Faculty Bibliography

BACKGROUND CONTEXT: Intraoperative neuromonitoring (IOM) of spinal cord and nerve root injury through somatosensory evoked potentials (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 or multimodal IOM (MIOM) for specific spinal surgeries. PURPOSE: This pilot study documents practice patterns of IOM for select spinal procedures. STUDY DESIGN/SETTING: Questionnaire survey. PATIENT SAMPLE: 22 fellowship-trained spine surgeons, both surgeons and neurosurgeons, were queried on use of IOM modality combination in various spine procedures. Surgical experience varied from three to 29 years, with an average of 14.4 years. OUTCOME MEASURES: Percentage of surgeons using IOM modality or MIOM combination was calculated for each procedure. METHODS: Spine surgeons at two hospitals were surveyed on practice patterns of use of intraoperative monitoring for three deformity procedures and 21 non-deformity procedures. RESULTS: Of the 18 (81%) responses received: 15 from orthopaedic surgeons and 3 from neurosurgeons. Deformity Surgery: For both cervical and thoracic deformity surgeries, all surgeons used at least SSEP+TcMEP. For cervical surgeries, 47% of surgeons additionally used sEMG while for thoracic 71% of surgeons additionally used sEMG+tEMG. Most surgeons (44%) used all four modalities for lumbar deformity surgery. Non-Deformity surgery: For patients having radiculopathy undergoing ACDF, SSEP alone was utilized by 29%. However, in patients undergoing ACDF with symptoms of myelopathy, most surgeons (31%) used SSEP+TcMEP with only 13% using SSEP only. Fourty-six percent of surgeons utilized SSEP+TcMEP+sEMG for cervical arthroplasty procedures. SSEP+ TcMEP+sEMG was most commonly used for posterior cervical laminoforaminotomy, posterior cervical laminectomy and posterior cervical laminect!

BACKGROUND: Postoperative venous thromboembolic events (VTEs), which include pulmonary emboli and deep venous thromboses, are potentially preventable causes of death. The aim of this study was to investigate the patient and procedure-related risk factors for the occurrence of VTEs in patients undergoing spinal fusion.METHODS: We used ICD-9-CM (International Classification of Diseases, 9th Revision, Clinical Modification) procedure codes to identify patients in the Nationwide Inpatient Sample (NIS) database for 2001 through 2010 who were treated with spinal fusion. The occurrence of a symptomatic VTE was identified with use of ICD-9-CM diagnosis codes. Patient demographics, hospital characteristics, and comorbidities in the VTE and non-VTE groups were analyzed, and independent risk factors for VTE were identified.RESULTS: A total of 710,154 spinal fusion procedures were identified in the NIS from 2001 to 2010, and 3525 (0.50%) of these patients were recorded as having 3777 VTEs, consisting of 2038 deep venous thromboses (0.29%) and 1739 pulmonary emboli (0.24%). Patients with a VTE were older on average (57.63 years compared with 52.88 years for patients without a VTE) and more often male (VTE incidence, 0.58% compared with 0.42% for female) and black (VTE incidence, 0.78% compared with 0.47% for white). Postoperative VTE occurrence was associated with a longer hospital stay (18.0 compared with 3.94 days) and higher total hospital charges ($207,253 compared with $66,823). A number of comorbidities and procedure-related factors were identified as independent risk factors for VTE.CONCLUSIONS: We present a VTE Risk Index, based on the independent risk factors identified in this study, for the VTE following spinal fusion. In conjunction with current guidelines, this risk index can be used to guide clinical decision-making regarding VTE prophylaxis in patients undergoing spinal fusion.LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND CONTEXT: The surgical management of degenerative spondylolisthesis (DS) has evolved over the past decade. The most cost effective and clinically effective procedure continues to be debated. With an aging US population and growing restraints on a financially burdened health care system, clear understanding of national trends in the surgical management of DS needs to be better defined. PURPOSE: To investigate national trends in relation to the surgical management of DS by analyzing the NIS database. STUDY DESIGN/SETTING: Analysis of the NIS database. PATIENT SAMPLE: All patients in NIS database between 2001 and 2010 treated surgically for DS. OUTCOME MEASURES: Type of surgical procedure performed, trends in surgical procedures performed, perioperative complications, length of hospital stay (LOS), total hospital charges, and Deyo index. METHODS: The NIS database was queried for patients with DS undergoing lumbar fusions between 2001 and 2010 using corresponding ICD-9 diagnosis and procedure codes. Multivariate analyses were carried out comparing instrumented posterolateral fusion alone (group 1), posterolateral fusion with anterior lumbar interbody fusion (classic 360degree procedure) (group 2), posterolateral fusion with posterior interbody fusion (single incision 360degree procedure) (group 3), anterior instrumented interbody fusion (group 4), posterior interbody fusion with posterior instrumentation (group 5). RESULTS: The total number of surgically treated DS patients increased from 29,403 in 2001 to 58,431 in 2010 with a total of 417,002 cases between 2001 and 2010. The percentage of total cases of group 1 increased from 13.7% to 18.8%, group 2 from .09% to 2.01%, group 3 from 1.92% to 2.7 %, group 4 remained constant at a rate of 4.44%, and group 5 decreased from 79.8% to 72.1%. Notable complications were acute blood loss related anemia in 14% of group 1, 20.1 % of group 2, 17% in group 3, 9% in group 4, 15% in group 5, and device related complications occurred in 1% of group 1, 4!

BACKGROUND CONTEXT: Postoperative venous thromboembolic events (VTEs), which include pulmonary embolisms (PEs) and deep venous thrombosis (DVTs), are important potentially preventable causes of death. Evidence is lacking regarding which patients are at highest risk of developing postoperative VTEs. PURPOSE: This study aims to investigate the patient and procedure determined risk factors for VTE in patients undergoing spinal surgery. STUDY DESIGN/SETTING: Retrospective analysis of a national database. PATIENT SAMPLE: Patients undergoing spinal fusion. OUTCOME MEASURES: Occurrence of postoperative complications, length of stay, total charges, mortality. METHODS: Using the National Inpatient Sample (NIS) database from 2001 through 2010 patients undergoing spinal fusions and occurrence of symptomatic VTE were identified via corresponding ICD-9 procedure and diagnosis codes. Univariate analysis of patient and hospital demographics, comorbidities, and postoperative complications was used to compare the VTE and non-VTE groups. Independent risk factors for VTE were identified via multivariate logistic regression. RESULTS: A total of 755,082 spinal fusion procedures were identified. The NIS dataset contained 2,234 DVTs (0.30%) and 1,870 PEs (0.25%), for a total of 4,104 (0.54%) VTEs in 3,831 patients. Patients who had a VTE were on average older (58.98 years for VTE, 53.53 years for no VTE, p<.01), more often women then men (VTE incidence in women 0.60% , men 0.4%, p<.01), black (white patients .48%, black .78%, p<.01), insured with Medicare or Medicaid (.77% Medicare, .71% Medicaid, .38% private insurance, p<.01), and had a higher comorbidity burden (Charlson index 1.27 versus 0.37, p<.01). Postoperative VTE was associated with longer hospital stays (18.7 days versus 4.09). VTE increased the total hospital costs (>=207,182 versus >=68,029, p<.01). The results of logistic regression models were used to construct a VTE Risk Index comprised of 29 patient and procedure related risk factors for VTE, a score!

BACKGROUND CONTEXT: Comparative effectiveness as well as cost analysis research are gaining popularity within the field of spinal surgery. In general, prior studies have shown that surgical interventions with a cost per Quality Adjusted Life Year (QALY) less than >=100,000 are cost-effective for our society. Cost-effectiveness studies for surgical management of spondylolisthesis are lacking. PURPOSE: The purpose of this study is to determine the cost/QALYof lumbar spondylolisthesis treated with multiple surgical techniques, and to identify preoperative factors that lead to cost-effectiveness at 2-year follow-up. STUDY DESIGN/SETTING: Retrospective analysis of prospectively collected data. PATIENT SAMPLE: Patients who underwent surgery for degenerative or isthmic spondylolisthesis at a single institution from 2009-2011. OUTCOME MEASURES: Oswestry Disability Index, change in QALY, cost/QALY. METHODS: We performed a retrospective analysis of prospectively collected data on 44 patients who underwent surgery for degenerative or isthmic spondylolisthesis. There were 30 cases of degenerative and 14 cases of isthmic spondylolisthesis. There were 27 women and 17 men, with an average age at surgery of 59.7 years old (SD 14.8). The change in QALY was determined from the 2-year outcome scores using EuroQol-5D. Outcomes were also assessed using the Oswestry Disability Index (ODI). Hospital DRG codes were used to assess Medicare based hospital costs. Surgical, neuromonitoring, and anesthesia CPT codes were used to determine additional direct care costs of surgery. Analysis was performed to determine which factors were associated with a cost/QALY less than >=100,000, thereby making the procedure cost-effective. Statistical analysis was performed using ANOVA, Chi Square, and linear regression analysis. RESULTS: The average length of follow up was 2 years (SD 0.82). The average postoperative improvement in ODI was 24.5 (SD 23.9) and change in QALYwas 0.4449 (SD 0.2984). The average cost/QALYat 2-year follow-up !

BACKGROUND CONTEXT: Recent research describes the use of a nerve root sedimentation sign to diagnose lumbar spinal stenosis (LSS). The lack of sedimentation of the nerve roots (positive sedimentation sign) to the dorsal part of the dural sac is the characteristic feature of this new radiological parameter. PURPOSE: To demonstrate how the nerve root sedimentation sign compares with other more traditional radiological parameters in patients who have been operated for LSS. STUDY DESIGN/SETTING: A retrospective chart and image review. PATIENT SAMPLE: Preoperative magnetic resonance images (MRIs) were reviewed from 71 consecutive operative patients who presented with LSS and received spinal decompression surgery from 2006 to 2010. OUTCOME MEASURES: Preoperative T2-weighted MRIs were reviewed for each patient. METHODS: One hundred thirty-four vertebral levels from L1 to L5 were measured for: sedimentation sign, cross-sectional area (CSA) and anterior/posterior (A/P) diameter of the dural sac, thickness of the ligamentum flavum, and Fujiwara grade of facet hypertrophy. Radiological measurements were made using Surgimap 1.1.2.169 software (Nemaris, Inc., New York, NY, USA). Statistical analyses were performed using the SPSS 17.0 statistical software (SPSS Inc., Chicago, IL, USA). Significance was demonstrated using unpaired t tests and chi-squared tests. Study funding was departmental. There were no study-specific conflicts of interest-associated biases. RESULTS: A positive sedimentation sign was determined in 120 operated levels (89.5%), whereas 14 levels (10.5%) had no sign (negative sedimentation sign). The mean CSA and A/P diameter were 140.62 mm(2) (standard deviation [SD]=53) and 11.76 mm (SD=3), respectively, for the no-sign group; the mean CSA and A/P diameter were 81.87 mm(2) (SD=35) and 8.76 mm (SD=2.2), respectively, for the sedimentation sign group (p<.001). We found that 60% of levels with Fujiwara Grade A facet hypertrophy did not have a sedimentation sign, whereas 86.3% of levels with Grade B, 93.2% of levels with Grade C, and 100.0% of levels with Grade D did have a sedimentation sign (p<.001). CONCLUSIONS: The sedimentation sign is a new measurement tool that can enable physicians to objectively assess and quantify spinal stenosis. The sign is most often present in patients who have clinically significant lumbar stenosis and require surgery.

BACKGROUND CONTEXT: Adult spinal deformity (ASD) is commonly associated with disability and represents a challenging condition for physicians. Although surgical management has been reported as superior to conservative care, the choice of patient-specific optimal strategy has been poorly defined. A key question remains selection of fusion levels as this implies careful balance of risks and benefits. PURPOSE: The aim of this review is to propose an update on current knowledge related to optimal fusion levels in the surgical treatment of ASD. STUDY DESIGN: Literature review. METHODS: Based on a comprehensive literature search, recent studies focusing on the management of ASD were reviewed to establish current concepts on fusion levels in the management of symptomatic ASD. RESULTS: Despite numerous published studies, the management of ASD and specifically optimal fusion levels is incompletely defined. Described approaches carry benefits and risks. However, the need for detailed analysis and preoperative planning is confirmed as a prerequisite to obtaining realignment objectives and good outcomes. CONCLUSIONS: The treatment of ASD is emerging as an important health-care issue of the 21st century because of prevalence and cost. Despite technical advances related to ASD surgery, complication rates remain elevated, particularly in the older population. Recent research, mostly driven by outcome measures, has improved our understanding of optimal treatment approaches to ASD. The development of a widely accepted classification system will help to share knowledge and improve our ability to treat these complex patients.

STUDY DESIGN.: A retrospective review. OBJECTIVE.: To compare the radiographical and clinical profiles between 2 surgical approaches for the correction of sagittal plane spinal deformity. SUMMARY OF BACKGROUND DATA.: Sagittal plane decompensation is the radiographical parameter that carries the greatest impact on adverse outcomes. Surgical correction methods are heterogeneous, and opposing views pervade the spine community in consideration of the most effective approach and techniques to achieve correction. METHODS.: A total of 33 cases with sagittal spinal deformity were assessed according to their surgical approach, posterior only versus combined anteroposterior group. Comparison was based on the demographic data, and radiographical parameters included pelvic tilt, pelvic incidence, sacral slope, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis. RESULTS.: Twenty two subjects were identified for the posterior-only and 11 subjects for the anteroposterior group. Average age was 58.7 years in the posterior-only and 55.7 years for the combined approach. Preoperative mean sagittal vertical axis was 186.6 and 147.7 mm, for the posterior-only and combined approaches, respectively (P = 0.1). Preoperative mean pelvic tilt was 34.2 degrees for the posterior-only and 36.9 degrees for the combined approach group (P = 0.5). A greater operative time for the combined approach was significant, 535 versus 333 minutes for the posterior-only approach (P < 0.001). In the posterior-only group, 8 of 22 patients and 7 of 11 patients in the combined-approach cohort experienced a postoperative complication (P = 0.16). The average follow-up was 41.8 and 47.7 months for the posterior-only and combined approaches, respectively (P = 0.4). CONCLUSION.: A posterior-only or combined surgical approach had comparable radiographical outcomes. Higher morbidity was significant in regard to operative time in the combined-approach group. Deciding on the approach best suited for achieving correction in the sagittal plane likely resides on the surgeon's experience and expertise.

Two case reports illustrate a delayed clinical presentation of incidental durotomy following surgical posterior decompression of the lumbar spine. The clinical presentation as well as radiographic imaging studies used in diagnosing this relatively rare surgical complication are discussed. Both nonoperative as well as surgical treatment alternatives are outlined.