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: Multiple options exist for the surgical correction of adult spinal deformity. The choice of these surgical procedures is often based on surgeon preference, patient profile and curve pattern. There remains little guidance for surgeons to determine which options will provide them with the appropriate correction. PURPOSE: Evaluate the curve correction, change in health related quality of life measures (HRQOL), and complications in deformity matched anterior/ posterior (AP) or posterior only (PO) surgical correction. STUDY DESIGN/SETTING: Multicenter, prospective, consecutive case/ control series. PATIENT SAMPLE: 54 ASD patients. OUTCOME MEASURES: Oswestry Disability Index (ODI), SF36 and SRS-22. METHODS: Prospective, multicenter database. Inclusion criteria age>18, adult spinal deformity, no prior fusion surgery,>4 levels fused, fusion to sacrum, complete radiographic and HRQOL outcomes, min 2-yr followup. Complications were defined as minor or major per previously published criteria. Health related quality of life measures Oswestry Disability Index (ODI), SF36, and SRS-22 were determined for each patient for baseline, one and two years. Anterior/posterior (AP) surgery was propensitymatched to posterior only (PO) based on baseline SVA, PI-LL mismatch and PT by using linear regression. RESULTS: 54 patients met inclusion criteria and were matched; AP (27) and PO (27). Baseline demographics were similar for age, BMI, comorbidity, SVA (76 vs 62mm), PT (24 vs 23), LL (31 vs 40) and PI-LL (19 vs 17); p>0.05. However baseline HRQOL measures were all better for the AP group. At 1 and 2 years HRQL improved statistically for each group, and there was no longer any statistical difference between groups. Radiographic improvement, 1-yr and 2-yr were similar except for 2-yr PI-LL which was lower for AP (-0.4 vs 7.1; p=.044). Total OR time was greater for AP (528 vs 416 min; p=.003), but had similar EBL and hospital stay. More Smith-Peterson Osteotomies and longer fusion in AP group (4.2 vs 1!

BACKGROUND CONTEXT: High-risk spinal surgeries such as intramedullary spinal cord tumor resection and complex deformity correction may result in spinal cord injury (SCI). Currently, intravenous (IV) high-dose methylprednisolone (MP) is the only pharmacological treatment for SCI. However, its use has been controversial, in part due to the high rate of systemic adverse effects. We hypothesized that prophylactic intrathecal (IT) MP would result in increased local bioavailabilty at the injury site resulting in better motor recovery while minimizing adverse effects associated with systemic MP administration. PURPOSE: We investigated the effect of prophylactic administration of IT MP on motor recovery in a rat SCI model in comparison to controls (IV MP and IT saline). STUDY DESIGN/SETTING: Rat model SCI. PATIENT SAMPLE: Sprague-Dawley (SD) rats. OUTCOME MEASURES: Basso, Beattie, Bresnahan (BBB) motor scores; histolopathological evaluation METHODS: Twenty-six female SD rats were randomly assigned to one of the three below groups and received drug or control 30 minutes before SCI. Group I (n=9): IT 10mul steroid solution containing 625mug MP; Group II (n=9): IV MP 30mg/kg; Group III (n=8): IT saline 10mul. After laminectomy, SCI was inflicted at the T9-T10 level using a MASCIS II weightdrop impactor. A weight of 10g was dropped from a height of 25cm. The animals were evaluated by the BBB functional scale on days 1, 7, 14, 21, 28, 35, 42, 49 and 52 following injury. Luxol fast blue-cresyl violet stain histopathological evaluation was performed. RESULTS: The results showed that there was an improvement in BBB score in Group 1 (9.9+1.6) compared to group two (9.2+1.8) and three (9.0+0.9) at eight weeks post-injury. However the improvement was not statistically significant between the three groups (p=0.4). Though at week 5 and 7, two-way ANOVA did not show an overall statistical significance between groups, Bonneferoni's post-hoc test revealed a significant difference between IT MP and IT saline groups (p=!

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: Sagittal spinal deformity (SSD) patients recruit compensatory mechanisms to maintain erect posture and align the head over the pelvis. Spinopelvic mechanisms of compensation involving retroversion of the pelvis have been described. Additionally, knee flexion and pelvic shift have been proposed as limbs mechanisms, but how and when these mechanisms contribute is poorly understood. PURPOSE: To determine the percentage of spinal, pelvic and lower extremity compensatory response based on global spinal deformity. STUDY DESIGN/SETTING: Single-center, retrospective review of fullbody head-to-foot stereoradiographs. PATIENT SAMPLE: 435 patients with spinal sagittal deformity from November 2012 to November 2013. OUTCOME MEASURES: Oswestry Disability Index (ODI), Short Form 36 Health Questionnaire (SF-36; Physical Component Score [PCS] and Mental Component Score [MCS]), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), knee angle (KA) and pelvic shift angle (PSh). METHODS: This is a retrospective review of adult SSD patients who underwent stereoradiography (EOS imaging system) between 2012- 2013. Radiographic measurements were performed with Surgimap (Nemaris Inc.). Patients with a PI greater than LL were categorized based on their mismatch and compared in terms of compensatory mechanisms normalized to each patient's PI-LL: PT, Knee flexion and pelvic shift angle (the angle between the lines formed from the posterior-superior corner of S1 to the anterior distal cortex of the tibia and the vertical). RESULTS: 161 Patients were included with a mean age of 62.93+12.8yrs, BMI 27, and 80.6% females. At baseline, patients had a mean SVA 62.3+61.5mm, PT 29.2+8.4 degree , and PI-LL 21.0+14.9 degree . Patients were categorized based on their PI-LL in 4 groups of PI-LL by mismatch 10 degree (Group 1: PI-LL 0-10 degree , Group 2: 10-20 degree , Group 3: 20-30 degree , and Group 4: >40 degree ). There were significant differences between all groups in PT!

BACKGROUND CONTEXT: Understanding various components of global alignment is essential in the effective treatment of sagittal spinal deformity patients (SSD). Despite the development of EOS and full body radiographic technology, sagittal plane assessment commonly remains limited to the spinopelvic area. Evaluation of lower limb compensatory mechanisms has been poorly understood to date. PURPOSE: The objective of this study was to investigate the role of the lower limbs in maintaining erect posture and horizontal gaze in the setting of SSD. STUDY DESIGN/SETTING: Single-center, retrospective review of fulllength head to foot stereoradiographs. PATIENT SAMPLE: 435 patients with spinal sagittal deformity from November 2012 to November 2013. OUTCOME MEASURES: Oswestry Disability Index (ODI), Short Form 36 Health Questionnaire (SF-36; Physical Component Score [PCS] and Mental Component Score [MCS]), Chin Brow Vertical Angle (CBVA), pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt (PT), sagittal vertical axis (SVA), T1 pelvic angle (TPA), knee angle flexion (KA), ankle angle flexion (AA) and sacral femoral angle (SFA). METHODS: In this retrospective study, patients with spinal pathology underwent low dose stereoradiography X-rays (EOS imaging systemdegree). The inclusion criteria were SSD with a PI-LL mismatch>15degree and functional horizontal gaze (CBVA between -4 and 17degree). Patients were divided in 2 groups based on their PI-LL mismatch after surgery: over corrected (OC, PI-LL<-15degree) and under corrected (UC, PI-LL>15degree). Groups were compared in terms of sagittal alignment and lower limb compensatory mechanisms (Student T test). Correlations and regression were performed to predict lower extremity compensation. RESULTS: Eighty-six patients (mean age 55.5 years, BMI 26.4kg/m2, 75% female) were included: 29 UC and 57 OC. By definition, UC patients had a significantly more sagittal spinopelvic deformity (PI-LL, SVA, and TPA) as well as a larger PI, SFA (hip hyperextension), KA and AA!

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: Radiographic deterioration and persistent deformity is not an uncommon outcome after major sagittal spinal deformity surgery. The high rate of sagittal misalignment after surgery for patients with sagittal spinal deformity (SSD) has highlighted the need to develop better preoperative surgical planning, which can include Smith Peterson Osteomy (SPO), pedicle substraction osteotomy (PSO), transforaminal lumbar interbody fusion (TLIF), and selection of upper instrumented vertebrae (UIV). PURPOSE: This study evaluates preoperative planning and changes in procedure execution as a root cause analysis of radiographic outcomes. STUDY DESIGN/SETTING: Prospective, single-center study of consecutive SSD patients undergoing major sagittal realignment surgery. PATIENT SAMPLE: 40 adults treated surgically for spinopelvic misalignment (SVA>50mm, PT>20degree, or PI-LL>20degree). OUTCOME MEASURES: Thoracic Kyphosis (TK), Lumbar Lordosis (LL), Pelvic Incidence - Lumbar Lordosis (PI-LL). METHODS: Consecutive SSD patients who required osteotomies were included. Preoperative plans, and radiographs at baseline and 3 months were collected. Major changes in the surgeries were classified in 2 groups: less aggressive procedure (LAP, >1 SPO (Smith Peterson osteotomy) not done, PSO (pedicle subtraction osteotomy) replaced by SPO) and more aggressive procedure (MAP, add>1 SPO). Patients without major change were grouped as no major change (NMC). Preoperative, anticipated (by Surgimap planning software), and postoperative alignments were compared between LAP and NMC cohorts. RESULTS: There were 40 patients (mean 62 +12 years) with 25 NMC patients and 15 with major change (13 LAP and 2 MAP). Comparison of planned and postoperative alignments demonstrated that postoperative TK was greater than expected and LL was under corrected (NMC: 48% and LAP: 62%). The LAP cohort had greater mismatch between pelvic incidence and lumbar lordosis (PI-LL) at baseline (49+12 vs 29+17, p=0.001), was planned for greater cha!