Donald A. Ross, MD

Surgical treatment of degenerative lumbar spine disease has been rising steadily in the United States, and an increasing fraction of surgery involves lumbar fusion.^1,2 Various techniques are used to accomplish a lumbar fusion, including noninstrumented fusion, anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (XLIF, OLIF), posterior pedicle screw fusion, posterior cortical screw fusion, posterior interbody fusion (TLIF, PLIF), and interspinous process fusion. Rigid, metallic fusion hardware provides high stability and fusion rates, but it likely leads to stress shielding and adjacent segment disease.³ There is interest in less rigid and dynamic stabilization techniques to reduce the risk of adjacent segment disease, such as polyetheretherketone (PEEK) rods, which have been available since 2007. However, literature regarding PEEK rod utility is sparse and of mixed outcomes.^3,4 Additional patient reported outcome (PRO) information would be useful to both surgeons and patients. Using institutional data, this review was designed to examine our experience with PEEK rod lumbar fusion and to document PROs.

Methods

The study was approved by the institutional review board at the US Department of Veterans Affairs (VA) Portland Health Care System (VAPHCS) in Oregon with a waiver of authorization. In this retrospective, single center study, data were queried from the senior author’s (DAR) case logs from VA Computerized Patient Record System (CPRS). Electronic medical records, imaging, and PROs of all consecutive patients undergoing lumbar fusion at 1 or 2 levels with PEEK rods for degenerative disease were retrospectively reviewed. Cases of trauma, malignancy, or infection were excluded. From March 2011 through October 2019, 108 patients underwent lumbar fusion with PEEK rods.

Surgeries were conducted on a Mizuho OSI Jackson Table via bilateral 3 to 4 cm Wiltse incisions using the Medtronic Quadrant retractor system. Medtronic O-Arm images were acquired and delivered to a Medtronic Stealth Station for navigation of the screws. Monopolar coagulation was not used. PEEK pedicle screws were placed and verified with a second O-Arm spin before placing lordotic PEEK rods in the screw heads. No attempt was made to reduce any spondylolisthesis, but distraction was used to open the foramina and indirectly decompress the canal. An interbody device was placed only in treatment of multiply recurrent disc protrusion. After decortication of the transverse processes and facets, intertransverse fusion constructs consisting of calcium hydroxyapatite soaked in autologous bone marrow blood and wrapped in 6-mg bone morphogenetic protein-soaked sponges were placed on the bone. If canal decompression was indicated, a Medtronic Metrx retractor tube was then placed through one of the incisions and decompression carried out. Wounds were closed with absorbable suture. No bracing was used postoperatively. Figure 1 shows a typical single level PEEK rod fusion construct.

Statistical Analysis

Pre- and postoperative pairwise t tests were completed for patients with a complete data, using SAS 9.2 statistical package. Data are presented as standard deviation (SD) of the mean.

Results

Following application of the inclusion/exclusion criteria, 108 patients had undergone lumbar fusion with PEEK rods. Mean (SD) patient age was 60.2 (10.3) years and 88 patients were male (Table 1). Most surgeries were at L5-S1 and L4-5. There were 97 single-level fusions and 11 bilevel fusions. Seventy-four procedures were for spondylolisthesis, 23 for foraminal stenosis, 5 for degenerative disc disease, 3 for coronal imbalance with foraminal stenosis, 2 for pseudarthrosis after surgery elsewhere, and 1 for multiple recurrent disc herniation (Table 2). Twenty-five patients (23.1%) were current tobacco users and 28 (25.9%) were former smokers, 26 (24.1%) had diabetes mellitus (DM), 16 (14.8%) had low bone density by dual energy X-ray absorptiometry (DEXA) imaging, 35 (32.4%) had depression, and 7 (6.5%) were taking an immunosuppressive agent (chronic steroids, biological response modifiers, or methotrexate). Mean body mass index was 30.1.

Surgical Procedure

Of the 108 patients, the first 18 underwent a procedure with fluoroscopic guidance and the Medtronic FluoroNav and Stealth Systems. The next 90 patients underwent a procedure with O-Arm intraoperative CT scanning and Stealth frameless stereotactic navigation. The mean (SD) length of stay was 1.7 (1.3) days. There were no wound infections and no new neurologic deficits. Mean (SD) follow up time was 30.3 (21.8) months.

Imaging

Final imaging was by radiograph in 73 patients, CT in 31, and magnetic resonance imaging (MRI) in 3 (1 patient had no imaging). Sixty-seven patients (62.0%) had a bilateral arthrodesis, and 15 (13.9%) had at least a unilateral arthrodesis. MRI was not used to assess arthrodesis. Eight patients (7.4%) had no definite arthrodesis. Seventeen patients had inadequate or early imaging from which a fusion determination could not be made. Of 81 patients with > 11 months of follow up, 58 (71.6%) had a bilateral arthrodesis, 12 (14.8%) had a unilateral arthrodesis, 8 (9.9%) had no arthrodesis, and 3 (3.7%) were indeterminate.

No patient had any revision fusion surgery at the index level during follow up. Two patients had adjacent level fusions at 27 and 60 months after the index procedure. One patient had a laminectomy at an adjacent segment at 18 months postfusion, and 1 had a foraminotomy at an adjacent segment 89 months post fusion (Figure 3). Overall, there were 4 (3.7%) adjacent segment surgeries at a mean of 48.5 months after surgery. One patient had a sacro-iliac joint fusion below an L5-S1 fusion 17 months prior for persisting pain after the fusion procedure.

Patient Reported Outcomes

Preoperative SF-36 PF and ODI scores were available for 81 patients (Table 3). Postoperative SF-36 PF scores were obtained at 3 months for 65 of these patients, and at 1 year for 63 patients. Postoperative ODI scores were obtained at 3 months for 65 patients, and at 1 year for 55 patients. Among the 65 patients with completed SF-36 scores at 3 months, a mean increase of 22.4 (95% CI, 17-27; P < .001) was noted, and for the 63 patients at 1 year a mean increase of 30.3 (95% CI, 25-35; P < .001) was noted. Among the 65 patients with completed ODI scores at 3 months, a mean decrease of 6.8 (95% CI, 4.9-8.6; P < .001) was noted, and for the 55 patients with completed ODI scores at 1 year a mean decrease of 10.3 (n = 55; 95% CI, 8.4-12.2; P < .001) was noted.

Cost

We compared the hardware cost of a single level construct consisting of 4 pedicle screws, 4 locking caps, and 2 rods using a PEEK system with that of 2 other titanium construct systems. At VAPHCS, the PEEK system cost was about 71% of the cost of 2 other titanium construct systems and 62% of the cost when compared with Medtronic titanium rods.

Discussion

PEEK is useful for spine and cranial implants. It is inert and fully biocompatible with a modulus of elasticity between that of cortical and cancellous bone, and much lower than that of titanium, and is therefore considered to be semirigid.^3,4,6 PEEK rods are intermediate in stiffness between titanium rods (110 Gigapascals) and dynamic devices such as the Zimmer Biomet DYNESYS dynamic stabilization system or the Premia Spine TOPS system.³ Carbon fiber rods and carbon fiber reinforced PEEK implants are other semirigid rod alternatives.^7,8 PEEK rods for posterior lumbar fusion surgery were introduced in 2007. Li and colleagues provide a thorough review of the biomechanical properties of PEEK rods.³

PEEK is thought to have several advantages when compared with titanium. These advantages include more physiologic load sharing and reduction in stress shielding, improved durability, reduced risk of failure in osteoporotic bone, less wear debris, no change in bone forming environment, and imaging radiolucency.^4,9 Spinal PEEK cages have been reported to allow more uniform radiation dose distribution compared with metal constructs, an advantage that also may pertain to PEEK rods.¹⁰ Disadvantages of PEEK rods include an inability to detect rod breakage easily, lack of data on the use in more than minimally unstable clinical situations, and greater expense, although this was not the authors’ observation.^3,4,11

Importantly, it has been reported that PEEK rods permit a greater range of motion in all planes when compared with titanium rods.⁹ Polyetheretherketone rods unload the bone screw interface and increased the anterior column load to a more physiologic 75% when compared with titanium rods.^6,9 However, in another biomechanical study that compared titanium rods, PEEK rods, and a dynamic stabilization device, it was reported that anterior load sharing was 55%, 59%, and 75%, respectively.¹² This indicated that PEEK rods are closer to metal rods than truly dynamic devices for anterior load sharing. The endurance limit of a PEEK rod construct was similar to that of clinically useful metal systems.⁹ PEEK rods resulted in no increase in postfatigue motion compared with titanium rods in a biomechanical model.¹³ Intradiscal pressures at PEEK instrumented segments were similar to uninstrumented segments and greater than those with titanium rod constructs.¹⁴ Intradiscal pressures at adjacent segments were highest with dynamic devices, intermediate with semirigid rods, and lowest with rigid constructs; however, stress values at adjacent segments were lower in PEEK than titanium constructs in any direction of motion.^15,16

Fusion Rates

The use of PEEK rods in lumbar fusion has been reported previously.^3,4,17,18 However, these studies featured small sample sizes, short follow up times, and contradictory results.⁴ Of 8 outcome reports found in a systematic review, 2 studies reported on procedures designed to create nonfusion outcomes (a third similar trial from 2013 was not included in the systematic review), and 1 study reported only on the condition of PEEK rods removed at subsequent surgery.^3,19-21 Reported fusion rates varied from 86 to 100%.

In 42 patients with PEEK rod fusions who were followed for a mean of 31.4 months, 5 patients required adjacent segment surgery and 3 patients were treated for interbody cage migration and nonunion.¹⁷ Radiographic fusion rate was 86%. These authors concluded that PEEK rod fusion results were similar to those of other constructs, but not better, or perhaps worse than, metal rods.

Other studies have reported better results with PEEK.^{11,18,19,22-24} Highsmith and colleagues reported on 3 successful example cases of the use of PEEK rods.¹¹ De Iure and colleagues reported on 30 cases up to 5 levels (mean, 2.9) using autograft bone, with a mean follow up of 18 months.²³ Results were reported as satisfactory. Three patients had radiographic nonunions, 1 of which required revision for asymptomatic screw loosening at the cranial end of the construct. Qi and colleagues, reported on 20 patients with PEEK rods compared to 21 patients with titanium alloy rods.²⁴ Both groups had similar clinical outcomes, structural parameters, and 100% fusion rates. Athanasakopoulos and colleagues reported on 52 patients with up to 3 level fusions followed for a mean of 3 years.²² There were significant improvements in PROs: at 1 year 96% had radiographic union. Two patients had screw breakage, 1 of whom required revision to a metal rod construct. Colangeli and colleagues reported on 12 patients treated with PEEK rods compared with 12 who were treated with a dynamic system.¹⁸ They reported significant improvements, no complications, and 100% fusion at 6 months. Huang and colleagues reported on 38 patients intended to undergo a nonfusion procedure with 2 years of follow up.¹⁹ They reported good outcomes and 1 case of screw loosening. As no fusion was intended, no fusion outcomes were reported. All these studies suggested that longer follow up and more patients would be needed to assess the role of PEEK rods in lumbar fusion.³

Our results show a radiographic fusion rate of 86.4% and a radiographic nonunion rate of 9.9% in patients followed for at least 12 months. There was no clinical need for revision fusion at the index level. In our retrospective review, patients had high levels of smoking, DM, depression, immunosuppression, and obesity, which may negatively influence radiographic fusion rates when compared with other studies with 100% reported fusion rates. There was no instance of construct breakage or screw breakout, indicating that PEEK rods may allow enough flexibility to avoid construct failure under stress as in a fall.

Patient Reported Outcomes

Recent large studies were reviewed to assess the pre- and postoperative patient PROs reported in comparison with our study population (Table 4). In the Swedish Spine Registry analysis of 765 patients with 3 different types of lumbar fusion, the mean preoperative ODI score was 37 and mean SF-36 physical component score (PCS) was 35 for the most similar approach (posterolateral fusion with instrumentation).²⁵ At 1 year postoperation, the mean ODI was 26 and mean SF-36 PCS was 43. In the Spine Patient Outcomes Research Trial (SPORT) spondylolisthesis trial of 3 fusion types, the mean preoperative ODI was 41.2 and mean SF-36 PF score was 31.2 for the most similar approach (posterolateral instrumented fusion with pedicle screws).²⁶ Postoperative ODI scores at 1 year decreased by a mean 20.9 points and mean SF-36 PF scores increased by 29.9.

We report a mean preoperative SF-36 PF score of 28.9, which is lower than the SPORT study score for posterolateral fusion with instrumentation and the Swedish Study score for posterolateral instrumented fusion with pedicle screws. Similarly, our mean ODI score of 24.8 was better than the scores reported in the Swedish and SPORT studies. Our mean SF-36 PF score at 1 year postoperation was 59.3, compared with 58.5 for the SPORT study group and 46.0 in the Swedish study group. Mean ODI score at 1 year postoperatively was 14.5, which is better than the scores reported in the Swedish and SPORT studies.

Minimally clinically important difference (MCID) is a parameter used to gauge the efficacy of spine surgery. The utility of the MCID based upon PROs has been questioned in lumbar fusion surgery, as it has been thought to measure if the patient is “feeling” rather than “doing” better, the latter of which can be better measured by functional performance measures and objective, external socioeconomic anchors such as return to work and health care costs.²⁷ Nevertheless, validated PROs are reported widely in the spine surgery literature. The MCID in the SF-36 is not well established and can depend upon whether the scores are at the extremes or more in the central range and whether there is large variability in the scores.²⁸ Rheumatoid arthritis was estimated to be 7.1 points on the PF scale and 7.2 on the physical component summary (PCS).²⁹ For total knee replacement, it has been estimated to be 10 points on the SF-36 PCS.³⁰ Lumbar surgery was estimated to be 4.9 points for the SF-36 PCS and 12.8 points for the ODI.³¹ And the SPORT trial it has been estimated that a 30% change in the possible gain (or loss) may be an appropriate criterion.²⁸

With a preoperative mean SF-36 PF of 28.9, a 30% improvement in the available range (70.1) would be 21 points, making our data mean improvement of 30 points above the MCID. With a mean preoperative ODI of 24.6, a 30% improvement in the available range (25.4) would be 7.6 points, making our data mean improvement of 10.3 points better than the MCID. Therefore, our outcome results are comparable with other lumbar fusion outcome studies in terms of degree of disability prior to surgery and amount of improvement from surgery.

Adjacent Segment Disease

The precise factors resulting in adjacent segment disease are not fully defined.^3,32 In reviews of lumbar adjacent segment disease, reported rates ranged from 2.5% at 1 year up to 80 to 100% at 10 years, with lower rates with noninstrumented fusions.^4,32-34 Annual incidence of symptomatic adjacent segment disease following lumbar fusion ranges from 0.6 to 3.9% per year.^32,35,36 Mismatch between lumbar lordosis and pelvic incidence after fusion is thought to lead to higher rates of adjacent segment disease, as can a laminectomy at an adjacent segment.^32,36 Percutaneous fusion techniques or use of the Wiltse approach may lower the risk of adjacent segment disease due to avoidance of facet capsule disruption.^37,38

Dynamic stabilization techniques do not appear be clearly protective against adjacent segment disease, although biomechanical models suggest that they may do so.^33,39,40 A review by Wang and colleagues pooled studies to assess the risk of lumbar adjacent segment disease in spinal fusion to compare to disc arthroplasty and concluded that fusion carried a higher risk of adjacent segment disease.⁴¹ Definitive data on other types of motion preservation devices is lacking.³We show 3 adjacent segment fusions and 1 laminectomy have been needed in 108 patients and at a mean of 46 months after the index procedure and over 2.5 years of mean overall follow up. This is a low adjacent segment surgery rate compared to the historical data cited above, and may suggest some advantage for PEEK rods over more rigid constructs.

Strengths and Limitations

Strengths of this study include larger numbers than prior series of PEEK rod use and use in a population with high comorbidities linked to poor results without reduction in good outcomes. PEEK rods as used at the VAPHCS do not result in higher instrumentation costs than all metal constructs.

Study limitations include the retrospective nature with loss of follow up on some patients and incomplete radiographic and PROs in some patients. The use of 100% stereotactic guidance, the avoidance of interbody devices, and the off-label use of bone morphogenetic protein as part of the fusion construct introduce additional variables that may influence comparison to other studies. To avoid unnecessary radiation exposure, flexion extension films or CT scans were not routinely obtained if patients were doing well.⁴² Additionally, the degree of motion on dynamic views that would differentiate pseudarthrosis from arthrodesis has not been defined.⁵

Conclusions

The results presented show that lumbar fusion with PEEK rods can be undertaken with short hospitalization times and low complication rates, produce satisfactory clinical improvements, and result in radiographic fusion rates similar to metal constructs. Low rates of hardware failure or need for revision surgery were found. Preliminarily results of low rates of adjacent segment surgery are comparable with previously published metal construct rates. Longer follow up is needed to confirm these findings and to investigate whether semirigid constructs truly offer some protection from adjacent segment disease when compared to all metal constructs.

Acknowledgments
The authors thank Shirley McCartney, PhD, for editorial assistance.

Surgical treatment of degenerative lumbar spine disease has been rising steadily in the United States, and an increasing fraction of surgery involves lumbar fusion.^1,2 Various techniques are used to accomplish a lumbar fusion, including noninstrumented fusion, anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (XLIF, OLIF), posterior pedicle screw fusion, posterior cortical screw fusion, posterior interbody fusion (TLIF, PLIF), and interspinous process fusion. Rigid, metallic fusion hardware provides high stability and fusion rates, but it likely leads to stress shielding and adjacent segment disease.³ There is interest in less rigid and dynamic stabilization techniques to reduce the risk of adjacent segment disease, such as polyetheretherketone (PEEK) rods, which have been available since 2007. However, literature regarding PEEK rod utility is sparse and of mixed outcomes.^3,4 Additional patient reported outcome (PRO) information would be useful to both surgeons and patients. Using institutional data, this review was designed to examine our experience with PEEK rod lumbar fusion and to document PROs.

Methods

The study was approved by the institutional review board at the US Department of Veterans Affairs (VA) Portland Health Care System (VAPHCS) in Oregon with a waiver of authorization. In this retrospective, single center study, data were queried from the senior author’s (DAR) case logs from VA Computerized Patient Record System (CPRS). Electronic medical records, imaging, and PROs of all consecutive patients undergoing lumbar fusion at 1 or 2 levels with PEEK rods for degenerative disease were retrospectively reviewed. Cases of trauma, malignancy, or infection were excluded. From March 2011 through October 2019, 108 patients underwent lumbar fusion with PEEK rods.

Surgeries were conducted on a Mizuho OSI Jackson Table via bilateral 3 to 4 cm Wiltse incisions using the Medtronic Quadrant retractor system. Medtronic O-Arm images were acquired and delivered to a Medtronic Stealth Station for navigation of the screws. Monopolar coagulation was not used. PEEK pedicle screws were placed and verified with a second O-Arm spin before placing lordotic PEEK rods in the screw heads. No attempt was made to reduce any spondylolisthesis, but distraction was used to open the foramina and indirectly decompress the canal. An interbody device was placed only in treatment of multiply recurrent disc protrusion. After decortication of the transverse processes and facets, intertransverse fusion constructs consisting of calcium hydroxyapatite soaked in autologous bone marrow blood and wrapped in 6-mg bone morphogenetic protein-soaked sponges were placed on the bone. If canal decompression was indicated, a Medtronic Metrx retractor tube was then placed through one of the incisions and decompression carried out. Wounds were closed with absorbable suture. No bracing was used postoperatively. Figure 1 shows a typical single level PEEK rod fusion construct.

Statistical Analysis

Pre- and postoperative pairwise t tests were completed for patients with a complete data, using SAS 9.2 statistical package. Data are presented as standard deviation (SD) of the mean.

Results

Following application of the inclusion/exclusion criteria, 108 patients had undergone lumbar fusion with PEEK rods. Mean (SD) patient age was 60.2 (10.3) years and 88 patients were male (Table 1). Most surgeries were at L5-S1 and L4-5. There were 97 single-level fusions and 11 bilevel fusions. Seventy-four procedures were for spondylolisthesis, 23 for foraminal stenosis, 5 for degenerative disc disease, 3 for coronal imbalance with foraminal stenosis, 2 for pseudarthrosis after surgery elsewhere, and 1 for multiple recurrent disc herniation (Table 2). Twenty-five patients (23.1%) were current tobacco users and 28 (25.9%) were former smokers, 26 (24.1%) had diabetes mellitus (DM), 16 (14.8%) had low bone density by dual energy X-ray absorptiometry (DEXA) imaging, 35 (32.4%) had depression, and 7 (6.5%) were taking an immunosuppressive agent (chronic steroids, biological response modifiers, or methotrexate). Mean body mass index was 30.1.

Surgical Procedure

Of the 108 patients, the first 18 underwent a procedure with fluoroscopic guidance and the Medtronic FluoroNav and Stealth Systems. The next 90 patients underwent a procedure with O-Arm intraoperative CT scanning and Stealth frameless stereotactic navigation. The mean (SD) length of stay was 1.7 (1.3) days. There were no wound infections and no new neurologic deficits. Mean (SD) follow up time was 30.3 (21.8) months.

Imaging

Final imaging was by radiograph in 73 patients, CT in 31, and magnetic resonance imaging (MRI) in 3 (1 patient had no imaging). Sixty-seven patients (62.0%) had a bilateral arthrodesis, and 15 (13.9%) had at least a unilateral arthrodesis. MRI was not used to assess arthrodesis. Eight patients (7.4%) had no definite arthrodesis. Seventeen patients had inadequate or early imaging from which a fusion determination could not be made. Of 81 patients with > 11 months of follow up, 58 (71.6%) had a bilateral arthrodesis, 12 (14.8%) had a unilateral arthrodesis, 8 (9.9%) had no arthrodesis, and 3 (3.7%) were indeterminate.

No patient had any revision fusion surgery at the index level during follow up. Two patients had adjacent level fusions at 27 and 60 months after the index procedure. One patient had a laminectomy at an adjacent segment at 18 months postfusion, and 1 had a foraminotomy at an adjacent segment 89 months post fusion (Figure 3). Overall, there were 4 (3.7%) adjacent segment surgeries at a mean of 48.5 months after surgery. One patient had a sacro-iliac joint fusion below an L5-S1 fusion 17 months prior for persisting pain after the fusion procedure.

Patient Reported Outcomes

Preoperative SF-36 PF and ODI scores were available for 81 patients (Table 3). Postoperative SF-36 PF scores were obtained at 3 months for 65 of these patients, and at 1 year for 63 patients. Postoperative ODI scores were obtained at 3 months for 65 patients, and at 1 year for 55 patients. Among the 65 patients with completed SF-36 scores at 3 months, a mean increase of 22.4 (95% CI, 17-27; P < .001) was noted, and for the 63 patients at 1 year a mean increase of 30.3 (95% CI, 25-35; P < .001) was noted. Among the 65 patients with completed ODI scores at 3 months, a mean decrease of 6.8 (95% CI, 4.9-8.6; P < .001) was noted, and for the 55 patients with completed ODI scores at 1 year a mean decrease of 10.3 (n = 55; 95% CI, 8.4-12.2; P < .001) was noted.

Cost

We compared the hardware cost of a single level construct consisting of 4 pedicle screws, 4 locking caps, and 2 rods using a PEEK system with that of 2 other titanium construct systems. At VAPHCS, the PEEK system cost was about 71% of the cost of 2 other titanium construct systems and 62% of the cost when compared with Medtronic titanium rods.

Discussion

PEEK is useful for spine and cranial implants. It is inert and fully biocompatible with a modulus of elasticity between that of cortical and cancellous bone, and much lower than that of titanium, and is therefore considered to be semirigid.^3,4,6 PEEK rods are intermediate in stiffness between titanium rods (110 Gigapascals) and dynamic devices such as the Zimmer Biomet DYNESYS dynamic stabilization system or the Premia Spine TOPS system.³ Carbon fiber rods and carbon fiber reinforced PEEK implants are other semirigid rod alternatives.^7,8 PEEK rods for posterior lumbar fusion surgery were introduced in 2007. Li and colleagues provide a thorough review of the biomechanical properties of PEEK rods.³

PEEK is thought to have several advantages when compared with titanium. These advantages include more physiologic load sharing and reduction in stress shielding, improved durability, reduced risk of failure in osteoporotic bone, less wear debris, no change in bone forming environment, and imaging radiolucency.^4,9 Spinal PEEK cages have been reported to allow more uniform radiation dose distribution compared with metal constructs, an advantage that also may pertain to PEEK rods.¹⁰ Disadvantages of PEEK rods include an inability to detect rod breakage easily, lack of data on the use in more than minimally unstable clinical situations, and greater expense, although this was not the authors’ observation.^3,4,11

Importantly, it has been reported that PEEK rods permit a greater range of motion in all planes when compared with titanium rods.⁹ Polyetheretherketone rods unload the bone screw interface and increased the anterior column load to a more physiologic 75% when compared with titanium rods.^6,9 However, in another biomechanical study that compared titanium rods, PEEK rods, and a dynamic stabilization device, it was reported that anterior load sharing was 55%, 59%, and 75%, respectively.¹² This indicated that PEEK rods are closer to metal rods than truly dynamic devices for anterior load sharing. The endurance limit of a PEEK rod construct was similar to that of clinically useful metal systems.⁹ PEEK rods resulted in no increase in postfatigue motion compared with titanium rods in a biomechanical model.¹³ Intradiscal pressures at PEEK instrumented segments were similar to uninstrumented segments and greater than those with titanium rod constructs.¹⁴ Intradiscal pressures at adjacent segments were highest with dynamic devices, intermediate with semirigid rods, and lowest with rigid constructs; however, stress values at adjacent segments were lower in PEEK than titanium constructs in any direction of motion.^15,16

Fusion Rates

The use of PEEK rods in lumbar fusion has been reported previously.^3,4,17,18 However, these studies featured small sample sizes, short follow up times, and contradictory results.⁴ Of 8 outcome reports found in a systematic review, 2 studies reported on procedures designed to create nonfusion outcomes (a third similar trial from 2013 was not included in the systematic review), and 1 study reported only on the condition of PEEK rods removed at subsequent surgery.^3,19-21 Reported fusion rates varied from 86 to 100%.

In 42 patients with PEEK rod fusions who were followed for a mean of 31.4 months, 5 patients required adjacent segment surgery and 3 patients were treated for interbody cage migration and nonunion.¹⁷ Radiographic fusion rate was 86%. These authors concluded that PEEK rod fusion results were similar to those of other constructs, but not better, or perhaps worse than, metal rods.

Other studies have reported better results with PEEK.^{11,18,19,22-24} Highsmith and colleagues reported on 3 successful example cases of the use of PEEK rods.¹¹ De Iure and colleagues reported on 30 cases up to 5 levels (mean, 2.9) using autograft bone, with a mean follow up of 18 months.²³ Results were reported as satisfactory. Three patients had radiographic nonunions, 1 of which required revision for asymptomatic screw loosening at the cranial end of the construct. Qi and colleagues, reported on 20 patients with PEEK rods compared to 21 patients with titanium alloy rods.²⁴ Both groups had similar clinical outcomes, structural parameters, and 100% fusion rates. Athanasakopoulos and colleagues reported on 52 patients with up to 3 level fusions followed for a mean of 3 years.²² There were significant improvements in PROs: at 1 year 96% had radiographic union. Two patients had screw breakage, 1 of whom required revision to a metal rod construct. Colangeli and colleagues reported on 12 patients treated with PEEK rods compared with 12 who were treated with a dynamic system.¹⁸ They reported significant improvements, no complications, and 100% fusion at 6 months. Huang and colleagues reported on 38 patients intended to undergo a nonfusion procedure with 2 years of follow up.¹⁹ They reported good outcomes and 1 case of screw loosening. As no fusion was intended, no fusion outcomes were reported. All these studies suggested that longer follow up and more patients would be needed to assess the role of PEEK rods in lumbar fusion.³

Our results show a radiographic fusion rate of 86.4% and a radiographic nonunion rate of 9.9% in patients followed for at least 12 months. There was no clinical need for revision fusion at the index level. In our retrospective review, patients had high levels of smoking, DM, depression, immunosuppression, and obesity, which may negatively influence radiographic fusion rates when compared with other studies with 100% reported fusion rates. There was no instance of construct breakage or screw breakout, indicating that PEEK rods may allow enough flexibility to avoid construct failure under stress as in a fall.

Patient Reported Outcomes

Recent large studies were reviewed to assess the pre- and postoperative patient PROs reported in comparison with our study population (Table 4). In the Swedish Spine Registry analysis of 765 patients with 3 different types of lumbar fusion, the mean preoperative ODI score was 37 and mean SF-36 physical component score (PCS) was 35 for the most similar approach (posterolateral fusion with instrumentation).²⁵ At 1 year postoperation, the mean ODI was 26 and mean SF-36 PCS was 43. In the Spine Patient Outcomes Research Trial (SPORT) spondylolisthesis trial of 3 fusion types, the mean preoperative ODI was 41.2 and mean SF-36 PF score was 31.2 for the most similar approach (posterolateral instrumented fusion with pedicle screws).²⁶ Postoperative ODI scores at 1 year decreased by a mean 20.9 points and mean SF-36 PF scores increased by 29.9.

We report a mean preoperative SF-36 PF score of 28.9, which is lower than the SPORT study score for posterolateral fusion with instrumentation and the Swedish Study score for posterolateral instrumented fusion with pedicle screws. Similarly, our mean ODI score of 24.8 was better than the scores reported in the Swedish and SPORT studies. Our mean SF-36 PF score at 1 year postoperation was 59.3, compared with 58.5 for the SPORT study group and 46.0 in the Swedish study group. Mean ODI score at 1 year postoperatively was 14.5, which is better than the scores reported in the Swedish and SPORT studies.

Minimally clinically important difference (MCID) is a parameter used to gauge the efficacy of spine surgery. The utility of the MCID based upon PROs has been questioned in lumbar fusion surgery, as it has been thought to measure if the patient is “feeling” rather than “doing” better, the latter of which can be better measured by functional performance measures and objective, external socioeconomic anchors such as return to work and health care costs.²⁷ Nevertheless, validated PROs are reported widely in the spine surgery literature. The MCID in the SF-36 is not well established and can depend upon whether the scores are at the extremes or more in the central range and whether there is large variability in the scores.²⁸ Rheumatoid arthritis was estimated to be 7.1 points on the PF scale and 7.2 on the physical component summary (PCS).²⁹ For total knee replacement, it has been estimated to be 10 points on the SF-36 PCS.³⁰ Lumbar surgery was estimated to be 4.9 points for the SF-36 PCS and 12.8 points for the ODI.³¹ And the SPORT trial it has been estimated that a 30% change in the possible gain (or loss) may be an appropriate criterion.²⁸

With a preoperative mean SF-36 PF of 28.9, a 30% improvement in the available range (70.1) would be 21 points, making our data mean improvement of 30 points above the MCID. With a mean preoperative ODI of 24.6, a 30% improvement in the available range (25.4) would be 7.6 points, making our data mean improvement of 10.3 points better than the MCID. Therefore, our outcome results are comparable with other lumbar fusion outcome studies in terms of degree of disability prior to surgery and amount of improvement from surgery.

Adjacent Segment Disease

The precise factors resulting in adjacent segment disease are not fully defined.^3,32 In reviews of lumbar adjacent segment disease, reported rates ranged from 2.5% at 1 year up to 80 to 100% at 10 years, with lower rates with noninstrumented fusions.^4,32-34 Annual incidence of symptomatic adjacent segment disease following lumbar fusion ranges from 0.6 to 3.9% per year.^32,35,36 Mismatch between lumbar lordosis and pelvic incidence after fusion is thought to lead to higher rates of adjacent segment disease, as can a laminectomy at an adjacent segment.^32,36 Percutaneous fusion techniques or use of the Wiltse approach may lower the risk of adjacent segment disease due to avoidance of facet capsule disruption.^37,38

Dynamic stabilization techniques do not appear be clearly protective against adjacent segment disease, although biomechanical models suggest that they may do so.^33,39,40 A review by Wang and colleagues pooled studies to assess the risk of lumbar adjacent segment disease in spinal fusion to compare to disc arthroplasty and concluded that fusion carried a higher risk of adjacent segment disease.⁴¹ Definitive data on other types of motion preservation devices is lacking.³We show 3 adjacent segment fusions and 1 laminectomy have been needed in 108 patients and at a mean of 46 months after the index procedure and over 2.5 years of mean overall follow up. This is a low adjacent segment surgery rate compared to the historical data cited above, and may suggest some advantage for PEEK rods over more rigid constructs.

Strengths and Limitations

Strengths of this study include larger numbers than prior series of PEEK rod use and use in a population with high comorbidities linked to poor results without reduction in good outcomes. PEEK rods as used at the VAPHCS do not result in higher instrumentation costs than all metal constructs.

Study limitations include the retrospective nature with loss of follow up on some patients and incomplete radiographic and PROs in some patients. The use of 100% stereotactic guidance, the avoidance of interbody devices, and the off-label use of bone morphogenetic protein as part of the fusion construct introduce additional variables that may influence comparison to other studies. To avoid unnecessary radiation exposure, flexion extension films or CT scans were not routinely obtained if patients were doing well.⁴² Additionally, the degree of motion on dynamic views that would differentiate pseudarthrosis from arthrodesis has not been defined.⁵

Conclusions

The results presented show that lumbar fusion with PEEK rods can be undertaken with short hospitalization times and low complication rates, produce satisfactory clinical improvements, and result in radiographic fusion rates similar to metal constructs. Low rates of hardware failure or need for revision surgery were found. Preliminarily results of low rates of adjacent segment surgery are comparable with previously published metal construct rates. Longer follow up is needed to confirm these findings and to investigate whether semirigid constructs truly offer some protection from adjacent segment disease when compared to all metal constructs.

Acknowledgments
The authors thank Shirley McCartney, PhD, for editorial assistance.

Surgical treatment of degenerative lumbar spine disease has been rising steadily in the United States, and an increasing fraction of surgery involves lumbar fusion.^1,2 Various techniques are used to accomplish a lumbar fusion, including noninstrumented fusion, anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (XLIF, OLIF), posterior pedicle screw fusion, posterior cortical screw fusion, posterior interbody fusion (TLIF, PLIF), and interspinous process fusion. Rigid, metallic fusion hardware provides high stability and fusion rates, but it likely leads to stress shielding and adjacent segment disease.³ There is interest in less rigid and dynamic stabilization techniques to reduce the risk of adjacent segment disease, such as polyetheretherketone (PEEK) rods, which have been available since 2007. However, literature regarding PEEK rod utility is sparse and of mixed outcomes.^3,4 Additional patient reported outcome (PRO) information would be useful to both surgeons and patients. Using institutional data, this review was designed to examine our experience with PEEK rod lumbar fusion and to document PROs.

Methods

The study was approved by the institutional review board at the US Department of Veterans Affairs (VA) Portland Health Care System (VAPHCS) in Oregon with a waiver of authorization. In this retrospective, single center study, data were queried from the senior author’s (DAR) case logs from VA Computerized Patient Record System (CPRS). Electronic medical records, imaging, and PROs of all consecutive patients undergoing lumbar fusion at 1 or 2 levels with PEEK rods for degenerative disease were retrospectively reviewed. Cases of trauma, malignancy, or infection were excluded. From March 2011 through October 2019, 108 patients underwent lumbar fusion with PEEK rods.

Surgeries were conducted on a Mizuho OSI Jackson Table via bilateral 3 to 4 cm Wiltse incisions using the Medtronic Quadrant retractor system. Medtronic O-Arm images were acquired and delivered to a Medtronic Stealth Station for navigation of the screws. Monopolar coagulation was not used. PEEK pedicle screws were placed and verified with a second O-Arm spin before placing lordotic PEEK rods in the screw heads. No attempt was made to reduce any spondylolisthesis, but distraction was used to open the foramina and indirectly decompress the canal. An interbody device was placed only in treatment of multiply recurrent disc protrusion. After decortication of the transverse processes and facets, intertransverse fusion constructs consisting of calcium hydroxyapatite soaked in autologous bone marrow blood and wrapped in 6-mg bone morphogenetic protein-soaked sponges were placed on the bone. If canal decompression was indicated, a Medtronic Metrx retractor tube was then placed through one of the incisions and decompression carried out. Wounds were closed with absorbable suture. No bracing was used postoperatively. Figure 1 shows a typical single level PEEK rod fusion construct.

Statistical Analysis

Pre- and postoperative pairwise t tests were completed for patients with a complete data, using SAS 9.2 statistical package. Data are presented as standard deviation (SD) of the mean.

Results

Following application of the inclusion/exclusion criteria, 108 patients had undergone lumbar fusion with PEEK rods. Mean (SD) patient age was 60.2 (10.3) years and 88 patients were male (Table 1). Most surgeries were at L5-S1 and L4-5. There were 97 single-level fusions and 11 bilevel fusions. Seventy-four procedures were for spondylolisthesis, 23 for foraminal stenosis, 5 for degenerative disc disease, 3 for coronal imbalance with foraminal stenosis, 2 for pseudarthrosis after surgery elsewhere, and 1 for multiple recurrent disc herniation (Table 2). Twenty-five patients (23.1%) were current tobacco users and 28 (25.9%) were former smokers, 26 (24.1%) had diabetes mellitus (DM), 16 (14.8%) had low bone density by dual energy X-ray absorptiometry (DEXA) imaging, 35 (32.4%) had depression, and 7 (6.5%) were taking an immunosuppressive agent (chronic steroids, biological response modifiers, or methotrexate). Mean body mass index was 30.1.

Surgical Procedure

Of the 108 patients, the first 18 underwent a procedure with fluoroscopic guidance and the Medtronic FluoroNav and Stealth Systems. The next 90 patients underwent a procedure with O-Arm intraoperative CT scanning and Stealth frameless stereotactic navigation. The mean (SD) length of stay was 1.7 (1.3) days. There were no wound infections and no new neurologic deficits. Mean (SD) follow up time was 30.3 (21.8) months.

Imaging

Final imaging was by radiograph in 73 patients, CT in 31, and magnetic resonance imaging (MRI) in 3 (1 patient had no imaging). Sixty-seven patients (62.0%) had a bilateral arthrodesis, and 15 (13.9%) had at least a unilateral arthrodesis. MRI was not used to assess arthrodesis. Eight patients (7.4%) had no definite arthrodesis. Seventeen patients had inadequate or early imaging from which a fusion determination could not be made. Of 81 patients with > 11 months of follow up, 58 (71.6%) had a bilateral arthrodesis, 12 (14.8%) had a unilateral arthrodesis, 8 (9.9%) had no arthrodesis, and 3 (3.7%) were indeterminate.

No patient had any revision fusion surgery at the index level during follow up. Two patients had adjacent level fusions at 27 and 60 months after the index procedure. One patient had a laminectomy at an adjacent segment at 18 months postfusion, and 1 had a foraminotomy at an adjacent segment 89 months post fusion (Figure 3). Overall, there were 4 (3.7%) adjacent segment surgeries at a mean of 48.5 months after surgery. One patient had a sacro-iliac joint fusion below an L5-S1 fusion 17 months prior for persisting pain after the fusion procedure.

Patient Reported Outcomes

Preoperative SF-36 PF and ODI scores were available for 81 patients (Table 3). Postoperative SF-36 PF scores were obtained at 3 months for 65 of these patients, and at 1 year for 63 patients. Postoperative ODI scores were obtained at 3 months for 65 patients, and at 1 year for 55 patients. Among the 65 patients with completed SF-36 scores at 3 months, a mean increase of 22.4 (95% CI, 17-27; P < .001) was noted, and for the 63 patients at 1 year a mean increase of 30.3 (95% CI, 25-35; P < .001) was noted. Among the 65 patients with completed ODI scores at 3 months, a mean decrease of 6.8 (95% CI, 4.9-8.6; P < .001) was noted, and for the 55 patients with completed ODI scores at 1 year a mean decrease of 10.3 (n = 55; 95% CI, 8.4-12.2; P < .001) was noted.

Cost

We compared the hardware cost of a single level construct consisting of 4 pedicle screws, 4 locking caps, and 2 rods using a PEEK system with that of 2 other titanium construct systems. At VAPHCS, the PEEK system cost was about 71% of the cost of 2 other titanium construct systems and 62% of the cost when compared with Medtronic titanium rods.

Discussion

PEEK is useful for spine and cranial implants. It is inert and fully biocompatible with a modulus of elasticity between that of cortical and cancellous bone, and much lower than that of titanium, and is therefore considered to be semirigid.^3,4,6 PEEK rods are intermediate in stiffness between titanium rods (110 Gigapascals) and dynamic devices such as the Zimmer Biomet DYNESYS dynamic stabilization system or the Premia Spine TOPS system.³ Carbon fiber rods and carbon fiber reinforced PEEK implants are other semirigid rod alternatives.^7,8 PEEK rods for posterior lumbar fusion surgery were introduced in 2007. Li and colleagues provide a thorough review of the biomechanical properties of PEEK rods.³

PEEK is thought to have several advantages when compared with titanium. These advantages include more physiologic load sharing and reduction in stress shielding, improved durability, reduced risk of failure in osteoporotic bone, less wear debris, no change in bone forming environment, and imaging radiolucency.^4,9 Spinal PEEK cages have been reported to allow more uniform radiation dose distribution compared with metal constructs, an advantage that also may pertain to PEEK rods.¹⁰ Disadvantages of PEEK rods include an inability to detect rod breakage easily, lack of data on the use in more than minimally unstable clinical situations, and greater expense, although this was not the authors’ observation.^3,4,11

Importantly, it has been reported that PEEK rods permit a greater range of motion in all planes when compared with titanium rods.⁹ Polyetheretherketone rods unload the bone screw interface and increased the anterior column load to a more physiologic 75% when compared with titanium rods.^6,9 However, in another biomechanical study that compared titanium rods, PEEK rods, and a dynamic stabilization device, it was reported that anterior load sharing was 55%, 59%, and 75%, respectively.¹² This indicated that PEEK rods are closer to metal rods than truly dynamic devices for anterior load sharing. The endurance limit of a PEEK rod construct was similar to that of clinically useful metal systems.⁹ PEEK rods resulted in no increase in postfatigue motion compared with titanium rods in a biomechanical model.¹³ Intradiscal pressures at PEEK instrumented segments were similar to uninstrumented segments and greater than those with titanium rod constructs.¹⁴ Intradiscal pressures at adjacent segments were highest with dynamic devices, intermediate with semirigid rods, and lowest with rigid constructs; however, stress values at adjacent segments were lower in PEEK than titanium constructs in any direction of motion.^15,16

Fusion Rates

The use of PEEK rods in lumbar fusion has been reported previously.^3,4,17,18 However, these studies featured small sample sizes, short follow up times, and contradictory results.⁴ Of 8 outcome reports found in a systematic review, 2 studies reported on procedures designed to create nonfusion outcomes (a third similar trial from 2013 was not included in the systematic review), and 1 study reported only on the condition of PEEK rods removed at subsequent surgery.^3,19-21 Reported fusion rates varied from 86 to 100%.

In 42 patients with PEEK rod fusions who were followed for a mean of 31.4 months, 5 patients required adjacent segment surgery and 3 patients were treated for interbody cage migration and nonunion.¹⁷ Radiographic fusion rate was 86%. These authors concluded that PEEK rod fusion results were similar to those of other constructs, but not better, or perhaps worse than, metal rods.

Other studies have reported better results with PEEK.^{11,18,19,22-24} Highsmith and colleagues reported on 3 successful example cases of the use of PEEK rods.¹¹ De Iure and colleagues reported on 30 cases up to 5 levels (mean, 2.9) using autograft bone, with a mean follow up of 18 months.²³ Results were reported as satisfactory. Three patients had radiographic nonunions, 1 of which required revision for asymptomatic screw loosening at the cranial end of the construct. Qi and colleagues, reported on 20 patients with PEEK rods compared to 21 patients with titanium alloy rods.²⁴ Both groups had similar clinical outcomes, structural parameters, and 100% fusion rates. Athanasakopoulos and colleagues reported on 52 patients with up to 3 level fusions followed for a mean of 3 years.²² There were significant improvements in PROs: at 1 year 96% had radiographic union. Two patients had screw breakage, 1 of whom required revision to a metal rod construct. Colangeli and colleagues reported on 12 patients treated with PEEK rods compared with 12 who were treated with a dynamic system.¹⁸ They reported significant improvements, no complications, and 100% fusion at 6 months. Huang and colleagues reported on 38 patients intended to undergo a nonfusion procedure with 2 years of follow up.¹⁹ They reported good outcomes and 1 case of screw loosening. As no fusion was intended, no fusion outcomes were reported. All these studies suggested that longer follow up and more patients would be needed to assess the role of PEEK rods in lumbar fusion.³

Our results show a radiographic fusion rate of 86.4% and a radiographic nonunion rate of 9.9% in patients followed for at least 12 months. There was no clinical need for revision fusion at the index level. In our retrospective review, patients had high levels of smoking, DM, depression, immunosuppression, and obesity, which may negatively influence radiographic fusion rates when compared with other studies with 100% reported fusion rates. There was no instance of construct breakage or screw breakout, indicating that PEEK rods may allow enough flexibility to avoid construct failure under stress as in a fall.

Patient Reported Outcomes

Recent large studies were reviewed to assess the pre- and postoperative patient PROs reported in comparison with our study population (Table 4). In the Swedish Spine Registry analysis of 765 patients with 3 different types of lumbar fusion, the mean preoperative ODI score was 37 and mean SF-36 physical component score (PCS) was 35 for the most similar approach (posterolateral fusion with instrumentation).²⁵ At 1 year postoperation, the mean ODI was 26 and mean SF-36 PCS was 43. In the Spine Patient Outcomes Research Trial (SPORT) spondylolisthesis trial of 3 fusion types, the mean preoperative ODI was 41.2 and mean SF-36 PF score was 31.2 for the most similar approach (posterolateral instrumented fusion with pedicle screws).²⁶ Postoperative ODI scores at 1 year decreased by a mean 20.9 points and mean SF-36 PF scores increased by 29.9.

We report a mean preoperative SF-36 PF score of 28.9, which is lower than the SPORT study score for posterolateral fusion with instrumentation and the Swedish Study score for posterolateral instrumented fusion with pedicle screws. Similarly, our mean ODI score of 24.8 was better than the scores reported in the Swedish and SPORT studies. Our mean SF-36 PF score at 1 year postoperation was 59.3, compared with 58.5 for the SPORT study group and 46.0 in the Swedish study group. Mean ODI score at 1 year postoperatively was 14.5, which is better than the scores reported in the Swedish and SPORT studies.

Minimally clinically important difference (MCID) is a parameter used to gauge the efficacy of spine surgery. The utility of the MCID based upon PROs has been questioned in lumbar fusion surgery, as it has been thought to measure if the patient is “feeling” rather than “doing” better, the latter of which can be better measured by functional performance measures and objective, external socioeconomic anchors such as return to work and health care costs.²⁷ Nevertheless, validated PROs are reported widely in the spine surgery literature. The MCID in the SF-36 is not well established and can depend upon whether the scores are at the extremes or more in the central range and whether there is large variability in the scores.²⁸ Rheumatoid arthritis was estimated to be 7.1 points on the PF scale and 7.2 on the physical component summary (PCS).²⁹ For total knee replacement, it has been estimated to be 10 points on the SF-36 PCS.³⁰ Lumbar surgery was estimated to be 4.9 points for the SF-36 PCS and 12.8 points for the ODI.³¹ And the SPORT trial it has been estimated that a 30% change in the possible gain (or loss) may be an appropriate criterion.²⁸

With a preoperative mean SF-36 PF of 28.9, a 30% improvement in the available range (70.1) would be 21 points, making our data mean improvement of 30 points above the MCID. With a mean preoperative ODI of 24.6, a 30% improvement in the available range (25.4) would be 7.6 points, making our data mean improvement of 10.3 points better than the MCID. Therefore, our outcome results are comparable with other lumbar fusion outcome studies in terms of degree of disability prior to surgery and amount of improvement from surgery.

Adjacent Segment Disease

The precise factors resulting in adjacent segment disease are not fully defined.^3,32 In reviews of lumbar adjacent segment disease, reported rates ranged from 2.5% at 1 year up to 80 to 100% at 10 years, with lower rates with noninstrumented fusions.^4,32-34 Annual incidence of symptomatic adjacent segment disease following lumbar fusion ranges from 0.6 to 3.9% per year.^32,35,36 Mismatch between lumbar lordosis and pelvic incidence after fusion is thought to lead to higher rates of adjacent segment disease, as can a laminectomy at an adjacent segment.^32,36 Percutaneous fusion techniques or use of the Wiltse approach may lower the risk of adjacent segment disease due to avoidance of facet capsule disruption.^37,38

Dynamic stabilization techniques do not appear be clearly protective against adjacent segment disease, although biomechanical models suggest that they may do so.^33,39,40 A review by Wang and colleagues pooled studies to assess the risk of lumbar adjacent segment disease in spinal fusion to compare to disc arthroplasty and concluded that fusion carried a higher risk of adjacent segment disease.⁴¹ Definitive data on other types of motion preservation devices is lacking.³We show 3 adjacent segment fusions and 1 laminectomy have been needed in 108 patients and at a mean of 46 months after the index procedure and over 2.5 years of mean overall follow up. This is a low adjacent segment surgery rate compared to the historical data cited above, and may suggest some advantage for PEEK rods over more rigid constructs.

Strengths and Limitations

Strengths of this study include larger numbers than prior series of PEEK rod use and use in a population with high comorbidities linked to poor results without reduction in good outcomes. PEEK rods as used at the VAPHCS do not result in higher instrumentation costs than all metal constructs.

Study limitations include the retrospective nature with loss of follow up on some patients and incomplete radiographic and PROs in some patients. The use of 100% stereotactic guidance, the avoidance of interbody devices, and the off-label use of bone morphogenetic protein as part of the fusion construct introduce additional variables that may influence comparison to other studies. To avoid unnecessary radiation exposure, flexion extension films or CT scans were not routinely obtained if patients were doing well.⁴² Additionally, the degree of motion on dynamic views that would differentiate pseudarthrosis from arthrodesis has not been defined.⁵

Conclusions

The results presented show that lumbar fusion with PEEK rods can be undertaken with short hospitalization times and low complication rates, produce satisfactory clinical improvements, and result in radiographic fusion rates similar to metal constructs. Low rates of hardware failure or need for revision surgery were found. Preliminarily results of low rates of adjacent segment surgery are comparable with previously published metal construct rates. Longer follow up is needed to confirm these findings and to investigate whether semirigid constructs truly offer some protection from adjacent segment disease when compared to all metal constructs.

Acknowledgments
The authors thank Shirley McCartney, PhD, for editorial assistance.

The VA Portland Healthcare System (VAPHCS) is a 277-bed facility that serves more than 85,000 inpatient and 880,000 outpatient visits each year from veterans in Oregon and southwestern Washington. The VAPHCS consists of a main tertiary care VAMC with an acute medical and surgical facility that includes 30 beds serving qualifying veterans. Supported surgical specialties include urology, general surgery, vascular surgery, otolaryngology, orthopedic surgery, ophthalmology, cardiothoracic surgery, transplant surgery, and neurological surgery. Neurosurgical patients account for about 12% to 13% of annual surgical patients. The VAPHCS also is partnered with Oregon Health & Science University in the training of health care professionals, such as physicians and nurses.

The expectation at the VAPHCS is that medical-surgical nurses care for 4 to 5 concurrent patients, often from different surgical services. Caring for patients with different medical and surgical needs, variable ambulatory, swallowing, and elimination functions, and different physician teams can become confusing; even within a single surgical service, postoperative care due to procedure complexity, specificity of care orders, and the real possibility of medical catastrophe can seem overwhelming. Therefore, subspecialty nursing training poses a challenge that requires technical in-service and didactic education and allocation of resources.

Despite systems level subspecialty nursing training, medical emergencies identified at the bedside can be mismanaged.¹ Errors in care can be due to an incomplete knowledge of the patient’s procedure and misunderstanding of positioning and activity limitations.

To encourage medical-surgical nurses to become more engaged and confident in subspecialty patient care, the authors developed a bedside neurosurgical nursing guide to allow for independent procedure related education. The comprehensive guide summarized the clinical course for postoperative neurosurgical patients undergoing cranial and spinal surgeries. This guide included appropriate surgery-related images, procedure overviews, management decisions, potential postoperative complications, and wound care directions. The guide was distributed to medical-surgical nurses caring for neurosurgical patients. The authors hypothesized that the guide would enable nurses to better predict adverse outcomes and respond appropriately and would improve confidence in patient care.

Methods

For educational purposes, a bedside neurosurgical nursing guide (text and graphics) was created for the 16 surgical subspecialty nurses at the VAPHCS. The guide detailed the most common cranial and spinal neurosurgical procedures performed at VAPHCS and was written based on a typical postoperative course for each procedure by the chief neurosurgery resident at VAPHCS with collaboration from the attending neurosurgeons (Figure).

A quality improvement (QI) project was undertaken to assess nursing confidence with neurosurgical patients’ care pre- and postfamiliarity with the bedside neurosurgical nursing guide. A literature search revealed no validated survey assessing nursing confidence, so one was created using the Likert scale. Specifically, an anonymous 6-question survey was completed by all 16 surgical nurses prior to familiarization with the guide. Responses were recorded as scores of 1 to 5 for questions 1, 3, and 4, with a response of 1 indicative of no comfort or confidence and a response of 5 indicative of the highest level of comfort or confidence. Responses were recorded as either true or false for questions 2 and 6, and never, occasionally, frequently, or always for question 5.

The guide was made available to nurses for 6 months without encouragement to use it. After 6 months, a 3-week period of familiarization with and education about the availability of the guide was instituted at morning nursing reports; the total availability of the guide to nursing staff was 6 months 3 weeks. After this period the same 6-question survey was distributed, and data were collected.

Survey responses were categorized into 2 groups. Responses to questions 1, 3, and 4 were categorized as group 1, and responses to questions 4 and 5 were categorized as group 2. Responses (never and occasionally) to question 5, were categorized as group 1 and responses (frequently and always) as group 2 (Table). Responses to questions 2 and 6 were grouped 1 for true and 2 for false. Nurses participating in this study ranged in age from 22 to 57 years, education level ranged from registered nurse to a bachelor of science in nursing, and years of experience ranged from < 1 year to 27 years.

Statistics were calculated using chi-square analysis with Yates correction online calculator. For the chi-square analysis, the prefamiliarization data for groups 1 and 2 were used as the expected values, and the postfamiliarization data were used for the observed values. In this manner, differences were discerned between the before and after questionnaire responses. The VAPHCS institutional review board determined that the study was not human research and exempt from review.

Findings

Anonymous survey responses were collected from all 16 surgical subspecialty nurses both prior and after familiarization with the nursing guide.The response rate was 100% with only a few incomplete responses excluded from the analysis. Three questions in the prefamiliarization questionnaire had no appropriate response, and 1 question in the postfamiliarization survey had no appropriate response.

Improvement was statistically significant in responses for questions 1, 3, 5, and 6 (P = .026, .008, .004, and .033, respectively). No significant differences were found for questions 2 and 4 (P = .974 and .116, respectively). It is possible that there was no significant difference in question 2 because prefamiliarization responses were already favorable. Even if nurses did not feel comfortable taking care of neurosurgical patients (as assessed in question 1), they noted confidence improvement by working on the ward and through informal assimilation of knowledge and skill, which would have accumulated naturally over 1 year.

Prior to familiarization with the guide, 7 nurses did not feel confident in assessing the need to contact a physician (question 4). After familiarization with the nursing guide, favorable responses increased from 9 to 14 nurses. Results trended toward but did not reach statistical significance, likely due to the small sample size.

Ultimately, in the 16 surgical subspecialty nurses surveyed, familiarization with the nursing guide was shown to improve comfort in taking care of neurosurgical patients and increase confidence in patient care skills. At the end of the QI project (6 months, 3 weeks), all nurses knew where to locate the bedside neurosurgical nursing guide and were familiar with it and its use. The guide remains accessible to the medical-surgical nurses and continues to be used.

Discussion

Nursing confidence has an undervalued effect on patient care.² Confidence, or a belief in one’s own ability, varies directly with competence. Systematic quantification of nursing competence has been extensively studied using self-report questionnaires and clinical simulations.^2,3 Competency can be quantified and normalized using formal assessment; however, confidence is somewhat intangible. Nursing confidence is a situation-dependent subjective feeling of security and is derived from an internalized assessment of skills that are commensurate with patient needs. Nursing confidence is further influenced by an intuited value within the care team, adequate knowledge of the patient’s condition, and procedures and protocols.⁴

A similar but less specific definition deconstructs nursing confidence as “significance of a professional network of coworkers” and the “importance of confirmation of professional role and competence.”⁵ The professional network of coworkers is invaluable as it underlies the essence of patient-centered care. The adaptive leadership framework is integral to the modern delivery of patient care, and via this framework frontline clinical staff, including nurses, are empowered.^6,7

The second portion of Haavardsholm and Nåden’s definition, “importance of confirmation of professional role and competence” describes the association of the most easily augmented correlate of confidence: competency.⁵ Nursing competency is supplemented continuously with in-service training and recertification processes; however, despite this, demands placed on nurses can be technologically advanced and extremely varied. Nursing competency is known to directly correlate with increasing education, as nurses holding a master’s degree have been shown to outperform those with a bachelor of nursing degree.³

Increased formal education as well as increased work experience (> 5 years) are correlated with increased critical thinking ability.^4,5 The critical thinking ability of health care providers can be fortified by clinical simulation, which leads to statistically significant improvement in clinical competency.^2,3

A literature review of Medline and the National Library of Medicine PubMed online databases for search terms (nurs*, confidence, bedside, guide) was performed but did not result in original research assessing nurse confidence related to bedside guides. In this population, nurses were anonymously compared against their own historical data obviating any effect of education or experience on survey measures.

Nursing Self-Confidence

Evidence suggests that nursing confidence is a complex manifestation of the security felt within the care team and the comfort of one’s own professional abilities.⁴ Patients’ trust in the team caring for them is based on the confidence exuded by the team.⁸ In this way, nursing confidence can affect the patient-care team profoundly. Value is maximized when a nurse’s self-confidence engenders patient confidence and trust. Due to the varied patient load and complexity of subspecialty nursing care, it is hypothesized that bedside manuals/guidelines can be used to educate the subspecialty nurses on specific patient-related issues.

Nursing practice competence and confidence is vital to providing care for patients with complex postsurgical health care needs. Patient safety and outcome are paramount. This can be intimidating for newly qualified surgical subspecialty nurses who have not yet had experience with or adequate exposure to patients with complex postsurgical needs. Surgical nursing continuing education places an emphasis on adaptation to ever-changing specialized surgical procedures and postoperative patient care. Nevertheless, it is difficult for surgical subspecialty nurses to learn and retain all the possible complexities of individual cases and to confidently, appropriately, and safely care for patients especially when adverse events arise.

Recognizing that leadership is personal and not dependent on hierarchy, surgical subspecialty nurses may be better suited to specific bedside training and counseling.^6,9 A key factor influencing nursing confidence is communication and collaboration with physicians.⁹ The role of the physician at VA medical facilities is no longer to be a commanding figure with complete medical autonomy; rather, a unified team of specialized practitioners collaboratively facilitate and deliver patient care.

There is no specific research detailing the use of bedside nursing guides in caring for postoperative patients. However, at VAPHCS, nurses created supplemental material regarding postoperative acute care of vascular surgery patients, which was found to be subjectively helpful in elevating nursing confidence. To the authors’ knowledge, no such supplemental information/guide exists for other specialty surgical services.

The surgical nursing guide created here detailed visuals of many common neurosurgical procedures performed at VAPHCS and included a prioritized checklist, which the 16 surgical subspecialty nurses could reference postoperatively. The authors hypothesized that this would enhance the nurses’ ability to efficiently manage specific situations while bridging communication gaps between surgical teams and nurses. The survey results agree with previous reports that suggested that the application of an adaptive leadership framework would empower nurses to deliver excellent patient-centered care, care that can be augmented with subspecialty nursing guides.^7,10

Based on these results the authors propose that subspecialty surgical services consider use of a practical nursing guide for all surgical subspecialty nurses to reference, improve familiarity with procedures, and provide guidance to manage adverse events. Since implementing this reader-friendly paradigm within neurosurgical care, a nurse driven expansion has now included other subspecialty services at the VAPHCS with success.

Limitations

Survey responses have inherent bias and sampling error rates. The sample size for this survey was small. Data were grouped for data analysis. Competency and patient outcomes were not measured.

Future Directions

Despite specific surgical specialty postoperative patient care training, an overall lack of confidence can persist. A physician-created neurosurgical nursing guide that detailed the most common neurosurgical procedures, expected postoperative care, and potential emergencies was shown to improve nursing confidence. Collaborative (physician and nursing leaders) QI projects, such as described here; development of specific surgical specialty initiatives designed to improve confidence and quality; and nurse-physician communication and teamwork could lead to improved patient satisfaction and outcome.

The costs associated with developing and using bedside nursing guides are relatively low, and efficiency can be considered high. Competency improvement could be measured by creating a specialty-specific case scenario question bank. Effects on patient satisfaction and outcome could be measured by a patient satisfaction survey. Improvements in beside catastrophe management could be prospectively tracked; for example, rates of mismanagement of mobility status, emergent transfers to the intensive care unit, or poor wound care could be compared pre- and postfamiliarization with a subspecialty guide.

Conclusion

Familiarization with the VAPHCS neurosurgical nursing guide had a positive impact on the confidence of medical-surgical nurses caring for neurosurgical patients. Medical-surgical nurses were more comfortable taking care of neurosurgical patients; they felt the guide helped improve skills and noted improved knowledge regarding involvement of physician oversight. Although objective parameters were not assessed, improvement in nursing confidence in general leads to improved overall nurse-physician communication and patient management. A further study might target objective parameters associated with guide usage, such as changes in the number of emergencies or calls to physicians regarding management.

Acknowledgments
The authors thank Andy Rekito, MS, for illustrative assistance.

The VA Portland Healthcare System (VAPHCS) is a 277-bed facility that serves more than 85,000 inpatient and 880,000 outpatient visits each year from veterans in Oregon and southwestern Washington. The VAPHCS consists of a main tertiary care VAMC with an acute medical and surgical facility that includes 30 beds serving qualifying veterans. Supported surgical specialties include urology, general surgery, vascular surgery, otolaryngology, orthopedic surgery, ophthalmology, cardiothoracic surgery, transplant surgery, and neurological surgery. Neurosurgical patients account for about 12% to 13% of annual surgical patients. The VAPHCS also is partnered with Oregon Health & Science University in the training of health care professionals, such as physicians and nurses.

The expectation at the VAPHCS is that medical-surgical nurses care for 4 to 5 concurrent patients, often from different surgical services. Caring for patients with different medical and surgical needs, variable ambulatory, swallowing, and elimination functions, and different physician teams can become confusing; even within a single surgical service, postoperative care due to procedure complexity, specificity of care orders, and the real possibility of medical catastrophe can seem overwhelming. Therefore, subspecialty nursing training poses a challenge that requires technical in-service and didactic education and allocation of resources.

Despite systems level subspecialty nursing training, medical emergencies identified at the bedside can be mismanaged.¹ Errors in care can be due to an incomplete knowledge of the patient’s procedure and misunderstanding of positioning and activity limitations.

To encourage medical-surgical nurses to become more engaged and confident in subspecialty patient care, the authors developed a bedside neurosurgical nursing guide to allow for independent procedure related education. The comprehensive guide summarized the clinical course for postoperative neurosurgical patients undergoing cranial and spinal surgeries. This guide included appropriate surgery-related images, procedure overviews, management decisions, potential postoperative complications, and wound care directions. The guide was distributed to medical-surgical nurses caring for neurosurgical patients. The authors hypothesized that the guide would enable nurses to better predict adverse outcomes and respond appropriately and would improve confidence in patient care.

Methods

For educational purposes, a bedside neurosurgical nursing guide (text and graphics) was created for the 16 surgical subspecialty nurses at the VAPHCS. The guide detailed the most common cranial and spinal neurosurgical procedures performed at VAPHCS and was written based on a typical postoperative course for each procedure by the chief neurosurgery resident at VAPHCS with collaboration from the attending neurosurgeons (Figure).

A quality improvement (QI) project was undertaken to assess nursing confidence with neurosurgical patients’ care pre- and postfamiliarity with the bedside neurosurgical nursing guide. A literature search revealed no validated survey assessing nursing confidence, so one was created using the Likert scale. Specifically, an anonymous 6-question survey was completed by all 16 surgical nurses prior to familiarization with the guide. Responses were recorded as scores of 1 to 5 for questions 1, 3, and 4, with a response of 1 indicative of no comfort or confidence and a response of 5 indicative of the highest level of comfort or confidence. Responses were recorded as either true or false for questions 2 and 6, and never, occasionally, frequently, or always for question 5.

The guide was made available to nurses for 6 months without encouragement to use it. After 6 months, a 3-week period of familiarization with and education about the availability of the guide was instituted at morning nursing reports; the total availability of the guide to nursing staff was 6 months 3 weeks. After this period the same 6-question survey was distributed, and data were collected.

Survey responses were categorized into 2 groups. Responses to questions 1, 3, and 4 were categorized as group 1, and responses to questions 4 and 5 were categorized as group 2. Responses (never and occasionally) to question 5, were categorized as group 1 and responses (frequently and always) as group 2 (Table). Responses to questions 2 and 6 were grouped 1 for true and 2 for false. Nurses participating in this study ranged in age from 22 to 57 years, education level ranged from registered nurse to a bachelor of science in nursing, and years of experience ranged from < 1 year to 27 years.

Statistics were calculated using chi-square analysis with Yates correction online calculator. For the chi-square analysis, the prefamiliarization data for groups 1 and 2 were used as the expected values, and the postfamiliarization data were used for the observed values. In this manner, differences were discerned between the before and after questionnaire responses. The VAPHCS institutional review board determined that the study was not human research and exempt from review.

Findings

Anonymous survey responses were collected from all 16 surgical subspecialty nurses both prior and after familiarization with the nursing guide.The response rate was 100% with only a few incomplete responses excluded from the analysis. Three questions in the prefamiliarization questionnaire had no appropriate response, and 1 question in the postfamiliarization survey had no appropriate response.

Improvement was statistically significant in responses for questions 1, 3, 5, and 6 (P = .026, .008, .004, and .033, respectively). No significant differences were found for questions 2 and 4 (P = .974 and .116, respectively). It is possible that there was no significant difference in question 2 because prefamiliarization responses were already favorable. Even if nurses did not feel comfortable taking care of neurosurgical patients (as assessed in question 1), they noted confidence improvement by working on the ward and through informal assimilation of knowledge and skill, which would have accumulated naturally over 1 year.

Prior to familiarization with the guide, 7 nurses did not feel confident in assessing the need to contact a physician (question 4). After familiarization with the nursing guide, favorable responses increased from 9 to 14 nurses. Results trended toward but did not reach statistical significance, likely due to the small sample size.

Ultimately, in the 16 surgical subspecialty nurses surveyed, familiarization with the nursing guide was shown to improve comfort in taking care of neurosurgical patients and increase confidence in patient care skills. At the end of the QI project (6 months, 3 weeks), all nurses knew where to locate the bedside neurosurgical nursing guide and were familiar with it and its use. The guide remains accessible to the medical-surgical nurses and continues to be used.

Discussion

Nursing confidence has an undervalued effect on patient care.² Confidence, or a belief in one’s own ability, varies directly with competence. Systematic quantification of nursing competence has been extensively studied using self-report questionnaires and clinical simulations.^2,3 Competency can be quantified and normalized using formal assessment; however, confidence is somewhat intangible. Nursing confidence is a situation-dependent subjective feeling of security and is derived from an internalized assessment of skills that are commensurate with patient needs. Nursing confidence is further influenced by an intuited value within the care team, adequate knowledge of the patient’s condition, and procedures and protocols.⁴

A similar but less specific definition deconstructs nursing confidence as “significance of a professional network of coworkers” and the “importance of confirmation of professional role and competence.”⁵ The professional network of coworkers is invaluable as it underlies the essence of patient-centered care. The adaptive leadership framework is integral to the modern delivery of patient care, and via this framework frontline clinical staff, including nurses, are empowered.^6,7

The second portion of Haavardsholm and Nåden’s definition, “importance of confirmation of professional role and competence” describes the association of the most easily augmented correlate of confidence: competency.⁵ Nursing competency is supplemented continuously with in-service training and recertification processes; however, despite this, demands placed on nurses can be technologically advanced and extremely varied. Nursing competency is known to directly correlate with increasing education, as nurses holding a master’s degree have been shown to outperform those with a bachelor of nursing degree.³

Increased formal education as well as increased work experience (> 5 years) are correlated with increased critical thinking ability.^4,5 The critical thinking ability of health care providers can be fortified by clinical simulation, which leads to statistically significant improvement in clinical competency.^2,3

A literature review of Medline and the National Library of Medicine PubMed online databases for search terms (nurs*, confidence, bedside, guide) was performed but did not result in original research assessing nurse confidence related to bedside guides. In this population, nurses were anonymously compared against their own historical data obviating any effect of education or experience on survey measures.

Nursing Self-Confidence

Evidence suggests that nursing confidence is a complex manifestation of the security felt within the care team and the comfort of one’s own professional abilities.⁴ Patients’ trust in the team caring for them is based on the confidence exuded by the team.⁸ In this way, nursing confidence can affect the patient-care team profoundly. Value is maximized when a nurse’s self-confidence engenders patient confidence and trust. Due to the varied patient load and complexity of subspecialty nursing care, it is hypothesized that bedside manuals/guidelines can be used to educate the subspecialty nurses on specific patient-related issues.

Nursing practice competence and confidence is vital to providing care for patients with complex postsurgical health care needs. Patient safety and outcome are paramount. This can be intimidating for newly qualified surgical subspecialty nurses who have not yet had experience with or adequate exposure to patients with complex postsurgical needs. Surgical nursing continuing education places an emphasis on adaptation to ever-changing specialized surgical procedures and postoperative patient care. Nevertheless, it is difficult for surgical subspecialty nurses to learn and retain all the possible complexities of individual cases and to confidently, appropriately, and safely care for patients especially when adverse events arise.

Recognizing that leadership is personal and not dependent on hierarchy, surgical subspecialty nurses may be better suited to specific bedside training and counseling.^6,9 A key factor influencing nursing confidence is communication and collaboration with physicians.⁹ The role of the physician at VA medical facilities is no longer to be a commanding figure with complete medical autonomy; rather, a unified team of specialized practitioners collaboratively facilitate and deliver patient care.

There is no specific research detailing the use of bedside nursing guides in caring for postoperative patients. However, at VAPHCS, nurses created supplemental material regarding postoperative acute care of vascular surgery patients, which was found to be subjectively helpful in elevating nursing confidence. To the authors’ knowledge, no such supplemental information/guide exists for other specialty surgical services.

The surgical nursing guide created here detailed visuals of many common neurosurgical procedures performed at VAPHCS and included a prioritized checklist, which the 16 surgical subspecialty nurses could reference postoperatively. The authors hypothesized that this would enhance the nurses’ ability to efficiently manage specific situations while bridging communication gaps between surgical teams and nurses. The survey results agree with previous reports that suggested that the application of an adaptive leadership framework would empower nurses to deliver excellent patient-centered care, care that can be augmented with subspecialty nursing guides.^7,10

Based on these results the authors propose that subspecialty surgical services consider use of a practical nursing guide for all surgical subspecialty nurses to reference, improve familiarity with procedures, and provide guidance to manage adverse events. Since implementing this reader-friendly paradigm within neurosurgical care, a nurse driven expansion has now included other subspecialty services at the VAPHCS with success.

Limitations

Survey responses have inherent bias and sampling error rates. The sample size for this survey was small. Data were grouped for data analysis. Competency and patient outcomes were not measured.

Future Directions

Despite specific surgical specialty postoperative patient care training, an overall lack of confidence can persist. A physician-created neurosurgical nursing guide that detailed the most common neurosurgical procedures, expected postoperative care, and potential emergencies was shown to improve nursing confidence. Collaborative (physician and nursing leaders) QI projects, such as described here; development of specific surgical specialty initiatives designed to improve confidence and quality; and nurse-physician communication and teamwork could lead to improved patient satisfaction and outcome.

The costs associated with developing and using bedside nursing guides are relatively low, and efficiency can be considered high. Competency improvement could be measured by creating a specialty-specific case scenario question bank. Effects on patient satisfaction and outcome could be measured by a patient satisfaction survey. Improvements in beside catastrophe management could be prospectively tracked; for example, rates of mismanagement of mobility status, emergent transfers to the intensive care unit, or poor wound care could be compared pre- and postfamiliarization with a subspecialty guide.

Conclusion

Familiarization with the VAPHCS neurosurgical nursing guide had a positive impact on the confidence of medical-surgical nurses caring for neurosurgical patients. Medical-surgical nurses were more comfortable taking care of neurosurgical patients; they felt the guide helped improve skills and noted improved knowledge regarding involvement of physician oversight. Although objective parameters were not assessed, improvement in nursing confidence in general leads to improved overall nurse-physician communication and patient management. A further study might target objective parameters associated with guide usage, such as changes in the number of emergencies or calls to physicians regarding management.

Acknowledgments
The authors thank Andy Rekito, MS, for illustrative assistance.

The VA Portland Healthcare System (VAPHCS) is a 277-bed facility that serves more than 85,000 inpatient and 880,000 outpatient visits each year from veterans in Oregon and southwestern Washington. The VAPHCS consists of a main tertiary care VAMC with an acute medical and surgical facility that includes 30 beds serving qualifying veterans. Supported surgical specialties include urology, general surgery, vascular surgery, otolaryngology, orthopedic surgery, ophthalmology, cardiothoracic surgery, transplant surgery, and neurological surgery. Neurosurgical patients account for about 12% to 13% of annual surgical patients. The VAPHCS also is partnered with Oregon Health & Science University in the training of health care professionals, such as physicians and nurses.

The expectation at the VAPHCS is that medical-surgical nurses care for 4 to 5 concurrent patients, often from different surgical services. Caring for patients with different medical and surgical needs, variable ambulatory, swallowing, and elimination functions, and different physician teams can become confusing; even within a single surgical service, postoperative care due to procedure complexity, specificity of care orders, and the real possibility of medical catastrophe can seem overwhelming. Therefore, subspecialty nursing training poses a challenge that requires technical in-service and didactic education and allocation of resources.

Despite systems level subspecialty nursing training, medical emergencies identified at the bedside can be mismanaged.¹ Errors in care can be due to an incomplete knowledge of the patient’s procedure and misunderstanding of positioning and activity limitations.

To encourage medical-surgical nurses to become more engaged and confident in subspecialty patient care, the authors developed a bedside neurosurgical nursing guide to allow for independent procedure related education. The comprehensive guide summarized the clinical course for postoperative neurosurgical patients undergoing cranial and spinal surgeries. This guide included appropriate surgery-related images, procedure overviews, management decisions, potential postoperative complications, and wound care directions. The guide was distributed to medical-surgical nurses caring for neurosurgical patients. The authors hypothesized that the guide would enable nurses to better predict adverse outcomes and respond appropriately and would improve confidence in patient care.

Methods

For educational purposes, a bedside neurosurgical nursing guide (text and graphics) was created for the 16 surgical subspecialty nurses at the VAPHCS. The guide detailed the most common cranial and spinal neurosurgical procedures performed at VAPHCS and was written based on a typical postoperative course for each procedure by the chief neurosurgery resident at VAPHCS with collaboration from the attending neurosurgeons (Figure).

A quality improvement (QI) project was undertaken to assess nursing confidence with neurosurgical patients’ care pre- and postfamiliarity with the bedside neurosurgical nursing guide. A literature search revealed no validated survey assessing nursing confidence, so one was created using the Likert scale. Specifically, an anonymous 6-question survey was completed by all 16 surgical nurses prior to familiarization with the guide. Responses were recorded as scores of 1 to 5 for questions 1, 3, and 4, with a response of 1 indicative of no comfort or confidence and a response of 5 indicative of the highest level of comfort or confidence. Responses were recorded as either true or false for questions 2 and 6, and never, occasionally, frequently, or always for question 5.

The guide was made available to nurses for 6 months without encouragement to use it. After 6 months, a 3-week period of familiarization with and education about the availability of the guide was instituted at morning nursing reports; the total availability of the guide to nursing staff was 6 months 3 weeks. After this period the same 6-question survey was distributed, and data were collected.

Survey responses were categorized into 2 groups. Responses to questions 1, 3, and 4 were categorized as group 1, and responses to questions 4 and 5 were categorized as group 2. Responses (never and occasionally) to question 5, were categorized as group 1 and responses (frequently and always) as group 2 (Table). Responses to questions 2 and 6 were grouped 1 for true and 2 for false. Nurses participating in this study ranged in age from 22 to 57 years, education level ranged from registered nurse to a bachelor of science in nursing, and years of experience ranged from < 1 year to 27 years.

Statistics were calculated using chi-square analysis with Yates correction online calculator. For the chi-square analysis, the prefamiliarization data for groups 1 and 2 were used as the expected values, and the postfamiliarization data were used for the observed values. In this manner, differences were discerned between the before and after questionnaire responses. The VAPHCS institutional review board determined that the study was not human research and exempt from review.

Findings

Anonymous survey responses were collected from all 16 surgical subspecialty nurses both prior and after familiarization with the nursing guide.The response rate was 100% with only a few incomplete responses excluded from the analysis. Three questions in the prefamiliarization questionnaire had no appropriate response, and 1 question in the postfamiliarization survey had no appropriate response.

Improvement was statistically significant in responses for questions 1, 3, 5, and 6 (P = .026, .008, .004, and .033, respectively). No significant differences were found for questions 2 and 4 (P = .974 and .116, respectively). It is possible that there was no significant difference in question 2 because prefamiliarization responses were already favorable. Even if nurses did not feel comfortable taking care of neurosurgical patients (as assessed in question 1), they noted confidence improvement by working on the ward and through informal assimilation of knowledge and skill, which would have accumulated naturally over 1 year.

Prior to familiarization with the guide, 7 nurses did not feel confident in assessing the need to contact a physician (question 4). After familiarization with the nursing guide, favorable responses increased from 9 to 14 nurses. Results trended toward but did not reach statistical significance, likely due to the small sample size.

Ultimately, in the 16 surgical subspecialty nurses surveyed, familiarization with the nursing guide was shown to improve comfort in taking care of neurosurgical patients and increase confidence in patient care skills. At the end of the QI project (6 months, 3 weeks), all nurses knew where to locate the bedside neurosurgical nursing guide and were familiar with it and its use. The guide remains accessible to the medical-surgical nurses and continues to be used.

Discussion

Nursing confidence has an undervalued effect on patient care.² Confidence, or a belief in one’s own ability, varies directly with competence. Systematic quantification of nursing competence has been extensively studied using self-report questionnaires and clinical simulations.^2,3 Competency can be quantified and normalized using formal assessment; however, confidence is somewhat intangible. Nursing confidence is a situation-dependent subjective feeling of security and is derived from an internalized assessment of skills that are commensurate with patient needs. Nursing confidence is further influenced by an intuited value within the care team, adequate knowledge of the patient’s condition, and procedures and protocols.⁴

A similar but less specific definition deconstructs nursing confidence as “significance of a professional network of coworkers” and the “importance of confirmation of professional role and competence.”⁵ The professional network of coworkers is invaluable as it underlies the essence of patient-centered care. The adaptive leadership framework is integral to the modern delivery of patient care, and via this framework frontline clinical staff, including nurses, are empowered.^6,7

The second portion of Haavardsholm and Nåden’s definition, “importance of confirmation of professional role and competence” describes the association of the most easily augmented correlate of confidence: competency.⁵ Nursing competency is supplemented continuously with in-service training and recertification processes; however, despite this, demands placed on nurses can be technologically advanced and extremely varied. Nursing competency is known to directly correlate with increasing education, as nurses holding a master’s degree have been shown to outperform those with a bachelor of nursing degree.³

Increased formal education as well as increased work experience (> 5 years) are correlated with increased critical thinking ability.^4,5 The critical thinking ability of health care providers can be fortified by clinical simulation, which leads to statistically significant improvement in clinical competency.^2,3

A literature review of Medline and the National Library of Medicine PubMed online databases for search terms (nurs*, confidence, bedside, guide) was performed but did not result in original research assessing nurse confidence related to bedside guides. In this population, nurses were anonymously compared against their own historical data obviating any effect of education or experience on survey measures.

Nursing Self-Confidence

Evidence suggests that nursing confidence is a complex manifestation of the security felt within the care team and the comfort of one’s own professional abilities.⁴ Patients’ trust in the team caring for them is based on the confidence exuded by the team.⁸ In this way, nursing confidence can affect the patient-care team profoundly. Value is maximized when a nurse’s self-confidence engenders patient confidence and trust. Due to the varied patient load and complexity of subspecialty nursing care, it is hypothesized that bedside manuals/guidelines can be used to educate the subspecialty nurses on specific patient-related issues.

Nursing practice competence and confidence is vital to providing care for patients with complex postsurgical health care needs. Patient safety and outcome are paramount. This can be intimidating for newly qualified surgical subspecialty nurses who have not yet had experience with or adequate exposure to patients with complex postsurgical needs. Surgical nursing continuing education places an emphasis on adaptation to ever-changing specialized surgical procedures and postoperative patient care. Nevertheless, it is difficult for surgical subspecialty nurses to learn and retain all the possible complexities of individual cases and to confidently, appropriately, and safely care for patients especially when adverse events arise.

Recognizing that leadership is personal and not dependent on hierarchy, surgical subspecialty nurses may be better suited to specific bedside training and counseling.^6,9 A key factor influencing nursing confidence is communication and collaboration with physicians.⁹ The role of the physician at VA medical facilities is no longer to be a commanding figure with complete medical autonomy; rather, a unified team of specialized practitioners collaboratively facilitate and deliver patient care.

There is no specific research detailing the use of bedside nursing guides in caring for postoperative patients. However, at VAPHCS, nurses created supplemental material regarding postoperative acute care of vascular surgery patients, which was found to be subjectively helpful in elevating nursing confidence. To the authors’ knowledge, no such supplemental information/guide exists for other specialty surgical services.

The surgical nursing guide created here detailed visuals of many common neurosurgical procedures performed at VAPHCS and included a prioritized checklist, which the 16 surgical subspecialty nurses could reference postoperatively. The authors hypothesized that this would enhance the nurses’ ability to efficiently manage specific situations while bridging communication gaps between surgical teams and nurses. The survey results agree with previous reports that suggested that the application of an adaptive leadership framework would empower nurses to deliver excellent patient-centered care, care that can be augmented with subspecialty nursing guides.^7,10

Based on these results the authors propose that subspecialty surgical services consider use of a practical nursing guide for all surgical subspecialty nurses to reference, improve familiarity with procedures, and provide guidance to manage adverse events. Since implementing this reader-friendly paradigm within neurosurgical care, a nurse driven expansion has now included other subspecialty services at the VAPHCS with success.

Limitations

Survey responses have inherent bias and sampling error rates. The sample size for this survey was small. Data were grouped for data analysis. Competency and patient outcomes were not measured.

Future Directions

Despite specific surgical specialty postoperative patient care training, an overall lack of confidence can persist. A physician-created neurosurgical nursing guide that detailed the most common neurosurgical procedures, expected postoperative care, and potential emergencies was shown to improve nursing confidence. Collaborative (physician and nursing leaders) QI projects, such as described here; development of specific surgical specialty initiatives designed to improve confidence and quality; and nurse-physician communication and teamwork could lead to improved patient satisfaction and outcome.

The costs associated with developing and using bedside nursing guides are relatively low, and efficiency can be considered high. Competency improvement could be measured by creating a specialty-specific case scenario question bank. Effects on patient satisfaction and outcome could be measured by a patient satisfaction survey. Improvements in beside catastrophe management could be prospectively tracked; for example, rates of mismanagement of mobility status, emergent transfers to the intensive care unit, or poor wound care could be compared pre- and postfamiliarization with a subspecialty guide.

Conclusion

Familiarization with the VAPHCS neurosurgical nursing guide had a positive impact on the confidence of medical-surgical nurses caring for neurosurgical patients. Medical-surgical nurses were more comfortable taking care of neurosurgical patients; they felt the guide helped improve skills and noted improved knowledge regarding involvement of physician oversight. Although objective parameters were not assessed, improvement in nursing confidence in general leads to improved overall nurse-physician communication and patient management. A further study might target objective parameters associated with guide usage, such as changes in the number of emergencies or calls to physicians regarding management.

Acknowledgments
The authors thank Andy Rekito, MS, for illustrative assistance.