Faculty Bibliography

BACKGROUND CONTEXT: CES represents a surgical indication often requiring emergent surgical decompression. The standard surgical technique for CES management is wide bilateral lumbar laminectomies and discectomies with or without arthrodesis. Prior outcomes studies for CES have focused on the controversial topics of surgical timing and restoration of continence, and have been limited by small cohorts and lack of a control. To our knowledge, no studies have provided nationwide estimates of patient characteristics and procedure-related complication rates after spinal surgery for CES relative to an unaffected population. PURPOSE: To determine patient demographics, incidence of comorbidities and procedure-related complications, and identify risk factors associated with morbidity and mortality after spinal surgery for cauda equina syndrome (CES). STUDY DESIGN/SETTING: Retrospective nationwide database analysis. PATIENT SAMPLE: Nationwide Inpatient Sample data collected between 2001 and 2010 was analyzed. Discharges with procedural codes for lumbar spinal fusion, decompression, or discectomy were included. The CES cohort included diagnoses of CES, and the unaffected cohort included lumbar spinal pathology diagnoses. OUTCOME MEASURES: Measures included patient demographic and hospital system-related data and selected procedure-related complications and comorbidities. METHODS: Descriptive statistics compared patient demographics, incidence of comorbidities and procedure-related complications, and risk factors associated with morbidity and mortality were compared. RESULTS: Discharges for 11,207 CES and 689,799 unaffected patients were identified. Differences between cohorts were found for demographic and hospital data. Average comorbidity indices for the CES cohort were found to be increased (0.23 vs 0.13, p< 0.0001), as well as the incidence of total procedure-related complications (18.63% vs 13.12%, p< 0.0001). In-hospital mortality rate was significantly increased for the CES cohort (0.30% vs 0.08%, p!

BACKGROUND CONTEXT: Lumbar discectomy and laminectomy for patients with intervertebral disc herniations (IDH) is the most common spine surgery performed in the United States with variable reported reoperation rates. Though prospective studies have reported outcomes related to this patient population, few have examined risk factors for reoperation. PURPOSE: To investigate the incidence of re-operation and associated risk factors among the surgically treated patients from the IDH arm of the Spine Patient Outcomes Research Trial (SPORT), randomized and observational cohorts. Our study hypothesis was that specific patient baseline characteristics would emerge as risk factors for re-operation in patients treated surgically for IDH. STUDY DESIGN/SETTING: A retrospective subgroup analysis of the eight-year data from the SPORT trial. PATIENT SAMPLE: 810 patients who underwent surgery for IDH. OUTCOME MEASURES: Incidence of re-operation, risk factors. METHODS: A retrospective subgroup analysis was performed on surgically treated patients enrolled in the IDH arm of the multicenter SPORT trial, randomized and observational cohorts. Patients included in the IDH arm had radicular pain for at least six weeks, clinical evidence of nerveroot irritation, and imaging showing a disc herniation at a level and side consistent with the patient's symptoms. In our subgroup analysis patients were stratified into no re-operation versus re-operation. Baseline characteristics were analyzed using a multivariate regression analysis based on data collected from patients at eight years postoperatively. A Cox regression model Stepwise Method was implemented in SAS with p=0.10 significant for entry and p=0.05 significant for retention to the model with calculation of hazard ratios (HR). RESULTS: At eight years, the re-operation rate was 14.6% with 691 having no re-operation and 119 in the re-operation group. Forty-eight (40%) patients underwent re-operation within the first year, 66 (55%) at two years, 85 (71%) at four years, 1!

BACKGROUND CONTEXT: The pelvic incidence minus lumbar lordosis (PI-LL) is an important preoperative planning tool and a useful postoperative gauge of adequate correction in lumbar flatback deformity. In patients who have had prior interbody fusion at L5-S1, the exact plane of the S1 endplate can be blurred, creating error in the assessment of PILL. The T1 Pelvic angle (TPA), a direct measure of global spinopelvic alignment, correlates with HRQOL but it may not be measureable on all intraoperative radiographs. This study introduces the lumbar pelvic angle (LPA), a novel parameter of lumbopelvic alignment, which can be more readily measured on intraoperative imaging. LPA, the lumbar component of the TPA, creates part of the fan of spinopelvic alignment. PURPOSE: To investigate the relationship of the LPA (angle of a line from the center of L1 to the femoral heads (FH) and a line from the FH to the center of the S1 endplate) and other established radiographic measures of sagittal alignment such as PI-LL and to correlate these parameters with health related quality of life (HRQOL) measures. To determine targets for correction and postoperative outcomes using the LPA measure. STUDY DESIGN/SETTING: Multicenter, prospective database. PATIENT SAMPLE: 852 patients with adult spinal deformity. OUTCOME MEASURES: Oswestry Disability Index (ODI), Scoliosis Research Society (SRS)-22, and Short-Form (SF)-36 Physical Component Score (PCS). METHODS: Multicenter, prospective, analysis of adult spinal deformity (ASD) patients. Inclusion criteria were age>18, and any of the following: scoliosis Cobb angle >20degree, SVA>5 cm, thoracic kyphosis>60degree, and PT greater than 25degree. Baseline and 2-yr follow-up with radiographic and HRQOL outcomes were evaluated. RESULTS: 852 ASD patients (407 operative) were included (mean age 53.7). Baseline LPA correlated with PI-LL (r=0.79), PT (r=0.78), TPA (r=0.82) and SVA (r=0.61) (all p<0.001).PI-LL, LPA and TPA correlated with ODI (r=0.42/0.29/0.45), SF36 PCS (-0.43/-0.28/!

BACKGROUND CONTEXT: Targets for adult spinal deformity (ASD) correction have been proposed including SVA<5cm, PT<20degree, PI-LL< 9degree. A novel radiographic parameter of sagittal alignment, the TPA, has been proposed with a postoperative target of less than 15 degrees. TPA simultaneously accounts for both truncal inclination and pelvic retroversion and does not vary based on the extent of pelvic retroversion or patient support in standing. Published alignment targets are based on baseline HRQOL and radiographic data. There are few reports correlating postoperative corrections and HRQOL to confirm such proposed targets. PURPOSE: To investigate postoperative alignment parameters and HRQOL to determine the validity of ASD targets of correction. STUDY DESIGN/SETTING: Multicenter, prospective database. PATIENT SAMPLE: 844 patient ASD patients at baseline, 407 ASD patient at 2 years. OUTCOME MEASURES: Oswestry Disability Index (ODI), Scoliosis Research Society (SRS)-22, and Short-Form (SF)-36 Physical Component Score (PCS). METHODS: Multicenter, prospective, analysis of ASD patients. Inclusion criteria were age>18, and any of the following: scoliosis Cobb angle >20degree, SVA>5 cm, thoracic kyphosis>60degree, and PT greater than 25degree. Baseline and 2-yr follow-up radiographic and HRQL outcomes were evaluated. RESULTS: A total of 844 ASD patients were included in the baseline analysis, and 407 in the 2 years analysis. Baseline and 2-year TPA correlated with PT (r=0.92/0.91), PI-LL (r=0.89/0.86) and SVA (r=0.83/0.75) (all, p<0.001). Baseline TPA, PI-LL, PT and SVA correlated with ODI (r=0.45/0.42/0.35/0.47), SF36 PCS and SRS with all p<0.001. At 2-year follow up, TPA, PI-LL, PT and SVA correlated more weakly with ODI (r=0.28/0.25/0.20/0.32), SF36 PCS and SRS all with p<0.001. Utilizing a linear regression analysis, the thresholds for pre- and post-treatment severe disability were 20.6degree and 18.2degree for TPA, 5.1 and 3.8cm for SVA and 12.6degree and 4.9degree for PI-LL. Thresholds for mild d!

BACKGROUND CONTEXT: Surgery for degenerative spondylolisthesis (DS) is common with good clinical outcomes. Several high quality studies have examined outcomes following DS surgery, but few have identified risk factors for re-operation. PURPOSE: To investigate the incidence of re-operation and associated risk factors among the surgically treated patients from the DS arm of the Spine Patient Outcomes Research Trial (SPORT), randomized and observational cohorts. Our study hypothesis was that certain patient characteristics would emerge as risk factors for re-operation. STUDY DESIGN/SETTING: A retrospective subgroup analysis of the 8- year data from the SPORT trial. PATIENT SAMPLE: 406 patients who underwent surgery for DS. OUTCOME MEASURES: Incidence of re-operation, risk factors. METHODS: A retrospective subgroup analysis was performed on surgically treated patients enrolled in the DS arm of the multicenter SPORT trial, randomized and observational cohorts. Included patients had neurogenic claudication for at least 12 weeks, clinical neurological signs, spinal stenosis on cross-sectional imaging, and DS on standing lateral radiographs. In our subgroup analysis, patients were stratified into no re-operation versus re-operation. Baseline characteristics were analyzed using multivariate regression from data collected from patients at eight years postoperatively. A Cox regression model Stepwise Method was implemented in SAS with p=0.10 significant for entry and p=0.05 significant for retention with calculation of hazard ratios (HR). RESULTS: Of the 406 surgery patients, 73% underwent instrumented fusion, 21% non-instrumented fusion, and 6% decompression alone. At 8 years, the re-operation rate was 22%, 315 having no re-operation and 91 in the re-operation group. Twenty-five (28%) were within the first year, 49 (54%) within 2 years, 64 (70%) within 4 years, and 78 (86%) within 6 years. Forty-one revisions (10%) were for progressive DS, 33 (8%) for complication or other reason, and 13 (3%) for a new co!

BACKGROUND CONTEXT: Lumbar spinal stenosis (SpS) is a common degenerative disease involving narrowing of the spinal canal that may lead to pain and disability. Spinal stenosis is the most common indication for surgery in the elderly population and was the fastest growing spine surgery in the last three decades. Prospective studies have shown that timely surgical intervention can be effective in restoring function in these patients, with variable re-operation rates. Few long-term studies have identified consistent risk factors for re-operation following surgery for SpS. PURPOSE: To investigate the incidence of re-operation and associated risk factors among the surgically treated patients from the SpS arm of the Spine Patient Outcomes Research Trial (SPORT), randomized and observational cohorts. Our study hypothesis was that specific patient baseline characteristics would emerge as risk factors for re-operation in patients treated surgically for SpS. STUDY DESIGN/SETTING: A retrospective subgroup analysis of the eight-year data from the SPORT trial. PATIENT SAMPLE: 417 patients who underwent surgery for SpS. OUTCOME MEASURES: Incidence of re-operation, risk factors. METHODS: A retrospective subgroup analysis was performed on surgically treated patients enrolled in the SpS arm of the multicenter SPORT trial randomized and observational cohorts. Patients included in the SpS arm had neurogenic claudication for at least 12 weeks and spinal stenosis, without spondylolisthesis or instability, as confirmed on imaging. In our subanalysis, patients were stratified into no re-operation versus reoperation. Baseline characteristics were analyzed using a multivariate regression analysis based on data collected from patients at eight years postoperatively. A Cox regression model Stepwise Method was implemented in SAS with p=0.10 significant for entry and p=0.05 significant for retention to the model. RESULTS: Of the 417 surgery patients, 88% underwent decompression only, 6% noninstrumented fusion, and 6% instr!

BACKGROUND CONTEXT: Despite recognition of its occurrence, reliable predictors of the development of cervical deformity (CD) following ASD surgery are elusive and the effects unclear. PURPOSE: To quantify the incidence of CD after ASD surgery, identify predictors of development and determines the impact outcomes. STUDY DESIGN/SETTING: Retrospective review of a prospective multicenter ASD database. PATIENT SAMPLE: 215 patients>18 years of age with ASD. OUTCOME MEASURES: Risk factors for development of CD and HRQOL. METHODS: This was a retrospective review of a prospective multicenter database evaluating surgical ASD patients with complete 2-year follow-up. CD was defined by: T1S-CL>20degree, C2C7 SVA>40mm, or C2C7 kyphosis>10degree. Univariate testing was performed using t-tests, or tests of proportion. The impact of CD at 2 years on Health Related Quality of Life (HRQOL) and satisfaction was measured using repeated measures mixed models or logistic regression as appropriate. RESULTS: 215 patients were included. 63% were found to have CD at 2 years postop. CD patients had a higher incidence of preop CD (p=0.0001) and diabetes (p=0.05). They also had lower baseline C2-T3 lordosis (5.49 vs 11.97, p=0.003), lower C2 tilt (71.5 vs 79.28, p=0.0001) and higher C2 slope (18.49 vs 10.71, p=0.0001) and T1 (26.08 vs 22.2, p=0.036) slopes, and C2-S1 SVA (84.32 vs 57.57, p=0.002). Patients with and without CD at 2 years experienced significant improvements in their HRQL scores: SF- 36 (p=0.0001), ODI (p=0.0001) and SRS (p=0.0001). Rates of improvement and overall improvement were similar. CD was not a predictor of 2- year patient satisfaction (p=0.367). CONCLUSIONS: Predictors of CD at 2 years include the presence of the following at baseline: CD, diabetes, higher C2 and T1 slopes, higher C2-S1 SVA, and lower C2-T3 lordosis. Significant improvements in 2-year HRQOL scores occurred in the presence or absence of CD, and patient satisfaction was unaffected. While this study identifies several predictors of CD,!

BACKGROUND CONTEXT: A high prevalence of cervical deformity (CD) has been identified among adult spinal deformity (ASD) patients undergoing surgical treatment. The clinical impact of this is uncertain. PURPOSE: This study aims to quantify the difference in patient-reported outcomes among ASD patients based on presence of CD prior to treatment. STUDY DESIGN/SETTING: Retrospective review of a multicenter prospective database of surgical ASD patients with 2-year follow-up. PATIENT SAMPLE: 235 patients>18years of age with ASD, of which 65 with pre-op C2C7 SVA>4cm, and 57 with cervical kyphosis (CK). OUTCOME MEASURES: Health Related Quality of Life (HRQL) scores: SF-36, Oswestry Disability Index (ODI), Scoliosis Research Society (SRS), and patients obtaining Minimally Clinically Important Difference (MCID) at 2 years. METHODS: Retrospective review of a multicenter prospective database of surgical ASD patients with 2-year follow-up. CD was defined as: C2C7 SVA>4cm, CK C2C7angle>0. Univariate testing was performed using t-tests, or tests of proportion. Multivariate models determined impact of pre-op CD on HRQL. RESULTS: 235 patients met criteria, of which 65 with pre-op C2C7 SVA>4cm, 57 with CK. Patients with and without CD saw improvements in 2-year HRQL scores (p<0.001). Overall, patients with preop CD had inferior postop HRQL and were less likely to achieve MCID for HRQL at 2 years. Those with preop SVA>4cm had worse ODI, PCS, SRS activity, appearance, pain and total, and were less likely to meet MCID for ODI, PCS, SRS activity and pain scores (odds ratio 0.39 for ODI CI 0.19:0.81 p<0.05), (0.34 for PCS CI 0.16:0.72 p<0.05), (0.29 CI 0.14:0.62 p< 0.05 SRS activity) (0.41 CI 0.20:0.86 p<0.05 SRS pain). Similarly, patients with CK had inferior 2-year HRQL scores. Patients without any CD were 4x more likely to reach 2-year SRS activity MCID (OR 0.40 CI 0.19:0.86 p<0.05). CONCLUSIONS: Despite experiencing significant improvements in HRQL scores, preop CD in ASD patients is a strong predictor of inferio!

BACKGROUND CONTEXT: Patients undergoing adult spinal deformity (ASD) correction are at risk for an unplanned return to surgery due to complications following index surgery vs primary outcomes. Revision surgeries are often more technically challenging, and therefore, it is important to identify predictors to be included in preoperative discussion and to notify known risk factors to patients. However, there is no literature proposing predictors of revision surgery for ASD patients. PURPOSE: To investigate the incidence, predictors and impact on healthrelated quality of life (HRQL) outcomes and patient satisfaction of unplanned return to surgery after ASD correction. STUDY DESIGN/SETTING: Multicenter, retrospective review of consecutive surgical ASD patients. PATIENT SAMPLE: 243 adults treated surgically for spinal deformity. OUTCOME MEASURES: Pre- and postoperative HRQL scores and radiographic parameters, rate and predictors of revision surgery. METHODS: Two-year, multicenter, prospective analysis of surgical adult spinal deformity (ASD) patients (age >18 years and scoliosis >20degree, SVA >5cm, pelvic tilt >25degree, or thoracic kyphosis>60degree). Inclusion criteria for this study were complete demographic, radiographic, HRQL and operative data at 2-year follow-up. Patients were divided into Index Surgery only or Revisions. Primary infections were excluded. Potential predictors and confounders for revision surgery were identified using univariate analysis. Multivariate logistic regression modeling determined predictors of revision and impact on satisfaction. Multivariate repeated measured mixed models measured revision impact on HRQL. RESULTS: 243 patients met inclusion criteria. 42 (17.3%) patients underwent revisions (14.3% at 6 weeks, 38% between 6 weeks and 1 year, and 47.7% between 1-2 years). Non-rod implant complications were the most common indication for revision (9) followed by PJK (8) and rod failure (8). Positive predictors of revision surgery included: weight (OR 1.33 per 10kg incr!

Study Design Literature review. Objective Atlantoaxial dislocation (AAD) is a rare and potentially fatal disturbance to the normal occipital-cervical anatomy that affects some populations disproportionately, which may cause permanent neurologic deficits or sagittal deformity if not treated in a timely and appropriate manner. Currently, there is a lack of consensus among surgeons on the best approach to diagnose, characterize, and treat this condition. The objective of this review is to provide a comprehensive review of the literature to identify timely and effective diagnostic techniques and treatment modalities of AAD. Methods This review examined all articles published concerning "atlantoaxial dislocation" or "atlantoaxial subluxation" on the PubMed database. We included 112 articles published between 1966 and 2014. Results Results of these studies are summarized primarily as defining AAD, the normal anatomy, etiology of dislocation, clinical presentation, diagnostic techniques, classification, and recommendations for timely treatment modalities. Conclusions The Wang Classification System provides a practical means to diagnose and treat AAD. However, future research is required to identify the most salient intervention component or combination of components that lead to the best outcomes.