Extension of fusions to the pelvis in idiopathic scoliosis

Study Design. Retrospective study of patients after extension of previous scoliosis fusions to the pelvis. Objective. To determine whether modern instrumentation and surgical techniques provide for increased fusion rates with fewer complications. Summary of Background Data. Traditionally, long fusions to the pelvis in adults with idiopathic scoliosis have resulted in high complication rates, including pseudarthrosis. Methods. The hospital and clinic charts of 41 patients (40 female, 1 male) were reviewed 41 months (range: 24-116) after surgery for extension to the pelvis of previous scoliosis fusions. Thirty-nine of 41 had a combined anteroposterior fusion extension; two had posterior extension only. In 37 of 41 patients, Cotrel-Dubousset (CD) instrumentation was used; in two, Isola (Acromed Corp., Cleveland, OH), in one. TSRH; (Sofamor-Danek, Memphis, TN), and in one, Synergy (Cross Medical Products, Columbus, OH). Parameters analyzed were fusion rate, sagittal and coronal balance, lumbar lordosis, length of fusion extension, and distal fixation method. Results. Complications were seen in 30 of 41 patients. The pseudarthrosis rate was 37% (15/41) and was significantly related to the method of distal posterior fixation. With sacral fixation only, the rate was 53% (8/15), with iliac fixation only 42% (3/7), and with both iliac and sacral fixation 21% (4/19; P < 0.05). This was not correlated with fusion rate, and the length of fusion extension did not affect the pseudarthrosis rate or sagittal balance. Conclusion. When fixed to the ilium and sacrum, modern instrumentation appears capable of maintaining sagittal balance with lower rates of pseudarthrosis when previous scoliosis fusions are extended to the pelvis. The complication rate remains significant.