Imaging

Pedicle subtraction osteotomies (PSOs) have been used in the treatment of multiple spinal conditions involving a fixed sagittal imbalance, such as degenerative scoliosis, idiopathic scoliosis, posttraumatic deformities, iatrogenic flatback syndrome, and ankylosing spondylitis. The procedure was first described by Thomasen¹ for the treatment of ankylosing spondylitis. More recently, multiple centers have reported the expanded use and good success of PSO in the treatment of fixed sagittal imbalance of other etiologies.^2,3 According to Bridwell and colleagues,² lumbar lordosis can be increased 34.1°, and sagittal plumb line can be improved 13.5 cm.

PSO is a complex, extensive surgery most often performed in the revision setting. Multiple authors have described the technique for PSO.^4,5 There are significant technical challenges and many complications, including neurologic deficits, pseudarthrosis of adjacent levels, and wound infections.⁶ Short-term challenges include a large loss of blood, 2.4 L on average, according to Bridwell and colleagues.⁶ Time of closure of the osteotomy gap is a crucial point in the surgery. Blood loss, often large, slows only after the gap is closed and stabilized.

In this article, we describe a technique in which an additional rod or pedicle screw construct is used at the periosteotomy levels to close the osteotomy gap during PSO and simplify subsequent instrumentation. In addition, we report our experience with the procedure.

Materials and Methods

Seventeen consecutive patients (mean age, 58 years; range, 12-81 years) with fixed sagittal imbalance were treated with lumbar PSO. The indication in all cases was flatback syndrome after previous spinal surgery. Mean follow-up was 13 months. Mean number of prior surgeries was 3. Thirteen PSOs were performed at L3, and 4 were performed at L2.

Radiographic data were collected from before surgery, in the immediate postoperative period, and at final follow-up. All the radiographs were standing films. Established radiographic parameters were measured: thoracic kyphosis from T5 to T12, lumbar lordosis from L1 to S1, PSO angle (1 level above to 1 level below osteotomy level), sagittal plumb line (from center of C7 body to posterosuperior aspect of S1 body), and coronal plumb line (from center of C7 body to center of S1 body).²

Good clinical outcomes in the treatment of spinal disorders require careful attention to the alignment of the spine in the sagittal plane.^7,8 When evaluating the preoperative radiographs, we measured and documented pelvic parameters. Figure 1A shows how pelvic incidence was determined. We measured this as the angle between a line drawn from the center of the S1 endplate to the center of the femoral head and the perpendicular off the S1 endplate. Figure 1B shows pelvic tilt as determined by the angle between a line drawn from the center of S1 to the femoral head and a vertical line originating from the center of the femoral head. Figure 1C shows the sacral slope, which we measured as the angle between a line drawn parallel to the endplate of S1 and its intersection with a horizontal line.

Surgical Technique

The overall surgical technique for PSO has been well described.^4,5 Here we describe the “outrigger” modification to osteotomy closure (Figures 2, 3).

Most of our 17 cases were revisions. In these cases, new fixation points are first established. All fixation points that will be needed for the final fusion are placed. If a pedicle above or below the osteotomy level is not suitable for a screw, it can be skipped.

Wide decompression of the involved level is performed from pedicle to pedicle, ensuring that the nerve roots are completely decompressed. The dissection is then continued around the lateral wall of the vertebral body. While the neural elements are protected with gentle retraction, the pedicle and a portion of the posterior aspect of the vertebral body are removed with a combination of a rongeur and reverse-angle curettes. Resection of the vertebral body can be facilitated by attaching a short rod to the pedicle screws on either side of the osteotomy level and using it to provide gentle distraction.

Once sufficient bone has been removed to close the osteotomy, short rods are placed in the pedicle screws in the level above and the level below the osteotomy site. These rods are attached with offset connectors that allow the rods to be placed lateral to the screws. Before the surgical procedure is started, the patient is positioned on 2 sets of posts separated by the break in the table. The break in the table allows flexion to accommodate the preoperative kyphosis and allows hyperextension to help close the osteotomy site. Now, with the osteotomy site ready for closure, the table is gradually positioned in extension along with a combination of posterior pressure and compression between the pedicle screws above and below the osteotomy. Once the osteotomy is adequately compressed, the short rods are tightened, holding the osteotomy in good position. With the osteotomy held by the short rods and table positioning, decompression of the neural elements is confirmed and hemostasis obtained.

Final instrumentation is then performed with long rods that can bypass the osteotomized levels, allowing for simpler contouring. If desired, a cross connector can be placed between the long rod of the fusion construct and the short rod holding the osteotomy. The rest of the fusion procedure is completed in standard fashion with at least 1 subfascial drain.

Results

Our 17 patients’ results are summarized in the Table. Mean sagittal plumb line improved from 17.7 cm (range, 5.9 to 29 cm) before surgery to 4.5 cm (range, –0.2 to 12.9 cm) after surgery, for a mean improvement of 13.2 cm. At final follow-up, mean sagittal plumb line was 5.1 cm (range, –1.4 to 10.2 cm).

Mean lumbar lordosis improved from 10° (range, –14° to 34°) before surgery to 49° (range, 36° to 63°) after surgery, for a mean improvement of 39°. Mean PSO angle improved from 3° (range, –36° to 23°) before surgery to 41° (range, 25° to 65°) after surgery, for a mean improvement of 38°. At final follow-up, mean lumbar lordosis remained at 47° (range, 26° to 64°), and mean PSO angle was 39° (range, 24° to 59°).

Mean thoracic kyphosis improved from 18° (range, –8° to 52°) before surgery to 30° (range, 3° to 58°) after surgery, for a mean improvement of 12°. At final follow-up, mean thoracic kyphosis was 31° (range, 2° to 57°).

Fourteen patients did not have complications during the study period. Of the 3 patients with complications, 1 had an early infection, treated effectively with irrigation and débridement and intravenous antibiotics; 1 had a late deep infection, treated with multiple débridements, hardware removal, and, eventually, suppressive antibiotics; and 1 had cauda equina syndrome (caused by extensive scar tissue on the dura, which buckled with restoration of lordosis leading to cord compression), treated with duraplasty, which resulted in full neurologic recovery.

Discussion

In the present series of patients, the described technique for facilitating PSO for correction of sagittal imbalance was effective, and complications were similar to those previously reported.

The benefit of the outrigger construct is that it allows controlled compression of the osteotomy site and can be left in place at time of final instrumentation, locking in compression and correction. Other techniques involve removing the temporary rod and replacing it with final instrumentation^4,5—an extra step that complicates instrumentation of the additional levels of the fusion construct and possibly adds pedicle screw stress and contributes to loosening when the new rod is reduced to the pedicle screw. The final long rod construct can bypass the osteotomy levels and allow for simpler instrumentation.

 Mean age was 58 years in this series versus 52.4 years in the series reported by Bridwell and colleagues.² Given the higher mean age of our patients, though no objective measures of bone quality were available, this technique is likely applicable to patients with poor bone quality.

The complications we have reported are in line with those reported in previous series, and maintenance of radiographic parameters at final follow-up indicates that this osteotomy technique allows for solid fusion constructs.

The outrigger technique for controlling PSO closure is an effective method that simplifies instrumentation during a complex revision case.

Pedicle subtraction osteotomies (PSOs) have been used in the treatment of multiple spinal conditions involving a fixed sagittal imbalance, such as degenerative scoliosis, idiopathic scoliosis, posttraumatic deformities, iatrogenic flatback syndrome, and ankylosing spondylitis. The procedure was first described by Thomasen¹ for the treatment of ankylosing spondylitis. More recently, multiple centers have reported the expanded use and good success of PSO in the treatment of fixed sagittal imbalance of other etiologies.^2,3 According to Bridwell and colleagues,² lumbar lordosis can be increased 34.1°, and sagittal plumb line can be improved 13.5 cm.

PSO is a complex, extensive surgery most often performed in the revision setting. Multiple authors have described the technique for PSO.^4,5 There are significant technical challenges and many complications, including neurologic deficits, pseudarthrosis of adjacent levels, and wound infections.⁶ Short-term challenges include a large loss of blood, 2.4 L on average, according to Bridwell and colleagues.⁶ Time of closure of the osteotomy gap is a crucial point in the surgery. Blood loss, often large, slows only after the gap is closed and stabilized.

In this article, we describe a technique in which an additional rod or pedicle screw construct is used at the periosteotomy levels to close the osteotomy gap during PSO and simplify subsequent instrumentation. In addition, we report our experience with the procedure.

Materials and Methods

Seventeen consecutive patients (mean age, 58 years; range, 12-81 years) with fixed sagittal imbalance were treated with lumbar PSO. The indication in all cases was flatback syndrome after previous spinal surgery. Mean follow-up was 13 months. Mean number of prior surgeries was 3. Thirteen PSOs were performed at L3, and 4 were performed at L2.

Radiographic data were collected from before surgery, in the immediate postoperative period, and at final follow-up. All the radiographs were standing films. Established radiographic parameters were measured: thoracic kyphosis from T5 to T12, lumbar lordosis from L1 to S1, PSO angle (1 level above to 1 level below osteotomy level), sagittal plumb line (from center of C7 body to posterosuperior aspect of S1 body), and coronal plumb line (from center of C7 body to center of S1 body).²

Good clinical outcomes in the treatment of spinal disorders require careful attention to the alignment of the spine in the sagittal plane.^7,8 When evaluating the preoperative radiographs, we measured and documented pelvic parameters. Figure 1A shows how pelvic incidence was determined. We measured this as the angle between a line drawn from the center of the S1 endplate to the center of the femoral head and the perpendicular off the S1 endplate. Figure 1B shows pelvic tilt as determined by the angle between a line drawn from the center of S1 to the femoral head and a vertical line originating from the center of the femoral head. Figure 1C shows the sacral slope, which we measured as the angle between a line drawn parallel to the endplate of S1 and its intersection with a horizontal line.

Surgical Technique

The overall surgical technique for PSO has been well described.^4,5 Here we describe the “outrigger” modification to osteotomy closure (Figures 2, 3).

Most of our 17 cases were revisions. In these cases, new fixation points are first established. All fixation points that will be needed for the final fusion are placed. If a pedicle above or below the osteotomy level is not suitable for a screw, it can be skipped.

Wide decompression of the involved level is performed from pedicle to pedicle, ensuring that the nerve roots are completely decompressed. The dissection is then continued around the lateral wall of the vertebral body. While the neural elements are protected with gentle retraction, the pedicle and a portion of the posterior aspect of the vertebral body are removed with a combination of a rongeur and reverse-angle curettes. Resection of the vertebral body can be facilitated by attaching a short rod to the pedicle screws on either side of the osteotomy level and using it to provide gentle distraction.

Once sufficient bone has been removed to close the osteotomy, short rods are placed in the pedicle screws in the level above and the level below the osteotomy site. These rods are attached with offset connectors that allow the rods to be placed lateral to the screws. Before the surgical procedure is started, the patient is positioned on 2 sets of posts separated by the break in the table. The break in the table allows flexion to accommodate the preoperative kyphosis and allows hyperextension to help close the osteotomy site. Now, with the osteotomy site ready for closure, the table is gradually positioned in extension along with a combination of posterior pressure and compression between the pedicle screws above and below the osteotomy. Once the osteotomy is adequately compressed, the short rods are tightened, holding the osteotomy in good position. With the osteotomy held by the short rods and table positioning, decompression of the neural elements is confirmed and hemostasis obtained.

Final instrumentation is then performed with long rods that can bypass the osteotomized levels, allowing for simpler contouring. If desired, a cross connector can be placed between the long rod of the fusion construct and the short rod holding the osteotomy. The rest of the fusion procedure is completed in standard fashion with at least 1 subfascial drain.

Results

Our 17 patients’ results are summarized in the Table. Mean sagittal plumb line improved from 17.7 cm (range, 5.9 to 29 cm) before surgery to 4.5 cm (range, –0.2 to 12.9 cm) after surgery, for a mean improvement of 13.2 cm. At final follow-up, mean sagittal plumb line was 5.1 cm (range, –1.4 to 10.2 cm).

Mean lumbar lordosis improved from 10° (range, –14° to 34°) before surgery to 49° (range, 36° to 63°) after surgery, for a mean improvement of 39°. Mean PSO angle improved from 3° (range, –36° to 23°) before surgery to 41° (range, 25° to 65°) after surgery, for a mean improvement of 38°. At final follow-up, mean lumbar lordosis remained at 47° (range, 26° to 64°), and mean PSO angle was 39° (range, 24° to 59°).

Mean thoracic kyphosis improved from 18° (range, –8° to 52°) before surgery to 30° (range, 3° to 58°) after surgery, for a mean improvement of 12°. At final follow-up, mean thoracic kyphosis was 31° (range, 2° to 57°).

Fourteen patients did not have complications during the study period. Of the 3 patients with complications, 1 had an early infection, treated effectively with irrigation and débridement and intravenous antibiotics; 1 had a late deep infection, treated with multiple débridements, hardware removal, and, eventually, suppressive antibiotics; and 1 had cauda equina syndrome (caused by extensive scar tissue on the dura, which buckled with restoration of lordosis leading to cord compression), treated with duraplasty, which resulted in full neurologic recovery.

Discussion

In the present series of patients, the described technique for facilitating PSO for correction of sagittal imbalance was effective, and complications were similar to those previously reported.

The benefit of the outrigger construct is that it allows controlled compression of the osteotomy site and can be left in place at time of final instrumentation, locking in compression and correction. Other techniques involve removing the temporary rod and replacing it with final instrumentation^4,5—an extra step that complicates instrumentation of the additional levels of the fusion construct and possibly adds pedicle screw stress and contributes to loosening when the new rod is reduced to the pedicle screw. The final long rod construct can bypass the osteotomy levels and allow for simpler instrumentation.

 Mean age was 58 years in this series versus 52.4 years in the series reported by Bridwell and colleagues.² Given the higher mean age of our patients, though no objective measures of bone quality were available, this technique is likely applicable to patients with poor bone quality.

The complications we have reported are in line with those reported in previous series, and maintenance of radiographic parameters at final follow-up indicates that this osteotomy technique allows for solid fusion constructs.

The outrigger technique for controlling PSO closure is an effective method that simplifies instrumentation during a complex revision case.

Pedicle subtraction osteotomies (PSOs) have been used in the treatment of multiple spinal conditions involving a fixed sagittal imbalance, such as degenerative scoliosis, idiopathic scoliosis, posttraumatic deformities, iatrogenic flatback syndrome, and ankylosing spondylitis. The procedure was first described by Thomasen¹ for the treatment of ankylosing spondylitis. More recently, multiple centers have reported the expanded use and good success of PSO in the treatment of fixed sagittal imbalance of other etiologies.^2,3 According to Bridwell and colleagues,² lumbar lordosis can be increased 34.1°, and sagittal plumb line can be improved 13.5 cm.

PSO is a complex, extensive surgery most often performed in the revision setting. Multiple authors have described the technique for PSO.^4,5 There are significant technical challenges and many complications, including neurologic deficits, pseudarthrosis of adjacent levels, and wound infections.⁶ Short-term challenges include a large loss of blood, 2.4 L on average, according to Bridwell and colleagues.⁶ Time of closure of the osteotomy gap is a crucial point in the surgery. Blood loss, often large, slows only after the gap is closed and stabilized.

In this article, we describe a technique in which an additional rod or pedicle screw construct is used at the periosteotomy levels to close the osteotomy gap during PSO and simplify subsequent instrumentation. In addition, we report our experience with the procedure.

Materials and Methods

Seventeen consecutive patients (mean age, 58 years; range, 12-81 years) with fixed sagittal imbalance were treated with lumbar PSO. The indication in all cases was flatback syndrome after previous spinal surgery. Mean follow-up was 13 months. Mean number of prior surgeries was 3. Thirteen PSOs were performed at L3, and 4 were performed at L2.

Radiographic data were collected from before surgery, in the immediate postoperative period, and at final follow-up. All the radiographs were standing films. Established radiographic parameters were measured: thoracic kyphosis from T5 to T12, lumbar lordosis from L1 to S1, PSO angle (1 level above to 1 level below osteotomy level), sagittal plumb line (from center of C7 body to posterosuperior aspect of S1 body), and coronal plumb line (from center of C7 body to center of S1 body).²

Good clinical outcomes in the treatment of spinal disorders require careful attention to the alignment of the spine in the sagittal plane.^7,8 When evaluating the preoperative radiographs, we measured and documented pelvic parameters. Figure 1A shows how pelvic incidence was determined. We measured this as the angle between a line drawn from the center of the S1 endplate to the center of the femoral head and the perpendicular off the S1 endplate. Figure 1B shows pelvic tilt as determined by the angle between a line drawn from the center of S1 to the femoral head and a vertical line originating from the center of the femoral head. Figure 1C shows the sacral slope, which we measured as the angle between a line drawn parallel to the endplate of S1 and its intersection with a horizontal line.

Surgical Technique

The overall surgical technique for PSO has been well described.^4,5 Here we describe the “outrigger” modification to osteotomy closure (Figures 2, 3).

Most of our 17 cases were revisions. In these cases, new fixation points are first established. All fixation points that will be needed for the final fusion are placed. If a pedicle above or below the osteotomy level is not suitable for a screw, it can be skipped.

Wide decompression of the involved level is performed from pedicle to pedicle, ensuring that the nerve roots are completely decompressed. The dissection is then continued around the lateral wall of the vertebral body. While the neural elements are protected with gentle retraction, the pedicle and a portion of the posterior aspect of the vertebral body are removed with a combination of a rongeur and reverse-angle curettes. Resection of the vertebral body can be facilitated by attaching a short rod to the pedicle screws on either side of the osteotomy level and using it to provide gentle distraction.

Once sufficient bone has been removed to close the osteotomy, short rods are placed in the pedicle screws in the level above and the level below the osteotomy site. These rods are attached with offset connectors that allow the rods to be placed lateral to the screws. Before the surgical procedure is started, the patient is positioned on 2 sets of posts separated by the break in the table. The break in the table allows flexion to accommodate the preoperative kyphosis and allows hyperextension to help close the osteotomy site. Now, with the osteotomy site ready for closure, the table is gradually positioned in extension along with a combination of posterior pressure and compression between the pedicle screws above and below the osteotomy. Once the osteotomy is adequately compressed, the short rods are tightened, holding the osteotomy in good position. With the osteotomy held by the short rods and table positioning, decompression of the neural elements is confirmed and hemostasis obtained.

Final instrumentation is then performed with long rods that can bypass the osteotomized levels, allowing for simpler contouring. If desired, a cross connector can be placed between the long rod of the fusion construct and the short rod holding the osteotomy. The rest of the fusion procedure is completed in standard fashion with at least 1 subfascial drain.

Results

Our 17 patients’ results are summarized in the Table. Mean sagittal plumb line improved from 17.7 cm (range, 5.9 to 29 cm) before surgery to 4.5 cm (range, –0.2 to 12.9 cm) after surgery, for a mean improvement of 13.2 cm. At final follow-up, mean sagittal plumb line was 5.1 cm (range, –1.4 to 10.2 cm).

Mean lumbar lordosis improved from 10° (range, –14° to 34°) before surgery to 49° (range, 36° to 63°) after surgery, for a mean improvement of 39°. Mean PSO angle improved from 3° (range, –36° to 23°) before surgery to 41° (range, 25° to 65°) after surgery, for a mean improvement of 38°. At final follow-up, mean lumbar lordosis remained at 47° (range, 26° to 64°), and mean PSO angle was 39° (range, 24° to 59°).

Mean thoracic kyphosis improved from 18° (range, –8° to 52°) before surgery to 30° (range, 3° to 58°) after surgery, for a mean improvement of 12°. At final follow-up, mean thoracic kyphosis was 31° (range, 2° to 57°).

Fourteen patients did not have complications during the study period. Of the 3 patients with complications, 1 had an early infection, treated effectively with irrigation and débridement and intravenous antibiotics; 1 had a late deep infection, treated with multiple débridements, hardware removal, and, eventually, suppressive antibiotics; and 1 had cauda equina syndrome (caused by extensive scar tissue on the dura, which buckled with restoration of lordosis leading to cord compression), treated with duraplasty, which resulted in full neurologic recovery.

Discussion

In the present series of patients, the described technique for facilitating PSO for correction of sagittal imbalance was effective, and complications were similar to those previously reported.

The benefit of the outrigger construct is that it allows controlled compression of the osteotomy site and can be left in place at time of final instrumentation, locking in compression and correction. Other techniques involve removing the temporary rod and replacing it with final instrumentation^4,5—an extra step that complicates instrumentation of the additional levels of the fusion construct and possibly adds pedicle screw stress and contributes to loosening when the new rod is reduced to the pedicle screw. The final long rod construct can bypass the osteotomy levels and allow for simpler instrumentation.

 Mean age was 58 years in this series versus 52.4 years in the series reported by Bridwell and colleagues.² Given the higher mean age of our patients, though no objective measures of bone quality were available, this technique is likely applicable to patients with poor bone quality.

The complications we have reported are in line with those reported in previous series, and maintenance of radiographic parameters at final follow-up indicates that this osteotomy technique allows for solid fusion constructs.

The outrigger technique for controlling PSO closure is an effective method that simplifies instrumentation during a complex revision case.

Total hip arthroplasty (THA) effectively provides adequate pain relief and favorable outcomes in patients with hip osteoarthritis (OA). However, leg-length discrepancy (LLD) is still a significant cause of morbidity,¹ including nerve damage,^2,3 low back pain,^2,4,5 and abnormal gait.^2,6,7 Although most of the LLD values reported in the literature fall under the acceptable threshold of 10 mm,⁸ some patients report dissatisfaction,⁹ leading to litigation against orthopedic surgeons.² However, lower extremity lengthening is sometimes needed to achieve adequate hip joint stability and prevent dislocations.^2,10

Several methods have been developed to help surgeons estimate the change in leg length during surgery in an attempt to improve clinical outcomes. Use of guide pins as a reference on the pelvis decreased LLD and improved outcomes in some published studies.^11,12 Preoperative templating of implant size, cup position, and level of femoral neck cut is very important in helping minimize clinically significant LLD after THA.^2,13,14 Computer-assisted THA has also been introduced to try to improve component positioning, restoration of hip center of rotation, and minimizing of LLD.^15-17 However, cost and increased operative time have prevented widespread adoption of computer-assisted surgery in THA.

Proponents of different surgical approaches have argued about the superiority of one approach over another. The posterior approach is the gold standard in THA because it is safe, easy to perform, and, if needed, extensile.¹¹ However, exact determination of the intraoperative 3-dimensional (3-D) orientation of the pelvis, and subsequently of LLD, is challenging when the patient lies in the lateral position. The anterior approach has gained in popularity because of its advantages in accelerating postoperative rehabilitation and decreasing hospital length of stay.¹⁸ Placing the patient supine is advantageous because it allows leveling of the pelvis and estimation of LLD (by comparing the positions of the lower extremities).¹⁹ The anterior approach also allows for radiographic measurements on the operating table.^19,20 However, this approach has a high learning curve²¹ and is not extensile.²¹ To date, no study has shown superiority of the anterior approach over either the conventional posterior approach or the robot-assisted posterior approach in minimizing LLD after THA.

We conducted a study to compare LLD in patients who underwent THA performed with a robot-assisted posterior approach (RTHA), a fluoroscopy-guided anterior approach (ATHA), or a conventional posterior approach (PTHA). We hypothesized that, compared with PTHA, both RTHA and ATHA would result in reduced LLD.

Materials and Methods

We reviewed all RTHAs, ATHAs, and PTHAs performed by Dr. Domb between September 2008 and December 2012. Study inclusion criteria were a diagnosis of hip OA and the availability of postoperative supine anteroposterior pelvis radiographs. Exclusion criteria were a diagnosis other than hip OA, missing or improper postoperative radiographs (radiographs with rotated or tilted pelvis),²² and radiographs on which at least one of the lesser trochanters was difficult to define. Of the 155 cases included in the study, 67 were RTHAs, 29 were ATHAs, and 59 were PTHAs.

All patients scheduled for THA underwent preoperative planning; plain radiographs were used to determine component size and position, level of neck cut, and amount of leg lengthening or shortening needed. In all RTHA cases, computed tomography of the involved hip was performed before surgery. The MAKO system (MAKO Surgical Corporation, Davie, Florida) was used to develop a patient-specific 3-D model of the pelvis and proximal femur, and this model was used to guide THA execution. The system was then used to detect patient-specific landmarks during surgery, to register the femur and the acetabulum, and to help determine the position of the pelvis and proximal femur during surgery. This system, which uses a haptic robotic arm that guides acetabular reaming and cup placement, provides feedback regarding cup placement, stem version, leg length, and global offset. Pelvic tilt and rotation were accounted for by the MAKO software, and all provided measurements were made on the coronal (functional) plane of the body, as described by Murray.²³ ATHA was performed with the patient in the supine position on a Hana table (Mizuho OSI, Union City, California) with fluoroscopic guidance. PTHA was performed in the conventional way, with the patient in the lateral position.

Radiographic measurements of LLD were made with TraumaCad software (Build 2.2.535.0; Voyant Health, Petah-Tikva, Israel). The accuracy of this software has been studied and reported in the literature.^24-26 Radiographs were calibrated using the known size of each femoral head as a marker. The reference on the pelvis was the interobturator line (line tangent to inferior border of obturator foramina), and the reference on the femurs was the most superior and medial aspect of each lesser trochanter. Two lines were drawn, each perpendicular to the interobturator line, starting from the previously defined reference point on each lesser trochanter. The difference in length between these 2 lines was recorded as the LLD. Values were recorded relative to the operative extremity. For example, if the operative extremity was longer than the nonoperative extremity, the LLD was given a positive value.

To eliminate bias and increase measurement accuracy, the study had each of 2 observers collect the LLD data twice, 2 months apart. These observers were blinded to each other’s results and to the type of surgery performed. (Neither observer was Dr. Domb, the senior surgeon.) IBM SPSS Statistics software (Version 20; IBM, Armonk, New York) was used for statistical analysis. Each patient’s 4 measurements were averaged into a single number for LLD, and the absolute LLD values were used in all statistical analyses. Means, standard deviations (SDs), and 95% confidence intervals (CIs) were calculated for LLD in each of the 3 groups. Pearson correlation coefficient was used to determine interobserver and intraobserver reliability. One-way analysis of variance (ANOVA) was used to compare group means for age, body mass index (BMI), and LLD. In each group, number of outliers was determined with outliers set at LLDs of more than 3 mm and more than 5 mm. Fischer exact test was used to compare number of outliers in each group. P < .05 was considered statistically significant.

Results

Table 1 lists the demographic data, including age, sex, and BMI, and compares the means. There were strong interobserver and intraobserver correlations for all LLD measurements (r > 0.9; P < .001). Mean (SD) LLD was 2.7 (1.8) mm (95% CI, 2.3-3.2) in the RTHA group, 1.8 (1.6) mm (95% CI, 1.2-2.4) in the ATHA group, and 1.9 (1.6) mm (95% CI, 1.5-2.4) in the PTHA group (P = .01). When LLD of more than 3 mm was set as an outlier, percentage of outliers was 37.3% (RTHA), 17.2% (ATHA), and 22% (PTHA) (P = .06-.78). When LLD of more than 5 mm was set as an outlier, percentage of outliers was 10.4% (RTHA), 6.9% (ATHA), and 8.5% (PTHA) (P = .72 to >.99). No patient in any group had LLD of 10 mm or more (Figure). Table 2 lists percentages of patients’ operated extremities that were longer, shorter, or the same size as their contralateral extremities. Six (9.0%) of the 67 RTHA patients, 4 (13.8%) of the 29 ATHA patients, and 3 (5.1%) of the 59 PTHA patients had a contralateral THA.

Discussion

Our study results showed that RTHA, ATHA, and PTHA were equally effective in minimizing LLD. There was a statistically significant difference in mean LLD among the 3 groups studied. The RTHA group had the largest mean (SD) LLD: 2.7 (1.8) mm. However, statistically significant differences do not always indicate clinical significance.²⁷ Therefore, comparison of the 3 groups’ means is not enough for drawing significant conclusions. The more important point to consider is the number of cases of LLD of 10 mm or more—a discrepancy that would be perceptible to patients and thus become a source of dissatisfaction with painless THA.²⁸ Patients perceive LLD when shortening exceeds 10 mm and lengthening exceeds 6 mm,²⁹ or when LLD is more than 10 mm.^16,19,20 Despite significant differences in means, all our cases came in under the 10-mm threshold. When the threshold was decreased to 5 mm (and to 3 mm), there was no statistically significant difference among the groups in the number of cases above the threshold.

LLD remains a source of significant post-THA comorbidity and patient dissatisfaction.^1-7,19 Despite surgeons’ efforts to minimize LLD, some patients can detect even a subtle LLD after surgery.^1,8,29 Most LLD values reported in the literature fall under the 10-mm threshold.^16,19,20 In some cases, however, postoperative LLD is more than 1 cm, enough to prompt litigation against orthopedic surgeons.² Surgeons have tried to improve LLD with use of multiple techniques, including use of intraoperative measuring devices,³⁰ patient positioning during surgery,²⁰ use of computer-assisted surgery,¹⁹ and use of intraoperative fluoroscopy.²⁰

Proponents of computer-assisted THA have argued that this technique improves accuracy in placing the acetabular cup in the safe zone,³¹ minimizes LLD, and restores femoral offset.^32,33 Manzotti and colleagues¹⁶ reported on 48 cases of computer-assisted THA matched to 48 cases of conventional THA using the posterior approach. Mean (SD) LLD was 5.06 (2.99) mm in the computer-assisted group and 7.64 (4.36) mm in the conventional group; there was a statistically significant difference in favor of the computer-assisted group (P = .04). However, 5 patients in the computer-assisted group and 13 in the conventional group had LLD of more than 10 mm, and the difference was statistically significant.¹⁶ Moreover, the study population was heterogeneous, with 12 patients in both groups having developmental dysplasia as a primary diagnosis.¹⁶ All the cases in our study had a diagnosis of OA, and no case had LLD of 10 mm or more.

Several advantages have been proposed for the anterior approach. The supine position (with direct comparison of leg lengths) and the use of fluoroscopy have been described as advantageous in minimizing LLD.^20,21 In their study of 494 primary THAs performed with the anterior approach, Matta and colleagues²⁰ reported mean (SD) postoperative LLD of 3 (2) mm (range, 0-26 mm) and concluded that the anterior approach was effective in restoring leg lengths and ensuring proper cup placement while not increasing the dislocation rate. However, they did not compare this approach with others or with computer-assisted THA with respect to LLD.

In another study, Nam and colleagues¹⁹ compared LLD after THA performed with 3 different approaches (anterior, conventional posterior, posterior-navigated) and found no statistically significant difference in LLD among the groups. However, LLD was more than 10 mm in 2.2% of anterior cases, 4.4% of conventional posterior cases, and 4.4% of posterior-navigated cases. When 5 mm was used as a cutoff, percentage of patients who were outliers was 31.1% (anterior), 20% (conventional posterior), and 23.3% (navigated-posterior). Our data showed superior results in using 5 mm as a cutoff, with percentage of outliers of 6.9% with ATHA, 8.5% with PTHA, and 10.4% with RTHA. However, Nam and colleagues¹⁹ used a larger patient cohort and different techniques for measuring LLD on anteroposterior pelvis radiographs.

The most likely reason that the groups in our study were comparable in terms of LLD accuracy and lack of outliers over the 10-mm cutoff was Dr. Domb’s high accuracy in minimizing LLD using each of the 3 techniques. For ATHA, mean (SD) LLD was 1.8 (1.6) mm (no LLD of ≥10 mm), better than the 3 (2) mm (0.9% with LLD of >10 mm) reported by Matta and colleagues²⁰ and the 3.8 (3.9) mm (2.2% with LLD of >10 mm) reported by Nam and colleagues.¹⁹ For PTHA, mean (SD) LLD was 1.9 (1.6) mm (no LLD of ≥10 mm), comparable to some of the best results reported in the literature—for example, the 1 mm (3% with LLD of >10 mm) reported by Woolson and colleagues.³⁴ For RTHA, mean (SD) LLD was 2.7 (1.8) mm (no LLD of ≥10 mm), superior to the 3.9 (2.7) mm (4.4% with LLD of >10 mm) reported by Nam and colleagues¹⁹ for posterior-navigated THA and the 5.06 (2.99) mm (10.4% with LLD of >10 mm) reported by Manzotti and colleagues¹⁶ for computer-assisted THA.

This study had several notable strengths. All patients had a diagnosis of hip OA and were operated on by a single surgeon. Radiographs were calibrated using the size of the implanted femoral head. Radiographic data were measured using the same technique in all cases and were collected twice by 2 observers (not the senior surgeon) to decrease bias and determine interobserver and intraobserver reliability. In addition, surgeon experience might have played an important role in minimizing LLD regardless of technique and approach used for THA.

Study limitations were different number of cases in each group, lack of matching, lack of clinical follow-up, and lack of long-term assessment of clinical outcomes and complications.

Conclusion

As performed by an experienced surgeon, RTHA, ATHA, and PTHA did not differ in obtaining minimal LLD. All 3 groups had a low frequency of outliers, using thresholds of 3 mm and 5 mm, and no patient in any group had LLD of 10 mm or more. All 3 techniques are effective in achieving accuracy in LLD.

Total hip arthroplasty (THA) effectively provides adequate pain relief and favorable outcomes in patients with hip osteoarthritis (OA). However, leg-length discrepancy (LLD) is still a significant cause of morbidity,¹ including nerve damage,^2,3 low back pain,^2,4,5 and abnormal gait.^2,6,7 Although most of the LLD values reported in the literature fall under the acceptable threshold of 10 mm,⁸ some patients report dissatisfaction,⁹ leading to litigation against orthopedic surgeons.² However, lower extremity lengthening is sometimes needed to achieve adequate hip joint stability and prevent dislocations.^2,10

Several methods have been developed to help surgeons estimate the change in leg length during surgery in an attempt to improve clinical outcomes. Use of guide pins as a reference on the pelvis decreased LLD and improved outcomes in some published studies.^11,12 Preoperative templating of implant size, cup position, and level of femoral neck cut is very important in helping minimize clinically significant LLD after THA.^2,13,14 Computer-assisted THA has also been introduced to try to improve component positioning, restoration of hip center of rotation, and minimizing of LLD.^15-17 However, cost and increased operative time have prevented widespread adoption of computer-assisted surgery in THA.

Proponents of different surgical approaches have argued about the superiority of one approach over another. The posterior approach is the gold standard in THA because it is safe, easy to perform, and, if needed, extensile.¹¹ However, exact determination of the intraoperative 3-dimensional (3-D) orientation of the pelvis, and subsequently of LLD, is challenging when the patient lies in the lateral position. The anterior approach has gained in popularity because of its advantages in accelerating postoperative rehabilitation and decreasing hospital length of stay.¹⁸ Placing the patient supine is advantageous because it allows leveling of the pelvis and estimation of LLD (by comparing the positions of the lower extremities).¹⁹ The anterior approach also allows for radiographic measurements on the operating table.^19,20 However, this approach has a high learning curve²¹ and is not extensile.²¹ To date, no study has shown superiority of the anterior approach over either the conventional posterior approach or the robot-assisted posterior approach in minimizing LLD after THA.

We conducted a study to compare LLD in patients who underwent THA performed with a robot-assisted posterior approach (RTHA), a fluoroscopy-guided anterior approach (ATHA), or a conventional posterior approach (PTHA). We hypothesized that, compared with PTHA, both RTHA and ATHA would result in reduced LLD.

Materials and Methods

We reviewed all RTHAs, ATHAs, and PTHAs performed by Dr. Domb between September 2008 and December 2012. Study inclusion criteria were a diagnosis of hip OA and the availability of postoperative supine anteroposterior pelvis radiographs. Exclusion criteria were a diagnosis other than hip OA, missing or improper postoperative radiographs (radiographs with rotated or tilted pelvis),²² and radiographs on which at least one of the lesser trochanters was difficult to define. Of the 155 cases included in the study, 67 were RTHAs, 29 were ATHAs, and 59 were PTHAs.

All patients scheduled for THA underwent preoperative planning; plain radiographs were used to determine component size and position, level of neck cut, and amount of leg lengthening or shortening needed. In all RTHA cases, computed tomography of the involved hip was performed before surgery. The MAKO system (MAKO Surgical Corporation, Davie, Florida) was used to develop a patient-specific 3-D model of the pelvis and proximal femur, and this model was used to guide THA execution. The system was then used to detect patient-specific landmarks during surgery, to register the femur and the acetabulum, and to help determine the position of the pelvis and proximal femur during surgery. This system, which uses a haptic robotic arm that guides acetabular reaming and cup placement, provides feedback regarding cup placement, stem version, leg length, and global offset. Pelvic tilt and rotation were accounted for by the MAKO software, and all provided measurements were made on the coronal (functional) plane of the body, as described by Murray.²³ ATHA was performed with the patient in the supine position on a Hana table (Mizuho OSI, Union City, California) with fluoroscopic guidance. PTHA was performed in the conventional way, with the patient in the lateral position.

Radiographic measurements of LLD were made with TraumaCad software (Build 2.2.535.0; Voyant Health, Petah-Tikva, Israel). The accuracy of this software has been studied and reported in the literature.^24-26 Radiographs were calibrated using the known size of each femoral head as a marker. The reference on the pelvis was the interobturator line (line tangent to inferior border of obturator foramina), and the reference on the femurs was the most superior and medial aspect of each lesser trochanter. Two lines were drawn, each perpendicular to the interobturator line, starting from the previously defined reference point on each lesser trochanter. The difference in length between these 2 lines was recorded as the LLD. Values were recorded relative to the operative extremity. For example, if the operative extremity was longer than the nonoperative extremity, the LLD was given a positive value.

To eliminate bias and increase measurement accuracy, the study had each of 2 observers collect the LLD data twice, 2 months apart. These observers were blinded to each other’s results and to the type of surgery performed. (Neither observer was Dr. Domb, the senior surgeon.) IBM SPSS Statistics software (Version 20; IBM, Armonk, New York) was used for statistical analysis. Each patient’s 4 measurements were averaged into a single number for LLD, and the absolute LLD values were used in all statistical analyses. Means, standard deviations (SDs), and 95% confidence intervals (CIs) were calculated for LLD in each of the 3 groups. Pearson correlation coefficient was used to determine interobserver and intraobserver reliability. One-way analysis of variance (ANOVA) was used to compare group means for age, body mass index (BMI), and LLD. In each group, number of outliers was determined with outliers set at LLDs of more than 3 mm and more than 5 mm. Fischer exact test was used to compare number of outliers in each group. P < .05 was considered statistically significant.

Results

Table 1 lists the demographic data, including age, sex, and BMI, and compares the means. There were strong interobserver and intraobserver correlations for all LLD measurements (r > 0.9; P < .001). Mean (SD) LLD was 2.7 (1.8) mm (95% CI, 2.3-3.2) in the RTHA group, 1.8 (1.6) mm (95% CI, 1.2-2.4) in the ATHA group, and 1.9 (1.6) mm (95% CI, 1.5-2.4) in the PTHA group (P = .01). When LLD of more than 3 mm was set as an outlier, percentage of outliers was 37.3% (RTHA), 17.2% (ATHA), and 22% (PTHA) (P = .06-.78). When LLD of more than 5 mm was set as an outlier, percentage of outliers was 10.4% (RTHA), 6.9% (ATHA), and 8.5% (PTHA) (P = .72 to >.99). No patient in any group had LLD of 10 mm or more (Figure). Table 2 lists percentages of patients’ operated extremities that were longer, shorter, or the same size as their contralateral extremities. Six (9.0%) of the 67 RTHA patients, 4 (13.8%) of the 29 ATHA patients, and 3 (5.1%) of the 59 PTHA patients had a contralateral THA.

Discussion

Our study results showed that RTHA, ATHA, and PTHA were equally effective in minimizing LLD. There was a statistically significant difference in mean LLD among the 3 groups studied. The RTHA group had the largest mean (SD) LLD: 2.7 (1.8) mm. However, statistically significant differences do not always indicate clinical significance.²⁷ Therefore, comparison of the 3 groups’ means is not enough for drawing significant conclusions. The more important point to consider is the number of cases of LLD of 10 mm or more—a discrepancy that would be perceptible to patients and thus become a source of dissatisfaction with painless THA.²⁸ Patients perceive LLD when shortening exceeds 10 mm and lengthening exceeds 6 mm,²⁹ or when LLD is more than 10 mm.^16,19,20 Despite significant differences in means, all our cases came in under the 10-mm threshold. When the threshold was decreased to 5 mm (and to 3 mm), there was no statistically significant difference among the groups in the number of cases above the threshold.

LLD remains a source of significant post-THA comorbidity and patient dissatisfaction.^1-7,19 Despite surgeons’ efforts to minimize LLD, some patients can detect even a subtle LLD after surgery.^1,8,29 Most LLD values reported in the literature fall under the 10-mm threshold.^16,19,20 In some cases, however, postoperative LLD is more than 1 cm, enough to prompt litigation against orthopedic surgeons.² Surgeons have tried to improve LLD with use of multiple techniques, including use of intraoperative measuring devices,³⁰ patient positioning during surgery,²⁰ use of computer-assisted surgery,¹⁹ and use of intraoperative fluoroscopy.²⁰

Proponents of computer-assisted THA have argued that this technique improves accuracy in placing the acetabular cup in the safe zone,³¹ minimizes LLD, and restores femoral offset.^32,33 Manzotti and colleagues¹⁶ reported on 48 cases of computer-assisted THA matched to 48 cases of conventional THA using the posterior approach. Mean (SD) LLD was 5.06 (2.99) mm in the computer-assisted group and 7.64 (4.36) mm in the conventional group; there was a statistically significant difference in favor of the computer-assisted group (P = .04). However, 5 patients in the computer-assisted group and 13 in the conventional group had LLD of more than 10 mm, and the difference was statistically significant.¹⁶ Moreover, the study population was heterogeneous, with 12 patients in both groups having developmental dysplasia as a primary diagnosis.¹⁶ All the cases in our study had a diagnosis of OA, and no case had LLD of 10 mm or more.

Several advantages have been proposed for the anterior approach. The supine position (with direct comparison of leg lengths) and the use of fluoroscopy have been described as advantageous in minimizing LLD.^20,21 In their study of 494 primary THAs performed with the anterior approach, Matta and colleagues²⁰ reported mean (SD) postoperative LLD of 3 (2) mm (range, 0-26 mm) and concluded that the anterior approach was effective in restoring leg lengths and ensuring proper cup placement while not increasing the dislocation rate. However, they did not compare this approach with others or with computer-assisted THA with respect to LLD.

In another study, Nam and colleagues¹⁹ compared LLD after THA performed with 3 different approaches (anterior, conventional posterior, posterior-navigated) and found no statistically significant difference in LLD among the groups. However, LLD was more than 10 mm in 2.2% of anterior cases, 4.4% of conventional posterior cases, and 4.4% of posterior-navigated cases. When 5 mm was used as a cutoff, percentage of patients who were outliers was 31.1% (anterior), 20% (conventional posterior), and 23.3% (navigated-posterior). Our data showed superior results in using 5 mm as a cutoff, with percentage of outliers of 6.9% with ATHA, 8.5% with PTHA, and 10.4% with RTHA. However, Nam and colleagues¹⁹ used a larger patient cohort and different techniques for measuring LLD on anteroposterior pelvis radiographs.

The most likely reason that the groups in our study were comparable in terms of LLD accuracy and lack of outliers over the 10-mm cutoff was Dr. Domb’s high accuracy in minimizing LLD using each of the 3 techniques. For ATHA, mean (SD) LLD was 1.8 (1.6) mm (no LLD of ≥10 mm), better than the 3 (2) mm (0.9% with LLD of >10 mm) reported by Matta and colleagues²⁰ and the 3.8 (3.9) mm (2.2% with LLD of >10 mm) reported by Nam and colleagues.¹⁹ For PTHA, mean (SD) LLD was 1.9 (1.6) mm (no LLD of ≥10 mm), comparable to some of the best results reported in the literature—for example, the 1 mm (3% with LLD of >10 mm) reported by Woolson and colleagues.³⁴ For RTHA, mean (SD) LLD was 2.7 (1.8) mm (no LLD of ≥10 mm), superior to the 3.9 (2.7) mm (4.4% with LLD of >10 mm) reported by Nam and colleagues¹⁹ for posterior-navigated THA and the 5.06 (2.99) mm (10.4% with LLD of >10 mm) reported by Manzotti and colleagues¹⁶ for computer-assisted THA.

This study had several notable strengths. All patients had a diagnosis of hip OA and were operated on by a single surgeon. Radiographs were calibrated using the size of the implanted femoral head. Radiographic data were measured using the same technique in all cases and were collected twice by 2 observers (not the senior surgeon) to decrease bias and determine interobserver and intraobserver reliability. In addition, surgeon experience might have played an important role in minimizing LLD regardless of technique and approach used for THA.

Study limitations were different number of cases in each group, lack of matching, lack of clinical follow-up, and lack of long-term assessment of clinical outcomes and complications.

Conclusion

As performed by an experienced surgeon, RTHA, ATHA, and PTHA did not differ in obtaining minimal LLD. All 3 groups had a low frequency of outliers, using thresholds of 3 mm and 5 mm, and no patient in any group had LLD of 10 mm or more. All 3 techniques are effective in achieving accuracy in LLD.

Total hip arthroplasty (THA) effectively provides adequate pain relief and favorable outcomes in patients with hip osteoarthritis (OA). However, leg-length discrepancy (LLD) is still a significant cause of morbidity,¹ including nerve damage,^2,3 low back pain,^2,4,5 and abnormal gait.^2,6,7 Although most of the LLD values reported in the literature fall under the acceptable threshold of 10 mm,⁸ some patients report dissatisfaction,⁹ leading to litigation against orthopedic surgeons.² However, lower extremity lengthening is sometimes needed to achieve adequate hip joint stability and prevent dislocations.^2,10

Several methods have been developed to help surgeons estimate the change in leg length during surgery in an attempt to improve clinical outcomes. Use of guide pins as a reference on the pelvis decreased LLD and improved outcomes in some published studies.^11,12 Preoperative templating of implant size, cup position, and level of femoral neck cut is very important in helping minimize clinically significant LLD after THA.^2,13,14 Computer-assisted THA has also been introduced to try to improve component positioning, restoration of hip center of rotation, and minimizing of LLD.^15-17 However, cost and increased operative time have prevented widespread adoption of computer-assisted surgery in THA.

Proponents of different surgical approaches have argued about the superiority of one approach over another. The posterior approach is the gold standard in THA because it is safe, easy to perform, and, if needed, extensile.¹¹ However, exact determination of the intraoperative 3-dimensional (3-D) orientation of the pelvis, and subsequently of LLD, is challenging when the patient lies in the lateral position. The anterior approach has gained in popularity because of its advantages in accelerating postoperative rehabilitation and decreasing hospital length of stay.¹⁸ Placing the patient supine is advantageous because it allows leveling of the pelvis and estimation of LLD (by comparing the positions of the lower extremities).¹⁹ The anterior approach also allows for radiographic measurements on the operating table.^19,20 However, this approach has a high learning curve²¹ and is not extensile.²¹ To date, no study has shown superiority of the anterior approach over either the conventional posterior approach or the robot-assisted posterior approach in minimizing LLD after THA.

We conducted a study to compare LLD in patients who underwent THA performed with a robot-assisted posterior approach (RTHA), a fluoroscopy-guided anterior approach (ATHA), or a conventional posterior approach (PTHA). We hypothesized that, compared with PTHA, both RTHA and ATHA would result in reduced LLD.

Materials and Methods

We reviewed all RTHAs, ATHAs, and PTHAs performed by Dr. Domb between September 2008 and December 2012. Study inclusion criteria were a diagnosis of hip OA and the availability of postoperative supine anteroposterior pelvis radiographs. Exclusion criteria were a diagnosis other than hip OA, missing or improper postoperative radiographs (radiographs with rotated or tilted pelvis),²² and radiographs on which at least one of the lesser trochanters was difficult to define. Of the 155 cases included in the study, 67 were RTHAs, 29 were ATHAs, and 59 were PTHAs.

All patients scheduled for THA underwent preoperative planning; plain radiographs were used to determine component size and position, level of neck cut, and amount of leg lengthening or shortening needed. In all RTHA cases, computed tomography of the involved hip was performed before surgery. The MAKO system (MAKO Surgical Corporation, Davie, Florida) was used to develop a patient-specific 3-D model of the pelvis and proximal femur, and this model was used to guide THA execution. The system was then used to detect patient-specific landmarks during surgery, to register the femur and the acetabulum, and to help determine the position of the pelvis and proximal femur during surgery. This system, which uses a haptic robotic arm that guides acetabular reaming and cup placement, provides feedback regarding cup placement, stem version, leg length, and global offset. Pelvic tilt and rotation were accounted for by the MAKO software, and all provided measurements were made on the coronal (functional) plane of the body, as described by Murray.²³ ATHA was performed with the patient in the supine position on a Hana table (Mizuho OSI, Union City, California) with fluoroscopic guidance. PTHA was performed in the conventional way, with the patient in the lateral position.

Radiographic measurements of LLD were made with TraumaCad software (Build 2.2.535.0; Voyant Health, Petah-Tikva, Israel). The accuracy of this software has been studied and reported in the literature.^24-26 Radiographs were calibrated using the known size of each femoral head as a marker. The reference on the pelvis was the interobturator line (line tangent to inferior border of obturator foramina), and the reference on the femurs was the most superior and medial aspect of each lesser trochanter. Two lines were drawn, each perpendicular to the interobturator line, starting from the previously defined reference point on each lesser trochanter. The difference in length between these 2 lines was recorded as the LLD. Values were recorded relative to the operative extremity. For example, if the operative extremity was longer than the nonoperative extremity, the LLD was given a positive value.

To eliminate bias and increase measurement accuracy, the study had each of 2 observers collect the LLD data twice, 2 months apart. These observers were blinded to each other’s results and to the type of surgery performed. (Neither observer was Dr. Domb, the senior surgeon.) IBM SPSS Statistics software (Version 20; IBM, Armonk, New York) was used for statistical analysis. Each patient’s 4 measurements were averaged into a single number for LLD, and the absolute LLD values were used in all statistical analyses. Means, standard deviations (SDs), and 95% confidence intervals (CIs) were calculated for LLD in each of the 3 groups. Pearson correlation coefficient was used to determine interobserver and intraobserver reliability. One-way analysis of variance (ANOVA) was used to compare group means for age, body mass index (BMI), and LLD. In each group, number of outliers was determined with outliers set at LLDs of more than 3 mm and more than 5 mm. Fischer exact test was used to compare number of outliers in each group. P < .05 was considered statistically significant.

Results

Table 1 lists the demographic data, including age, sex, and BMI, and compares the means. There were strong interobserver and intraobserver correlations for all LLD measurements (r > 0.9; P < .001). Mean (SD) LLD was 2.7 (1.8) mm (95% CI, 2.3-3.2) in the RTHA group, 1.8 (1.6) mm (95% CI, 1.2-2.4) in the ATHA group, and 1.9 (1.6) mm (95% CI, 1.5-2.4) in the PTHA group (P = .01). When LLD of more than 3 mm was set as an outlier, percentage of outliers was 37.3% (RTHA), 17.2% (ATHA), and 22% (PTHA) (P = .06-.78). When LLD of more than 5 mm was set as an outlier, percentage of outliers was 10.4% (RTHA), 6.9% (ATHA), and 8.5% (PTHA) (P = .72 to >.99). No patient in any group had LLD of 10 mm or more (Figure). Table 2 lists percentages of patients’ operated extremities that were longer, shorter, or the same size as their contralateral extremities. Six (9.0%) of the 67 RTHA patients, 4 (13.8%) of the 29 ATHA patients, and 3 (5.1%) of the 59 PTHA patients had a contralateral THA.

Discussion

Our study results showed that RTHA, ATHA, and PTHA were equally effective in minimizing LLD. There was a statistically significant difference in mean LLD among the 3 groups studied. The RTHA group had the largest mean (SD) LLD: 2.7 (1.8) mm. However, statistically significant differences do not always indicate clinical significance.²⁷ Therefore, comparison of the 3 groups’ means is not enough for drawing significant conclusions. The more important point to consider is the number of cases of LLD of 10 mm or more—a discrepancy that would be perceptible to patients and thus become a source of dissatisfaction with painless THA.²⁸ Patients perceive LLD when shortening exceeds 10 mm and lengthening exceeds 6 mm,²⁹ or when LLD is more than 10 mm.^16,19,20 Despite significant differences in means, all our cases came in under the 10-mm threshold. When the threshold was decreased to 5 mm (and to 3 mm), there was no statistically significant difference among the groups in the number of cases above the threshold.

LLD remains a source of significant post-THA comorbidity and patient dissatisfaction.^1-7,19 Despite surgeons’ efforts to minimize LLD, some patients can detect even a subtle LLD after surgery.^1,8,29 Most LLD values reported in the literature fall under the 10-mm threshold.^16,19,20 In some cases, however, postoperative LLD is more than 1 cm, enough to prompt litigation against orthopedic surgeons.² Surgeons have tried to improve LLD with use of multiple techniques, including use of intraoperative measuring devices,³⁰ patient positioning during surgery,²⁰ use of computer-assisted surgery,¹⁹ and use of intraoperative fluoroscopy.²⁰

Proponents of computer-assisted THA have argued that this technique improves accuracy in placing the acetabular cup in the safe zone,³¹ minimizes LLD, and restores femoral offset.^32,33 Manzotti and colleagues¹⁶ reported on 48 cases of computer-assisted THA matched to 48 cases of conventional THA using the posterior approach. Mean (SD) LLD was 5.06 (2.99) mm in the computer-assisted group and 7.64 (4.36) mm in the conventional group; there was a statistically significant difference in favor of the computer-assisted group (P = .04). However, 5 patients in the computer-assisted group and 13 in the conventional group had LLD of more than 10 mm, and the difference was statistically significant.¹⁶ Moreover, the study population was heterogeneous, with 12 patients in both groups having developmental dysplasia as a primary diagnosis.¹⁶ All the cases in our study had a diagnosis of OA, and no case had LLD of 10 mm or more.

Several advantages have been proposed for the anterior approach. The supine position (with direct comparison of leg lengths) and the use of fluoroscopy have been described as advantageous in minimizing LLD.^20,21 In their study of 494 primary THAs performed with the anterior approach, Matta and colleagues²⁰ reported mean (SD) postoperative LLD of 3 (2) mm (range, 0-26 mm) and concluded that the anterior approach was effective in restoring leg lengths and ensuring proper cup placement while not increasing the dislocation rate. However, they did not compare this approach with others or with computer-assisted THA with respect to LLD.

In another study, Nam and colleagues¹⁹ compared LLD after THA performed with 3 different approaches (anterior, conventional posterior, posterior-navigated) and found no statistically significant difference in LLD among the groups. However, LLD was more than 10 mm in 2.2% of anterior cases, 4.4% of conventional posterior cases, and 4.4% of posterior-navigated cases. When 5 mm was used as a cutoff, percentage of patients who were outliers was 31.1% (anterior), 20% (conventional posterior), and 23.3% (navigated-posterior). Our data showed superior results in using 5 mm as a cutoff, with percentage of outliers of 6.9% with ATHA, 8.5% with PTHA, and 10.4% with RTHA. However, Nam and colleagues¹⁹ used a larger patient cohort and different techniques for measuring LLD on anteroposterior pelvis radiographs.

The most likely reason that the groups in our study were comparable in terms of LLD accuracy and lack of outliers over the 10-mm cutoff was Dr. Domb’s high accuracy in minimizing LLD using each of the 3 techniques. For ATHA, mean (SD) LLD was 1.8 (1.6) mm (no LLD of ≥10 mm), better than the 3 (2) mm (0.9% with LLD of >10 mm) reported by Matta and colleagues²⁰ and the 3.8 (3.9) mm (2.2% with LLD of >10 mm) reported by Nam and colleagues.¹⁹ For PTHA, mean (SD) LLD was 1.9 (1.6) mm (no LLD of ≥10 mm), comparable to some of the best results reported in the literature—for example, the 1 mm (3% with LLD of >10 mm) reported by Woolson and colleagues.³⁴ For RTHA, mean (SD) LLD was 2.7 (1.8) mm (no LLD of ≥10 mm), superior to the 3.9 (2.7) mm (4.4% with LLD of >10 mm) reported by Nam and colleagues¹⁹ for posterior-navigated THA and the 5.06 (2.99) mm (10.4% with LLD of >10 mm) reported by Manzotti and colleagues¹⁶ for computer-assisted THA.

This study had several notable strengths. All patients had a diagnosis of hip OA and were operated on by a single surgeon. Radiographs were calibrated using the size of the implanted femoral head. Radiographic data were measured using the same technique in all cases and were collected twice by 2 observers (not the senior surgeon) to decrease bias and determine interobserver and intraobserver reliability. In addition, surgeon experience might have played an important role in minimizing LLD regardless of technique and approach used for THA.

Study limitations were different number of cases in each group, lack of matching, lack of clinical follow-up, and lack of long-term assessment of clinical outcomes and complications.

Conclusion

As performed by an experienced surgeon, RTHA, ATHA, and PTHA did not differ in obtaining minimal LLD. All 3 groups had a low frequency of outliers, using thresholds of 3 mm and 5 mm, and no patient in any group had LLD of 10 mm or more. All 3 techniques are effective in achieving accuracy in LLD.

Total knee arthroplasty (TKA) is a good surgical option to relieve pain and improve function in patients with osteoarthritis. The goal of surgery is to achieve a well-aligned prosthesis with well-balanced ligaments in order to minimize wear and improve implant survival. Overall, 82% to 89% of patients are satisfied with their outcomes after TKA, with good 10- to 15-year implant survivorship; however, there is still a subset of patients that are unsatisfied. In many cases, patient dissatisfaction is attributed to improper component alignment.^1-3 Over the past decade, computer navigation and robotics have been introduced to control surgical variables so as to gain greater consistency in implant placement and postoperative component alignment.

Computer-assisted navigation tools were introduced not only to improve implant alignment but, more importantly, to optimize clinical outcomes. Most studies have demonstrated that the use of navigation is associated with fewer radiographic outliers after TKA.⁴ Various studies have compared radiographic results of navigated TKA with results of TKA using standard instrumentation.^4-7 While long-term studies are necessary, short-term follow-up has shown that computer-assisted TKA can improve alignment, especially in patients with severe deformity.^8-10 Currently, there is no definitive consensus that computer-assisted TKA leads to significantly better component alignment or postoperative outcomes due to the fact that many studies are limited by study design or small cohorts. However, the currently published articles support better component alignment and clinical outcomes with computer-assisted TKA. While some argue that the use of computer-assisted surgery is dependent on the user’s experience, computer-assisted surgery can assist less-experienced surgeons to reliably achieve good midterm outcomes with a low complication rate.^8,11 Various studies have looked at computer-assisted TKA at midterm follow-up, with no significant differences in clinical outcome between navigated and traditional techniques. However, long-term studies showing the benefits of computer navigation are beginning to emerge. For example, de Steiger and colleagues¹² recently found that computer-assisted TKA reduced the overall revision rate for loosening after TKA in patients less than 65 years of age.

While surgical navigation helps improve implant planning, robotic tools have emerged as a tool to help refine surgical execution. Coupled with surgical navigation tools, robotic control of surgical gestures may further enhance precision in implant placement and/or enable novel implant design features. At present, robotic techniques are increasingly used in unicompartmental knee arthroplasty (UKA) and TKA.¹³ Studies have demonstrated that the robotic tool is 3 times more accurate with 3 times less variability than conventional techniques in UKA.¹⁴ The utility of robotic tools for TKA remains unclear. Robotic-driven automatic cutting guides have been shown to reduce time and improve accuracy compared with navigation guides in femoral TKA cutting procedures in a cadaveric model.¹⁵ However, robotic-enabled TKA procedures are poorly described at present, and the clinical implications of their proposed improved precision remain unclear.

Computer navigation and robotic tools in TKA hold the promise of enhanced control of surgical variables that influence clinical outcome. The variables that may be impacted by these advanced tools include implant positioning, lower limb alignment, soft-tissue balance, and, potentially, implant design and fixation. At present, these tools have primarily been shown to improve lower limb alignment in TKA. The clinical impact of the enhanced control of this single surgical variable (lower limb alignment) has been muted in short-term and midterm studies. Future studies should be directed at understanding which surgical variable, or combination of variables, it is most essential to precisely control so as to positively impact clinical outcomes. ◾

Total knee arthroplasty (TKA) is a good surgical option to relieve pain and improve function in patients with osteoarthritis. The goal of surgery is to achieve a well-aligned prosthesis with well-balanced ligaments in order to minimize wear and improve implant survival. Overall, 82% to 89% of patients are satisfied with their outcomes after TKA, with good 10- to 15-year implant survivorship; however, there is still a subset of patients that are unsatisfied. In many cases, patient dissatisfaction is attributed to improper component alignment.^1-3 Over the past decade, computer navigation and robotics have been introduced to control surgical variables so as to gain greater consistency in implant placement and postoperative component alignment.

Computer-assisted navigation tools were introduced not only to improve implant alignment but, more importantly, to optimize clinical outcomes. Most studies have demonstrated that the use of navigation is associated with fewer radiographic outliers after TKA.⁴ Various studies have compared radiographic results of navigated TKA with results of TKA using standard instrumentation.^4-7 While long-term studies are necessary, short-term follow-up has shown that computer-assisted TKA can improve alignment, especially in patients with severe deformity.^8-10 Currently, there is no definitive consensus that computer-assisted TKA leads to significantly better component alignment or postoperative outcomes due to the fact that many studies are limited by study design or small cohorts. However, the currently published articles support better component alignment and clinical outcomes with computer-assisted TKA. While some argue that the use of computer-assisted surgery is dependent on the user’s experience, computer-assisted surgery can assist less-experienced surgeons to reliably achieve good midterm outcomes with a low complication rate.^8,11 Various studies have looked at computer-assisted TKA at midterm follow-up, with no significant differences in clinical outcome between navigated and traditional techniques. However, long-term studies showing the benefits of computer navigation are beginning to emerge. For example, de Steiger and colleagues¹² recently found that computer-assisted TKA reduced the overall revision rate for loosening after TKA in patients less than 65 years of age.

While surgical navigation helps improve implant planning, robotic tools have emerged as a tool to help refine surgical execution. Coupled with surgical navigation tools, robotic control of surgical gestures may further enhance precision in implant placement and/or enable novel implant design features. At present, robotic techniques are increasingly used in unicompartmental knee arthroplasty (UKA) and TKA.¹³ Studies have demonstrated that the robotic tool is 3 times more accurate with 3 times less variability than conventional techniques in UKA.¹⁴ The utility of robotic tools for TKA remains unclear. Robotic-driven automatic cutting guides have been shown to reduce time and improve accuracy compared with navigation guides in femoral TKA cutting procedures in a cadaveric model.¹⁵ However, robotic-enabled TKA procedures are poorly described at present, and the clinical implications of their proposed improved precision remain unclear.

Computer navigation and robotic tools in TKA hold the promise of enhanced control of surgical variables that influence clinical outcome. The variables that may be impacted by these advanced tools include implant positioning, lower limb alignment, soft-tissue balance, and, potentially, implant design and fixation. At present, these tools have primarily been shown to improve lower limb alignment in TKA. The clinical impact of the enhanced control of this single surgical variable (lower limb alignment) has been muted in short-term and midterm studies. Future studies should be directed at understanding which surgical variable, or combination of variables, it is most essential to precisely control so as to positively impact clinical outcomes. ◾

Total knee arthroplasty (TKA) is a good surgical option to relieve pain and improve function in patients with osteoarthritis. The goal of surgery is to achieve a well-aligned prosthesis with well-balanced ligaments in order to minimize wear and improve implant survival. Overall, 82% to 89% of patients are satisfied with their outcomes after TKA, with good 10- to 15-year implant survivorship; however, there is still a subset of patients that are unsatisfied. In many cases, patient dissatisfaction is attributed to improper component alignment.^1-3 Over the past decade, computer navigation and robotics have been introduced to control surgical variables so as to gain greater consistency in implant placement and postoperative component alignment.

Computer-assisted navigation tools were introduced not only to improve implant alignment but, more importantly, to optimize clinical outcomes. Most studies have demonstrated that the use of navigation is associated with fewer radiographic outliers after TKA.⁴ Various studies have compared radiographic results of navigated TKA with results of TKA using standard instrumentation.^4-7 While long-term studies are necessary, short-term follow-up has shown that computer-assisted TKA can improve alignment, especially in patients with severe deformity.^8-10 Currently, there is no definitive consensus that computer-assisted TKA leads to significantly better component alignment or postoperative outcomes due to the fact that many studies are limited by study design or small cohorts. However, the currently published articles support better component alignment and clinical outcomes with computer-assisted TKA. While some argue that the use of computer-assisted surgery is dependent on the user’s experience, computer-assisted surgery can assist less-experienced surgeons to reliably achieve good midterm outcomes with a low complication rate.^8,11 Various studies have looked at computer-assisted TKA at midterm follow-up, with no significant differences in clinical outcome between navigated and traditional techniques. However, long-term studies showing the benefits of computer navigation are beginning to emerge. For example, de Steiger and colleagues¹² recently found that computer-assisted TKA reduced the overall revision rate for loosening after TKA in patients less than 65 years of age.

While surgical navigation helps improve implant planning, robotic tools have emerged as a tool to help refine surgical execution. Coupled with surgical navigation tools, robotic control of surgical gestures may further enhance precision in implant placement and/or enable novel implant design features. At present, robotic techniques are increasingly used in unicompartmental knee arthroplasty (UKA) and TKA.¹³ Studies have demonstrated that the robotic tool is 3 times more accurate with 3 times less variability than conventional techniques in UKA.¹⁴ The utility of robotic tools for TKA remains unclear. Robotic-driven automatic cutting guides have been shown to reduce time and improve accuracy compared with navigation guides in femoral TKA cutting procedures in a cadaveric model.¹⁵ However, robotic-enabled TKA procedures are poorly described at present, and the clinical implications of their proposed improved precision remain unclear.

Computer navigation and robotic tools in TKA hold the promise of enhanced control of surgical variables that influence clinical outcome. The variables that may be impacted by these advanced tools include implant positioning, lower limb alignment, soft-tissue balance, and, potentially, implant design and fixation. At present, these tools have primarily been shown to improve lower limb alignment in TKA. The clinical impact of the enhanced control of this single surgical variable (lower limb alignment) has been muted in short-term and midterm studies. Future studies should be directed at understanding which surgical variable, or combination of variables, it is most essential to precisely control so as to positively impact clinical outcomes. ◾

Ruptures of the patellar tendon usually occur in patients under age 40 years, with men having a higher incidence than women.¹ History of local steroid injection,^2,3 total knee arthroplasty,^4-8 anterior cruciate ligament reconstruction with central third patellar tendon autograft,^9-11 and a variety of systemic diseases are associated with an increased tendency to rupture.^12-15 Primary acute ruptures of the patellar tendon can be difficult to repair because of the quality of remaining tissues. In cases of chronic tendon ruptures subject to delayed treatment, additional complications such as tissue contracture and scar-tissue formation are likely to exist.^15-17

Complications after intramedullary (IM) nailing of the tibia include infection, compartment syndrome, deep vein thrombosis, thermal necrosis of the bone with alteration of its endosteal architecture, failure of the hardware, malunion, and nonunion.¹⁸ The most common complaint after IM nailing of the tibia is chronic anterior knee pain and symptoms similar to tendonitis; incidences as high as 86% have been reported.^18-20 Extensive review of the literature found only 2 reports of patellar tendon rupture after IM nailing of the tibia; both cases used a patellar tendon–splitting approach. The first report described patellar tendon rupture 8 years after IM nailing of the tibia during a forced deep-flexion movement.²¹ Radiographic examination showed the IM nail positioned proud relative to the tibial plateau, impinging upon the patellar tendon. An intraoperative examination confirmed the radiographic findings and found rupture of the patellar tendon to be consistent with the exposed tip of the IM nail. The second report described patellar tendon rupture 2 months postoperatively in a patient with Ehlers-Danlos syndrome, a hereditary disorder characterized by alterations to muscle/tendon tissue and hyperextensible skin.²²

Patellar tendon rupture after IM nailing of the tibia is a rare complication. Patellar tendon re-rupture after primary repair in a patient with history of IM tibial nailing has not been reported. This case outlines the progression of such a patient with a recurrent patellar tendon rupture that was successfully reconstructed using an Achilles tendon allograft. The patient’s surgical history of IM tibial nailing through a mid-patellar tendon–splitting approach 4 years prior to initial tendon rupture is noteworthy and potentially predisposed the patient to injury. The patient provided written informed consent for print and electronic publication of this case report.   

Case Report

A 44-year-old woman, 5 ft, 3 in tall, and weighing 129 lb (body mass index, 22.8), with a history of osteoporosis and transverse myelitis, presented with pain and persistent swelling about the left knee. Her baseline ambulatory status required crutches because of decreased sensation and strength in her lower extremity in conjunction with a foot drop; she had mild quadriceps and hamstring muscle weakness but otherwise normal knee function. The patient had been seen 4 years earlier at our facility for IM fixation of a distal tibia fracture through a patellar tendon–splitting approach. The fracture was well healed and showed no signs of complication or nail migration; the nail was not proud.

Initially, the patient was admitted to another hospital through the emergency department for swelling and pain about the left knee. She was believed to have an infection and was placed on antibiotics by the primary care team. An orthopedic evaluation showed induration, edema, and warmth in the patellar tendon region of the left knee. Magnetic resonance imaging (MRI) showed a full-thickness patellar tendon rupture. Aspiration of the knee was performed and cultures were negative; white blood cell, erythrocyte sedimentation rate, and C-reactive protein values were normal. The risks and benefits of various treatments were discussed, and surgical intervention was elected to repair the patellar tendon.

Intraoperative findings showed a massive midsubstance rupture of the patellar tendon, accompanied by medial and lateral retinacular tears and a quadriceps tendon partial rupture; the central aspect of the quadriceps tendon attaching to the patella remained intact. The patella was retracted proximally; no evidence of active infection was present. Good-quality tissue remained attached to both the tibial tuberosity and the inferior pole of the patella. A No. 2 FiberWire suture (Arthrex, Inc, Naples, Florida) was used to run whip stitches in the distal end of the patellar tendon and a second No. 2 FiberWire suture was used to run whip stitches in the proximal aspect of the patellar tendon rupture. The 4 ends of the sutures were tied together, thus re-approximating the distal and proximal ends of the ruptured patellar tendon. No bone drilling was used because the midsubstance tear was amenable to good repair with reasonable expectation of healing based on tissue quality. The quadriceps tendon, which was partially torn, was repaired with a No. 1 Vicryl suture (Ethicon, Somerville, New Jersey). The medial and lateral retinacula were also repaired with a No. 1 Vicryl suture. The suturing scheme effectively re-approximated the knee extensor mechanism, and the patient was placed in a knee immobilizer that permitted no flexion for 6 weeks postoperatively.

After 3 months of gradual improvement with physical therapy, the patient returned for a follow-up visit, concerned that her knee function was beginning to decline. Physical examination showed patella alta with a thinned and diminutive palpable tendon in the patellar tendon region. She was capable of active flexion to 90º and extension to 50º, but beyond 50º, she was unable to actively extend; she was capable of full passive extension. MRI showed a repeat full-thickness patellar tendon tear with retraction from the inferior pole of the patella; previous tears to the quadriceps tendon were healed. Because of the recurrent nature of the injury, the patient’s physical examination, MRI findings, and anticipated poor quality of remaining tendon tissue, patellar tendon reconstruction using a cadaveric Achilles tendon allograft was recommended. The patient chose surgery for potential improvement in knee range of motion, active extension, and ambulation.

The previous anterior midline incision was used and carried down through the subcutaneous tissues where a complete rupture of the patellar tendon was identified. A limited amount of good-quality tendon tissue remained at the medial aspect of the tibial tuberosity. The remaining tissue located at the patella’s inferior pole was nonviable for use in surgical repair. Retinacular contractures were released to bring the patella distally; the trochlear groove was used as the anatomic landmark for the patella resting position. During reconstruction, the knee was placed into 30° of flexion, with the patella located in the trochlear groove, and the cadaveric Achilles tendon was placed on the midline of the patella, where measurements were done to assess proper length and tension (Figure 1).

The patient’s remaining native tissue on the medial aspect of the tibial tuberosity was used to augment the Achilles tendon graft medially. The cadaveric Achilles tendon graft was primarily used to replace the central and lateral aspects of the patellar tendon. Additionally, the calcaneal bone segment at the end of the Achilles tendon graft was removed prior to use. Cadaveric and host tissues at the medial aspect of the tibial tuberosity were sutured together with a No. 1 Vicryl suture (Figure 2). The distal aspect of the cadaveric Achilles tendon was used to re-approximate the patient’s native patellar tendon insertion at the tibial tuberosity. To supplement the graft anchor, a Richards metallic ligament staple (Smith & Nephew, Memphis, Tennessee) was used to fix the distal aspect of the Achilles tendon graft into the tibial tuberosity.

Proper tensioning of the graft was performed by visualizing patella tracking during the arc-of-knee motion and properly suturing the graft to allow for functional range. The proximal aspect of the cadaveric Achilles tendon was sutured into host tissues surrounding the superior pole of the patellar and quadriceps tendon. The edges of the graft were sutured with supplemental No. 1 Vicryl sutures (Figure 3).

Before surgical closure, knee range of motion was checked and noted to be 0º to 100º.  The repaired construct was stable and uncompromised throughout the entire range of motion. Patella tracking was central and significantly improved; knee stability was normal to varus and valgus stress.

The patient was placed in a knee immobilizer for 6 weeks before range of motion was allowed. Seven months postoperatively, the patient returned for a follow-up visit, ambulating with 2 forearm crutches, which was her baseline ambulatory status. Physical examination revealed passive range of motion from 0º to 130º, an extension lag of 10º, and 4/5 quadriceps strength. It was recommended the patient continue physical therapy to improve strength and range of motion.

Conclusion

This is the first report in the literature documenting a recurrent patellar tendon rupture after primary repair in a patient with a history of IM tibial nailing. It is also the first report of a cadaveric Achilles tendon allograft used as a solution to this problem. Complete reconstruction of the patellar tendon using an Achilles tendon allograft is a method commonly used for ruptures after total knee arthroplasty.^4-7,23,24 This case report highlights the utility of a cadaveric Achilles tendon in the setting of a recurrent patellar tendon rupture with poor remaining tissue quality.

Ruptures of the patellar tendon usually occur in patients under age 40 years, with men having a higher incidence than women.¹ History of local steroid injection,^2,3 total knee arthroplasty,^4-8 anterior cruciate ligament reconstruction with central third patellar tendon autograft,^9-11 and a variety of systemic diseases are associated with an increased tendency to rupture.^12-15 Primary acute ruptures of the patellar tendon can be difficult to repair because of the quality of remaining tissues. In cases of chronic tendon ruptures subject to delayed treatment, additional complications such as tissue contracture and scar-tissue formation are likely to exist.^15-17

Complications after intramedullary (IM) nailing of the tibia include infection, compartment syndrome, deep vein thrombosis, thermal necrosis of the bone with alteration of its endosteal architecture, failure of the hardware, malunion, and nonunion.¹⁸ The most common complaint after IM nailing of the tibia is chronic anterior knee pain and symptoms similar to tendonitis; incidences as high as 86% have been reported.^18-20 Extensive review of the literature found only 2 reports of patellar tendon rupture after IM nailing of the tibia; both cases used a patellar tendon–splitting approach. The first report described patellar tendon rupture 8 years after IM nailing of the tibia during a forced deep-flexion movement.²¹ Radiographic examination showed the IM nail positioned proud relative to the tibial plateau, impinging upon the patellar tendon. An intraoperative examination confirmed the radiographic findings and found rupture of the patellar tendon to be consistent with the exposed tip of the IM nail. The second report described patellar tendon rupture 2 months postoperatively in a patient with Ehlers-Danlos syndrome, a hereditary disorder characterized by alterations to muscle/tendon tissue and hyperextensible skin.²²

Patellar tendon rupture after IM nailing of the tibia is a rare complication. Patellar tendon re-rupture after primary repair in a patient with history of IM tibial nailing has not been reported. This case outlines the progression of such a patient with a recurrent patellar tendon rupture that was successfully reconstructed using an Achilles tendon allograft. The patient’s surgical history of IM tibial nailing through a mid-patellar tendon–splitting approach 4 years prior to initial tendon rupture is noteworthy and potentially predisposed the patient to injury. The patient provided written informed consent for print and electronic publication of this case report.   

Case Report

A 44-year-old woman, 5 ft, 3 in tall, and weighing 129 lb (body mass index, 22.8), with a history of osteoporosis and transverse myelitis, presented with pain and persistent swelling about the left knee. Her baseline ambulatory status required crutches because of decreased sensation and strength in her lower extremity in conjunction with a foot drop; she had mild quadriceps and hamstring muscle weakness but otherwise normal knee function. The patient had been seen 4 years earlier at our facility for IM fixation of a distal tibia fracture through a patellar tendon–splitting approach. The fracture was well healed and showed no signs of complication or nail migration; the nail was not proud.

Initially, the patient was admitted to another hospital through the emergency department for swelling and pain about the left knee. She was believed to have an infection and was placed on antibiotics by the primary care team. An orthopedic evaluation showed induration, edema, and warmth in the patellar tendon region of the left knee. Magnetic resonance imaging (MRI) showed a full-thickness patellar tendon rupture. Aspiration of the knee was performed and cultures were negative; white blood cell, erythrocyte sedimentation rate, and C-reactive protein values were normal. The risks and benefits of various treatments were discussed, and surgical intervention was elected to repair the patellar tendon.

Intraoperative findings showed a massive midsubstance rupture of the patellar tendon, accompanied by medial and lateral retinacular tears and a quadriceps tendon partial rupture; the central aspect of the quadriceps tendon attaching to the patella remained intact. The patella was retracted proximally; no evidence of active infection was present. Good-quality tissue remained attached to both the tibial tuberosity and the inferior pole of the patella. A No. 2 FiberWire suture (Arthrex, Inc, Naples, Florida) was used to run whip stitches in the distal end of the patellar tendon and a second No. 2 FiberWire suture was used to run whip stitches in the proximal aspect of the patellar tendon rupture. The 4 ends of the sutures were tied together, thus re-approximating the distal and proximal ends of the ruptured patellar tendon. No bone drilling was used because the midsubstance tear was amenable to good repair with reasonable expectation of healing based on tissue quality. The quadriceps tendon, which was partially torn, was repaired with a No. 1 Vicryl suture (Ethicon, Somerville, New Jersey). The medial and lateral retinacula were also repaired with a No. 1 Vicryl suture. The suturing scheme effectively re-approximated the knee extensor mechanism, and the patient was placed in a knee immobilizer that permitted no flexion for 6 weeks postoperatively.

After 3 months of gradual improvement with physical therapy, the patient returned for a follow-up visit, concerned that her knee function was beginning to decline. Physical examination showed patella alta with a thinned and diminutive palpable tendon in the patellar tendon region. She was capable of active flexion to 90º and extension to 50º, but beyond 50º, she was unable to actively extend; she was capable of full passive extension. MRI showed a repeat full-thickness patellar tendon tear with retraction from the inferior pole of the patella; previous tears to the quadriceps tendon were healed. Because of the recurrent nature of the injury, the patient’s physical examination, MRI findings, and anticipated poor quality of remaining tendon tissue, patellar tendon reconstruction using a cadaveric Achilles tendon allograft was recommended. The patient chose surgery for potential improvement in knee range of motion, active extension, and ambulation.

The previous anterior midline incision was used and carried down through the subcutaneous tissues where a complete rupture of the patellar tendon was identified. A limited amount of good-quality tendon tissue remained at the medial aspect of the tibial tuberosity. The remaining tissue located at the patella’s inferior pole was nonviable for use in surgical repair. Retinacular contractures were released to bring the patella distally; the trochlear groove was used as the anatomic landmark for the patella resting position. During reconstruction, the knee was placed into 30° of flexion, with the patella located in the trochlear groove, and the cadaveric Achilles tendon was placed on the midline of the patella, where measurements were done to assess proper length and tension (Figure 1).

The patient’s remaining native tissue on the medial aspect of the tibial tuberosity was used to augment the Achilles tendon graft medially. The cadaveric Achilles tendon graft was primarily used to replace the central and lateral aspects of the patellar tendon. Additionally, the calcaneal bone segment at the end of the Achilles tendon graft was removed prior to use. Cadaveric and host tissues at the medial aspect of the tibial tuberosity were sutured together with a No. 1 Vicryl suture (Figure 2). The distal aspect of the cadaveric Achilles tendon was used to re-approximate the patient’s native patellar tendon insertion at the tibial tuberosity. To supplement the graft anchor, a Richards metallic ligament staple (Smith & Nephew, Memphis, Tennessee) was used to fix the distal aspect of the Achilles tendon graft into the tibial tuberosity.

Proper tensioning of the graft was performed by visualizing patella tracking during the arc-of-knee motion and properly suturing the graft to allow for functional range. The proximal aspect of the cadaveric Achilles tendon was sutured into host tissues surrounding the superior pole of the patellar and quadriceps tendon. The edges of the graft were sutured with supplemental No. 1 Vicryl sutures (Figure 3).

Before surgical closure, knee range of motion was checked and noted to be 0º to 100º.  The repaired construct was stable and uncompromised throughout the entire range of motion. Patella tracking was central and significantly improved; knee stability was normal to varus and valgus stress.

The patient was placed in a knee immobilizer for 6 weeks before range of motion was allowed. Seven months postoperatively, the patient returned for a follow-up visit, ambulating with 2 forearm crutches, which was her baseline ambulatory status. Physical examination revealed passive range of motion from 0º to 130º, an extension lag of 10º, and 4/5 quadriceps strength. It was recommended the patient continue physical therapy to improve strength and range of motion.

Conclusion

This is the first report in the literature documenting a recurrent patellar tendon rupture after primary repair in a patient with a history of IM tibial nailing. It is also the first report of a cadaveric Achilles tendon allograft used as a solution to this problem. Complete reconstruction of the patellar tendon using an Achilles tendon allograft is a method commonly used for ruptures after total knee arthroplasty.^4-7,23,24 This case report highlights the utility of a cadaveric Achilles tendon in the setting of a recurrent patellar tendon rupture with poor remaining tissue quality.

Ruptures of the patellar tendon usually occur in patients under age 40 years, with men having a higher incidence than women.¹ History of local steroid injection,^2,3 total knee arthroplasty,^4-8 anterior cruciate ligament reconstruction with central third patellar tendon autograft,^9-11 and a variety of systemic diseases are associated with an increased tendency to rupture.^12-15 Primary acute ruptures of the patellar tendon can be difficult to repair because of the quality of remaining tissues. In cases of chronic tendon ruptures subject to delayed treatment, additional complications such as tissue contracture and scar-tissue formation are likely to exist.^15-17

Complications after intramedullary (IM) nailing of the tibia include infection, compartment syndrome, deep vein thrombosis, thermal necrosis of the bone with alteration of its endosteal architecture, failure of the hardware, malunion, and nonunion.¹⁸ The most common complaint after IM nailing of the tibia is chronic anterior knee pain and symptoms similar to tendonitis; incidences as high as 86% have been reported.^18-20 Extensive review of the literature found only 2 reports of patellar tendon rupture after IM nailing of the tibia; both cases used a patellar tendon–splitting approach. The first report described patellar tendon rupture 8 years after IM nailing of the tibia during a forced deep-flexion movement.²¹ Radiographic examination showed the IM nail positioned proud relative to the tibial plateau, impinging upon the patellar tendon. An intraoperative examination confirmed the radiographic findings and found rupture of the patellar tendon to be consistent with the exposed tip of the IM nail. The second report described patellar tendon rupture 2 months postoperatively in a patient with Ehlers-Danlos syndrome, a hereditary disorder characterized by alterations to muscle/tendon tissue and hyperextensible skin.²²

Patellar tendon rupture after IM nailing of the tibia is a rare complication. Patellar tendon re-rupture after primary repair in a patient with history of IM tibial nailing has not been reported. This case outlines the progression of such a patient with a recurrent patellar tendon rupture that was successfully reconstructed using an Achilles tendon allograft. The patient’s surgical history of IM tibial nailing through a mid-patellar tendon–splitting approach 4 years prior to initial tendon rupture is noteworthy and potentially predisposed the patient to injury. The patient provided written informed consent for print and electronic publication of this case report.   

Case Report

A 44-year-old woman, 5 ft, 3 in tall, and weighing 129 lb (body mass index, 22.8), with a history of osteoporosis and transverse myelitis, presented with pain and persistent swelling about the left knee. Her baseline ambulatory status required crutches because of decreased sensation and strength in her lower extremity in conjunction with a foot drop; she had mild quadriceps and hamstring muscle weakness but otherwise normal knee function. The patient had been seen 4 years earlier at our facility for IM fixation of a distal tibia fracture through a patellar tendon–splitting approach. The fracture was well healed and showed no signs of complication or nail migration; the nail was not proud.

Initially, the patient was admitted to another hospital through the emergency department for swelling and pain about the left knee. She was believed to have an infection and was placed on antibiotics by the primary care team. An orthopedic evaluation showed induration, edema, and warmth in the patellar tendon region of the left knee. Magnetic resonance imaging (MRI) showed a full-thickness patellar tendon rupture. Aspiration of the knee was performed and cultures were negative; white blood cell, erythrocyte sedimentation rate, and C-reactive protein values were normal. The risks and benefits of various treatments were discussed, and surgical intervention was elected to repair the patellar tendon.

Intraoperative findings showed a massive midsubstance rupture of the patellar tendon, accompanied by medial and lateral retinacular tears and a quadriceps tendon partial rupture; the central aspect of the quadriceps tendon attaching to the patella remained intact. The patella was retracted proximally; no evidence of active infection was present. Good-quality tissue remained attached to both the tibial tuberosity and the inferior pole of the patella. A No. 2 FiberWire suture (Arthrex, Inc, Naples, Florida) was used to run whip stitches in the distal end of the patellar tendon and a second No. 2 FiberWire suture was used to run whip stitches in the proximal aspect of the patellar tendon rupture. The 4 ends of the sutures were tied together, thus re-approximating the distal and proximal ends of the ruptured patellar tendon. No bone drilling was used because the midsubstance tear was amenable to good repair with reasonable expectation of healing based on tissue quality. The quadriceps tendon, which was partially torn, was repaired with a No. 1 Vicryl suture (Ethicon, Somerville, New Jersey). The medial and lateral retinacula were also repaired with a No. 1 Vicryl suture. The suturing scheme effectively re-approximated the knee extensor mechanism, and the patient was placed in a knee immobilizer that permitted no flexion for 6 weeks postoperatively.

After 3 months of gradual improvement with physical therapy, the patient returned for a follow-up visit, concerned that her knee function was beginning to decline. Physical examination showed patella alta with a thinned and diminutive palpable tendon in the patellar tendon region. She was capable of active flexion to 90º and extension to 50º, but beyond 50º, she was unable to actively extend; she was capable of full passive extension. MRI showed a repeat full-thickness patellar tendon tear with retraction from the inferior pole of the patella; previous tears to the quadriceps tendon were healed. Because of the recurrent nature of the injury, the patient’s physical examination, MRI findings, and anticipated poor quality of remaining tendon tissue, patellar tendon reconstruction using a cadaveric Achilles tendon allograft was recommended. The patient chose surgery for potential improvement in knee range of motion, active extension, and ambulation.

The previous anterior midline incision was used and carried down through the subcutaneous tissues where a complete rupture of the patellar tendon was identified. A limited amount of good-quality tendon tissue remained at the medial aspect of the tibial tuberosity. The remaining tissue located at the patella’s inferior pole was nonviable for use in surgical repair. Retinacular contractures were released to bring the patella distally; the trochlear groove was used as the anatomic landmark for the patella resting position. During reconstruction, the knee was placed into 30° of flexion, with the patella located in the trochlear groove, and the cadaveric Achilles tendon was placed on the midline of the patella, where measurements were done to assess proper length and tension (Figure 1).

The patient’s remaining native tissue on the medial aspect of the tibial tuberosity was used to augment the Achilles tendon graft medially. The cadaveric Achilles tendon graft was primarily used to replace the central and lateral aspects of the patellar tendon. Additionally, the calcaneal bone segment at the end of the Achilles tendon graft was removed prior to use. Cadaveric and host tissues at the medial aspect of the tibial tuberosity were sutured together with a No. 1 Vicryl suture (Figure 2). The distal aspect of the cadaveric Achilles tendon was used to re-approximate the patient’s native patellar tendon insertion at the tibial tuberosity. To supplement the graft anchor, a Richards metallic ligament staple (Smith & Nephew, Memphis, Tennessee) was used to fix the distal aspect of the Achilles tendon graft into the tibial tuberosity.

Proper tensioning of the graft was performed by visualizing patella tracking during the arc-of-knee motion and properly suturing the graft to allow for functional range. The proximal aspect of the cadaveric Achilles tendon was sutured into host tissues surrounding the superior pole of the patellar and quadriceps tendon. The edges of the graft were sutured with supplemental No. 1 Vicryl sutures (Figure 3).

Before surgical closure, knee range of motion was checked and noted to be 0º to 100º.  The repaired construct was stable and uncompromised throughout the entire range of motion. Patella tracking was central and significantly improved; knee stability was normal to varus and valgus stress.

The patient was placed in a knee immobilizer for 6 weeks before range of motion was allowed. Seven months postoperatively, the patient returned for a follow-up visit, ambulating with 2 forearm crutches, which was her baseline ambulatory status. Physical examination revealed passive range of motion from 0º to 130º, an extension lag of 10º, and 4/5 quadriceps strength. It was recommended the patient continue physical therapy to improve strength and range of motion.

Conclusion

This is the first report in the literature documenting a recurrent patellar tendon rupture after primary repair in a patient with a history of IM tibial nailing. It is also the first report of a cadaveric Achilles tendon allograft used as a solution to this problem. Complete reconstruction of the patellar tendon using an Achilles tendon allograft is a method commonly used for ruptures after total knee arthroplasty.^4-7,23,24 This case report highlights the utility of a cadaveric Achilles tendon in the setting of a recurrent patellar tendon rupture with poor remaining tissue quality.