Greater improvement in Neck Disability Index scores in women after surgery for cervical myelopathy: an analysis of the Quality Outcomes Database.

OBJECTIVE: There is a high prevalence of cervical myelopathy that requires surgery; as such, it is important to identify how different groups benefit from surgery. The American Association of Neurological Surgeons launched the Quality Outcomes Database (QOD), a prospective longitudinal registry, that includes demographic, clinical, and patient-reported outcome data to measure the safety and quality of neurosurgical procedures. In this study, the authors assessed the impact of gender on patient-reported outcomes in patients who underwent surgery for cervical myelopathy. METHODS: The authors analyzed 1152 patients who underwent surgery for cervical myelopathy and were included in the QOD cervical module. Univariate comparison of baseline patient characteristics between males and females who underwent surgery for cervical spondylotic myelopathy was performed. Baseline characteristics that significantly differed between males and females were included in a multivariate generalized linear model comparing baseline and 1-year postoperative Neck Disability Index (NDI) scores. RESULTS: This study included 546 females and 604 males. Females demonstrated significantly greater improvement in NDI score 1 year after surgery (p = 0.036). In addition to gender, the presence of axial neck pain and insurance status were also significantly predictive of improvement in NDI score after surgery (p = 0.0013 and p = 0.0058, respectively). CONCLUSIONS: Females were more likely to benefit from surgery for cervical myelopathy compared with males. It is important to identify gender differences in postoperative outcomes after surgery in order to deliver more personalized and patient-centric care.

Cost-Utility Analysis of rhBMP-2 Use in Adult Spinal Deformity Surgery.

STUDY DESIGN: Economic modeling of data from a multicenter, prospective registry. OBJECTIVE: The aim of this study was to analyze the cost utility of recombinant human bone morphogenetic protein-2 (BMP) in adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: ASD surgery is expensive and presents risk of major complications. BMP is frequently used off-label to reduce the risk of pseudarthrosis. METHODS: Of 522 ASD patients with fusion of five or more spinal levels, 367 (70%) had at least 2-year follow-up. Total direct cost was calculated by adding direct costs of the index surgery and any subsequent reoperations or readmissions. Cumulative quality-adjusted life years (QALYs) gained were calculated from the change in preoperative to final follow-up SF-6D health utility score. A decision-analysis model comparing BMP versus no-BMP was developed with pseudarthrosis as the primary outcome. Costs and benefits were discounted at 3%. Probabilistic sensitivity analysis was performed using mixed first-order and second-order Monte Carlo simulations. One-way sensitivity analyses were performed by varying cost, probability, and QALY estimates (Alpha = 0.05). RESULTS: BMP was used in the index surgery for 267 patients (73%). The mean (±standard deviation) direct cost of BMP for the index surgery was $14,000 ±â€Š$6400. Forty patients (11%) underwent revision surgery for symptomatic pseudarthrosis (BMP group, 8.6%; no-BMP group, 17%; P = 0.022). The mean 2-year direct cost was significantly higher for patients with pseudarthrosis ($138,000 ±â€Š$17,000) than for patients without pseudarthrosis ($61,000 ±â€Š$25,000) (P < 0.001). Simulation analysis revealed that BMP was associated with positive incremental utility in 67% of patients and considered favorable at a willingness-to-pay threshold of $150,000/QALY in >52% of patients. CONCLUSION: BMP use was associated with reduction in revisions for symptomatic pseudarthrosis in ASD surgery. Cost-utility analysis suggests that BMP use may be favored in ASD surgery; however, this determination requires further research. LEVEL OF EVIDENCE: 2.

What are the risk factors for surgical site infection after spinal fusion? A meta-analysis.

PURPOSE: Although many risk factors for surgical site infection (SSI) following spinal fusion have been described in the literature, methodologies and study cohorts vary widely. Patient- and procedure-specific risk factors for (SSI) can be identified via a meta-analysis. We sought to review the existing data and isolate significant risk factors for SSI in patients undergoing thoracolumbar spinal fusion. METHODS: The literature was searched through December of 2016. Studies including adult patients undergoing thoracolumbar spinal fusion surgery (single or multilevel, anterior, posterior or combined approach) were identified. Only studies that included an odds ratio (OR) for SSI or sufficient data to calculate it were included. A meta-analysis was performed using RevMan 5.1. Depending on heterogeneity (I2), OR with 95% confidence intervals was calculated using either the fixed-effects model (when I2 < 60%) or the random-effects model (when I2 > 60%). RESULTS: 6482 manuscripts were identified and reviewed. 29 manuscripts with 374,488 patients met the criteria for inclusion. Twelve risk factors were assessed by the meta-analysis and grouped into two categories (patient related and procedure related). Significant patient-related factors for SSI included obesity, diabetes, ASA score, tobacco use and revision status. Procedure-related risk factors included operative time, use of osteotomy, fusion length and extension of fusion to the sacrum or pelvis. CONCLUSIONS: This meta-analysis identified significant risk factors for SSI following spine arthrodesis. These included potentially modifiable factors such as obesity, diabetes, smoking status and procedure-related parameters. Non-modifiable risk factors were identified, including ASA score and age. These factors may prove useful for patient counseling as well as surgical planning. LEVEL OF EVIDENCE: Level III (Meta-analysis including studies with a level of evidence of III or higher). These slides can be retrieved under Electronic Supplementary Material.

Age-Adjusted Alignment Goals Have the Potential to Reduce PJK.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To explore proximal junctional kyphosis (PJK) as a function of age-adjusted surgical correction goals. SUMMARY OF BACKGROUND DATA: Recent adult spinal deformity (ASD) studies show that alignment targets are age-specific. Despite recognizing age and malalignment as PJK risk factors, no study has assessed the age-specific effects of alignment on PJK. METHODS: ASD patients with fusions to the pelvis were included and stratified into three groups: young adults (YA <40 years old), middle aged (MA: 40-65 years old), and the elderly (ED >65 years old). Analysis of variance compared the groups with respect to 1-year postoperative alignments and 1-year offsets from age-specific alignment targets. RESULTS: A total of 679 patients were enrolled (mean age = 61 years old, 77% female, body mass index = 28.1). At 1 year postoperatively, there was a significant decrease in pelvic tilt (PT; 29-23°), spinopelvic mismatch (pelvic incidence [PI]-lumbar lordosis [LL]) (28-5°), and sagittal vertical axis (SVA; 110-37 mm); overall incidence of PJK was 45.1%. Stratification by age (YA, n = 28; MA, n = 389; ED, n = 262) revealed an increase in PJK incidence with age: YA = 17.9%, MA = 43.8%, and ED = 50.2% (P < 0.001). PJK patients had smaller postoperative PI-LL mismatches (ED 0.8° vs. 9.8°, MA 3.1° vs. 7.3°) than non-PJK patients, without any significant differences in PT or SVA. Analysis of the postoperative offsets from age-specific norms revealed that PJK patients in the two older subgroups and in the study cohort as a whole were overcorrected as compared to non-PJK patients (PI-LL offset-all: -5.2° vs. 2.8°, MA: -1° vs. +4°, ED: -11° vs. -2°; SVA offset-all: -10 mm vs. 7 mm, MA: -3 mm vs. 10 mm, ED: -18 mm vs. -6 mm). The correlation coefficients between PJK angles and the offsets from age-adjusted objective were small (0.320 for PI-LL, 0.114 for PT, and 0.136 for SVA). CONCLUSION: Overall, this study suggests that PJK patients were overcorrected when compared to age-adjusted alignment goals. Certainly, elderly patients are subject to independent risk factors for PJK, making the prevention of PJK complex. However, individualized optimization of surgical alignment can improve outcomes. This emphasizes the need for surgeons to incorporate age-specific alignment targets into the standard preoperative planning process. LEVEL OF EVIDENCE: 3.

Virtual Modeling of Postoperative Alignment After Adult Spinal Deformity Surgery Helps Predict Associations Between Compensatory Spinopelvic Alignment Changes, Overcorrection, and Proximal Junctional Kyphosis.

STUDY DESIGN: Retrospective review of a prospective multicenter database. OBJECTIVE: To develop a method to analyze sagittal alignment, free of the influence of proximal junctional kyphosis (PJK), and then compare PJK to non-PJK patients using this method. SUMMARY OF BACKGROUND DATA: PJK after adult spinal deformity (ASD) surgery remains problematic as it alters sagittal alignment. The present study proposes a novel virtual modeling technique that attempts to eliminate the confounding effects of PJK on postoperative spinal alignment. METHODS: A virtual spinal modeling technique was developed on a retrospective ASD cohort of patients with multilevel spinal fusions to the pelvis with at least 2-year postoperative follow-up. The virtual postoperative alignment (VIRTUAL) was created from the postoperative alignment of the instrumented segments and the preoperative alignment of the unfused segments. VIRTUAL was validated by comparisons to actual 2-year postoperative alignment (REAL) in non-PJK patients. Patients were then divided into two groups: PJK and non-PJK based on the presence/absence of PJK at 2 years postoperatively. PJK and non-PJK patients were compared using VIRTUAL and REAL. RESULTS: A total of 458 patients (78F, mean 57.9 yr) were analyzed. The validation of VIRTUAL versus REAL demonstrated correlation coefficients greater than 0.7 for all measures except sagittal vertical axis (SVA; r = 0.604). At 2 years, REAL alignment in PJK patients demonstrated a smaller pelvic incidence minus lumbar lordosis and a larger thoracic kyphosis than non-PJK patients, but similar SVA, T1 pelvic angle, and pelvic tilt. An analysis of VIRTUAL demonstrated that patients with PJK had a smaller pelvic incidence minus lumbar lordosis, pelvic tilt, SVA, and T1 pelvic angle than non-PJK patients (P < 0.05). CONCLUSION: This technique demonstrated strong correlations with actual postoperative alignment. Comparisons between REAL and VIRTUAL alignments revealed that postoperative PJK may develop partially as a compensatory mechanism to the overcorrection of sagittal deformities. Future research will evaluate the appropriate thresholds for deformity correction according to age and ASD severity. LEVEL OF EVIDENCE: 3.