Faculty Bibliography

BACKGROUND CONTEXT: Osteoarthritis of the hip often co-exists with sagittal spinal deformity (SSD). Clinical manifestations overlap, and debate exists whether spinal deformity correction or total hip arthroplasty (THA) should be performed first. Hip extension and pelvic tilt are important compensatory mechanisms in SSD. In theory, spinal deformity correction may cause reciprocal changes in acetabular position. PURPOSE: To assess the changes in acetabular anteversion (AV) as a result of SSD correction, and to quantify the relationship between changes in AV and spino-pelvic parameters. STUDY DESIGN/SETTING: Retrospective analysis of a multicenter prospective database of adult spinal deformity patients. PATIENT SAMPLE: SSD patients who underwent surgical realignment were reviewed and included if they had a THA on baseline radiographs. Patients were excluded if they had large metal-on-metal bearings or revision THA in the study period. OUTCOME MEASURES: Radiographic anteversion of the acetabular component was measured pre- and postoperatively, and compared to the changes in spino-pelvic parameters as result of SSD correction. METHODS: Acetabular anteversion (AV) was calculated via the ellipse method (Lewinneck) on a standing PA 36" X-ray image with a wellcentered pelvis to avoid projectional measurement error. AV was measured preoperatively, and on the 6-week or 3-month postoperative X-ray study. Spino-pelvic parameters were measured including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), T1-pelvic angle (TPA), sagittal vertical axis (SVA), truncal tilt (T1SPi) and thoracic kyphosis (TK). Correlation coefficient and linear regression was performed to assess their relationships. RESULTS: Forty-one hips (33 patients) were identified. AV reduces after SSD correction by a mean 4.9degree (range +2 to -23). The change in AV was significantly correlated with the changes in PT (R=0.80), SS (R=-0.693), LL (R=-0.682), PI-LL (R=0.7237), SVA (R=0.561) and TPA (R=0.696). There was a weak correlation with TK and T1SPi. AV was decreased by 1degree for each of the following iatrogenic changes in spino-pelvic parameters (p<0001): 1.1degree PT, -1degree SS, 3.2degree LL, 1.67degree TPA and -11mm SVA. Thirty (73%) of acetabular components had a preoperative AVoutside the Lewinneck "safe zones." Twenty-eight of these 30 were excessively anteverted as a result of increased preoperative pelvic tilt. Postoperatively, 49% of patients still had an AV outside the safe zone, with 65% of these having residual pelvic tilt>20degree. Correction of SSD moved one acetabulum (2.4%) from a safe to unsafe AV. CONCLUSIONS: Correction of SSD results in reduction in AV, with potential implications for THA stability. SSD correction, when indicated, should be performed prior to THA to enable accurate acetabular positioning and minimize potential for dislocation. This study provides an algorithm for the sequence of THA and SSD correction in the patient with concominant pathologies

Intraoperative monitoring (IOM) of spinal cord and nerve root injury through somatosensory evoked po - tentials (SSEP), transcranial motor evoked potentials (TcMEP), spontaneous electromyography (sEMG), and triggered electromyography (tEMG) modalities is vital during spinal surgery. However, there are currently no practice guidelines or practice patterns for the utilization of unimodal and multimodal IOM for specific surger - ies. This study reviews IOM modalities and documents practice patterns of spine surgeons at our single-center tertiary hospital about their use of various IOM modali - ties on 23 spinal procedures. As different intraoperative monitoring modalities have shown to have different sen - sitivities and specificities, devising practice guidelines for IOM utilization in specific spinal procedures should be considered.

Hypothesis: A single T1 Spino Pelvic Angle (TPA) can be associated with drastically different HRQOL but it can easily be supplemented to convey both global alignment and meaningful clinical outcome. Design: Retrospective cohort. Introduction: TPA is a valuable perioperative planning tool that accounts for both pelvic tilt (PT) and trunk inclination. However, it is limited as a standalone parameter because it does not distinguish patients' ability to compensate with pelvic retroversion. For a given TPA, patients who are unable to recruit compensatory mechanisms may have significantly worse HRQOL scores than those who can. Can TPA be augmented to better describe a patient's global alignment and more accurately predict HRQOL? Methods: Single-center study of patients with full body X-ray, HRQOL and TPA >10degree. Proportions of PT to TPA (PTp = PT/TPA) and T1SPi to TPA (T1SPip = T1SPi/TPA) were calculated and investigated against increased values of TPA. Then, 2 sub-groups were created (HighPT and LowPT) based on mean (PTp) +/- 0.5 standard deviation. HighPT and LowPT were compared across the entire cohort using an unpaired T-test. Results: 230 patients were included (58.7 +/- 15.5 y, 60 %F). Mean sagittal parameters included: PI-LL 12.3 +/- 16.3degree, SVA 41 +/- 49 mm, TPA 21.9 +/- 10.1degree and PT 24.4 +/- 8.6degree. The analysis of PTp distribution revealed a decrease in PT recruitment as TPA increases (137 +/- 39 % for patients with TPA <15degree, 87 +/- 15 % for patients with TPA>40degree). Comparing LowPT (n = 57) with HighPT (n = 69) revealed that for a similar TPA (24.1 vs. 22.1degree, p = 0.308), patients with LowPT (and therefore little compensatory PT) had significantly worse HRQL scores in terms of ODI (45 vs. 32 in HighPT; p = 0.002) and EQ-5D (9.7 vs. 8.5 in HighPT, p = 0.003). Conclusions: While TPA captures the severity of deformity, disability is a product of deformity severity and the inability to recruit compensatory mechanisms. TPA measures the severity of the thoracolumbar deformity separate from pelvic compensation. Therefore for a complete picture of standing sagittal alignment, TPA should be considered in conjunction with PT to convey the full radiological and clinical picture. Failing to do so potentially masks a patient's disability

BACKGROUND: Hip osteoarthritis often coexists with adult spinal deformity, an abnormality in which sagittal spinopelvic malalignment is present. Debate exists whether to perform spinal realignment correction or total hip arthroplasty first. Hip extension and pelvic tilt are important compensatory mechanisms in the setting of sagittal spinopelvic malalignment and change after spinal realignment. We performed this study to evaluate the effect that the spinal realignment surgical procedure has on acetabular anteversion. METHODS: This study is a retrospective review of a multicenter, prospective, consecutive database of patients with adult spinal deformity who underwent surgical spinal realignment. Only patients who already had undergone a total hip arthroplasty prior to the spinal realignment procedure were retained for analysis. Patients were excluded if they had insufficient imaging or large-head, metal-on-metal bearings or they had undergone revision total hip arthroplasty in the study period. Acetabular anteversion was calculated via the ellipse method on a standing, posterior-anterior, 90-cm radiograph with a well-centered pelvis. Anteversion was measured preoperatively and at six weeks or three months after the spinal realignment procedure. Spinopelvic parameters measured included pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, T1 pelvic angle, sagittal vertical axis, T1-spinopelvic inclination, and thoracic kyphosis. RESULTS: Forty-one hips (thirty-three patients) were identified. Acetabular anteversion significantly reduced (p < 0.001) after spinal correction by mean change of -4.96 degrees (range, -22.32 degrees to +2.36 degrees ). The change in anteversion correlated with the changes in sagittal pelvic orientation (0.828 for the pelvic tilt, -0.757 for the sacral slope, and -0.691 for the lumbar lordosis) and global spinopelvic alignment (0.579 for the sagittal vertical axis and 0.585 for the T1 pelvic angle). Regression analysis revealed that anteversion decreased by 1 degrees for each of the following spinopelvic parameter changes (p < 0.001): 1.105 degrees for spinopelvic tilt, 1.032 degrees for sacral slope, and 3.163 degrees for lumbar lordosis. CONCLUSIONS: Patients with spinopelvic malalignment had a high prevalence of excessively anteverted acetabular components. Sagittal spinal correction following total hip arthroplasty resulted in reduced acetabular anteversion, which may have implications for stability. Changes in anteversion are most closely related to changes in pelvic tilt in an almost one-to-one ratio. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

STUDY DESIGN: A multicenter, prospective review of surgical patients with adult spine deformity. OBJECTIVE: Assessment of the incidence, risk factor, and impact of radiographical and implant-related complications (RIC) on health-related quality of life measures. SUMMARY OF BACKGROUND DATA: This study provides assessment of the incidence of RIC in adult spinal deformity surgery and impact of these complications on need for reoperation. Risk factors for development of RIC are also assessed, as well as the impact of these complications on health-related quality of life (HRQOL) outcomes measures. METHODS: A multicenter, prospective database of surgical patients with adult spinal deformity was reviewed. All patients with complete 2-year follow-up were included. HRQOL was measured using the Oswestry Disability Index, General Health Survey (36-Item Short Form Health Survey [SF-36]), and Scoliosis Research Society-22 (SRS-22r) at baseline, 6 weeks, 1 year, and 2 years postoperatively. Univariate testing was performed as appropriate. Multivariate logistic regression modeling was used to determine independent predictors of RIC. Multivariate repeated-measures mixed models were used to examine HRQOL, accounting for confounders. RESULTS: A total of 245 patients met inclusion criteria. The incidence of RIC was 31.7% and 52.6% of those patients required reoperation. Rod breakage accounted for 47% of the implant-related complications, and proximal junctional kyphosis accounted for 54.5% of radiographical complications. Univariate analysis identified the following potential risk factors for RIC: weight, American Society of Anesthesiologists score, revision, stopping the fusion in the lower thoracic spine, worse SRS-Schwab classification modifiers (pelvic tilt++, pelvic incidence minus lumbar lordosis++, sagittal vertical axis++), higher T1 spinopelvic inclination, and higher T1 slope. Independent predictors of RIC as identified on multivariate logistic regression included American Society of Anesthesiologists (odds ratio: 1.75, P = 0.029) and sagittal vertical axis modifier ++ (odds ratio 3.43, P = 0.0001). The RIC and no RIC groups each experienced significant improvement over time, as measured on the Oswestry Disability Index (P = 0.0001), SF-36 (P = 0.0001), and SRS-22r (P = 0.0001). However, the rate of improvement over time was less for patients with RIC (SRS-22r P = 0.043, SF-36 P = 0.0001). CONCLUSION: This study identified that nearly one-third of patients undergoing adult spinal deformity surgery experienced a radiographical or implant-related complication, and that just more than one-half of these patients experiencing complication required a reoperation within 2 years of surgery. These complications significantly affected HRQOL measures. Baseline patient characteristics and parameters of the SRS-Schwab classification can be used to help identify those patients at greater risk. LEVEL OF EVIDENCE: 3.

BACKGROUND CONTEXT: Numerous studies have demonstrated poorer outcomes in patients with Workers' Compensation (WC) when compared to those without WC following treatment of various of health conditions including spine disorders. It is thus important to consider compensation status when assessing treatment outcomes in spine surgery. However, reported strengths of association have varied significantly (1.31-7.22). PURPOSE: The objective of this study was to evaluate the association of unsatisfactory outcomes on compensation status in spine surgery patients. STUDY DESIGN/SETTING: Meta-analysis PATIENT SAMPLE: Not applicable OUTCOME MEASURE: Demographics, type of surgery, country, follow-up time, patient satisfaction, return to work and non-union events. METHODS: Both prospective and retrospective studies that compared outcomes between compensated and non-compensated patients in spine surgery were included. Two independent investigators extracted outcome data. The meta-analysis was performed using Revman software. Random effects model was used to calculate risk ratio (RR, 95% confidence interval (CI) for dichotomous variables. There are no conflicts of interest to report among the authors, and no funding was received for this study. RESULTS: 31 studies (13 prospective; 18 retrospective) with a total of 3567 patients were included in the analysis. Follow-up time varied from 4 months to 10 years. 12 studies involved only decompression; the rest were fusion. Overall RR of an unsatisfactory outcome was 2.12 [1.74, 2.58; p<0.001] in patients with WC when compared to those without WC after surgery. RR of an unsatisfactory outcome in patients with WC, compared to those without, was 2.09 [1.38, 3.17]; p<0.01 among studies from Europe and Australia and 2.14 [1.48, 2.60]; p<0.01 among US studies. RR of decompression-only procedures was 2.53 [1.85, 3.47]; p<0.01 and 1.79 [1.45, 2.21]; p<0.01 for fusion. 43% (209/491) of patients with WC returned to work versus 17% (214/1250) of those without WC (RR 2.07 [1.43, 2.98]; p<0.001). 25 % (74/292) and 13.5% (39/287) of patients had non-union in the compensated and non-compensated groups, respectively. This was not statistically significant (RR 1.33 [0.92, 1.91]; p=0.07). CONCLUSIONS: Workers' compensation patients have a two-fold increased risk of an unsatisfactory outcome compared to non-compensated patients after surgery. This association was consistent when studies were grouped by country or procedure. Compensation status must be considered in all surgical intervention studies.

OBJECT Adult spinal deformity (ASD) surgery is known for its high complication rate. This study examined the impact of obesity on complication rates, infection, and patient-reported outcomes in patients undergoing surgery for ASD. METHODS This study was a retrospective review of a multicenter prospective database of patients with ASD who were treated surgically. Patients with available 2-year follow-up data were included. Obesity was defined as having a body mass index (BMI) >/= 30 kg/m2. Data collected included complications (total, minor, major, implant-related, radiographic, infection, revision surgery, and neurological injury), estimated blood loss (EBL), operating room (OR) time, length of stay (LOS), and patient-reported questionnaires (Oswestry Disability Index [ODI], Short Form-36 [SF-36], and Scoliosis Research Society [SRS]) at baseline and at 6 weeks, 1 year, and 2 years postoperatively. The impact of obesity was studied using multivariate modeling, accounting for confounders. RESULTS Of 241 patients who satisfied inclusion criteria, 175 patients were nonobese and 66 were obese. Regression models showed that obese patients had a higher overall incidence of major complications (IRR 1.54, p = 0.02) and wound infections (odds ratio 4.88, p = 0.02). Obesity did not increase the number of minor complications (p = 0.62), radiographic complications (p = 0.62), neurological complications (p = 0.861), or need for revision surgery (p = 0.846). Obesity was not significantly correlated with OR time (p = 0.23), LOS (p = 0.9), or EBL (p = 0.98). Both groups experienced significant improvement overtime, as measured on the ODI (p = 0.0001), SF-36 (p = 0.0001), and SRS (p = 0.0001) questionnaires. However, the overall magnitude of improvement was less for obese patients (ODI, p = 0.0035; SF-36, p = 0.0012; SRS, p = 0.022). Obese patients also had a lower rate of improvement over time (SRS, p = 0.0085; ODI, p = 0.0001; SF-36, p = 0.0001). CONCLUSIONS This study revealed that obese patients have an increased risk of complications following ASD correction. Despite these increased complications, obese patients do benefit from surgical intervention; however, their improvement in health-related quality of life (HRQL) is less than that of nonobese patients.

STUDY DESIGN: Retrospective review of a prospectively collected database. OBJECTIVE: This study compares patient demographics, incidence of comorbidities, procedure-related complications, and mortality following primary vs. revision adult spinal deformity surgerySummary of Background Data. While adult spinal deformity (ASD) surgery has been extensively investigated, no previous study has provided nationwide estimates of patient characteristics and procedure-related complications for primary vs. revision spinal deformity surgery comparatively. METHODS: Nationwide Inpatient Sample data collected between 2001 and 2010 was analyzed. Discharges with procedural codes for anterior and/or posterior thoracic and/or lumbar spinal fusion and refusion were included for patients aged 25+ and 4+ levels fused with any diagnoses specific for scoliosis. Patient demographics, comorbidity and procedure-related complications incidence were determined for primary vs. revision cohorts. Multivariate analysis reported as (OR [95% CI]). RESULTS: Discharges for 9133 primary and 850 revision cases were identified. Patients differed on the basis of demographic and hospital data. Average comorbidity indices for the cohorts were similar (p = 0.580), as was in-hospital mortality (p = 0.163). The incidence of procedure-related complications was higher for the revision cohort (46.96% vs. 71.97%, p = 0.001). The mean hospital course for the revision cohort was longer (6.37 vs. 7.13 days, p<0.0001). Revisions had an increased risk of complications involving the nervous system (1.34[1.10-1.6]), hematoma/seroma formation (2.31[1.92-2.78]), accidental vessel or nerve puncture (1.44[1.29-1.61]), wound dehiscence (2.18[1.48-3.21]), post-op infection (3.10[2.50-3.85]) and ARDS complications (1.43[1.28-1.60]). The primary cohort had a decreased risk for GI (0.65[0.55-0.76]) and GU complications (0.71[0.51-0.99]). CONCLUSIONS: Relative to primary cases, those undergoing revision correction of spinal deformity have a higher risk of many procedure-related complications with a longer hospital course despite similar baseline comorbidity burden and in-hospital mortality rate. This study provides clinically useful data for surgeons to educate patients at risk for morbidity and mortality and direct future research to improve outcomes.