^4,5 An online version of the algorithm (orthoguidelines.org) is available for physicians and surgeons to judge appropriateness of nonarthroplasty treatments; however, it is not intended to mandate candidacy for treatment or intervention.

Clinical evaluation of the AAOS AUC is necessary to determine how treatment recommendations correlate with current practice. A recent examination of the AAOS Appropriateness System for Surgical Management of Knee OA found that prognostic/predictor variables, such as patient age, OA severity, and pattern of knee OA involvement were more heavily weighted when determining arthroplasty appropriateness than was pain severity or functional loss.⁶ Furthermore, non-AAOS AUC prognostic/predictor variables, such as race and gender, have been linked to disparities in utilization of knee OA interventions.^7-9 Such disparities can be costly not just from a patient perceptive, but also employer and societal perspectives.¹⁰

The Department of Veterans Affairs (VA) health care system represents a model of equal-access-to care system in the US that is ideal for examination of issues about health care utilization and any disparities within the AAOS AUC model and has previously been used to assess utilization of total knee arthroplasty.⁹ The aim of this study was to characterize utilization of the AAOS AUC for nonarthroplasty treatment of knee OA in a VA patient population. We asked the following questions: (1) What variables are predictive of receiving a greater number of AAOS AUC evaluated nonarthroplasty treatments? (2) What variables are predictive of receiving “rarely appropriate” AAOS AUC evaluated nonarthroplasty treatment? (3) What factors are predictive of duration of nonarthroplasty care until total knee arthroplasty (TKA)?

Methods

The institutional review board at the Louis Stokes Cleveland VA Medical Center in Ohio approved a retrospective chart review of nonarthroplasty treatments utilized by patients presenting to its orthopaedic section who subsequently underwent knee arthroplasty between 2013 and 2016. Eligibility criteria included patients aged ≥ 30 years with a diagnosis of unilateral or bilateral primary knee OA. Patients with posttraumatic OA, inflammatory arthritis, and a history of infectious arthritis or Charcot arthropathy of the knee were excluded. Patients with a body mass index (BMI) > 40 or a hemoglobin A_1c > 8.0 at presentation were excluded as nonarthroplasty care was the recommended course of treatment above these thresholds.

Data collected included race, gender, duration of nonarthroplasty treatment, BMI, and Kellgren-Lawrence classification of knee OA at time of presentation for symptomatic knee OA.¹¹ All AAOS AUC-evaluated nonarthroplasty treatments utilized prior to arthroplasty intervention also were recorded (Table 1). 

Statistical Analysis

Statistical analysis was completed with GraphPad Software Prism 7.0a (La Jolla, CA) and Mathworks MatLab R2016b software (Natick, MA). Univariate analysis with Student t tests with Welch corrections in the setting of unequal variance, Mann-Whitney nonparametric tests, and Fisher exact test were generated in the appropriate setting. Multivariable analyses also were conducted. For continuous outcomes, stepwise multiple linear regression was used to generate predictive models; for binary outcomes, binomial logistic regression was used.

Factors analyzed in regression modeling for the total number of AAOS AUC evaluated nonarthroplasty treatments utilized and the likelihood of receiving a rarely appropriate treatment included gender, race, function-limiting pain, range of motion (ROM), ligamentous instability, arthritis pattern, limb alignment, mechanical symptoms, BMI, age, and Kellgren-Lawrence grade. Factors analyzed in timing of TKA included the above variables plus the total number of AUC interventions, whether the patient received an inappropriate intervention, and average appropriateness of the interventions received. Residual analysis with Cook’s distance was used to identify outliers in regression. Observations with Cook’s distance > 3 times the mean Cook’s distance were identified as potential outliers, and models were adjusted accordingly. All statistical analyses were 2-tailed. Statistical significance was set to P ≤ .05 for all outputs.

Results

In the study, 97.8% of participants identified as male, and the mean age was 62.8 years (Table 3). 

Appropriate Use Criteria Interventions

Patients received a mean of 5.2 AAOS AUC evaluated interventions before undergoing arthroplasty management at a mean of 32.3 months (range 2-181 months) from initial presentation. The majority of these interventions were classified as either appropriate or may be appropriate, according to the AUC definitions (95.1%). Self-management and physical therapy programs were widely utilized (100% and 90.1%, respectively), with all use of these interventions classified as appropriate.

Hinged or unloader knee braces were utilized in about half the study patients; this intervention was classified as rarely appropriate in 4.4% of these patients. Medical therapy was also widely used, with all use of NSAIDs, acetaminophen, and tramadol classified as appropriate or may be appropriate. Oral or transcutaneous opioid medications were prescribed in 14.3% of patients, with 92.3% of this use classified as rarely appropriate. Although the opioid medication prescribing provider was not specifically evaluated, there were no instances in which the orthopaedic service provided an oral or transcutaneous opioid prescriptions. Procedural interventions, with the exception of corticosteroid injections, were uncommon; no patient received realignment osteotomy, and only 12.1% of patients underwent arthroscopy. The use of arthroscopy was deemed rarely appropriate in 72.7% of these cases.

Factors Associated With AAOS AUC Intervention Use

There was no difference in the number of AAOS AUC evaluated interventions received based on BMI (mean [SD] BMI < 35, 5.2 [1.0] vs BMI ≥ 35, 5.3 [1.1], P = .49), age (mean [SD] aged < 60 years, 5.4 [1.0] vs aged ≥ 60 years, 5.1 [1.2], P = .23), or Kellgren-Lawrence arthritic grade (mean [SD] grade ≤ 2, 5.5 [1.0] vs grade > 2, 5.1 [1.1], P = .06). These variables also were not associated with receiving a rarely appropriate intervention (mean [SD] BMI < 35, 0.27 [0.5] vs BMI > 35, 0.2 [0.4], P = .81; aged > 60 years, 0.3 [0.5] vs aged < 60 years, 0.2 [0.4], P = .26; Kellgren-Lawrence grade < 2, 0.4 [0.6] vs grade > 2, 0.2 [0.4], P = .1).

Regression modeling to predict total number of AAOS AUC evaluated interventions received produced a significant model (R² = 0.111, P = .006). The presence of ligamentous instability (β coefficient, -1.61) and the absence of mechanical symptoms (β coefficient, -0.67) were negative predictors of number of AUC interventions received. Variance inflation factors were 1.014 and 1.012, respectively. Likewise, regression modeling to identify factors predictive of receiving a rarely appropriate intervention also produced a significant model (pseudo R²= 0.06, P = .025), with lower Kellgren-Lawrence grade the only significant predictor of receiving a rarely appropriate intervention (odds ratio [OR] 0.54; 95% CI, 0.42 -0.72, per unit increase).

Timing from presentation to arthroplasty intervention was also evaluated. Age was a negative predictor (β coefficient -1.61), while positive predictors were reduced ROM (β coefficient 15.72) and having more AUC interventions (β coefficient 7.31) (model R²= 0.29, P = < .001). Age was the most significant predictor. Variance inflations factors were 1.02, 1.01, and 1.03, respectively. Receiving a rarely appropriate intervention was not associated with TKA timing.

Discussion

This single-center retrospective study examined the utilization of AAOS AUC-evaluated nonarthroplasty interventions for symptomatic knee OA prior to TKA. The aims of this study were to validate the AAOS AUC in a clinical setting and identify predictors of AAOS AUC utilization. In particular, this study focused on the number of interventions utilized prior to knee arthroplasty, whether interventions receiving a designation of rarely appropriate were used, and the duration of nonarthroplasty treatment.

Patients with knee instability used fewer total AAOS AUC evaluated interventions prior to TKA. Subjective instability has been reported as high as 27% in patients with OA and has been associated with fear of falling, poor balance confidence, activity limitations, and lower Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function scores.¹² However, it has not been found to correlate with knee laxity.¹³ Nevertheless, significant functional impairment with the risk of falling may reduce the number of nonarthroplasty interventions attempted. On the other hand, the presence of mechanical symptoms resulted in greater utilization of nonarthroplasty interventions. This is likely due to the greater utilization of arthroscopic partial menisectomy or loose body removal in this group of patients. Despite its inclusion as an AAOS AUC evaluated intervention, arthroscopy remains a contentious treatment for symptomatic knee pain in the setting of OA.^14,15

For every unit decrease in Kellgren-Lawrence OA grade, patients were 54% more likely to receive a rarely appropriate intervention prior to knee arthroplasty. This is supported by the recent literature examining the AAOS AUC for surgical management of knee OA. Riddle and colleagues developed a classification tree to determine the contributions of various prognostic variables in final classifications of the 864 clinical vignettes used to develop the appropriateness algorithm and found that OA severity was strongly favored, with only 4 of the 432 vignettes with severe knee OA judged as rarely appropriate for surgical intervention.⁶

Our findings, too, may be explained by an AAOS AUC system that too heavily weighs radiographic severity of knee OA, resulting in more frequent rarely appropriate interventions in patients with less severe arthritis, including nonarthroplasty treatments. It is likely that rarely appropriate interventions were attempted in this subset of our study cohort based on patient’s subjective symptoms and functional status, both of which have been shown to be discordant with radiographic severity of knee OA.¹⁶

Oral or transcutaneous prescribed opioid medications were the most frequent intervention that received a rarely appropriate designation. Patients with preoperative opioid use undergoing TKA have been shown to have a greater risk for postoperative complications and longer hospital stay, particularly those patients aged < 75 years. Younger age, use of more interventions, and decreased knee ROM at presentation were predictive of longer duration of nonarthroplasty treatment. The use of more AAOS AUC evaluated interventions in these patients suggests that the AAOS AUC model may effectively be used to manage symptomatic OA, increasing the time from presentation to knee arthroplasty.

Interestingly, the use of rarely appropriate interventions did not affect TKA timing, as would be expected in a clinically effective nonarthroplasty treatment model. The reasons for rarely appropriate nonsurgical interventions are complex and require further investigation. One possible explanation is that decreased ROM was a marker for mechanical symptoms that necessitated additional intervention in the form of knee arthroscopy, delaying time to TKA.

Limitations

There are several limitations of this study. First, the small sample size (N = 90) requires acknowledgment; however, this limitation reflects the difficulty in following patients for years prior to an operative intervention. Second, the study population consists of veterans using the VA system and may not be reflective of the general population, differing with respect to gender, racial, and socioeconomic factors. Nevertheless, studies examining TKA utilization found, aside from racial and ethnic variability, patient gender and age do not affect arthroplasty utilization rate in the VA system.¹⁷

Additional limitations stem from the retrospective nature of this study. While the Computerized Patient Record System and centralized care of the VA system allows for review of all physical therapy consultations, orthotic consultations, and medications within the VA system, any treatments and intervention delivered by non-VA providers were not captured. Furthermore, the ability to assess for confounding variables limiting the prescription of certain medications, such as chronic kidney disease with NSAIDs or liver disease with acetaminophen, was limited by our study design.

Although our study suffers from selection bias with respect to examination of nonarthroplasty treatment in patients who have ultimately undergone TKA, we feel that this subset of patients with symptomatic knee OA represents the majority of patients evaluated for knee OA by orthopaedic surgeons in the clinic setting. It should be noted that although realignment osteotomies were sometimes indicated as appropriate by AAOS AUC model in our study population, this intervention was never performed due to patient and surgeon preference. Additionally, although it is not an AAOS AUC evaluated intervention, viscosupplementation was sporadically used during the study period; however, it is now off formulary at the investigation institution.

Conclusion

Our study suggests that patients without knee instability use more nonarthroplasty treatments over a longer period before TKA, and those patients with less severe knee OA are at risk of receiving an intervention judged to be rarely appropriate by the AAOS AUC. Such interventions do not affect timing of TKA. Nonarthroplasty care should be individualized to patients’ needs, and the decision to proceed with arthroplasty should be considered only after exhausting appropriate conservative measures. We recommend that providers use the AAOS AUC, especially when treating younger patients with less severe knee OA, particularly if considering opiate therapy or knee arthroscopy.

Acknowledgments
The authors would like to acknowledge Patrick Getty, MD, for his surgical care of some of the study patients. This material is the result of work supported with resources and the use of facilities at the Louis Stokes Cleveland VA Medical Center in Ohio.

Knee osteoarthritis (OA) affects almost 9.3 million adults in the US and accounts for $27 billion in annual health care expenses.^1,2 Due to the increasing cost of health care and an aging population, there has been renewed interest in establishing criteria for nonarthroplasty treatment of knee OA.

In 2013, using the RAND/UCLA Appropriateness method, the American Academy of Orthopaedic Surgeons (AAOS) developed an appropriate use criteria (AUC) for nonarthroplasty management of primary OA of the knee, based on orthopaedic literature and expert opinion.³ Interventions such as activity modification, weight loss, prescribed physical therapy, nonsteroidal anti-inflammatory drugs, tramadol, prescribed oral or transcutaneous opioids, acetaminophen, intra-articular corticosteroids, hinged or unloading knee braces, arthroscopic partial menisectomy or loose body removal, and realignment osteotomy were assessed. An algorithm was developed for 576 patients scenarios that incorporated patient-specific, prognostic/predictor variables to assign designations of “appropriate,” “may be appropriate,” or “rarely appropriate,” to treatment interventions.^4,5 An online version of the algorithm (orthoguidelines.org) is available for physicians and surgeons to judge appropriateness of nonarthroplasty treatments; however, it is not intended to mandate candidacy for treatment or intervention.

Clinical evaluation of the AAOS AUC is necessary to determine how treatment recommendations correlate with current practice. A recent examination of the AAOS Appropriateness System for Surgical Management of Knee OA found that prognostic/predictor variables, such as patient age, OA severity, and pattern of knee OA involvement were more heavily weighted when determining arthroplasty appropriateness than was pain severity or functional loss.⁶ Furthermore, non-AAOS AUC prognostic/predictor variables, such as race and gender, have been linked to disparities in utilization of knee OA interventions.^7-9 Such disparities can be costly not just from a patient perceptive, but also employer and societal perspectives.¹⁰

The Department of Veterans Affairs (VA) health care system represents a model of equal-access-to care system in the US that is ideal for examination of issues about health care utilization and any disparities within the AAOS AUC model and has previously been used to assess utilization of total knee arthroplasty.⁹ The aim of this study was to characterize utilization of the AAOS AUC for nonarthroplasty treatment of knee OA in a VA patient population. We asked the following questions: (1) What variables are predictive of receiving a greater number of AAOS AUC evaluated nonarthroplasty treatments? (2) What variables are predictive of receiving “rarely appropriate” AAOS AUC evaluated nonarthroplasty treatment? (3) What factors are predictive of duration of nonarthroplasty care until total knee arthroplasty (TKA)?

Methods

The institutional review board at the Louis Stokes Cleveland VA Medical Center in Ohio approved a retrospective chart review of nonarthroplasty treatments utilized by patients presenting to its orthopaedic section who subsequently underwent knee arthroplasty between 2013 and 2016. Eligibility criteria included patients aged ≥ 30 years with a diagnosis of unilateral or bilateral primary knee OA. Patients with posttraumatic OA, inflammatory arthritis, and a history of infectious arthritis or Charcot arthropathy of the knee were excluded. Patients with a body mass index (BMI) > 40 or a hemoglobin A_1c > 8.0 at presentation were excluded as nonarthroplasty care was the recommended course of treatment above these thresholds.

Data collected included race, gender, duration of nonarthroplasty treatment, BMI, and Kellgren-Lawrence classification of knee OA at time of presentation for symptomatic knee OA.¹¹ All AAOS AUC-evaluated nonarthroplasty treatments utilized prior to arthroplasty intervention also were recorded (Table 1). 

Statistical Analysis

Statistical analysis was completed with GraphPad Software Prism 7.0a (La Jolla, CA) and Mathworks MatLab R2016b software (Natick, MA). Univariate analysis with Student t tests with Welch corrections in the setting of unequal variance, Mann-Whitney nonparametric tests, and Fisher exact test were generated in the appropriate setting. Multivariable analyses also were conducted. For continuous outcomes, stepwise multiple linear regression was used to generate predictive models; for binary outcomes, binomial logistic regression was used.

Factors analyzed in regression modeling for the total number of AAOS AUC evaluated nonarthroplasty treatments utilized and the likelihood of receiving a rarely appropriate treatment included gender, race, function-limiting pain, range of motion (ROM), ligamentous instability, arthritis pattern, limb alignment, mechanical symptoms, BMI, age, and Kellgren-Lawrence grade. Factors analyzed in timing of TKA included the above variables plus the total number of AUC interventions, whether the patient received an inappropriate intervention, and average appropriateness of the interventions received. Residual analysis with Cook’s distance was used to identify outliers in regression. Observations with Cook’s distance > 3 times the mean Cook’s distance were identified as potential outliers, and models were adjusted accordingly. All statistical analyses were 2-tailed. Statistical significance was set to P ≤ .05 for all outputs.

Results

In the study, 97.8% of participants identified as male, and the mean age was 62.8 years (Table 3). 

Appropriate Use Criteria Interventions

Patients received a mean of 5.2 AAOS AUC evaluated interventions before undergoing arthroplasty management at a mean of 32.3 months (range 2-181 months) from initial presentation. The majority of these interventions were classified as either appropriate or may be appropriate, according to the AUC definitions (95.1%). Self-management and physical therapy programs were widely utilized (100% and 90.1%, respectively), with all use of these interventions classified as appropriate.

Hinged or unloader knee braces were utilized in about half the study patients; this intervention was classified as rarely appropriate in 4.4% of these patients. Medical therapy was also widely used, with all use of NSAIDs, acetaminophen, and tramadol classified as appropriate or may be appropriate. Oral or transcutaneous opioid medications were prescribed in 14.3% of patients, with 92.3% of this use classified as rarely appropriate. Although the opioid medication prescribing provider was not specifically evaluated, there were no instances in which the orthopaedic service provided an oral or transcutaneous opioid prescriptions. Procedural interventions, with the exception of corticosteroid injections, were uncommon; no patient received realignment osteotomy, and only 12.1% of patients underwent arthroscopy. The use of arthroscopy was deemed rarely appropriate in 72.7% of these cases.

Factors Associated With AAOS AUC Intervention Use

There was no difference in the number of AAOS AUC evaluated interventions received based on BMI (mean [SD] BMI < 35, 5.2 [1.0] vs BMI ≥ 35, 5.3 [1.1], P = .49), age (mean [SD] aged < 60 years, 5.4 [1.0] vs aged ≥ 60 years, 5.1 [1.2], P = .23), or Kellgren-Lawrence arthritic grade (mean [SD] grade ≤ 2, 5.5 [1.0] vs grade > 2, 5.1 [1.1], P = .06). These variables also were not associated with receiving a rarely appropriate intervention (mean [SD] BMI < 35, 0.27 [0.5] vs BMI > 35, 0.2 [0.4], P = .81; aged > 60 years, 0.3 [0.5] vs aged < 60 years, 0.2 [0.4], P = .26; Kellgren-Lawrence grade < 2, 0.4 [0.6] vs grade > 2, 0.2 [0.4], P = .1).

Regression modeling to predict total number of AAOS AUC evaluated interventions received produced a significant model (R² = 0.111, P = .006). The presence of ligamentous instability (β coefficient, -1.61) and the absence of mechanical symptoms (β coefficient, -0.67) were negative predictors of number of AUC interventions received. Variance inflation factors were 1.014 and 1.012, respectively. Likewise, regression modeling to identify factors predictive of receiving a rarely appropriate intervention also produced a significant model (pseudo R²= 0.06, P = .025), with lower Kellgren-Lawrence grade the only significant predictor of receiving a rarely appropriate intervention (odds ratio [OR] 0.54; 95% CI, 0.42 -0.72, per unit increase).

Timing from presentation to arthroplasty intervention was also evaluated. Age was a negative predictor (β coefficient -1.61), while positive predictors were reduced ROM (β coefficient 15.72) and having more AUC interventions (β coefficient 7.31) (model R²= 0.29, P = < .001). Age was the most significant predictor. Variance inflations factors were 1.02, 1.01, and 1.03, respectively. Receiving a rarely appropriate intervention was not associated with TKA timing.

Discussion

This single-center retrospective study examined the utilization of AAOS AUC-evaluated nonarthroplasty interventions for symptomatic knee OA prior to TKA. The aims of this study were to validate the AAOS AUC in a clinical setting and identify predictors of AAOS AUC utilization. In particular, this study focused on the number of interventions utilized prior to knee arthroplasty, whether interventions receiving a designation of rarely appropriate were used, and the duration of nonarthroplasty treatment.

Patients with knee instability used fewer total AAOS AUC evaluated interventions prior to TKA. Subjective instability has been reported as high as 27% in patients with OA and has been associated with fear of falling, poor balance confidence, activity limitations, and lower Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function scores.¹² However, it has not been found to correlate with knee laxity.¹³ Nevertheless, significant functional impairment with the risk of falling may reduce the number of nonarthroplasty interventions attempted. On the other hand, the presence of mechanical symptoms resulted in greater utilization of nonarthroplasty interventions. This is likely due to the greater utilization of arthroscopic partial menisectomy or loose body removal in this group of patients. Despite its inclusion as an AAOS AUC evaluated intervention, arthroscopy remains a contentious treatment for symptomatic knee pain in the setting of OA.^14,15

For every unit decrease in Kellgren-Lawrence OA grade, patients were 54% more likely to receive a rarely appropriate intervention prior to knee arthroplasty. This is supported by the recent literature examining the AAOS AUC for surgical management of knee OA. Riddle and colleagues developed a classification tree to determine the contributions of various prognostic variables in final classifications of the 864 clinical vignettes used to develop the appropriateness algorithm and found that OA severity was strongly favored, with only 4 of the 432 vignettes with severe knee OA judged as rarely appropriate for surgical intervention.⁶

Our findings, too, may be explained by an AAOS AUC system that too heavily weighs radiographic severity of knee OA, resulting in more frequent rarely appropriate interventions in patients with less severe arthritis, including nonarthroplasty treatments. It is likely that rarely appropriate interventions were attempted in this subset of our study cohort based on patient’s subjective symptoms and functional status, both of which have been shown to be discordant with radiographic severity of knee OA.¹⁶

Oral or transcutaneous prescribed opioid medications were the most frequent intervention that received a rarely appropriate designation. Patients with preoperative opioid use undergoing TKA have been shown to have a greater risk for postoperative complications and longer hospital stay, particularly those patients aged < 75 years. Younger age, use of more interventions, and decreased knee ROM at presentation were predictive of longer duration of nonarthroplasty treatment. The use of more AAOS AUC evaluated interventions in these patients suggests that the AAOS AUC model may effectively be used to manage symptomatic OA, increasing the time from presentation to knee arthroplasty.

Interestingly, the use of rarely appropriate interventions did not affect TKA timing, as would be expected in a clinically effective nonarthroplasty treatment model. The reasons for rarely appropriate nonsurgical interventions are complex and require further investigation. One possible explanation is that decreased ROM was a marker for mechanical symptoms that necessitated additional intervention in the form of knee arthroscopy, delaying time to TKA.

Limitations

There are several limitations of this study. First, the small sample size (N = 90) requires acknowledgment; however, this limitation reflects the difficulty in following patients for years prior to an operative intervention. Second, the study population consists of veterans using the VA system and may not be reflective of the general population, differing with respect to gender, racial, and socioeconomic factors. Nevertheless, studies examining TKA utilization found, aside from racial and ethnic variability, patient gender and age do not affect arthroplasty utilization rate in the VA system.¹⁷

Additional limitations stem from the retrospective nature of this study. While the Computerized Patient Record System and centralized care of the VA system allows for review of all physical therapy consultations, orthotic consultations, and medications within the VA system, any treatments and intervention delivered by non-VA providers were not captured. Furthermore, the ability to assess for confounding variables limiting the prescription of certain medications, such as chronic kidney disease with NSAIDs or liver disease with acetaminophen, was limited by our study design.

Although our study suffers from selection bias with respect to examination of nonarthroplasty treatment in patients who have ultimately undergone TKA, we feel that this subset of patients with symptomatic knee OA represents the majority of patients evaluated for knee OA by orthopaedic surgeons in the clinic setting. It should be noted that although realignment osteotomies were sometimes indicated as appropriate by AAOS AUC model in our study population, this intervention was never performed due to patient and surgeon preference. Additionally, although it is not an AAOS AUC evaluated intervention, viscosupplementation was sporadically used during the study period; however, it is now off formulary at the investigation institution.

Conclusion

Our study suggests that patients without knee instability use more nonarthroplasty treatments over a longer period before TKA, and those patients with less severe knee OA are at risk of receiving an intervention judged to be rarely appropriate by the AAOS AUC. Such interventions do not affect timing of TKA. Nonarthroplasty care should be individualized to patients’ needs, and the decision to proceed with arthroplasty should be considered only after exhausting appropriate conservative measures. We recommend that providers use the AAOS AUC, especially when treating younger patients with less severe knee OA, particularly if considering opiate therapy or knee arthroscopy.

Acknowledgments
The authors would like to acknowledge Patrick Getty, MD, for his surgical care of some of the study patients. This material is the result of work supported with resources and the use of facilities at the Louis Stokes Cleveland VA Medical Center in Ohio.

ABSTRACT

Publications on the prevalence of unicompartmental knee arthroplasty in the United States using a single database may have underestimated the “true” number of cases performed, given that several unicondylar knee arthroplasty (UKA) patients are <65 years and have private insurance. The prevalence of UKA in elderly (≥65 years) and younger (<65 years) populations was evaluated using the 2002 to 2011 5% sample of the Medicare data (Part B) and the 2004 to June 2012 MarketScan Commercial and Medicare Supplemental databases, respectively. The prevalence of UKA was stratified by age, gender, census region, Charlson comorbidity index, Medicare buy-in status, and diagnosis. The annual rate of change in the UKA rate was examined using Poisson regression to evaluate temporal changes considering year as a covariate.

A total of 5235 and 23,310 UKA procedures were identified from the 5% Medicare and MarketScan databases, respectively. The rates of UKA generally increased until 2008, after which there was a decline. In both cohorts, gender and year of operation were found to be significantly associated with UKA rate. Analysis of data obtained over the past few years revealed that males 55 to 64 years, 65 to 69 years, and 70 to 74 years were the only age-gender groups whose UKA rates appeared to be trending upward.

From 2002 to 2011, the rate of UKAs performed in the United States has increased, and a significant proportion of the surgeries were performed in younger (<65 years) patients.

Continue to: Unicondylar knee arthroplasty...

Unicondylar knee arthroplasty (UKA) is an effective surgical treatment for symptomatic degenerative joint disease of a single compartment of the knee, providing improved functional outcomes compared with total knee arthroplasty (TKA).^1-3 It has been estimated that the proportion of patients undergoing TKA, who meet the criteria for UKA, varies between 21% and 47%.^4,5 However, it has been variably estimated that the usage of UKA ranges from 0% to 50% (mean, 8%) of all primary knee arthroplasties.^5-8 It is believed that this discrepancy between the percentage of patients who meet indications for the surgery and those who receive it is associated with various factors, including surgeon training and experiences, diverse indications, economic factors, as well as acknowledgment of the reportedly higher revision rates of UKA than those of TKA in national joint registries.^7,9-11

According to their classic article, Kozinn and Scott¹² outlined the indications for UKA that, in their experience, led to the most successful outcomes, including age >60 years, weight <82 kg, low physical demand, localized arthritis with no full-thickness chondromalacia elsewhere in the joint, intact anterior cruciate ligament, minimal deformity, and flexion >90°. More recently, indications have been expanded to include younger and more active patients, higher body mass index, and some patterns of patellofemoral chondromalacia, with an increasing number of publications reporting successful clinical outcomes in these cohorts as well.^13-17 Taken together, it is clear that the “classic” strict indications for UKA can be safely expanded, which have and will result in an increased number of these procedures being performed above and beyond that which might be predicted based on demographic trends alone.

A growing body of literature has been published on the prevalence and projections of orthopedic procedures in the United States.^18-20 Several studies have focused their analysis on 1 of several large administrative databases, including the Nationwide Inpatient Sample, the 5% Medicare Part B database, and the National Hospital Discharge Survey.^18,20-23 A concern with limiting an analysis of the prevalence of unicompartmental knee arthroplasty to these particular databases is that it may underestimate the “true” number of cases performed in the United States, given that several UKA patients are <65 years and have private insurance, and therefore, would not be captured statistically by a database that collects data on patients ≥65 years.

The purpose of this study was to quantify the current prevalence and epidemiology of UKA in the U.S. patient population. Our hypothesis was that the number of procedures and the procedural rate of UKA are increasing over time. Furthermore, this increase may be attributed to an increase in select age- or gender-based segments of the population. To test this hypothesis, we analyzed 2 separate large claims databases to capture patients over a spectrum of age and inclusive of both private and public payers, including the 5% Medicare Part B database (2002–2011) for patients ≥65 years and the MarketScan database (2004 to June 2011) for patients <65 years. Understanding the accurate trends in the use of UKA on a national scale is important for legislative bodies, healthcare administrators, and physicians.

MATERIALS AND METHODS

The 2002 to 2011 5% sample of the Medicare data (Part B) and the 2004 to June 2012 MarketScan Commercial and Medicare Supplemental databases were used to evaluate the prevalence of UKA in elderly (≥65 years) and younger (<65 years) populations, respectively. The UKA procedures were identified using the CPT code 27446.

The prevalence of UKA was stratified by age, gender, census region, Charlson Comorbidity Index, Medicare buy-in status, and diagnosis. The buy-in status is a proxy for the socioeconomic status as it reflects the state subsidizing the health insurance premium for the beneficiary. The Charlson Comorbidity Index is a composite score that has been used to assess the comorbidity level of a patient by taking into account the number and the severity of comorbid conditions.²⁴ For the elderly population, the rate of UKA was subsequently evaluated based on the number of beneficiaries for that particular age-gender group and year in both databases. Poisson regression was used to evaluate the annual rate of change in the UKA rate for assessing temporal changes considering year as a covariate. Age and gender, as well as 2-way interaction terms for age, gender, and year, were also considered as covariates. 

Continue to: RESULTS...

 

 

RESULTS

For the time periods analyzed, a total of 5235 and 23,310 UKA procedures were identified from the 5% Medicare and MarketScan databases, respectively. A peak in the prevalence appeared around 2008 for the elderly population and in 2009 for the younger population (Figure 1). When normalized by the size of the population segment, the rate of UKA was found to be approximately 5 times greater in the elderly population, increasing from 369 in 2002 to 639 in 2008, but plateauing to 561 in 2011. Extrapolating to the 100% Medicare population, these numbers increased to 7380, 12,780, and 11,220, respectively. Temporal changes in the UKA rate were significant, increasing from 24.5 UKAs per 100,000 persons in 2002 to 43.1 UKAs in 2008, followed by a decline to 36.5 in 2011 (P < .0001) (Figure 2). The rates of UKA generally increased from 2002 to 2008 for both males and females in the Medicare cohort; however, the rates of UKA in female patients continuously declined from 2008 onward, whereas the UKA rates in male patients decreased in 2009, followed by an increase in 2010 and 2011 (Figure 2). For the younger population, there was a slight increase in the rate of UKA from 2004 to approximately 2009, after which the rates for both males and females remained relatively steady. When put in the context of the prevalence of TKA, the prevalence of UKA fluctuated during the same time period. In the Medicare population, the prevalence of UKA ranged from 4.3% (2005) to 5.9% (2008) of the TKA prevalence between 2002 and 2011. In the younger MarketScan population, the prevalence of UKA ranged from 6.7% (2005) to 8.9% (2008) between 2004 and June 2012.

The UKA rate differed significantly according to gender (P = .0209), with higher rates for males. Although there were no age-related differences (P = .3723), age–gender interactions were found to be significant (P < .0001). For males, the largest rate of UKA in the most recent year of data was observed in the 70- to 74-year-old group, followed by the 75- to 79- and the 65- to 69-year-old groups (Figure 3). For females, those in the 65- to 69- and the 70- to 74-year-old groups had the highest rate of UKA. In the younger cohort, there were increases in the UKA rates since 2004. These rates appeared to be relatively stable from the 2008 or 2009 period onward, except for females 55–64 years, which demonstrated a steady decline since 2008. Analysis of data obtained over the past few years showed that males 55–64, 65–69, and 70–74 years were the only age–gender groups whose UKA rates appeared to be trending upward.

The vast majority of elderly UKA patients were white (95.5%), and when stratified by census region, the highest proportion of UKA procedures was observed in the South and the Midwest (Figure 4). Furthermore, among patients <65 years, 64.2% had a Charlson score of 0 compared to 40.8% in the elderly group (Figure 5). For the Medicare population, based on their receipt of state subsidies for their insurance premiums, 5.1% of patients were of lower socioeconomic status. Osteoarthritis was diagnosed in 99.4% and 97.3% of the MarketScan and Medicare cohorts, respectively.

In the Medicare cohort, gender (P = .0209) and year of operation (P < .0001) were found to be significantly associated with the rate of UKA, along with age-gender (P < .0001) and gender-year (P = .0202) interaction terms. In the MarketScan cohort, age (P = .0173), gender (P = .0017), and year of operation (P = .0002) were found to be significantly associated with UKA rate. Two-way interactions between age-gender (P = .0018), age–year (P = .0207), and gender-year (P = .0017) were also found to be statistically significant factors.

Continue to: DISCUSSION...

 

 

DISCUSSION

The results of our study indicate that between 2002 and 2011, a steadily increasing number of UKA procedures was performed in the United States, and a significant proportion of the surgeries was performed on patients <65 years. Without the MarketScan database data, we would have missed more than 23,000 UKA cases performed during this 10-year time period. This finding validates our research methodology that incorporated data on privately insured younger (<65 years) patients, which is something that has not been done when examining the epidemiology of UKA.

To our knowledge, there are only 2 other publications attempting to quantify the incidence of UKA procedures performed in the United States. Bolognesi and colleagues²³ used the Medicare 5% sample to assess trends in the use of knee arthroplasty from 2000 to 2009. The authors reported that a total of 68,603 patients underwent unilateral total knee arthroplasty (n = 65,505) or unicompartmental knee arthroplasty (n = 3098) over this 10-year time period. Given that there is substantial overlap of our time periods, it is not surprising that our Medicare numbers are similar (3098 vs 5235). In their study, the use of TKA increased 1.7-fold, whereas the use of UKA increased 6.2-fold²³. In our analysis of the Medicare (2011 vs 2002) and MarketScan (2011 vs 2004) databases, there was a 1.3-fold and a 3.4-fold increase in the number of TKAs performed. Concomitantly, the use of UKA increased 1.5-fold and 2.8-fold, respectively, in these databases over the same time periods. The reason for the slight discrepancy in the numbers may be attributable to the peak occurring in 2008. The other publication on the subject by Riddle and colleagues⁸ focused on the time period 1998 to 2005 and used implant manufacturer’s sales data cross-referenced to a database of 44 hospitals to derive their national estimates. Using their unique methodology, the authors calculated an incidence of UKA, ranging from 6570 implants in 1998 to 44,990 in 2005. They reported that UKA use during the study period increased by 3 times the rate of TKA in the United States, with an average yearly percentage increase in the number of UKA procedures of 32.5% compared to 9.4% for TKA procedures. It is difficult to account for the discrepancy in the number of UKAs performed reported between our current study and that of Riddle and colleagues;⁸ however, the fact that the authors used implant manufacturer’s individual sales numbers may indicate that a portion of UKA patients was not captured in either the Medicare 5% or the MarketScan database. Nonetheless, in our analysis, the annual increase in the number of UKA procedures performed during the time periods studied averaged 5.8% in the older population and 25.4% in the younger population compared to the increase in the number of TKA procedures, which averaged 3.6% and 33.9% in the older and younger populations, respectively. In addition, in our study, the percentage of UKAs performed relative to the number of TKAs during the time intervals studied varied from a low of 4.3% to a high of 5.9% in the older population and from a low of 6.7% to a high of 8.9% in the younger population.

During the 10-year period of this study, a general upward trend appeared in the total number of unicompartmental knee arthroplasties performed in both the Medicare and the MarketScan databases. The rate at which the procedure was performed increased in the Medicare population from 24.5 to 36.5 (per 100,000 persons) over a 10-year time period and in the MarketScan cohort from 5.9 to 7.4 (per 100,000 persons) over an 8.5-year time period. This indicates both a larger absolute and a relative rate increase in UKA procedures in the elderly population. Around 2008 and 2009, the data showed a slight dip in the rate of UKA in the Medicare population and a plateau in the rate in the MarketScan database. Although this may be a spurious finding in the data that would be smoothed out with a longer time period investigated, it is interesting that this finding coincided with a national economic downturn. Although it might be expected that macroeconomics may affect the utilization of elective surgery such as total joint replacement, Kurtz and colleagues²⁵ investigated this particular question and found that neither the economic downturns of 2001 or those of 2008 and 2009 had a significant impact on the incidence of total joint replacement surgeries.

Incorporation of the MarketScan database data indicated that a significant proportion of patients undergoing UKA were <65 years and that there was a slight but increasing rate of procedures performed on this age cohort over the past decade. A similar finding has been reported in the Finnish Arthroplasty Registry. Leskinen and colleagues²⁶ reported that the incidence of UKAs among individuals 30 to 59 years increased from 0.2 (per 100,000 persons) to 10 (per 100,000 persons) from 1980 to 2006 and that most of the increase occurred among patients 50 to 59 years. The fact that younger age is no longer observed as a relative contraindication to this procedure is supported by several clinical investigations. Cartier and colleagues²⁷ reported 93% survival at 10 years in patients with a mean age of 65 years, but included patients as young as 28 years, claiming that the results for younger patients were no worse than those for older patients in the series. Pandit and colleagues¹⁷ compared the results of 245 young patients (<60 years) to those of 755 older patients (>60 years) and found a survival rate of 97% at 10 years, with no significant difference in mean functional outcomes, failure rate, or survival between the groups at >5 years of follow-up. Given that patients <65 years now account for approximately half of the TKAs performed each year, with the greatest increase in volume among patients between 45 and 54, it is clear that investigations on the epidemiology of UKA must take into account this increasingly relevant younger patient cohort.²⁸

Continue to: Our data indicate...

 

 

Our data indicate that only approximately 5% of UKA patients were non-white and another 5% were from lower socioeconomic status. These findings have been observed in multiple other studies looking at the epidemiology of total joint replacement in the United States.²⁹ Bolognesi and colleagues²³ reported that although “non-white race” patients made up 12% of the general Medicare sample they were analyzing, these patients accounted for only 5% and 3% of the total knee arthroplasty and unicompartmental knee arthroplasty populations, respectively. Although it is beyond the scope of this paper to delve into the reasons for this discrepancy, it may be related to differences in access to care, healthcare literacy, and trust of patients in the healthcare system.^30,31

Our study, like all those based on administrative claims, has several notable inherent limitations. Coding inaccuracies as well as the potential for systematic bias (eg, underreporting) may affect the accuracy of our results. Although the MarketScan Commercial Research Database (Truven Health Analytics) includes nationally representative information for >180 million patients covered with private insurance, it is possible that we have missed some patients who underwent UKA during the time period investigated. However, we feel that the number missed is probably small and does not affect our conclusions in any meaningful manner.

CONCLUSION

This novel analysis of 2 separate administrative claims databases, which more accurately captures all patients undergoing UKA, indicates that there has been a steady increase in the rate of the procedure over the past decade and that a significant proportion of the surgeries were performed in younger (<65 years) patients. Understanding the accurate trends in the use of UKA on a national scale is important for legislative bodies, healthcare administrators, as well as physicians. Furthermore, given the increasing rates of UKA in patients <65 years old, and the increased burden on implants for withstanding increased activities and repetitive loads, it remains imperative to strive to optimize materials, implant designs, and surgical techniques to enhance implant durability.

ABSTRACT

Publications on the prevalence of unicompartmental knee arthroplasty in the United States using a single database may have underestimated the “true” number of cases performed, given that several unicondylar knee arthroplasty (UKA) patients are <65 years and have private insurance. The prevalence of UKA in elderly (≥65 years) and younger (<65 years) populations was evaluated using the 2002 to 2011 5% sample of the Medicare data (Part B) and the 2004 to June 2012 MarketScan Commercial and Medicare Supplemental databases, respectively. The prevalence of UKA was stratified by age, gender, census region, Charlson comorbidity index, Medicare buy-in status, and diagnosis. The annual rate of change in the UKA rate was examined using Poisson regression to evaluate temporal changes considering year as a covariate.

A total of 5235 and 23,310 UKA procedures were identified from the 5% Medicare and MarketScan databases, respectively. The rates of UKA generally increased until 2008, after which there was a decline. In both cohorts, gender and year of operation were found to be significantly associated with UKA rate. Analysis of data obtained over the past few years revealed that males 55 to 64 years, 65 to 69 years, and 70 to 74 years were the only age-gender groups whose UKA rates appeared to be trending upward.

From 2002 to 2011, the rate of UKAs performed in the United States has increased, and a significant proportion of the surgeries were performed in younger (<65 years) patients.

Continue to: Unicondylar knee arthroplasty...

Unicondylar knee arthroplasty (UKA) is an effective surgical treatment for symptomatic degenerative joint disease of a single compartment of the knee, providing improved functional outcomes compared with total knee arthroplasty (TKA).^1-3 It has been estimated that the proportion of patients undergoing TKA, who meet the criteria for UKA, varies between 21% and 47%.^4,5 However, it has been variably estimated that the usage of UKA ranges from 0% to 50% (mean, 8%) of all primary knee arthroplasties.^5-8 It is believed that this discrepancy between the percentage of patients who meet indications for the surgery and those who receive it is associated with various factors, including surgeon training and experiences, diverse indications, economic factors, as well as acknowledgment of the reportedly higher revision rates of UKA than those of TKA in national joint registries.^7,9-11

According to their classic article, Kozinn and Scott¹² outlined the indications for UKA that, in their experience, led to the most successful outcomes, including age >60 years, weight <82 kg, low physical demand, localized arthritis with no full-thickness chondromalacia elsewhere in the joint, intact anterior cruciate ligament, minimal deformity, and flexion >90°. More recently, indications have been expanded to include younger and more active patients, higher body mass index, and some patterns of patellofemoral chondromalacia, with an increasing number of publications reporting successful clinical outcomes in these cohorts as well.^13-17 Taken together, it is clear that the “classic” strict indications for UKA can be safely expanded, which have and will result in an increased number of these procedures being performed above and beyond that which might be predicted based on demographic trends alone.

A growing body of literature has been published on the prevalence and projections of orthopedic procedures in the United States.^18-20 Several studies have focused their analysis on 1 of several large administrative databases, including the Nationwide Inpatient Sample, the 5% Medicare Part B database, and the National Hospital Discharge Survey.^18,20-23 A concern with limiting an analysis of the prevalence of unicompartmental knee arthroplasty to these particular databases is that it may underestimate the “true” number of cases performed in the United States, given that several UKA patients are <65 years and have private insurance, and therefore, would not be captured statistically by a database that collects data on patients ≥65 years.

The purpose of this study was to quantify the current prevalence and epidemiology of UKA in the U.S. patient population. Our hypothesis was that the number of procedures and the procedural rate of UKA are increasing over time. Furthermore, this increase may be attributed to an increase in select age- or gender-based segments of the population. To test this hypothesis, we analyzed 2 separate large claims databases to capture patients over a spectrum of age and inclusive of both private and public payers, including the 5% Medicare Part B database (2002–2011) for patients ≥65 years and the MarketScan database (2004 to June 2011) for patients <65 years. Understanding the accurate trends in the use of UKA on a national scale is important for legislative bodies, healthcare administrators, and physicians.

MATERIALS AND METHODS

The 2002 to 2011 5% sample of the Medicare data (Part B) and the 2004 to June 2012 MarketScan Commercial and Medicare Supplemental databases were used to evaluate the prevalence of UKA in elderly (≥65 years) and younger (<65 years) populations, respectively. The UKA procedures were identified using the CPT code 27446.

The prevalence of UKA was stratified by age, gender, census region, Charlson Comorbidity Index, Medicare buy-in status, and diagnosis. The buy-in status is a proxy for the socioeconomic status as it reflects the state subsidizing the health insurance premium for the beneficiary. The Charlson Comorbidity Index is a composite score that has been used to assess the comorbidity level of a patient by taking into account the number and the severity of comorbid conditions.²⁴ For the elderly population, the rate of UKA was subsequently evaluated based on the number of beneficiaries for that particular age-gender group and year in both databases. Poisson regression was used to evaluate the annual rate of change in the UKA rate for assessing temporal changes considering year as a covariate. Age and gender, as well as 2-way interaction terms for age, gender, and year, were also considered as covariates. 

Continue to: RESULTS...

 

 

RESULTS

For the time periods analyzed, a total of 5235 and 23,310 UKA procedures were identified from the 5% Medicare and MarketScan databases, respectively. A peak in the prevalence appeared around 2008 for the elderly population and in 2009 for the younger population (Figure 1). When normalized by the size of the population segment, the rate of UKA was found to be approximately 5 times greater in the elderly population, increasing from 369 in 2002 to 639 in 2008, but plateauing to 561 in 2011. Extrapolating to the 100% Medicare population, these numbers increased to 7380, 12,780, and 11,220, respectively. Temporal changes in the UKA rate were significant, increasing from 24.5 UKAs per 100,000 persons in 2002 to 43.1 UKAs in 2008, followed by a decline to 36.5 in 2011 (P < .0001) (Figure 2). The rates of UKA generally increased from 2002 to 2008 for both males and females in the Medicare cohort; however, the rates of UKA in female patients continuously declined from 2008 onward, whereas the UKA rates in male patients decreased in 2009, followed by an increase in 2010 and 2011 (Figure 2). For the younger population, there was a slight increase in the rate of UKA from 2004 to approximately 2009, after which the rates for both males and females remained relatively steady. When put in the context of the prevalence of TKA, the prevalence of UKA fluctuated during the same time period. In the Medicare population, the prevalence of UKA ranged from 4.3% (2005) to 5.9% (2008) of the TKA prevalence between 2002 and 2011. In the younger MarketScan population, the prevalence of UKA ranged from 6.7% (2005) to 8.9% (2008) between 2004 and June 2012.

The UKA rate differed significantly according to gender (P = .0209), with higher rates for males. Although there were no age-related differences (P = .3723), age–gender interactions were found to be significant (P < .0001). For males, the largest rate of UKA in the most recent year of data was observed in the 70- to 74-year-old group, followed by the 75- to 79- and the 65- to 69-year-old groups (Figure 3). For females, those in the 65- to 69- and the 70- to 74-year-old groups had the highest rate of UKA. In the younger cohort, there were increases in the UKA rates since 2004. These rates appeared to be relatively stable from the 2008 or 2009 period onward, except for females 55–64 years, which demonstrated a steady decline since 2008. Analysis of data obtained over the past few years showed that males 55–64, 65–69, and 70–74 years were the only age–gender groups whose UKA rates appeared to be trending upward.

The vast majority of elderly UKA patients were white (95.5%), and when stratified by census region, the highest proportion of UKA procedures was observed in the South and the Midwest (Figure 4). Furthermore, among patients <65 years, 64.2% had a Charlson score of 0 compared to 40.8% in the elderly group (Figure 5). For the Medicare population, based on their receipt of state subsidies for their insurance premiums, 5.1% of patients were of lower socioeconomic status. Osteoarthritis was diagnosed in 99.4% and 97.3% of the MarketScan and Medicare cohorts, respectively.

In the Medicare cohort, gender (P = .0209) and year of operation (P < .0001) were found to be significantly associated with the rate of UKA, along with age-gender (P < .0001) and gender-year (P = .0202) interaction terms. In the MarketScan cohort, age (P = .0173), gender (P = .0017), and year of operation (P = .0002) were found to be significantly associated with UKA rate. Two-way interactions between age-gender (P = .0018), age–year (P = .0207), and gender-year (P = .0017) were also found to be statistically significant factors.

Continue to: DISCUSSION...

 

 

DISCUSSION

The results of our study indicate that between 2002 and 2011, a steadily increasing number of UKA procedures was performed in the United States, and a significant proportion of the surgeries was performed on patients <65 years. Without the MarketScan database data, we would have missed more than 23,000 UKA cases performed during this 10-year time period. This finding validates our research methodology that incorporated data on privately insured younger (<65 years) patients, which is something that has not been done when examining the epidemiology of UKA.

To our knowledge, there are only 2 other publications attempting to quantify the incidence of UKA procedures performed in the United States. Bolognesi and colleagues²³ used the Medicare 5% sample to assess trends in the use of knee arthroplasty from 2000 to 2009. The authors reported that a total of 68,603 patients underwent unilateral total knee arthroplasty (n = 65,505) or unicompartmental knee arthroplasty (n = 3098) over this 10-year time period. Given that there is substantial overlap of our time periods, it is not surprising that our Medicare numbers are similar (3098 vs 5235). In their study, the use of TKA increased 1.7-fold, whereas the use of UKA increased 6.2-fold²³. In our analysis of the Medicare (2011 vs 2002) and MarketScan (2011 vs 2004) databases, there was a 1.3-fold and a 3.4-fold increase in the number of TKAs performed. Concomitantly, the use of UKA increased 1.5-fold and 2.8-fold, respectively, in these databases over the same time periods. The reason for the slight discrepancy in the numbers may be attributable to the peak occurring in 2008. The other publication on the subject by Riddle and colleagues⁸ focused on the time period 1998 to 2005 and used implant manufacturer’s sales data cross-referenced to a database of 44 hospitals to derive their national estimates. Using their unique methodology, the authors calculated an incidence of UKA, ranging from 6570 implants in 1998 to 44,990 in 2005. They reported that UKA use during the study period increased by 3 times the rate of TKA in the United States, with an average yearly percentage increase in the number of UKA procedures of 32.5% compared to 9.4% for TKA procedures. It is difficult to account for the discrepancy in the number of UKAs performed reported between our current study and that of Riddle and colleagues;⁸ however, the fact that the authors used implant manufacturer’s individual sales numbers may indicate that a portion of UKA patients was not captured in either the Medicare 5% or the MarketScan database. Nonetheless, in our analysis, the annual increase in the number of UKA procedures performed during the time periods studied averaged 5.8% in the older population and 25.4% in the younger population compared to the increase in the number of TKA procedures, which averaged 3.6% and 33.9% in the older and younger populations, respectively. In addition, in our study, the percentage of UKAs performed relative to the number of TKAs during the time intervals studied varied from a low of 4.3% to a high of 5.9% in the older population and from a low of 6.7% to a high of 8.9% in the younger population.

During the 10-year period of this study, a general upward trend appeared in the total number of unicompartmental knee arthroplasties performed in both the Medicare and the MarketScan databases. The rate at which the procedure was performed increased in the Medicare population from 24.5 to 36.5 (per 100,000 persons) over a 10-year time period and in the MarketScan cohort from 5.9 to 7.4 (per 100,000 persons) over an 8.5-year time period. This indicates both a larger absolute and a relative rate increase in UKA procedures in the elderly population. Around 2008 and 2009, the data showed a slight dip in the rate of UKA in the Medicare population and a plateau in the rate in the MarketScan database. Although this may be a spurious finding in the data that would be smoothed out with a longer time period investigated, it is interesting that this finding coincided with a national economic downturn. Although it might be expected that macroeconomics may affect the utilization of elective surgery such as total joint replacement, Kurtz and colleagues²⁵ investigated this particular question and found that neither the economic downturns of 2001 or those of 2008 and 2009 had a significant impact on the incidence of total joint replacement surgeries.

Incorporation of the MarketScan database data indicated that a significant proportion of patients undergoing UKA were <65 years and that there was a slight but increasing rate of procedures performed on this age cohort over the past decade. A similar finding has been reported in the Finnish Arthroplasty Registry. Leskinen and colleagues²⁶ reported that the incidence of UKAs among individuals 30 to 59 years increased from 0.2 (per 100,000 persons) to 10 (per 100,000 persons) from 1980 to 2006 and that most of the increase occurred among patients 50 to 59 years. The fact that younger age is no longer observed as a relative contraindication to this procedure is supported by several clinical investigations. Cartier and colleagues²⁷ reported 93% survival at 10 years in patients with a mean age of 65 years, but included patients as young as 28 years, claiming that the results for younger patients were no worse than those for older patients in the series. Pandit and colleagues¹⁷ compared the results of 245 young patients (<60 years) to those of 755 older patients (>60 years) and found a survival rate of 97% at 10 years, with no significant difference in mean functional outcomes, failure rate, or survival between the groups at >5 years of follow-up. Given that patients <65 years now account for approximately half of the TKAs performed each year, with the greatest increase in volume among patients between 45 and 54, it is clear that investigations on the epidemiology of UKA must take into account this increasingly relevant younger patient cohort.²⁸

Continue to: Our data indicate...

 

 

Our data indicate that only approximately 5% of UKA patients were non-white and another 5% were from lower socioeconomic status. These findings have been observed in multiple other studies looking at the epidemiology of total joint replacement in the United States.²⁹ Bolognesi and colleagues²³ reported that although “non-white race” patients made up 12% of the general Medicare sample they were analyzing, these patients accounted for only 5% and 3% of the total knee arthroplasty and unicompartmental knee arthroplasty populations, respectively. Although it is beyond the scope of this paper to delve into the reasons for this discrepancy, it may be related to differences in access to care, healthcare literacy, and trust of patients in the healthcare system.^30,31

Our study, like all those based on administrative claims, has several notable inherent limitations. Coding inaccuracies as well as the potential for systematic bias (eg, underreporting) may affect the accuracy of our results. Although the MarketScan Commercial Research Database (Truven Health Analytics) includes nationally representative information for >180 million patients covered with private insurance, it is possible that we have missed some patients who underwent UKA during the time period investigated. However, we feel that the number missed is probably small and does not affect our conclusions in any meaningful manner.

CONCLUSION

This novel analysis of 2 separate administrative claims databases, which more accurately captures all patients undergoing UKA, indicates that there has been a steady increase in the rate of the procedure over the past decade and that a significant proportion of the surgeries were performed in younger (<65 years) patients. Understanding the accurate trends in the use of UKA on a national scale is important for legislative bodies, healthcare administrators, as well as physicians. Furthermore, given the increasing rates of UKA in patients <65 years old, and the increased burden on implants for withstanding increased activities and repetitive loads, it remains imperative to strive to optimize materials, implant designs, and surgical techniques to enhance implant durability.

ABSTRACT

Publications on the prevalence of unicompartmental knee arthroplasty in the United States using a single database may have underestimated the “true” number of cases performed, given that several unicondylar knee arthroplasty (UKA) patients are <65 years and have private insurance. The prevalence of UKA in elderly (≥65 years) and younger (<65 years) populations was evaluated using the 2002 to 2011 5% sample of the Medicare data (Part B) and the 2004 to June 2012 MarketScan Commercial and Medicare Supplemental databases, respectively. The prevalence of UKA was stratified by age, gender, census region, Charlson comorbidity index, Medicare buy-in status, and diagnosis. The annual rate of change in the UKA rate was examined using Poisson regression to evaluate temporal changes considering year as a covariate.

A total of 5235 and 23,310 UKA procedures were identified from the 5% Medicare and MarketScan databases, respectively. The rates of UKA generally increased until 2008, after which there was a decline. In both cohorts, gender and year of operation were found to be significantly associated with UKA rate. Analysis of data obtained over the past few years revealed that males 55 to 64 years, 65 to 69 years, and 70 to 74 years were the only age-gender groups whose UKA rates appeared to be trending upward.

From 2002 to 2011, the rate of UKAs performed in the United States has increased, and a significant proportion of the surgeries were performed in younger (<65 years) patients.

Continue to: Unicondylar knee arthroplasty...

Unicondylar knee arthroplasty (UKA) is an effective surgical treatment for symptomatic degenerative joint disease of a single compartment of the knee, providing improved functional outcomes compared with total knee arthroplasty (TKA).^1-3 It has been estimated that the proportion of patients undergoing TKA, who meet the criteria for UKA, varies between 21% and 47%.^4,5 However, it has been variably estimated that the usage of UKA ranges from 0% to 50% (mean, 8%) of all primary knee arthroplasties.^5-8 It is believed that this discrepancy between the percentage of patients who meet indications for the surgery and those who receive it is associated with various factors, including surgeon training and experiences, diverse indications, economic factors, as well as acknowledgment of the reportedly higher revision rates of UKA than those of TKA in national joint registries.^7,9-11

According to their classic article, Kozinn and Scott¹² outlined the indications for UKA that, in their experience, led to the most successful outcomes, including age >60 years, weight <82 kg, low physical demand, localized arthritis with no full-thickness chondromalacia elsewhere in the joint, intact anterior cruciate ligament, minimal deformity, and flexion >90°. More recently, indications have been expanded to include younger and more active patients, higher body mass index, and some patterns of patellofemoral chondromalacia, with an increasing number of publications reporting successful clinical outcomes in these cohorts as well.^13-17 Taken together, it is clear that the “classic” strict indications for UKA can be safely expanded, which have and will result in an increased number of these procedures being performed above and beyond that which might be predicted based on demographic trends alone.

A growing body of literature has been published on the prevalence and projections of orthopedic procedures in the United States.^18-20 Several studies have focused their analysis on 1 of several large administrative databases, including the Nationwide Inpatient Sample, the 5% Medicare Part B database, and the National Hospital Discharge Survey.^18,20-23 A concern with limiting an analysis of the prevalence of unicompartmental knee arthroplasty to these particular databases is that it may underestimate the “true” number of cases performed in the United States, given that several UKA patients are <65 years and have private insurance, and therefore, would not be captured statistically by a database that collects data on patients ≥65 years.

The purpose of this study was to quantify the current prevalence and epidemiology of UKA in the U.S. patient population. Our hypothesis was that the number of procedures and the procedural rate of UKA are increasing over time. Furthermore, this increase may be attributed to an increase in select age- or gender-based segments of the population. To test this hypothesis, we analyzed 2 separate large claims databases to capture patients over a spectrum of age and inclusive of both private and public payers, including the 5% Medicare Part B database (2002–2011) for patients ≥65 years and the MarketScan database (2004 to June 2011) for patients <65 years. Understanding the accurate trends in the use of UKA on a national scale is important for legislative bodies, healthcare administrators, and physicians.

MATERIALS AND METHODS

The 2002 to 2011 5% sample of the Medicare data (Part B) and the 2004 to June 2012 MarketScan Commercial and Medicare Supplemental databases were used to evaluate the prevalence of UKA in elderly (≥65 years) and younger (<65 years) populations, respectively. The UKA procedures were identified using the CPT code 27446.

The prevalence of UKA was stratified by age, gender, census region, Charlson Comorbidity Index, Medicare buy-in status, and diagnosis. The buy-in status is a proxy for the socioeconomic status as it reflects the state subsidizing the health insurance premium for the beneficiary. The Charlson Comorbidity Index is a composite score that has been used to assess the comorbidity level of a patient by taking into account the number and the severity of comorbid conditions.²⁴ For the elderly population, the rate of UKA was subsequently evaluated based on the number of beneficiaries for that particular age-gender group and year in both databases. Poisson regression was used to evaluate the annual rate of change in the UKA rate for assessing temporal changes considering year as a covariate. Age and gender, as well as 2-way interaction terms for age, gender, and year, were also considered as covariates. 

Continue to: RESULTS...

 

 

RESULTS

For the time periods analyzed, a total of 5235 and 23,310 UKA procedures were identified from the 5% Medicare and MarketScan databases, respectively. A peak in the prevalence appeared around 2008 for the elderly population and in 2009 for the younger population (Figure 1). When normalized by the size of the population segment, the rate of UKA was found to be approximately 5 times greater in the elderly population, increasing from 369 in 2002 to 639 in 2008, but plateauing to 561 in 2011. Extrapolating to the 100% Medicare population, these numbers increased to 7380, 12,780, and 11,220, respectively. Temporal changes in the UKA rate were significant, increasing from 24.5 UKAs per 100,000 persons in 2002 to 43.1 UKAs in 2008, followed by a decline to 36.5 in 2011 (P < .0001) (Figure 2). The rates of UKA generally increased from 2002 to 2008 for both males and females in the Medicare cohort; however, the rates of UKA in female patients continuously declined from 2008 onward, whereas the UKA rates in male patients decreased in 2009, followed by an increase in 2010 and 2011 (Figure 2). For the younger population, there was a slight increase in the rate of UKA from 2004 to approximately 2009, after which the rates for both males and females remained relatively steady. When put in the context of the prevalence of TKA, the prevalence of UKA fluctuated during the same time period. In the Medicare population, the prevalence of UKA ranged from 4.3% (2005) to 5.9% (2008) of the TKA prevalence between 2002 and 2011. In the younger MarketScan population, the prevalence of UKA ranged from 6.7% (2005) to 8.9% (2008) between 2004 and June 2012.

The UKA rate differed significantly according to gender (P = .0209), with higher rates for males. Although there were no age-related differences (P = .3723), age–gender interactions were found to be significant (P < .0001). For males, the largest rate of UKA in the most recent year of data was observed in the 70- to 74-year-old group, followed by the 75- to 79- and the 65- to 69-year-old groups (Figure 3). For females, those in the 65- to 69- and the 70- to 74-year-old groups had the highest rate of UKA. In the younger cohort, there were increases in the UKA rates since 2004. These rates appeared to be relatively stable from the 2008 or 2009 period onward, except for females 55–64 years, which demonstrated a steady decline since 2008. Analysis of data obtained over the past few years showed that males 55–64, 65–69, and 70–74 years were the only age–gender groups whose UKA rates appeared to be trending upward.

The vast majority of elderly UKA patients were white (95.5%), and when stratified by census region, the highest proportion of UKA procedures was observed in the South and the Midwest (Figure 4). Furthermore, among patients <65 years, 64.2% had a Charlson score of 0 compared to 40.8% in the elderly group (Figure 5). For the Medicare population, based on their receipt of state subsidies for their insurance premiums, 5.1% of patients were of lower socioeconomic status. Osteoarthritis was diagnosed in 99.4% and 97.3% of the MarketScan and Medicare cohorts, respectively.

In the Medicare cohort, gender (P = .0209) and year of operation (P < .0001) were found to be significantly associated with the rate of UKA, along with age-gender (P < .0001) and gender-year (P = .0202) interaction terms. In the MarketScan cohort, age (P = .0173), gender (P = .0017), and year of operation (P = .0002) were found to be significantly associated with UKA rate. Two-way interactions between age-gender (P = .0018), age–year (P = .0207), and gender-year (P = .0017) were also found to be statistically significant factors.

Continue to: DISCUSSION...

 

 

DISCUSSION

The results of our study indicate that between 2002 and 2011, a steadily increasing number of UKA procedures was performed in the United States, and a significant proportion of the surgeries was performed on patients <65 years. Without the MarketScan database data, we would have missed more than 23,000 UKA cases performed during this 10-year time period. This finding validates our research methodology that incorporated data on privately insured younger (<65 years) patients, which is something that has not been done when examining the epidemiology of UKA.

To our knowledge, there are only 2 other publications attempting to quantify the incidence of UKA procedures performed in the United States. Bolognesi and colleagues²³ used the Medicare 5% sample to assess trends in the use of knee arthroplasty from 2000 to 2009. The authors reported that a total of 68,603 patients underwent unilateral total knee arthroplasty (n = 65,505) or unicompartmental knee arthroplasty (n = 3098) over this 10-year time period. Given that there is substantial overlap of our time periods, it is not surprising that our Medicare numbers are similar (3098 vs 5235). In their study, the use of TKA increased 1.7-fold, whereas the use of UKA increased 6.2-fold²³. In our analysis of the Medicare (2011 vs 2002) and MarketScan (2011 vs 2004) databases, there was a 1.3-fold and a 3.4-fold increase in the number of TKAs performed. Concomitantly, the use of UKA increased 1.5-fold and 2.8-fold, respectively, in these databases over the same time periods. The reason for the slight discrepancy in the numbers may be attributable to the peak occurring in 2008. The other publication on the subject by Riddle and colleagues⁸ focused on the time period 1998 to 2005 and used implant manufacturer’s sales data cross-referenced to a database of 44 hospitals to derive their national estimates. Using their unique methodology, the authors calculated an incidence of UKA, ranging from 6570 implants in 1998 to 44,990 in 2005. They reported that UKA use during the study period increased by 3 times the rate of TKA in the United States, with an average yearly percentage increase in the number of UKA procedures of 32.5% compared to 9.4% for TKA procedures. It is difficult to account for the discrepancy in the number of UKAs performed reported between our current study and that of Riddle and colleagues;⁸ however, the fact that the authors used implant manufacturer’s individual sales numbers may indicate that a portion of UKA patients was not captured in either the Medicare 5% or the MarketScan database. Nonetheless, in our analysis, the annual increase in the number of UKA procedures performed during the time periods studied averaged 5.8% in the older population and 25.4% in the younger population compared to the increase in the number of TKA procedures, which averaged 3.6% and 33.9% in the older and younger populations, respectively. In addition, in our study, the percentage of UKAs performed relative to the number of TKAs during the time intervals studied varied from a low of 4.3% to a high of 5.9% in the older population and from a low of 6.7% to a high of 8.9% in the younger population.

During the 10-year period of this study, a general upward trend appeared in the total number of unicompartmental knee arthroplasties performed in both the Medicare and the MarketScan databases. The rate at which the procedure was performed increased in the Medicare population from 24.5 to 36.5 (per 100,000 persons) over a 10-year time period and in the MarketScan cohort from 5.9 to 7.4 (per 100,000 persons) over an 8.5-year time period. This indicates both a larger absolute and a relative rate increase in UKA procedures in the elderly population. Around 2008 and 2009, the data showed a slight dip in the rate of UKA in the Medicare population and a plateau in the rate in the MarketScan database. Although this may be a spurious finding in the data that would be smoothed out with a longer time period investigated, it is interesting that this finding coincided with a national economic downturn. Although it might be expected that macroeconomics may affect the utilization of elective surgery such as total joint replacement, Kurtz and colleagues²⁵ investigated this particular question and found that neither the economic downturns of 2001 or those of 2008 and 2009 had a significant impact on the incidence of total joint replacement surgeries.

Incorporation of the MarketScan database data indicated that a significant proportion of patients undergoing UKA were <65 years and that there was a slight but increasing rate of procedures performed on this age cohort over the past decade. A similar finding has been reported in the Finnish Arthroplasty Registry. Leskinen and colleagues²⁶ reported that the incidence of UKAs among individuals 30 to 59 years increased from 0.2 (per 100,000 persons) to 10 (per 100,000 persons) from 1980 to 2006 and that most of the increase occurred among patients 50 to 59 years. The fact that younger age is no longer observed as a relative contraindication to this procedure is supported by several clinical investigations. Cartier and colleagues²⁷ reported 93% survival at 10 years in patients with a mean age of 65 years, but included patients as young as 28 years, claiming that the results for younger patients were no worse than those for older patients in the series. Pandit and colleagues¹⁷ compared the results of 245 young patients (<60 years) to those of 755 older patients (>60 years) and found a survival rate of 97% at 10 years, with no significant difference in mean functional outcomes, failure rate, or survival between the groups at >5 years of follow-up. Given that patients <65 years now account for approximately half of the TKAs performed each year, with the greatest increase in volume among patients between 45 and 54, it is clear that investigations on the epidemiology of UKA must take into account this increasingly relevant younger patient cohort.²⁸

Continue to: Our data indicate...

 

 

Our data indicate that only approximately 5% of UKA patients were non-white and another 5% were from lower socioeconomic status. These findings have been observed in multiple other studies looking at the epidemiology of total joint replacement in the United States.²⁹ Bolognesi and colleagues²³ reported that although “non-white race” patients made up 12% of the general Medicare sample they were analyzing, these patients accounted for only 5% and 3% of the total knee arthroplasty and unicompartmental knee arthroplasty populations, respectively. Although it is beyond the scope of this paper to delve into the reasons for this discrepancy, it may be related to differences in access to care, healthcare literacy, and trust of patients in the healthcare system.^30,31

Our study, like all those based on administrative claims, has several notable inherent limitations. Coding inaccuracies as well as the potential for systematic bias (eg, underreporting) may affect the accuracy of our results. Although the MarketScan Commercial Research Database (Truven Health Analytics) includes nationally representative information for >180 million patients covered with private insurance, it is possible that we have missed some patients who underwent UKA during the time period investigated. However, we feel that the number missed is probably small and does not affect our conclusions in any meaningful manner.

CONCLUSION

This novel analysis of 2 separate administrative claims databases, which more accurately captures all patients undergoing UKA, indicates that there has been a steady increase in the rate of the procedure over the past decade and that a significant proportion of the surgeries were performed in younger (<65 years) patients. Understanding the accurate trends in the use of UKA on a national scale is important for legislative bodies, healthcare administrators, as well as physicians. Furthermore, given the increasing rates of UKA in patients <65 years old, and the increased burden on implants for withstanding increased activities and repetitive loads, it remains imperative to strive to optimize materials, implant designs, and surgical techniques to enhance implant durability.

ABSTRACT

The subvastus (SV) approach is a well-known muscle- and tendon-sparing approach for total knee arthroplasty (TKA), which has been shown in some studies to provide better outcomes in the visual analog pain score (VAS), knee range of motion (ROM), straight-leg raise, as well as faster rehabilitation, compared with the standard medial parapatellar (MP) approach. We previously described a new knee replacement technique known as the modified intervastus (MIV) approach. The MIV approach is a muscle- and tendon-sparing approach that is extensile and simple to perform. It may be used in the majority of complex primary cases and revisions. Here we describe the surgical technique for performing the MIV approach and provide functional outcome measures. A total of 127 patients (mean age, 66.75 years) underwent TKA using the MIV approach with 1-year follow-up. Clinical outcomes were assessed by recording both a VAS and knee ROM preoperatively, and again at several postoperative time points when the length of time required to ambulate independently (without assistive devices) was also measured. The VAS decreased significantly from the preoperative period (3.69 ± 2.22) to postoperative day 1 (3.17 ± 1.97) (P < .05). Although knee ROM decreased 1 week after surgery, the ROM increased by 6 weeks after surgery compared with the preoperative ROM, and the trend continued over the 1-year follow-up. One-third (33%) of patients were able to walk independently (without assistive devices) at 2 weeks and 78% at 8 weeks. The MIV approach to the knee is a muscle- and tendon-sparing approach that offers advantages over the SV approach and may be used for complex primary and revision total knee cases.

Continue to: Total knee arthroplasty... 

Total knee arthroplasty (TKA) is one of the most common orthopedic surgical procedures, with more than 600,000 TKAs performed annually in the United States, and by 2030 the number is expected to reach 3.48 million per year.¹Several approaches have been described for total TKA, and the medial parapatellar (MP) approach to the knee is considered the workhorse of total knee replacements. It is an extensile approach that is easy to perform but may delay active knee extension and straight-leg raise after surgery.²  Alternative approaches such as the subvastus (SV) and midvastus approaches to the knee (Figure 1A) typically allow a more rapid straight-leg raise but may be more challenging to perform and time-consuming in morbidly obese patients, muscular patients, and patients with severe deformities.³

The intervastus approach (Figure 1A) described by Jojima⁴ and others utilizes the interval between the quadriceps tendon and vastus medialis. Although it is a simple approach to perform that is extensile, it is not considered tendon-sparing since the vastus medialis inserts onto the medial aspect of the quadriceps tendon (Figure 2).⁵  Therefore, dissecting through this interval, without elevation of the vastus medialis (Figure 3A), damages the quadriceps tendon, and strangulation of the muscle occurs with repair of the arthrotomy site (Figure 3B).  This situation is even more likely in patients with a low-lying vastus medialis.⁶

The modified intervastus (MIV) approach described previously,⁷ may be used in the majority of patients undergoing TKA. The advantages of this approach include its extensile nature, similarities to an MP approach, and preservation of both the extensor mechanism and the vastus medialis, leading to a more rapid return to active knee extension than is traditionally observed.^2,7 The approach is simple to perform, easy to close, and is compatible with more extensile approaches such as a quadriceps snip if required in revision scenarios.⁷ However, functional outcomes of the MIV approach have not been quantified. It is unknown whether these outcomes will offer any advantages compared with the SV approach. Therefore, the objective of this study was to measure functional outcomes of the MIV approach and to compare the results with those previously published for the SV approach. We hypothesized that using the MIV approach for TKA surgery would lead to early straight-leg raise and increase in knee range of motion (ROM) postoperatively.

SURGICAL TECHNIQUE

The MIV approach preserves the quadriceps tendon and vastus medialis.⁷ After exposure of the vastus medialis muscle, the interval between the quadriceps tendon and vastus medialis is identified (Figure 4).  The fascia overlying the lateral edge of the vastus medialis is incised where it meets the quadriceps tendon (Figure 5).  The muscle is then bluntly elevated off the underlying capsule just enough to allow for a capsular repair later (Figure 6).  An arthrotomy is then performed from cephalad to caudal (Figure 7).  This interval may be extended proximally between the vastus intermedius and vastus medialis to expose the distal femur if needed. The closure is performed by repairing the capsule with absorbable suture (Figure 8A), and the vastus medialis fascia is repaired back to the medial edge of the quadriceps tendon, restoring the anatomy (Figure 8B).

Continue to: PATIENTS AND METHODS...

 

 

PATIENTS AND METHODS

A retrospective review of functional outcomes after TKA using the MIV approach was conducted; the study was approved by the University of Illinois Institutional Review Board. A total of 127 patients of mean age 66.75 years (range, 48–86 years) with primary osteoarthritis of the knee who were indicated for a total knee replacement with 1-year follow-up were included. The patient demographics are shown in Table 1.  All patients underwent TKA using the MIV approach described above by 2 experienced orthopedic surgeons at the same institution. Patients received spinal anesthesia and a periarticular pain block intraoperatively. A measured resection technique was used by 1 surgeon, and a gap-balancing technique by the other. Surgeon 1 used the Persona PS cemented knee system (Zimmer Biomet, and Surgeon 2 used the Sigma PS cemented knee system (Depuy). Patellar resurfacing was done in all cases. Patellar tracking was checked intraoperatively using the ‘no-touch’ technique, and the need for a lateral release was noted. Drains were removed on postoperative day 1. Oral opioids were given as needed. Intravenous antibiotics were continued for 24 hours. Oral anticoagulants were used for thromboembolism prophylaxis for 3 weeks. Patients were mobilized on the day of surgery with full weight-bearing under the supervision of an experienced physical therapist. Static and dynamic quadriceps exercises were started on the same day of surgery along with active knee ROM exercises. Pain score, extensor lag, ROM, walking ability, and complications were recorded in all patients.

Table 1. Patient Demographics

Total no. of patients		127
Gender	Male	44
	Female	83
Age (years)	Mean ± Standard deviation	66.75 ± 9.12
	Range	48 – 86
Weight (lb)	Mean ± Standard deviation	218.38 ± 54.47
	Range	125 – 364
BMI (kg/m2)	Mean ± Standard deviation	34.10 ± 7.22
	Range	21.1 – 62.5

The visual analog score (VAS) was obtained preoperatively and recorded on postoperative day 1. Patient walking distance with assistance was measured on the day of surgery, after surgery, and on the day of hospital discharge. Patients were assessed preoperatively and postoperatively at 1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year for knee ROM. A one-way ANOVA was conducted to compare the preoperative and postoperative day 1 VAS with significance set at P < .05 (OriginPro 2015, OriginLab Corporation). Differences in knee ROM between preoperative and postoperative follow-up periods (1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year) were identified using a 1-way ANOVA with a post hoc Tukey test. Significance was set at P < .05.

RESULTS

All patients were able to fully straight-leg raise and demonstrate functional knee ROM by postoperative day 1. The patella tracked centrally in all patients, and none required a lateral retinacular release. The majority of patients were discharged in the first 48 hours after surgery on oral narcotics. None required IV narcotics during their hospital stay or a blood transfusion. Two cases were complicated by severe knee skin blistering postoperatively due to a reaction to an adhesive dressing; one was complicated by skin necrosis leading to a flap reconstruction that became infected, requiring a 2-stage revision. A separate case had an acute postoperative infection that required irrigation and debridement with polyethylene exchange. After a 12-week course of antibiotics, the infection was eradicated. All patients reported a high satisfaction rate during their acute postoperative phase.

Postoperatively, all patients were able to walk on the day of surgery either independently or with some assistance. On the day of surgery, 10% of patients were able to walk >200 feet, and this increased to 65% of patients able to walk >200 feet on the day of discharge (compare Figure 9A and Figure 9B).  Within 2 weeks of surgery, 30% of patients could walk independently (without assistive devices), and this number increased to 78% by 8 weeks after surgery (Figure 10).

Pain assessed using the VAS was lower on postoperative day 1 (3.17 ± 1.97) than the preoperative score (3.69 ± 2.22, P< .05). Overall, knee ROM significantly increased during the follow-up after surgery. Initially, the ROM decreased 1 week after surgery (90.82 ± 10.28) compared with preoperative ROM (101.04 ± 19.48, P < .001) (Figure 10).  At 2 weeks after surgery, knee ROM returned to the preoperative value (100.70 ± 13.36). By 6 weeks after surgery, knee ROM was 17° greater than the preoperative ROM (118.45 ± 11.89, P < .001). Knee ROM remained stable at 3- and 6-month assessments, and showed further improvement by 1 year (126.62 ± 9.81, P < .001) compared with the preoperative state (Figure 10). The net improvement in knee ROM was 25° of increased knee flexion by 1 year.

Continue to: DISCUSSION...

 

 

DISCUSSION

TKA is a successful procedure that restores knee function with pain relief in osteoarthritis patients. The SV approach for TKA has better outcomes in terms of the VAS, ROM, straight-leg raise with faster rehabilitation compared with the standard MP approach;^8–12 however, it can be challenging and time-consuming when used in morbidly obese and muscular patients.³ The SV approach can also increase the risk of complications such as patellar tendon avulsion or medial collateral injury because of the difficulty in exposure specifically for knees with limited ROM.¹³ Here we introduce the MIV approach as an alternative to the SV approach, overcoming most of these difficulties.

With the prevalence of morbid obesity and the market demand for minimally invasive techniques, we believe the MIV approach represents a good approach for surgeons since it is easy to perform, does not require specialized instrumentation, and is a reproducible approach even on the most complex deformities. The minimal time added to ensure blunt elevation of the vastus medialis muscle and an anatomic repair of the underlying knee capsule and vastus medialis fascia to the medial edge of the quadriceps tendon allows restoration of the anatomy and a robust double-layered watertight seal closure with no strangulation of soft tissues. We believe this reproducible muscle- and tendon-sparing approach that allows gentle, soft tissue handling even in the most complex primary total knee cases may lead to less soft tissue swelling, and therefore, less postoperative pain resulting in an accelerated recovery.

The pain level in this group of patients was reduced after the MIV approach as indicated by the VAS. The VAS was significantly decreased on postoperative day 1 compared with the VAS recorded preoperatively (P < .05), indicating patients felt less pain on the day after surgery. The average VAS on postoperative day 1 from other studies for SV approach ranged from 2.1 to 5,^9,12,14–19 whereas our MIV approach value was 3.17. Periarticular blocks were available for this study group, and no peripheral nerve blocks were used. Some studies of the SV approach mention the use of peripheral nerve blocks, while others did not describe the method used for treatment or control of postoperative pain. The decreased reported pain levels and the observed increased knee ROM seen in the MIV and SV approach study groups might be attributable to the treatment of postoperative pain.

Patient ambulation also increased from the day of surgery to the day of discharge for the MIV approach. Only 10% of patients were able to walk with assistance >200 feet on the day of surgery; however, this percentage increased to 65% on the discharge day showing an excellent recovery of walking ability within 2 days of surgery. Mehta and colleagues²⁰reported that 95% of patients undergoing subvastus/midvastus approaches could walk >10 blocks at 6 months follow-up. For the MIV approach, 78% of patients were able to walk independently within 8 weeks of surgery.

Continue to: The MIV approach shows improvement...

 

 

The MIV approach shows improvement in functional outcomes in terms of knee ROM from preoperative to postoperative. Although knee ROM decreased significantly at postoperative week 1, which is most likely because of a peak in postoperative pain and swelling; the ROM started to increase significantly at postoperative week 6. After 1 year, the knee ROM increased by 25% compared with preoperative ROM for the MIV approach. We found the average knee ROM at postoperative 3 months using the MIV approach to be 120.4°. Knee ROM at postoperative 3 months using the SV approach reported by other studies ranged from 87.1° to 120°.^19,21–23 Similarly, after 1 year, the average ROM by MIV approach was 126.62°, whereas average knee ROM from other studies using the SV approach was 114.1°.^2,10,19,21 Achieving a knee ROM of 120° allows patients to return to their baseline function and perform activities of daily living without limitation. With the prevalence of knee osteoarthritis in the younger population, the need for increased knee ROM post-TKA becomes more important so patients can return to work and function at their baseline.

In addition to being both a muscle- and tendon-sparing approach, other advantages of the MIV approach are that it is simple to perform and gives similar exposure to the MP approach even in difficult primary cases. It is also as extensile as the medial parapatellar approach, and it can be converted to a quadriceps snip if required. There is also minimal, if any, muscle retraction preventing muscle injury that may be seen with some other muscle-sparing approaches to the knee, especially in more difficult primary total knee cases. Another advantage to this approach, as opposed to the other approaches to the knee described here, is that it allows a double-layered closure, decreasing the possibility of arthrotomy dehiscence. Because of this double-layered closure, there is no muscle strangulation with repair of the arthrotomy site as seen in some other approaches to the knee, and both vascularity and innervation to the vastus medialis are preserved.

One limitation of this study is that it is a retrospective analysis. Future studies of the consequences of using this approach need to include quantitative assessment of muscle function using electromyography or dynamometer measurements, utilization of any number of validated knee score systems to measure functional outcomes, and incorporation of a randomized controlled trial.

In summary, the new MIV approach is easy to perform and is compatible with more extensile approaches such as a quadriceps snip, if required in revision scenarios. The MIV approach preserves the extensor mechanism, vascularity, and innervation to the vastus medialis. Our study documents both safety and good clinical outcomes using the MIV approach in TKA. Therefore, the MIV approach may be used in the majority of patients undergoing TKA.

ABSTRACT

The subvastus (SV) approach is a well-known muscle- and tendon-sparing approach for total knee arthroplasty (TKA), which has been shown in some studies to provide better outcomes in the visual analog pain score (VAS), knee range of motion (ROM), straight-leg raise, as well as faster rehabilitation, compared with the standard medial parapatellar (MP) approach. We previously described a new knee replacement technique known as the modified intervastus (MIV) approach. The MIV approach is a muscle- and tendon-sparing approach that is extensile and simple to perform. It may be used in the majority of complex primary cases and revisions. Here we describe the surgical technique for performing the MIV approach and provide functional outcome measures. A total of 127 patients (mean age, 66.75 years) underwent TKA using the MIV approach with 1-year follow-up. Clinical outcomes were assessed by recording both a VAS and knee ROM preoperatively, and again at several postoperative time points when the length of time required to ambulate independently (without assistive devices) was also measured. The VAS decreased significantly from the preoperative period (3.69 ± 2.22) to postoperative day 1 (3.17 ± 1.97) (P < .05). Although knee ROM decreased 1 week after surgery, the ROM increased by 6 weeks after surgery compared with the preoperative ROM, and the trend continued over the 1-year follow-up. One-third (33%) of patients were able to walk independently (without assistive devices) at 2 weeks and 78% at 8 weeks. The MIV approach to the knee is a muscle- and tendon-sparing approach that offers advantages over the SV approach and may be used for complex primary and revision total knee cases.

Continue to: Total knee arthroplasty... 

Total knee arthroplasty (TKA) is one of the most common orthopedic surgical procedures, with more than 600,000 TKAs performed annually in the United States, and by 2030 the number is expected to reach 3.48 million per year.¹Several approaches have been described for total TKA, and the medial parapatellar (MP) approach to the knee is considered the workhorse of total knee replacements. It is an extensile approach that is easy to perform but may delay active knee extension and straight-leg raise after surgery.²  Alternative approaches such as the subvastus (SV) and midvastus approaches to the knee (Figure 1A) typically allow a more rapid straight-leg raise but may be more challenging to perform and time-consuming in morbidly obese patients, muscular patients, and patients with severe deformities.³

The intervastus approach (Figure 1A) described by Jojima⁴ and others utilizes the interval between the quadriceps tendon and vastus medialis. Although it is a simple approach to perform that is extensile, it is not considered tendon-sparing since the vastus medialis inserts onto the medial aspect of the quadriceps tendon (Figure 2).⁵  Therefore, dissecting through this interval, without elevation of the vastus medialis (Figure 3A), damages the quadriceps tendon, and strangulation of the muscle occurs with repair of the arthrotomy site (Figure 3B).  This situation is even more likely in patients with a low-lying vastus medialis.⁶

The modified intervastus (MIV) approach described previously,⁷ may be used in the majority of patients undergoing TKA. The advantages of this approach include its extensile nature, similarities to an MP approach, and preservation of both the extensor mechanism and the vastus medialis, leading to a more rapid return to active knee extension than is traditionally observed.^2,7 The approach is simple to perform, easy to close, and is compatible with more extensile approaches such as a quadriceps snip if required in revision scenarios.⁷ However, functional outcomes of the MIV approach have not been quantified. It is unknown whether these outcomes will offer any advantages compared with the SV approach. Therefore, the objective of this study was to measure functional outcomes of the MIV approach and to compare the results with those previously published for the SV approach. We hypothesized that using the MIV approach for TKA surgery would lead to early straight-leg raise and increase in knee range of motion (ROM) postoperatively.

SURGICAL TECHNIQUE

The MIV approach preserves the quadriceps tendon and vastus medialis.⁷ After exposure of the vastus medialis muscle, the interval between the quadriceps tendon and vastus medialis is identified (Figure 4).  The fascia overlying the lateral edge of the vastus medialis is incised where it meets the quadriceps tendon (Figure 5).  The muscle is then bluntly elevated off the underlying capsule just enough to allow for a capsular repair later (Figure 6).  An arthrotomy is then performed from cephalad to caudal (Figure 7).  This interval may be extended proximally between the vastus intermedius and vastus medialis to expose the distal femur if needed. The closure is performed by repairing the capsule with absorbable suture (Figure 8A), and the vastus medialis fascia is repaired back to the medial edge of the quadriceps tendon, restoring the anatomy (Figure 8B).

Continue to: PATIENTS AND METHODS...

 

 

PATIENTS AND METHODS

A retrospective review of functional outcomes after TKA using the MIV approach was conducted; the study was approved by the University of Illinois Institutional Review Board. A total of 127 patients of mean age 66.75 years (range, 48–86 years) with primary osteoarthritis of the knee who were indicated for a total knee replacement with 1-year follow-up were included. The patient demographics are shown in Table 1.  All patients underwent TKA using the MIV approach described above by 2 experienced orthopedic surgeons at the same institution. Patients received spinal anesthesia and a periarticular pain block intraoperatively. A measured resection technique was used by 1 surgeon, and a gap-balancing technique by the other. Surgeon 1 used the Persona PS cemented knee system (Zimmer Biomet, and Surgeon 2 used the Sigma PS cemented knee system (Depuy). Patellar resurfacing was done in all cases. Patellar tracking was checked intraoperatively using the ‘no-touch’ technique, and the need for a lateral release was noted. Drains were removed on postoperative day 1. Oral opioids were given as needed. Intravenous antibiotics were continued for 24 hours. Oral anticoagulants were used for thromboembolism prophylaxis for 3 weeks. Patients were mobilized on the day of surgery with full weight-bearing under the supervision of an experienced physical therapist. Static and dynamic quadriceps exercises were started on the same day of surgery along with active knee ROM exercises. Pain score, extensor lag, ROM, walking ability, and complications were recorded in all patients.

Table 1. Patient Demographics

Total no. of patients		127
Gender	Male	44
	Female	83
Age (years)	Mean ± Standard deviation	66.75 ± 9.12
	Range	48 – 86
Weight (lb)	Mean ± Standard deviation	218.38 ± 54.47
	Range	125 – 364
BMI (kg/m2)	Mean ± Standard deviation	34.10 ± 7.22
	Range	21.1 – 62.5

The visual analog score (VAS) was obtained preoperatively and recorded on postoperative day 1. Patient walking distance with assistance was measured on the day of surgery, after surgery, and on the day of hospital discharge. Patients were assessed preoperatively and postoperatively at 1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year for knee ROM. A one-way ANOVA was conducted to compare the preoperative and postoperative day 1 VAS with significance set at P < .05 (OriginPro 2015, OriginLab Corporation). Differences in knee ROM between preoperative and postoperative follow-up periods (1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year) were identified using a 1-way ANOVA with a post hoc Tukey test. Significance was set at P < .05.

RESULTS

All patients were able to fully straight-leg raise and demonstrate functional knee ROM by postoperative day 1. The patella tracked centrally in all patients, and none required a lateral retinacular release. The majority of patients were discharged in the first 48 hours after surgery on oral narcotics. None required IV narcotics during their hospital stay or a blood transfusion. Two cases were complicated by severe knee skin blistering postoperatively due to a reaction to an adhesive dressing; one was complicated by skin necrosis leading to a flap reconstruction that became infected, requiring a 2-stage revision. A separate case had an acute postoperative infection that required irrigation and debridement with polyethylene exchange. After a 12-week course of antibiotics, the infection was eradicated. All patients reported a high satisfaction rate during their acute postoperative phase.

Postoperatively, all patients were able to walk on the day of surgery either independently or with some assistance. On the day of surgery, 10% of patients were able to walk >200 feet, and this increased to 65% of patients able to walk >200 feet on the day of discharge (compare Figure 9A and Figure 9B).  Within 2 weeks of surgery, 30% of patients could walk independently (without assistive devices), and this number increased to 78% by 8 weeks after surgery (Figure 10).

Pain assessed using the VAS was lower on postoperative day 1 (3.17 ± 1.97) than the preoperative score (3.69 ± 2.22, P< .05). Overall, knee ROM significantly increased during the follow-up after surgery. Initially, the ROM decreased 1 week after surgery (90.82 ± 10.28) compared with preoperative ROM (101.04 ± 19.48, P < .001) (Figure 10).  At 2 weeks after surgery, knee ROM returned to the preoperative value (100.70 ± 13.36). By 6 weeks after surgery, knee ROM was 17° greater than the preoperative ROM (118.45 ± 11.89, P < .001). Knee ROM remained stable at 3- and 6-month assessments, and showed further improvement by 1 year (126.62 ± 9.81, P < .001) compared with the preoperative state (Figure 10). The net improvement in knee ROM was 25° of increased knee flexion by 1 year.

Continue to: DISCUSSION...

 

 

DISCUSSION

TKA is a successful procedure that restores knee function with pain relief in osteoarthritis patients. The SV approach for TKA has better outcomes in terms of the VAS, ROM, straight-leg raise with faster rehabilitation compared with the standard MP approach;^8–12 however, it can be challenging and time-consuming when used in morbidly obese and muscular patients.³ The SV approach can also increase the risk of complications such as patellar tendon avulsion or medial collateral injury because of the difficulty in exposure specifically for knees with limited ROM.¹³ Here we introduce the MIV approach as an alternative to the SV approach, overcoming most of these difficulties.

With the prevalence of morbid obesity and the market demand for minimally invasive techniques, we believe the MIV approach represents a good approach for surgeons since it is easy to perform, does not require specialized instrumentation, and is a reproducible approach even on the most complex deformities. The minimal time added to ensure blunt elevation of the vastus medialis muscle and an anatomic repair of the underlying knee capsule and vastus medialis fascia to the medial edge of the quadriceps tendon allows restoration of the anatomy and a robust double-layered watertight seal closure with no strangulation of soft tissues. We believe this reproducible muscle- and tendon-sparing approach that allows gentle, soft tissue handling even in the most complex primary total knee cases may lead to less soft tissue swelling, and therefore, less postoperative pain resulting in an accelerated recovery.

The pain level in this group of patients was reduced after the MIV approach as indicated by the VAS. The VAS was significantly decreased on postoperative day 1 compared with the VAS recorded preoperatively (P < .05), indicating patients felt less pain on the day after surgery. The average VAS on postoperative day 1 from other studies for SV approach ranged from 2.1 to 5,^9,12,14–19 whereas our MIV approach value was 3.17. Periarticular blocks were available for this study group, and no peripheral nerve blocks were used. Some studies of the SV approach mention the use of peripheral nerve blocks, while others did not describe the method used for treatment or control of postoperative pain. The decreased reported pain levels and the observed increased knee ROM seen in the MIV and SV approach study groups might be attributable to the treatment of postoperative pain.

Patient ambulation also increased from the day of surgery to the day of discharge for the MIV approach. Only 10% of patients were able to walk with assistance >200 feet on the day of surgery; however, this percentage increased to 65% on the discharge day showing an excellent recovery of walking ability within 2 days of surgery. Mehta and colleagues²⁰reported that 95% of patients undergoing subvastus/midvastus approaches could walk >10 blocks at 6 months follow-up. For the MIV approach, 78% of patients were able to walk independently within 8 weeks of surgery.

Continue to: The MIV approach shows improvement...

 

 

The MIV approach shows improvement in functional outcomes in terms of knee ROM from preoperative to postoperative. Although knee ROM decreased significantly at postoperative week 1, which is most likely because of a peak in postoperative pain and swelling; the ROM started to increase significantly at postoperative week 6. After 1 year, the knee ROM increased by 25% compared with preoperative ROM for the MIV approach. We found the average knee ROM at postoperative 3 months using the MIV approach to be 120.4°. Knee ROM at postoperative 3 months using the SV approach reported by other studies ranged from 87.1° to 120°.^19,21–23 Similarly, after 1 year, the average ROM by MIV approach was 126.62°, whereas average knee ROM from other studies using the SV approach was 114.1°.^2,10,19,21 Achieving a knee ROM of 120° allows patients to return to their baseline function and perform activities of daily living without limitation. With the prevalence of knee osteoarthritis in the younger population, the need for increased knee ROM post-TKA becomes more important so patients can return to work and function at their baseline.

In addition to being both a muscle- and tendon-sparing approach, other advantages of the MIV approach are that it is simple to perform and gives similar exposure to the MP approach even in difficult primary cases. It is also as extensile as the medial parapatellar approach, and it can be converted to a quadriceps snip if required. There is also minimal, if any, muscle retraction preventing muscle injury that may be seen with some other muscle-sparing approaches to the knee, especially in more difficult primary total knee cases. Another advantage to this approach, as opposed to the other approaches to the knee described here, is that it allows a double-layered closure, decreasing the possibility of arthrotomy dehiscence. Because of this double-layered closure, there is no muscle strangulation with repair of the arthrotomy site as seen in some other approaches to the knee, and both vascularity and innervation to the vastus medialis are preserved.

One limitation of this study is that it is a retrospective analysis. Future studies of the consequences of using this approach need to include quantitative assessment of muscle function using electromyography or dynamometer measurements, utilization of any number of validated knee score systems to measure functional outcomes, and incorporation of a randomized controlled trial.

In summary, the new MIV approach is easy to perform and is compatible with more extensile approaches such as a quadriceps snip, if required in revision scenarios. The MIV approach preserves the extensor mechanism, vascularity, and innervation to the vastus medialis. Our study documents both safety and good clinical outcomes using the MIV approach in TKA. Therefore, the MIV approach may be used in the majority of patients undergoing TKA.

ABSTRACT

The subvastus (SV) approach is a well-known muscle- and tendon-sparing approach for total knee arthroplasty (TKA), which has been shown in some studies to provide better outcomes in the visual analog pain score (VAS), knee range of motion (ROM), straight-leg raise, as well as faster rehabilitation, compared with the standard medial parapatellar (MP) approach. We previously described a new knee replacement technique known as the modified intervastus (MIV) approach. The MIV approach is a muscle- and tendon-sparing approach that is extensile and simple to perform. It may be used in the majority of complex primary cases and revisions. Here we describe the surgical technique for performing the MIV approach and provide functional outcome measures. A total of 127 patients (mean age, 66.75 years) underwent TKA using the MIV approach with 1-year follow-up. Clinical outcomes were assessed by recording both a VAS and knee ROM preoperatively, and again at several postoperative time points when the length of time required to ambulate independently (without assistive devices) was also measured. The VAS decreased significantly from the preoperative period (3.69 ± 2.22) to postoperative day 1 (3.17 ± 1.97) (P < .05). Although knee ROM decreased 1 week after surgery, the ROM increased by 6 weeks after surgery compared with the preoperative ROM, and the trend continued over the 1-year follow-up. One-third (33%) of patients were able to walk independently (without assistive devices) at 2 weeks and 78% at 8 weeks. The MIV approach to the knee is a muscle- and tendon-sparing approach that offers advantages over the SV approach and may be used for complex primary and revision total knee cases.

Continue to: Total knee arthroplasty... 

Total knee arthroplasty (TKA) is one of the most common orthopedic surgical procedures, with more than 600,000 TKAs performed annually in the United States, and by 2030 the number is expected to reach 3.48 million per year.¹Several approaches have been described for total TKA, and the medial parapatellar (MP) approach to the knee is considered the workhorse of total knee replacements. It is an extensile approach that is easy to perform but may delay active knee extension and straight-leg raise after surgery.²  Alternative approaches such as the subvastus (SV) and midvastus approaches to the knee (Figure 1A) typically allow a more rapid straight-leg raise but may be more challenging to perform and time-consuming in morbidly obese patients, muscular patients, and patients with severe deformities.³

The intervastus approach (Figure 1A) described by Jojima⁴ and others utilizes the interval between the quadriceps tendon and vastus medialis. Although it is a simple approach to perform that is extensile, it is not considered tendon-sparing since the vastus medialis inserts onto the medial aspect of the quadriceps tendon (Figure 2).⁵  Therefore, dissecting through this interval, without elevation of the vastus medialis (Figure 3A), damages the quadriceps tendon, and strangulation of the muscle occurs with repair of the arthrotomy site (Figure 3B).  This situation is even more likely in patients with a low-lying vastus medialis.⁶

The modified intervastus (MIV) approach described previously,⁷ may be used in the majority of patients undergoing TKA. The advantages of this approach include its extensile nature, similarities to an MP approach, and preservation of both the extensor mechanism and the vastus medialis, leading to a more rapid return to active knee extension than is traditionally observed.^2,7 The approach is simple to perform, easy to close, and is compatible with more extensile approaches such as a quadriceps snip if required in revision scenarios.⁷ However, functional outcomes of the MIV approach have not been quantified. It is unknown whether these outcomes will offer any advantages compared with the SV approach. Therefore, the objective of this study was to measure functional outcomes of the MIV approach and to compare the results with those previously published for the SV approach. We hypothesized that using the MIV approach for TKA surgery would lead to early straight-leg raise and increase in knee range of motion (ROM) postoperatively.

SURGICAL TECHNIQUE

The MIV approach preserves the quadriceps tendon and vastus medialis.⁷ After exposure of the vastus medialis muscle, the interval between the quadriceps tendon and vastus medialis is identified (Figure 4).  The fascia overlying the lateral edge of the vastus medialis is incised where it meets the quadriceps tendon (Figure 5).  The muscle is then bluntly elevated off the underlying capsule just enough to allow for a capsular repair later (Figure 6).  An arthrotomy is then performed from cephalad to caudal (Figure 7).  This interval may be extended proximally between the vastus intermedius and vastus medialis to expose the distal femur if needed. The closure is performed by repairing the capsule with absorbable suture (Figure 8A), and the vastus medialis fascia is repaired back to the medial edge of the quadriceps tendon, restoring the anatomy (Figure 8B).

Continue to: PATIENTS AND METHODS...

 

 

PATIENTS AND METHODS

A retrospective review of functional outcomes after TKA using the MIV approach was conducted; the study was approved by the University of Illinois Institutional Review Board. A total of 127 patients of mean age 66.75 years (range, 48–86 years) with primary osteoarthritis of the knee who were indicated for a total knee replacement with 1-year follow-up were included. The patient demographics are shown in Table 1.  All patients underwent TKA using the MIV approach described above by 2 experienced orthopedic surgeons at the same institution. Patients received spinal anesthesia and a periarticular pain block intraoperatively. A measured resection technique was used by 1 surgeon, and a gap-balancing technique by the other. Surgeon 1 used the Persona PS cemented knee system (Zimmer Biomet, and Surgeon 2 used the Sigma PS cemented knee system (Depuy). Patellar resurfacing was done in all cases. Patellar tracking was checked intraoperatively using the ‘no-touch’ technique, and the need for a lateral release was noted. Drains were removed on postoperative day 1. Oral opioids were given as needed. Intravenous antibiotics were continued for 24 hours. Oral anticoagulants were used for thromboembolism prophylaxis for 3 weeks. Patients were mobilized on the day of surgery with full weight-bearing under the supervision of an experienced physical therapist. Static and dynamic quadriceps exercises were started on the same day of surgery along with active knee ROM exercises. Pain score, extensor lag, ROM, walking ability, and complications were recorded in all patients.

Table 1. Patient Demographics

Total no. of patients		127
Gender	Male	44
	Female	83
Age (years)	Mean ± Standard deviation	66.75 ± 9.12
	Range	48 – 86
Weight (lb)	Mean ± Standard deviation	218.38 ± 54.47
	Range	125 – 364
BMI (kg/m2)	Mean ± Standard deviation	34.10 ± 7.22
	Range	21.1 – 62.5

The visual analog score (VAS) was obtained preoperatively and recorded on postoperative day 1. Patient walking distance with assistance was measured on the day of surgery, after surgery, and on the day of hospital discharge. Patients were assessed preoperatively and postoperatively at 1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year for knee ROM. A one-way ANOVA was conducted to compare the preoperative and postoperative day 1 VAS with significance set at P < .05 (OriginPro 2015, OriginLab Corporation). Differences in knee ROM between preoperative and postoperative follow-up periods (1 week, 2 weeks, 6 weeks, 3 months, 6 months, and 1 year) were identified using a 1-way ANOVA with a post hoc Tukey test. Significance was set at P < .05.

RESULTS

All patients were able to fully straight-leg raise and demonstrate functional knee ROM by postoperative day 1. The patella tracked centrally in all patients, and none required a lateral retinacular release. The majority of patients were discharged in the first 48 hours after surgery on oral narcotics. None required IV narcotics during their hospital stay or a blood transfusion. Two cases were complicated by severe knee skin blistering postoperatively due to a reaction to an adhesive dressing; one was complicated by skin necrosis leading to a flap reconstruction that became infected, requiring a 2-stage revision. A separate case had an acute postoperative infection that required irrigation and debridement with polyethylene exchange. After a 12-week course of antibiotics, the infection was eradicated. All patients reported a high satisfaction rate during their acute postoperative phase.

Postoperatively, all patients were able to walk on the day of surgery either independently or with some assistance. On the day of surgery, 10% of patients were able to walk >200 feet, and this increased to 65% of patients able to walk >200 feet on the day of discharge (compare Figure 9A and Figure 9B).  Within 2 weeks of surgery, 30% of patients could walk independently (without assistive devices), and this number increased to 78% by 8 weeks after surgery (Figure 10).

Pain assessed using the VAS was lower on postoperative day 1 (3.17 ± 1.97) than the preoperative score (3.69 ± 2.22, P< .05). Overall, knee ROM significantly increased during the follow-up after surgery. Initially, the ROM decreased 1 week after surgery (90.82 ± 10.28) compared with preoperative ROM (101.04 ± 19.48, P < .001) (Figure 10).  At 2 weeks after surgery, knee ROM returned to the preoperative value (100.70 ± 13.36). By 6 weeks after surgery, knee ROM was 17° greater than the preoperative ROM (118.45 ± 11.89, P < .001). Knee ROM remained stable at 3- and 6-month assessments, and showed further improvement by 1 year (126.62 ± 9.81, P < .001) compared with the preoperative state (Figure 10). The net improvement in knee ROM was 25° of increased knee flexion by 1 year.

Continue to: DISCUSSION...

 

 

DISCUSSION

TKA is a successful procedure that restores knee function with pain relief in osteoarthritis patients. The SV approach for TKA has better outcomes in terms of the VAS, ROM, straight-leg raise with faster rehabilitation compared with the standard MP approach;^8–12 however, it can be challenging and time-consuming when used in morbidly obese and muscular patients.³ The SV approach can also increase the risk of complications such as patellar tendon avulsion or medial collateral injury because of the difficulty in exposure specifically for knees with limited ROM.¹³ Here we introduce the MIV approach as an alternative to the SV approach, overcoming most of these difficulties.

With the prevalence of morbid obesity and the market demand for minimally invasive techniques, we believe the MIV approach represents a good approach for surgeons since it is easy to perform, does not require specialized instrumentation, and is a reproducible approach even on the most complex deformities. The minimal time added to ensure blunt elevation of the vastus medialis muscle and an anatomic repair of the underlying knee capsule and vastus medialis fascia to the medial edge of the quadriceps tendon allows restoration of the anatomy and a robust double-layered watertight seal closure with no strangulation of soft tissues. We believe this reproducible muscle- and tendon-sparing approach that allows gentle, soft tissue handling even in the most complex primary total knee cases may lead to less soft tissue swelling, and therefore, less postoperative pain resulting in an accelerated recovery.

The pain level in this group of patients was reduced after the MIV approach as indicated by the VAS. The VAS was significantly decreased on postoperative day 1 compared with the VAS recorded preoperatively (P < .05), indicating patients felt less pain on the day after surgery. The average VAS on postoperative day 1 from other studies for SV approach ranged from 2.1 to 5,^9,12,14–19 whereas our MIV approach value was 3.17. Periarticular blocks were available for this study group, and no peripheral nerve blocks were used. Some studies of the SV approach mention the use of peripheral nerve blocks, while others did not describe the method used for treatment or control of postoperative pain. The decreased reported pain levels and the observed increased knee ROM seen in the MIV and SV approach study groups might be attributable to the treatment of postoperative pain.

Patient ambulation also increased from the day of surgery to the day of discharge for the MIV approach. Only 10% of patients were able to walk with assistance >200 feet on the day of surgery; however, this percentage increased to 65% on the discharge day showing an excellent recovery of walking ability within 2 days of surgery. Mehta and colleagues²⁰reported that 95% of patients undergoing subvastus/midvastus approaches could walk >10 blocks at 6 months follow-up. For the MIV approach, 78% of patients were able to walk independently within 8 weeks of surgery.

Continue to: The MIV approach shows improvement...

 

 

The MIV approach shows improvement in functional outcomes in terms of knee ROM from preoperative to postoperative. Although knee ROM decreased significantly at postoperative week 1, which is most likely because of a peak in postoperative pain and swelling; the ROM started to increase significantly at postoperative week 6. After 1 year, the knee ROM increased by 25% compared with preoperative ROM for the MIV approach. We found the average knee ROM at postoperative 3 months using the MIV approach to be 120.4°. Knee ROM at postoperative 3 months using the SV approach reported by other studies ranged from 87.1° to 120°.^19,21–23 Similarly, after 1 year, the average ROM by MIV approach was 126.62°, whereas average knee ROM from other studies using the SV approach was 114.1°.^2,10,19,21 Achieving a knee ROM of 120° allows patients to return to their baseline function and perform activities of daily living without limitation. With the prevalence of knee osteoarthritis in the younger population, the need for increased knee ROM post-TKA becomes more important so patients can return to work and function at their baseline.

In addition to being both a muscle- and tendon-sparing approach, other advantages of the MIV approach are that it is simple to perform and gives similar exposure to the MP approach even in difficult primary cases. It is also as extensile as the medial parapatellar approach, and it can be converted to a quadriceps snip if required. There is also minimal, if any, muscle retraction preventing muscle injury that may be seen with some other muscle-sparing approaches to the knee, especially in more difficult primary total knee cases. Another advantage to this approach, as opposed to the other approaches to the knee described here, is that it allows a double-layered closure, decreasing the possibility of arthrotomy dehiscence. Because of this double-layered closure, there is no muscle strangulation with repair of the arthrotomy site as seen in some other approaches to the knee, and both vascularity and innervation to the vastus medialis are preserved.

One limitation of this study is that it is a retrospective analysis. Future studies of the consequences of using this approach need to include quantitative assessment of muscle function using electromyography or dynamometer measurements, utilization of any number of validated knee score systems to measure functional outcomes, and incorporation of a randomized controlled trial.

In summary, the new MIV approach is easy to perform and is compatible with more extensile approaches such as a quadriceps snip, if required in revision scenarios. The MIV approach preserves the extensor mechanism, vascularity, and innervation to the vastus medialis. Our study documents both safety and good clinical outcomes using the MIV approach in TKA. Therefore, the MIV approach may be used in the majority of patients undergoing TKA.