P79. Segmental Direct Vertebral Rotational Technique for Scoliosis Correction

Proceedings of the NASS 22nd Annual Meeting / The Spine Journal 7 (2007) 1S–163S P78. Anterior Cervical Fusion Assessment: Surgical Exploration versus Radiologic Evaluation Jacob Buchowski, MD, MS1, Gabriel Liu, MD1, Torphong Bunmaprasert, MD1, K. Daniel Riew, MD1; 1Washington University in St. Louis, St. Louis, MO, USA BACKGROUND CONTEXT: Although anterior cervical fusions have been performed for more than fifty years, the diagnosis of pseudarthrosis following the procedure remains controversial. While detection of pseudarthrosis by MRI, CT and plain radiographs has been described, to our knowledge no studies have compared the findings on these studies against the gold standard of intra-operative exploration of fusion, to determine which is most accurate. PURPOSE: The goal of this prospective study was to assess the reliability of plain radiographs, CT, and MRI compared to intra-operative exploration. STUDY DESIGN/SETTING: Prospective clinical study. PATIENT SAMPLE: Patients undergoing exploration of prior anterioronly cervical fusion. OUTCOME MEASURES: Independent review by three spine surgeons of plain radiographs, CTs, and MRIs compared to intra-operative findings in patients undergoing exploration of prior anterior-only cervical fusion. METHODS: All explorations had to be performed O6 months after the index anterior-only cervical fusion and all radiologic studies had to be obtained from one institution within a month of the exploration. The indications for re-operations were adjacent level disease and/or pseudarthrosis repair. All patients meeting the criteria were thoroughly explored intraoperatively by the senior surgeon using a high-power microscope, uncinateto-uncinate exploration, and if necessary, removal of part of the corticalized graft. The A/P, lateral, flexion/extension radiographs (bridging bone; !1 mm motion), CT (axialþcoronal & sagittal reconstructions) and sagittal MRIs were then blindly and independently reviewed by three spine surgeons, uninvolved in the care of the patients, using established criteria. Each study was assessed independently from the other studies using the following grading scheme: 15successful fusion, 25pseudarthrosis, 35 fusion status uncertain, and 45inadequate study (e.g., inadequate motion on flexion/extension or too much artifact on CT or MRI). RESULTS: Of the 14 patients included, 8 had pseudarthroses. Assessment of the agreement between intra-operative and radiologic findings revealed a mean kappa value of 0.67 (range, 0.51–0.75) for plain radiographs, 0.48 (range, 0.32–0.71) for MRIs, and 0.81 (range, 0.71–0.87) for CTs. When all studies were taken into consideration, the mean kappa value increased to 0.85 (range, 0.71–1.00). Assessment of paired interobserver reliability revealed a mean kappa value of 0.46 (range, 0.31–0.55) for plain radiographs, 0.32 (range, 0.21–0.40) for MRIs, and 0.82 (range, 0.73–0.87) for CTs. When all radiologic studies were taken into consideration, paired interobserver reliability had a mean kappa value of 0.70 (range, 0.55–0.85). CONCLUSIONS: In this prospective study, we compared the results of a single surgeon’s thorough intra-operative explorations of anterior-only fusions with the blinded, independent interpretations of radiographic studies by 3 spine surgeons. Our results indicate that CT scans most closely agree with intra-operative findings than plain radiographs or MRI scans alone. We therefore recommend that reconstructed CTs be utilized in any study that relies on fusion diagnoses. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2007.07.285

P79. Segmental Direct Vertebral Rotational Technique for Scoliosis Correction Lauren Friend, MD1, John Czerwein, Jr., MD1, Alok Sharan, MD1, Terry Amaral, MD1, Vishal Sarwahi, MD1; 1Montefiore Medical Center, Bronx, NY, USA BACKGROUND CONTEXT: Different techniques of direct rotation include en bloc rotation or segmental technique. Our institution uses

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segmental rotation techniques, which involves a concave rod derotation maneuver followed by segmental direct vertebral rotation and compression/distraction. The segmental derotation is at every level starting from the apex. Suk et al in contrast, only has the juxta-apical vertebrae undergo single direct vertebral rotation maneuver. This study shows that segmental derotation technique can achieve improvement in rotation comparable to other techniques. PURPOSE: The purpose of this study is to evaluate rotational correction using preop and postop CT Scans. STUDY DESIGN/SETTING: The study was a retrospective, single surgeon, radiographic review of pre-operative and post-operative CT scans to assess vertebral rotation in 67 spine deformity patients. PATIENT SAMPLE: The patient sample included 67 patients over 3 years with an average age of 14.5 years that underwent posterior spinal fusion for scoliotic deformity. OUTCOME MEASURES: Average pre-operative and post-operative cob angles were measured using standard radiographs. Average pre-operative and post-operative apical vertebra rotation was measured using CT scans. METHODS: 67 patients over 3 years with an average age of 14.5 years were reviewed, of which 13 of these underwent pre and post-operative CT scans. Apical vertebrae rotation was measured using Ho et al. criteria, with neutral T1 or L5 as a control. 24 curves in thirteen patients were measured. RESULTS: Average pre-operative Cobb angle: 51.5 degrees; post-operative: 17.9 degrees (correction 62.7%). Average pre-operative apical vertebra rotation: 14.3 degrees. Average post op rotation: 9.95 degrees (28.7% improvement). Suk reviewed 17 patients with direct vertebral rotation technique showing an improvement from 16.7 degrees pre op rotation to 9.6 degrees post op (42.5% improvement). Our final post op rotation was comparable, though the percent improvement was less than that reported by Suk et al. CONCLUSIONS: This study shows that the segmental derotation technique can achieve comparable improvement in rotation compared to other techniques. The rod derotation maneuver may be limited temporarily by worsening the vertebral rotation. The maneuver is done following the placement of the rod which limits the degree of rotation that can be achieved. It may be more effective to achieve rotational correction prior to rod placement. It is also important to consider the resistance due to disc, ligament and facet joints. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs. doi: 10.1016/j.spinee.2007.07.286

P80. Patient Based Outcomes for the Operative Treatment of Degenerative Lumbar Spinal Stenosis Samo Fokter, MD, PhD1, Scott Yerby, PhD2; 1Orthopaedic Surgery and Sports Trauma, Celje, EU, Slovenia; 2VA Rehab R&D Center, Musculoskeletal Biomechanics, St. Francis Medical Technologies, Palo Alto, CA, USA BACKGROUND CONTEXT: Surgical decompression is the recommended treatment for patients with moderate to severe degenerative lumbar spinal stenosis (DLSS). Previous studies have reported that factors such as the number of operated levels and patient health status are predictors of surgical outcomes. PURPOSE: The goal of this study was to describe the outcomes predictors of decompressive surgery for DLSS. STUDY DESIGN/SETTING: A retrospective surgical case series was conducted using a condition-specific, patient-based outcomes assessment. PATIENT SAMPLE: This study analyzed the success rates of 58 DLSS patients treated with decompressive surgery. OUTCOME MEASURES: Outcomes were measured with the Zurich Claudication Questionnaire (ZCQ) completed pre-operatively and at least 12 months post-operatively (range 12–54 months).