Faculty Bibliography

BACKGROUND CONTEXT: Degenerative lumbar stenosis (DLS) patients adopt forward-bending posture as a compensatory mechanism, increasing spinal canal and foraminal volume. Previous data show laminectomy 6 short segment fusion results in improvement of sagittal vertical axis (SVA), pelvic tilt (PT) and PI-LL (pelvic incidence-lumbar lordosis) mismatch by SRS-Schwab classification in <25% of patients. The magnitude of deformity for which a DLS patient should have realignment remains unknown. PURPOSE: To identify differences in compensatory mechanisms between DLS and adult spinal deformity (ASD) patients with increasing, and to identify at what point DLS patients recruit ASD-type compensatory mechanisms. STUDY DESIGN/SETTING: Retrospective clinical and radiological review. PATIENT SAMPLE: Baseline X-ray images of 239 patients without spinal instrumentation, with the clinical radiological and diagnosis of DLS or ASD were assessed for patterns of spino-pelvic compensatory mechanisms. Patients were stratified by sagittal vertical axis (SVA) by the Schwab-SRS classification. OUTCOME MEASURES: Radiographic spino-pelvic parameters were measured in the DLS and ASD groups, including SVA, PI-LL, T1SPi, TPA and PT. METHODS: Patients were identified using a single-institution database with sole diagnosis of DLS, >40 years and if they had any of the following: PT >25degree, SVA >5cm, thoracic kyphosis (TK) >60degree or PI-LL mismatch >10degree. The patient's diagnosis was taken from the patient history chart based on correlation between history, examination and available imaging. Matched cohort with sole diagnosis of ASD was identified. Groups were stratified by SVA using Schwab-SRS classification: 0(<4cm), +(4-9.5cm), ++( >9.5cm). Sagittal spino-pelvic parameters were compared between the 2 groups with unpaired t-test. RESULTS: 239 patients were identified (122 DLS, 117 ASD). There was no difference in age or pelvic incidence between DLS and ASD with SVA stratifications. DLS patients with SVA 0 had less PT (19.8degree vs 29.2degree p<0.0001), less PI-LL mismatch (3.3degree vs 15.8degree, p<0.001), lower TPA (14.6degree vs 21.8degree, p<0.001) but higher T1SPi (-5.17degree vs -7.44degree, p< 0.001) than those with ASD. DLS patients with SVA+ had less PT (22.6degree vs 26.1degree, p=0.019) and higher T1SPi (0.64degree vs -0.70degree, p=0.008) than ASD patients. DLS patients resembled a decompensated deformity with a higher T1SPi relative to TPA when compared to the ASD cohort in groups 0 and +. No significant differences between ASD and DLS for any parameters in the SVA++ group were identified. No difference was found between DLS or ASD in TK for SVA groups 0, + or ++. CONCLUSIONS: The difference in PI-LL observed in ASD/DLS group '0' underlies the pathogenesis of ASD vs DLS. DLS patients increase SVA for neuronal decompression but without a PI-LL mismatch, they need not increase PT. As PI-LL increases in SVA >9.5cm, recruitment of PT ensues as the need for alignment overtakes desire for decompression. Their compensatory mechanism then resembles ASD. Laminectomy 6 fusion may be more appropriate for DLS patients with SVA< 9.5cm. Given <25% of patients improve in classification after fusion, surgeons should consider realignment surgery in DLS with SVA >9.5cm. Further understanding of HRQOL scores in mal-aligned DLS patients is required to best understand the importance of alignment in DLS

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.

BACKGROUND: Lumbosacral transitional vertebrae (LSTV) are increasingly recognized as a common anatomical variant associated with altered patterns of degenerative spine changes. This review will focus on the clinical significance of LSTV, disruptions in normal spine biomechanics, imaging techniques, diagnosis, and treatment. METHODS: A Pubmed search using the specific key words "LSTV," "lumbosacral transitional vertebrae," and "Bertolotti's Syndrome" was performed. The resulting group of manuscripts from our search was evaluated. RESULTS: LSTV are associated with alterations in biomechanics and anatomy of spinal and paraspinal structures, which have important implications on surgical approaches and techniques. LSTV are often inaccurately detected and classified on standard AP radiographs and MRI. The use of whole-spine images as well as geometric relationships between the sacrum and lumbar vertebra increase accuracy. Uncertainty regarding the cause, clinical significance, and treatment of LSTV persists. Some authors suggest an association between LSTV types II and IV and low back pain. Pseudoarticulation between the transverse process and the sacrum creates a "false joint" susceptible to arthritic changes and osteophyte formation potentially leading to nerve root entrapment. The diagnosis of symptomatic LSTV is considered with appropriate patient history, imaging studies, and diagnostic injections. A positive radionuclide study along with a positive effect from a local injection helps distinguish the transitional vertebra as a significant pain source. Surgical resection is reserved for a subgroup of LSTV patients who fail conservative treatment and whose pain is definitively attributed to the anomalous pseudoarticulation. CONCLUSIONS: Due to the common finding of low back pain and the wide prevalence of LSTV in the general population, it is essential to differentiate between symptoms originating from an anomalous psuedoarticulation from other potential sources of low back pain. Further studies with larger sample sizes and longer follow-up time would better demonstrate the effectiveness of surgical resection and help guide treatment.

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.

STUDY DESIGN: Analysis of the Nationwide Inpatient Sample database. OBJECTIVE: To investigate national trends, risks, and benefits of surgical interventions for degenerative spondylolisthesis (DS). SUMMARY OF BACKGROUND DATA: The surgical management of DS continues to evolve whereas the most clinically and cost-effective treatment is debated. With an aging US population and growing restraints on a financially burdened health care system, a clear understanding of national trends in the surgical management of DS is needed. METHODS: The Nationwide Inpatient Sample database was queried for patients with DS undergoing lumbar fusions from 2001 to 2010, using International Classification of Diseases, Ninth Revision (ICD-9) diagnosis and procedure codes. Analyses compared instrumented posterolateral fusion (PLF), posterolateral fusion with anterior lumbar interbody fusion (ALIF + PLF), PLF with posterior interbody fusion (P/TLIF + PLF), anterior instrumented interbody fusion (ALIF), and posterior interbody fusion with posterior instrumentation (P/TLIF). Clinical data were analyzed representing the initial acute phase care after surgery. RESULTS: There were 48,911 DS surgical procedures identified, representing 237,383 procedures. The percentage of patients undergoing PLF, ALIF + PLF, or ALIF increased whereas the percentage of P/TLIF or P/TLIF + PLF decreased over time. Total charges were less (P < 0.001), average length of hospital stay was shorter (P < 0.01), and average age was older (P < 0.01) for patients who underwent PLF compared with any other procedure. Type of procedure varied on the basis of the geographic region of the hospital, teaching versus nonteaching hospital, and size of hospital (P < 0.01). Patients who had P/TLIF + PLF or ALIF had a higher risk of mortality than patients who had PLF (odds ratios: 5.02, 2.22, respectively). Patients were more likely to develop a complication if they had ALIF + PLF, P/TLIF + PLF, ALIF, and P/TLIF than if they had PLF (odds ratios: 1.45, 1.23, 1.49, 1.12, respectively). CONCLUSION: Variation in the surgical management of DS related to patient demographics, hospital charges, length of hospital stay, insurance type, comorbidities, and complication rates was found within the Nationwide Inpatient Sample database. During the acute phase of care immediately after surgery, PLF procedures were found to reduce length of hospital stay, hospital charges, and postoperative complications. LEVEL OF EVIDENCE: 3.

BACKGROUND: Wound drains that are left in place for a prolonged period of time have a higher rate of bacterial contamination. Following spinal surgery, a drain is often left in place for a longer period of time if it maintains a high output. Given the major consequences of an infection following spinal surgery and the lack of data with regard to the use of antibiotics and drains, we performed a study of patients with a drain following spinal surgery to compare infection rates between those who were treated with antibiotics for twenty-four hours and those who received antibiotics for the duration for which the drain was in place. METHODS: We performed a prospective randomized trial of 314 patients who underwent multilevel thoracolumbar spinal surgery followed by use of a postoperative drain. The patients were randomized into two groups, one of which received perioperative antibiotics for twenty-four hours (twenty-four-hour group) and the other of which received antibiotics for the duration that the drain was in place (drain-duration group). Data collected included demographic characteristics, medical comorbidities, type of spinal surgery, and surgical site infection. RESULTS: Twenty-one (12.4%) of the 170 patients in the twenty-four-hour group and nineteen (13.2%) of the 144 in the drain-duration group developed a surgical site infection (p = 0.48). There were no significant differences between the twenty-four-hour and drain-duration groups with respect to demographic characteristics (except for the American Society of Anesthesiologists [ASA] classification), operative time, type of surgery, drain output, or length of hospital stay. CONCLUSIONS: Continuing perioperative administration of antibiotics for the entire duration that a drain is in place after spinal surgery did not decrease the rate of surgical site infections. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND: Few studies have provided nationwide estimates of patient characteristics and procedure-related complications, or examined postsurgical outcomes for patients with cervical spondylotic myelopathy (CSM) comparatively with respect to surgical approach. The objective of this study is to identify patients at risk for morbidity and mortality directly related with the selected approach, report an overall nation-wide complication rate for each approach against which surgeons can compare themselves, and direct future research to improve patient outcomes. METHODS: Patients surgically treated for CSM were retrospectively identified using ICD-9-CM codes from the Nationwide Inpatient Sample (NIS) database. Four cohorts were compared for demographics and hospital system-related data: anterior (ACDF, ACCF), posterior decompression without fusion, decompression with posterior fusion, and combined anterior-posterior. Multivariate analysis was also used to determine the odds ratio of morbidity and mortality among the cohorts. RESULTS: 54,416 discharges were identified between 2001 and 2010: 34,400 anterior, 9,014 decompression procedures without fusion, 8,741 decompression procedures with posterior fusion, and 2,261 combined anterior-posterior. Groups were statistically different with respect to age, length of hospital stay, mortality, and complications. Groups were statistically different for Deyo score except between posterior decompression only and combined approaches. Using multivariate analysis and adjusting for covariates, the combined (2.74[2.18-3.44]) and laminectomy (1.22[1.04-1.44]) cohorts had an increased risk of mortality when compared to anterior alone. CONCLUSION: These findings are the first to determine the rates and odds of perioperative risks directly related to combined anterior-posterior procedures. This study provides clinically useful data for surgeons to educate patients and direct future research to improve patient outcomes.

BACKGROUND: For the Adult Degenerative Scoliosis (ADS) patient with radiculopathy, there is no clear data in the literature to guide the spine surgeon's decision making in choosing between limited decompression alone, short segment fusion, or longer arthrodesis of the deformity. This study investigates the differences in operative planning, for patients with ADS and radiculopathy, between two groups of spine surgeons based on fellowship experience and practice composition. METHODS: Six Degenerative Spine surgeons (Group 1) and 6 Spinal Deformity surgeons (Group 2) were shown 7 cases of patients with ADS and radiculopathy. Surgeons completed a questionnaire detailing their planned operative intervention including the number of fusion levels, if any, approach, choice of bone graft, and interbody device. Pearson Correlation was used to investigate the association between fellowship training, practice composition, number of levels fused, and other variables. Intraclass correlation (ICC) analysis was used to investigate the internal consistency among the groups. RESULTS: There was a direct correlation between fellowship deformity experience and practice composition (r=0.75, p<0.01), and between deformity practice composition and the number of planned fusion levels (r=0.90, p<0.001). Group 1 surgeons fused a mean 3.7 vertebral levels (range 0-6.7), while Group 2 surgeons fused a mean 10.8 levels (range 4-16.5). Group 2 surgeons fused a significantly greater number of levels for each case than degenerative surgeons on paired student t-test (p=0.002). Group 1 surgeons chose decompression alone more commonly than deformity surgeons (p<0.05). Group 2 surgeons had significantly higher group consistency by ICC analysis (p=0.004). CONCLUSIONS: Fellowship and practice composition influence the physician's surgical planning in ADS. There is a lack of standardized treatment paradigms for the management of radiculopathy in patients with ADS.

BACKGROUND: Unplanned hospital readmissions result in significant clinical and financial burdens to patients and the healthcare system. Readmission rates and causes have been investigated using large administrative databases which have certain limitations in data reporting and coding. The objective of this study was to provide a description of 90 day post-discharge readmissions following surgery for common degenerative cervical spine pathologies at a large-volume tertiary hospital. The study also compared the readmission rates of patients who underwent anterior- and posterior-approach procedures. METHODS: The administrative records from a single-center, high-volume tertiary institution were queried using ICD-9 codes for common cervical pathology over a three year period to determine the rate and causes of readmissions within the 90 days following the index surgery. RESULTS: A total of 768 patients underwent degenerative cervical spine surgery during the three year study period. Within 90 days of discharge, 24 (3.13%) patients were readmitted; 16 (2.06%) readmissions were planned for lumbar surgery; 8 (1.04%) readmissions were unplanned. 640 patients underwent procedures involving an anterior approach and 128 patients underwent procedures involving a posterior approach. There were 14 (2.17%) planned readmissions in the anterior group and 2 (1.5%) in the posterior group. The unplanned readmission rate was 0.63% (4 patients) and 3.13% (4 patients) in the anterior and posterior groups, respectively. (p=0.0343). CONCLUSION: The 90 day post-discharge unplanned readmission rate that followed elective degenerative cervical spine surgery was 1.04%. The unplanned readmission rate associated with posterior-approach procedures (3.13%) was significantly higher than that of anterior-approach procedures (0.63%). LEVEL OF EVIDENCE: IV.

STUDY DESIGN: Cohort. OBJECTIVE: To compare the perioperative morbidity of patients with cardiac stents after spine surgery who continue to take aspirin before and after the operation with a similar group of patients who preoperatively discontinued aspirin. SUMMARY OF BACKGROUND DATA: The preoperative discontinuation of anticoagulant therapy has been the standard of care for orthopedic surgical procedures. However, recent literature has demonstrated significant cardiac risk associated with aspirin withdrawal in patients with cardiac stents. Although it has recently been demonstrated that performing orthopedic surgery while continuing low-dose aspirin therapy seems to be safe, studies focused on spinal surgery have not yet been performed. Because of the risk of intraspinal bleeding and the serious consequences of subsequent epidural hematoma with associated spinal cord compression, spinal surgeons have been reluctant to operate on patients taking aspirin. METHODS: This institutional review board-approved study included 200 patients. Preoperative parameters and postoperative outcome measures were analyzed for 100 patients who underwent spinal surgery after the discontinuation of anticoagulation therapy and 100 patients who continued to take daily aspirin through the perioperative period. The primary outcome measure was serious bleeding-related postoperative complications such as spinal epidural hematoma. The operative time, intraoperative estimated blood loss, hospital length of stay, transfusion of blood products, and 30-day hospital readmission rates were also recorded and compared. RESULTS: The patients who continued taking aspirin in the perioperative period had a shorter hospital length of stay on average (4.1 +/- 2.7 vs. 6.2 +/- 5.8; P < 0.005), as well as a reduced operative time (210 +/- 136 vs. 266 +/- 143; P < 0.01), whereas there was no significant difference in the estimated blood loss (642 +/- 905 vs. 697 +/- 1187), the amount of blood products transfused, overall intra- and postoperative complication rate (8% vs. 11%), or 30-day hospital readmission rate (5% vs. 5%). No clinically significant spinal epidural hematomas were observed in either of the study groups. CONCLUSION: The current study has observed no appreciable increase in bleeding-related complication rates in patients with cardiac stents undergoing spine surgery while continuing to take aspirin compared with patients who discontinued aspirin prior to surgery. Although very large studies will be needed to determine whether aspirin administration results in a small complication rate increase, the current study provides evidence that perioperative aspirin therapy is relatively safe in patients undergoing spinal surgery. LEVEL OF EVIDENCE: 2.