Faculty Bibliography

STUDY DESIGN: Retrospective clinical and radiographic single-center study OBJECTIVE.: Assess simultaneous cervical spine and lower extremity compensatory changes with changes in thoracolumbar spinal alignment. SUMMARY OF BACKGROUND DATA: Full-body stereoradiographic imaging allows better understanding of reciprocal changes in cervical and lower extremity alignment in the setting of thoracolumbar malalignment. Few studies describe the simultaneous effect of alignment correction on these mechanisms. METHODS: Patients >/=18 years undergoing instrumented thoracolumbar fusion without previous cervical spine fusion, hip, knee or ankle arthroplasty were included. Spinopelvic, lower extremity and cervical alignment were assessed from full-body standing stereoradiographs using validated software. Patients were matched for pelvic incidence and stratified based on baseline T1-pelvic angle (TPA) as: TPA-Low <14 degrees , TPA-Moderate =14-22 degrees and TPA-High >22 degrees . Perioperative changes between baseline and first postoperative visit <6 months in lower extremity alignment (pelvic shift: P Shift, sacrofemoral angle: SFA, Knee Angle: KA, Ankle Angle: AA, global sagittal axis: GSA) and cervical alignment (C0-C2 angle, C2-slope, C2-C7 lordosis and C2-C7 SVA:cSVA) were correlated with change in magnitude of TPA and sagittal vertical axis (SVA) correction. RESULTS: After matching, 87 patients were assessed. Increasing baseline TPA severity associated with a progressive increase in all regional spinopelvic parameters except thoracic kyphosis, in addition to increased SFA, P Shift, KA, GSA, and C2-C7 lordosis. As TPA correction increased, there was a reciprocal reduction in SFA, KA, P Shift, GSA and C2-C7 lordosis. Change in SVA correlated most with change in GSA (r = 0.886), P Shift (r = 0.601), KA (r = 0.534) and C2-C7 lordosis (r = 0.467). Change in TPA correlated with change in SFA (r = 0.372) while SVA did not. CONCLUSIONS: Patients with thoracolumbar malalignment exhibit compensatory changes in cervical spine and lower extremity simultaneously in the form of cervical hyperlordosis, pelvic shift, knee flexion, and pelvic retroversion. These compensatory mechanisms resolve reciprocally in a linear fashion following optimal surgical correction. LEVEL OF EVIDENCE: 3.

BACKGROUND: Changes in spinal alignment and pelvic tilt alter acetabular orientation in predictable ways, which may have implications on stability of total hip arthroplasty (THA). Patients with sagittal spinal deformity represent a subset of patients who may be at particularly high risk of THA instability because of postural compensation for abnormal spinal alignment. METHODS: Using standing stereoradiography, we evaluated the spinopelvic parameters, acetabular cup anteversion, and inclination of 139 THAs in 107 patients with sagittal spinal deformity. Standing images were compared with supine pelvic radiographs to evaluate dynamic changes in acetabular cup position. Dislocation and revision rates were procured through retrospective chart review. The spinal parameters and acetabular cup positions among dislocators were compared with those who did not dislocate. RESULTS: The rate of THA dislocation in this cohort was 8.0%, with a revision rate of 5.8% for instability. Patients who sustained dislocations had significantly higher spinopelvic tilt, T1-pelvic angle, and mismatch of lumbar lordosis and pelvic incidence. Among all patients, 78% had safe anteversion while supine, which decreased significantly to 58% when standing due to increases in spinopelvic tilt. Among dislocating THA, 80% had safe anteversion, 80% had safe inclination, and 60% had both parameters within the safe zone. CONCLUSION: In this cohort, patients with THA and concomitant spinal deformity have a particularly high rate of THA instability despite having an acetabular cup position traditionally thought of as within acceptable alignment. This dislocation risk may be driven by the degree of spinal deformity and by spinopelvic compensation. Surgeons should anticipate potential instability after hip arthroplasty and adjust their surgical plan accordingly.

STUDY DESIGN: Comparative effectiveness database study. OBJECTIVE: To describe variation in use of adjuvant therapies for managing postoperative pain in in patients undergoing posterior spinal fusion (PSF) for adolescent idiopathic (AIS) and determine association between use of these therapies and patient outcomes. SUMMARY OF BACKGROUND DATA: Variation in postoperative pain management for children undergoing PSF for AIS likely impacts outcomes. Minimal evidence exists to support strategies that most effectively minimize prolonged intravenous (IV) opioids and hospitalizations. METHODS: We included patients aged 10-18 years discharged from one of 38 freestanding children's hospitals participating in a national database from 1/12/2012-5/1/2015 with ICD9 codes indicating scoliosis and PSF procedure. Use of ketorolac, GABA analogues (GABAa), and benzodiazepines was compared across hospitals. Hierarchical logistic regression adjusting for confounders and accounting for clustering of patients within hospitals was used to estimate association between these therapies and odds of prolonged duration of IV opioids, prolonged length of stay (LOS), and early readmissions. RESULTS: Across hospitals, use of ketorolac and GABAa was highly variable and increased over time among 7349 subjects. Use of ketorolac was independently associated with significantly lower odds of prolonged LOS (OR 0.75, 95% CI 0.64, 0.89) and prolonged duration of IV opioid (OR 0.84, 95% CI 0.73, 0.98). GABAa use was significantly associated with decreased odds of prolonged IV opioid use (OR 0.63, 95% CI 0.53, 0.75). Readmission rate at 30d was 1.6% and most strongly associated with prolonged LOS. CONCLUSION: In this national cohort of children with AIS undergoing PSF, patients who received postoperative ketorolac or GABAa were less likely to have prolonged IV opioid exposure. Given the rapid increase in use of adjuvant therapies without strong evidence, resources should be devoted to multi-center trials in order to optimize effectiveness and outcomes. LEVEL OF EVIDENCE: 3.

BACKGROUND CONTEXT: Obesity's impact on standing sagittal alignment remains poorly understood, especially with respect to the role of the lower-limbs. Given energetic expenditure in standing, a complete understanding of compensation in obese patients with sagittal malalignment remains relevant. PURPOSE: This study compares obese and non-obese patients with progressive sagittal malalignment for differences in recruitment of pelvic and lower limb mechanisms. STUDY DESIGN/SETTING: Single center retrospective review. PATIENT SAMPLE: 554 patients (277 obese, 277 non-obese) identified for analysis. OUTCOME MEASURES: Upper body alignment parameters: sagittal vertical axis (SVA) and T1 spino-pelvic inclination (T1SPi). Compensatory lower-limb mechanisms: pelvic translation (PS: pelvic shift), knee (KA) and ankle (AA) flexion, hip extension (SFA: sacrofemoral angle), and global sagittal angle (GSA). METHODS: Inclusion criteria were patients>/=18 years that underwent full body stereographic x-rays. Included patients were categorized as non-obese (N-Ob: BMI<30 kg/m2) and obese (Ob: BMI>/=30 kg/m2). To control for potential confounders, groups were propensity score matched by age, gender and baseline pelvic incidence (PI), and subsequently categorized by increasing spino-pelvic (PI-LL) mismatch: <10 degrees , 10 degrees -20 degrees , >20 degrees . Independent t-tests and linear regression models compared sagittal (SVA, T1SPi) and lower limb (PS, KA, AA, SFA, GSA) parameters between obesity cohorts. RESULTS: 554 patients (277 Ob, 277 N-Ob) were included for analysis, and were stratified to the following mismatch categories: <10 degrees : n=367; 10 degrees -20 degrees : n=91; >20 degrees : n=96. Ob patients had higher SVA, KA, PS and GSA compared to N-Ob (p<0.001 all). Low PI-LL mismatch Ob patients had greater SVA with lower SFA (142.22 degrees vs. 156.66 degrees , p=0.032), higher KA (5.22 degrees vs. 2.93 degrees , p=0.004) and PS (4.91 vs. -5.20 mm, p<0.001) compared to N-Ob. With moderate PI-LL mismatch, Ob patients similarly demonstrated greater SVA, KA, and PS, combined with significantly lower PT (23.69 degrees vs. 27.14 degrees , p=0.012). Obese patients of highest (>20 degrees ) PI-LL mismatch showed greatest forward malalignment (SVA, T1SPi) with significantly greater PS, and a concomitantly high GSA (12.86 degrees vs. 9.67 degrees , p=0.005). Regression analysis for lower-limb compensation revealed that increasing BMI and PI-LL predicted KA (r2=0.234) and GSA (r2=0.563). CONCLUSIONS: With progressive sagittal malalignment, obese patients differentially recruit lower extremity compensatory mechanisms while non-obese preferentially recruit pelvic mechanisms. The ability to compensate for progressive sagittal malalignment with the pelvic retroversion is limited by obesity.

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction in patients older than age 55, with operative management being a widely adopted approach. Previous work has shown that private insurance status, gender and patient race are predictive of the operative approach patients receive (anterior-only, posterior-only, combined anterior-posterior). The Nationwide Inpatient Sample from 2001 to 2010 was used to assess the potential role of multilevel CSM as a contributing factor in determining which operative approach CSM patients receive, as it is rare for an anterior-only approach to be sufficient for CSM patients requiring fusion of four or more involved levels. Multivariate analyses revealed that female sex (OR=3.78; 95% CI=2.08-6.89; p<0.0001), private insurance (OR=5.02; 95% CI=2.26-11.12; p<0.0001), and elective admission type (OR=4.12; 95% CI=1.65-10.32; p=0.0025) were predictive of increased receipt of a 3+ level fusion in CSM. No other variables, including patient age, race, income, or admission source were predictive of either increased or decreased likelihood of receiving fusion of at least three levels for CSM. In conclusion, female sex, private insurance status, and elective admission type are each independent predictors in CSM for receipt of a 3+ level fusion, while patient age, race and income are not. Given the propensity of fusions greater than three levels to require posterior approaches and the association between posterior CSM approaches and increased morbidity/mortality, these findings may prove useful as to which patient demographics are predictive of increased morbidity and mortality in operative treatment of CSM.

BACKGROUND: Postoperative wound complications after posterior spinal fusion are difficult to manage. The incidence in the nonidiopathic patient population is significantly higher than the adolescent idiopathic population. A comparison of wound complications after posterior spinal fusion for nonidiopathic scoliosis between the utilization of the orthopaedic surgical team at the time of closure performing a nonstandardized wound closure versus a plastic surgeon with a plastic multilayered closure technique and rotational flap coverage when needed had not previously been evaluated. The purpose of this study was to compare the complication rate between nonstandardized and plastic multilayered closure of the surgical incision in patients undergoing posterior spinal fusion for nonidiopathic scoliosis. METHODS: The charts of 76 patients with a primary diagnosis of scoliosis associated with a syndrome or neuromuscular disease and who underwent a posterior spinal fusion were reviewed. Forty-two patients had their incisions closed using the nonstandardized technique and 34 using the plastic multilayered technique. These 2 groups were compared for age, sex, primary diagnosis, number of levels fused, estimated blood loss, number of units transfused, operating room time, wound complication, and return to operating room. RESULTS: The wound complication rate in the nonstandardized closure group was 19% (8/42) compared with 0% (0/34) in the plastic multilayered closure group (P=0.007). The unanticipated return to the operating room rate was 11.9% (5/42) for the nonstandardized closure patients versus 0% (0/34) for the plastic multilayered closure patients (P=0.061). CONCLUSIONS: The use of the plastic multilayered closure technique in this patient population is important in an effort to decrease postoperative wound complications. The ability of the surgical team to decrease the infection rate of nonidiopathic scoliosis cannot be overstated. The method of wound closure plays a major role in lowering this incidence. LEVEL OF EVIDENCE: Level III-therapeutic.

Degenerative spondylolisthesis is a common presentation, yet the best surgical treatment continues to be a matter of debate. Interbody fusion is one of a number of options, but its exact role remains ill defined. The aim of this study was to provide a contemporary review of the literature to help determine the role, if any, of interbody fusion in the surgical treatment of degenerative spondylolisthesis. A systematic review of the literature since 2005 was performed. Details on study size, patient age, surgical treatments, levels of slip, patient reported outcome measures, radiographic outcomes, complications and selected utility measures were recorded. Studies that compared a cohort treated with interbody fusion and at least one other surgical intervention for comparison were included for review. Only studies examining the effect in degenerative spondylolisthesis were included. Two authors independently reviewed the manuscripts and extracted key data. Thirteen studies were included in the final analysis. A total of 565 underwent interbody fusion and 761 underwent other procedures including decompression alone, interspinous stabilisation and posterolateral fusion with or without instrumentation. Most studies were graded Level III evidence. Heterogeneous reporting of outcomes prevented formal statistical analysis. However, in general, studies reviewed concluded no significant clinical or radiographic difference in outcome between interbody fusion and other treatments. Two small studies suggested interbody fusion is a better option in cases of definite instability. Interbody fusion only provided outcomes as good as instrumented posterolateral fusion. However, most studies were Level III, and hence, we remain limited in defining the exact role of interbody fusion-cases with clear instability appear to be most appropriate. Future work should use agreed-upon common outcome measures and definitions.

STUDY DESIGN: Retrospective cohort study OBJECTIVE.: To assess factors potentially impacting the operative approach chosen for CSM patients on a nationwide level. SUMMARY OF BACKGROUND DATA: Cervical spondylotic myelopathy (CSM) is one of the most common spinal disorders treated by spine surgeons, with operative management consisting of three approaches: anterior-only, posterior-only, or combined anterior-posterior. It is unknown whether the operative approach used differs based on patient demographics and/or insurance status. METHODS: The Nationwide Inpatient Sample from 2001-2010 was used for analysis. Admissions having a diagnosis code of 721.1 and a primary procedure code of 81.02/81.03, 81.32/81.33, 81.02/81.03 or 81.32/81.33 (combined anterior and posterior fusion/refusion at C2 or below), and 3.09 (decompression of the spinal canal including laminoplasty) were included. Analysis was adjusted for several variables including patient age, race, sex, primary payer for care, and admission source/type. RESULTS: Multivariate analyses revealed that non-Caucasian race [Black (OR = 1.39;95%CI = 1.32-1.47;p < 0.0001), Hispanic (OR = 1.51;95%CI = 1.38-1.66;p < 0.0001), Asian/Pacific Islander (OR = 1.40;95%CI = 1.15-1.70;p = 0.0007), Native American (OR = 1.33;95%CI = 1.02-1.73;p = 0.037)] and increasing age (OR = 1.03; p < 0.0001) were predictive of receiving posterior-only approaches. Female sex (OR = 1.39;95%CI = 1.34-1.43;p < 0.0001), private insurance (OR = 1.19;95%CI = 1.14-1.25;p < 0.0001), and non-trauma center admission type (OR = 1.29-1.39;95%CI = 1.16-1.56;p < 0.0001) were independently predictive of increased likelihood of receiving an anterior-only approach. Hispanic race (OR = 1.35;95%CI = 1.14-1.59;p = 0.0004) and admission source [another hospital (OR = 1.65;95%CI = 1.20-2.27;p = 0.0023), other health facility (OR = 1.68;95%CI = 1.13-2.51;p = 0.011)] were the only variables predictive of increased combined anterior-posterior approaches; Native American race (OR = 0.32;95%CI = 0.13-0.78;p = 0.013) decreased the likelihood of a combined anterior-posterior approach. CONCLUSIONS: Private insurance status, female sex, and Caucasian race independently predict receipt of anterior-only CSM approaches, while non-Caucasian race (Black, Hispanic, Asian/Pacific Islander, Native American) and non-private insurance predict receiving posterior-only CSM approaches. Given recent literature demonstrating posterior-only approaches as predictive of increased mortality in CSM (Kaye et al., 2015), our findings indicate that for CSM patients, non-Caucasian race may significantly increase mortality risk, while private insurance status may significantly decrease the risk of mortality. Further prospective study will be needed to more definitively address these issues. LEVEL OF EVIDENCE: 3.

Parkinson's disease (PD) is a neurodegenerative disorder manifesting over time to result in reduced mobility. The impact of PD on spinal fusion has yet to be addressed on a nationwide level. The Nationwide Inpatient Sample (NIS) from 2001 to 2012 was used for analysis. Admissions with spinal fusion of two or more vertebrae (ICD-9 codes=81.62, 81.63 and 81.64) were included and then stratified based on the presence or absence of PD (ICD-9 code=332.0); patients with cancer (ICD-9 codes=140-239) or trauma (ICD-9 codes=805.0-806.9) were excluded. Propensity score matching adjusted for potential confounding effects introduced by patient age, race, sex, and primary payer for care. 570,858 patients receiving spinal fusion of two or three vertebrae (1-2 levels) were identified, 2648 (0.5%) of whom had PD. Analysis revealed that PD was independently predictive for increased in-hospital mortality, durotomy, paraplegia, postoperative infection, venous thrombotic events, inferior vena cava filter placement, red blood cell transfusion, pulmonary embolism, total hospital charge >$200,000, length of stay >1week, non-routine discharge disposition, acute respiratory distress syndrome, acute posthemorrhagic anemia, multisystem complications (nervous system, cardiac, respiratory, urinary), and device-related complications (all P<0.001). In conclusion, these findings from a nationwide analysis comprising a 12-year period indicate that PD is significantly associated with increased in-hospital morbidity, mortality, and cost following spine fusion of 1-2 levels when compared with the general population. These findings point to the need for risk stratification and adjustment of quality metrics for this growing patient population, and should be integrated into operative decision-making and patient counseling.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) performed as an outpatient has become increasingly common for treating cervical spine pathology. Few reports have attempted to assess readmissions following outpatient ACDF. This study was performed to address this issue using population-based databases. METHODS: The State Ambulatory Services Database (SASD) for New Jersey (NJ) from 2003-2012 was used for analysis. Patients receiving ACDF (defined as anterior cervical fusion (ICD-0 code=81.02) + excision of intervertebral disc (80.51)) were extracted; those with three or more levels fused (ICD-9 codes 81.63-81.64), cancer (ICD-9 codes 140-239), or trauma (ICD-9 codes=805.0-806.9) were excluded. A series of perioperative complications including durotomy, red blood cell transfusion, acute posthemorrhagic anemia, paraplegia (weakness), and mortality were examined. Propensity score matching (PSM) was used to adjust the analysis for patient age, race, sex, primary payer for care, and number of diagnoses. The NJ SASD defined readmission as admission to the same facility within seven days of initial discharge. RESULTS: Two thousand sixteen (2,016) patients were found, 1,528 of whom had readmission data. Of these 1,528 patients, 83 (5.4%) required readmission. PSM was performed prior to comparing readmission versus non-readmission. While there was no difference in perioperative complications between the two groups, the small sample size of the readmission cohort prevented this analysis from having sufficient power. No patient requiring readmission had an initial length of stay greater than one day. CONCLUSION: Based on a 10-year outpatient analysis, fewer than 6% of outpatient 1-2 level ACDFs require readmission. Future studies involving outpatients from several states will be necessary to determine whether these results of outpatient ACDF are applicable nationwide.