Correction of Adolescent Idiopathic Scoliosis via Selective Anterior Instrumentation and Fusion

Chicago, IL, Park Ridge, IL

Radiographs of 25 patients (mean age 14.4yrs, range 12-18) with adolescent idiopathic scoliosis were evaluated to determine curve correction via selective anterior fusion using Moss-Miami instrumentation. Eighteen patients had King Type I curves, 4 patients had King Type Vcurves, 3 had King Type III curves. Anterior discectomies with iliac crest bone graft were performed; cages were used in three patients; all but one patient had thoracoplasties. Preoperative and postoperative radiographs were obtained; follow-up radiographs (2yrs to 5yrs 2 mos) were also assessed to determine loss of correction and decompensation. Intraoperative radiographs were taken after discectomy, then after rod placement to determine the percent correction generated from each portion of the procedure. Images were digitized using an Olympus c-2000 Z digital camera. Parameters were measured using image analysis software (Scion Image, www.scioncorp.com). Intraobserver and interobserver measurement variations of this method were comparable to those of standard measurement techniques. The data was analyzed using paired two-tailed t-tests (Microsoft Excel, Microsoft, Redmond, WA). The mean preoperative primary curve was 50.3 degrees (range 34 to 74); the mean postoperative primary curve was 19.2 degrees (range 5 to 37, p ‹ 0.05); mean percent correction obtained was 62%. The mean preoperative upper compensatory curve was 27.4 degrees (range 16 to 36); postoperative 15.6 degrees (range 2 to 27, p ‹ 0.05); mean percent correction was 54%. The mean preoperative lower compensatory curve was 30.6 degrees (range 8 to 50); postoperative 17.9 degrees (range 3 to 37, p ‹ 0.05); mean percent correction was 40%. Neither apical vertebra to center sacral line distance nor plumb line to center sacral line distance were significantly changed. Thoracic kyphosis and lumbar lordosis were not significantly changed postoperatively. The intraoperative correction generated was 35% greater than that measured on postoperative standing films; 64% of this correction was due to rod placement after discectomy. At follow up, average loss of correction of the primary curve was 24%; all secondary curves remained smaller than the primary curves. There were no statistically significant differences in coronal or sagittal balance at follow-up, but there was a trend towards increased thoracic kyphosis and increased lumbar lordosis. We conclude that selective anterior fusion is an effective method of obtaining primary and secondary curve correction in adolescent idiopathic scoliosis; there does not appear to be significant decompensation following selective fusion at follow-up.