Proceedings of the NASS 18 th Annual Meeting / The Spine Journal 3 (2003) 67S–171S 163S P10. Multisurgeon assessment of thoracolumbar fractures: reproducibility and repeatability of the AO and Denis classification systems Kirkham Wood, MD 1 , Alexander Vacarro, MD 2 , David Polly, MD 3 , Amir Mehbod, MD 4 , G. Khanna, MD 1 , Jill Wroblewski, MS 4 ; 1 University of Minnesota, Minneapolis, MN, USA; 2 Rothman Institute, Philadelphia, PA, USA; 3 Walter Reed Medical Center, Chevy Chase, MD, USA; 4 Twin Cities Spine Center, Minneapolis, MN, USA HYPOTHESIS: The reproducibility and repeatability of modern classifi- cation systems for thoracolumbar trauma have not been sufficiently studied. We studied the interobserver and intraobserver reproducibility of the AO (Magerl) classification and compared it with the older Denis classification. METHODS: AP and Lateral radiographs and complete 2D CT scans of thirty-one acute, traumatic fractures of the thoracolumbar spine were pre- sented to twenty observers, all trained spine surgeons, who classified the fractures according to both the AO and Denis classification systems. Agreement was measured using Cohen ´s e ˆ test. Three months later, the thirty-one fractures were scrambled into a different order and the observers repeated the classification. Cohen ´s e ˆ test was used for inter-observer and intra-observer agreement. For the AO system, agreement was measured for the basic classification system of A,B,C as well as that of the three subtypes of each ex. A1, A2, A3 etc. For the Denis classification, agreement was measured for the four basic categories (compression, burst, Chance and fracture-dislocation) and then for the 16 subtypes. RESULTS: According to the AO classification system, 66 percent of the fractures were classified as A type, 24 percent as B type and 10 percent as C type. 52 of the 55 possible subtypes were mentioned at least once. When broken down into separate subtypes, A3 (burst fractures) wee most common (37%) followed by simple compression fractures A1 (23%). When using the Denis classification, 41% were considered burst fractures and 31% compression fractures. The type classification of AO (A,B,C) was fairly reproducible with an average kappa of 0.475 (range 0.389 to 0.598). When the nine subgroups were tested, the kappa was .The average kappa for the four Denis fracture types was 0.606 (range: 0.325 to 0.702), and when divided out into the 16 subtypes. DISCUSSION: The agreement was slightly better with the Denis classifi- cation, however the variance was wider, due in part to difficulty finding categories for some fractures. The AO system does allow inclusion of all fracture types, however the reproducibility is somewhat less. CONCLUSIONS: The AO classification is an all inclusive classification system for thoracolumbar fractures, however its reproducibility and repeat- ability remain somewhat problematic. DISCLOSURES: No disclosures. CONFLICT OF INTEREST: No conflicts. doi: 10.1016/S1529-9430(03)00406-6 P15. Short segment bone-on-bone instrumentation for single curve idiopathic scoliosis Wolfram Brodner, MD 1 , Wai Mun Yue, MBBS, FRCSEd 2 , Hans Moeller, MD, PhD 3 , Kelly J. Hendricks, MD 4 , Timothy A. Burd, MD 4 , Robert W. Gaines 5 ; 1 University of Vienna, Vienna, Austria; 2 Singapore General Hospital, Singapore, Singapore; 3 Karolinska Institutet, Stockholm, Sweden; 4 University of Missouri, Columbia, MO, USA; 5 Columbia Orthopaedic Group, Columbia, MO, USA HYPOTHESIS: Scoliosis surgery traditionally was performed via a poste- rior approach, but anterior scoliosis instrumentation has proven to be su- perior regarding the amount of curve correction and the number of segments saved from fusion. We evaluated the outcomes of a new short segment anterior scoliosis technique with complete removal of the discs, bone-on- bone apposition of the vertebral bodies, and dual rod instrumentation. METHODS: Thirty-one patients (27 females and 4 males) with single curve idiopathic scoliosis (mean 51.8 degrees; range 40–72) were operated by the senior author (RWG) between 1996 and 2001. Patients’ mean age was 18.8 years (range 9 to 43). Selection of fusion levels was done on a supine “stretch film.” The vertebrae included in the Cobb angle of the “stretch film” were defined as the vertebrae to be fused. 20 of the surgeries were done for thoracic and 11 for thoracolumbar curves. After thorough discectomy (including the posterior annulus fibrosus), bone-on-bone apposi- tion through only the apical segments was achieved. Correction was com- pleted and maintained using KASS (Kaneda Anterior Scoliosis System) dual rod instrumentation. Average follow-up was 40 months (range 15–77). RESULTS: Surgical correction of the major curve averaged 73.9% over the instrumented levels and 51.4% over the entire curve. The average number of discs fused was 4.6 for thoracic curves and 3.3 for thoracolumbar curves. Thoracic primary curves were improved in the coronal plane from an average 52.1 degrees (range 40–72) to 28.3 degrees (range 10–51); the mean correction rate was 68.3% for the instrumented levels and 45.7% for the total curves. Thoracolumbar curves were improved from an average 51.2 degrees (range 40–70) to 19.5 degrees (range 0–38); the mean correction was 84.2% for the instrumented levels and 61.9% for the total curves. The kyphosis of the instrumented segments increased from an average 14.1 degrees before to 23.2 degrees after thoracic instrumentations, and decreased from an average 6.4 degrees before to 3.7 degrees after thoracolumbar instrumentations. Loss of correction of the instrumented levels between the first and the last postoperative radiographs was 1.1 degrees in the coronal plane and 1.0 degrees in the sagittal plane. Compensatory curves spontaneously improved by an average of 38.6%. The mean correction of the tilt angle was 47.1% (from 23.8–12.6) after thoracic instrumentations and 67.4% (from 29.8–9.7) after thoracolumbar instrumentations. There were no implant related complications. Uneventful healing of all fusions occurred (most within 8–12 weeks). One compensatory thoracic curve progressed and posterior instrumentation was done 28 months after correc- tion of the major thoracolumbar curve. DISCUSSION: As instrumentation was restricted to only the apical seg- ments of the major curves, motion segments were saved from fusion. Spontaneous correction of the compensatory curves followed surgery. By maintaining mobility, degenerative changes with chronic low back pain as seen after posterior fusions to the lower lumbar spine hopefully can be prevented. CONCLUSIONS: Surgical correction was performed over half the levels, which would have been operated by standard posterior segmental fixation. Bony healing due to bone-on-bone apposition was achieved uneventfully after apical correction of the spinal curvature in all patients. Use of dual rod instrumentation is fundamental in maintaining the correction of the curvature achieved in the operating room. DISCLOSURES: Device or drug: Kaneda anterior scoliosis system. Status: approved. CONFLICT OF INTEREST: Wolfram Brodner, MD, other support: Scholarship for Spine Fellowship. Robert W. Gaines, MD, other sup- port: royalties. doi: 10.1016/S1529-9430(03)00383-8 P20. Development of a computerized measure of perceived functional ability John Mayer, PhD 1 , Vert Mooney, MD 1 , Dawn Delar-Higgins 1 ; 1 Spine & Sport Foundation, San Diego, CA, USA HYPOTHESIS: The purpose of this study was to evaluate the reliability and validity of the Multidimensional Task Ability Profile (MTAP). The MTAP is a computer-administered questionnaire that is designed to assess perceived functional ability by utilizing pictures and captions that depict