An Analysis of Sagittal Curves and Balance After Cotrel-Dubousset Instrumentation for Kyphosis Secondary to Scheuermannʼs Disease

STUDY DESIGN: This study compared preoperative and postoperative saggittal curves and spinal balance in patients undergoing spinal fusion with Cotrel-Dubousset instrumentation for severe kyphosis secondary to Scheuermann's disease. Also determined was patient satisfaction regarding relief of pain and correction of the deformity. Thirty two patients with kyphosis > 75 degrees underwent spinal fusion with Cotrel-Dubousset instrumentation. OBJECTIVES: To evaluate the initial and long-term correction of the primary kyphosis and changes in lumbar lordosis and sagittal balance, and to determine the incidence and etiology of junctional sagittal deformities. SUMMARY OF BACKGROUND DATA: The average preoperative kyphosis was 85 degrees (range, 75 degrees to 105 degrees) with an average correction at final follow-up of 43 degrees (range, 26 degrees to 65 degrees). Preoperative lumbar lordosis averaged 75 degrees (range, 58 degrees to 100 degrees) and at final follow-up averaged 55 degrees (range, 23 degrees to 74 degrees). Most of the patients demonstrated negative sagittal balance and became slightly more negatively balanced postoperatively. RESULTS: Maintenance of correction postoperatively was excellent, with only a 4 degree average loss of correction. There was spontaneous reduction in lumbar lordosis of varying degrees. Proximal junctional kyphosis was associated with over-correction (> 50%) of the kyphotic deformity or a fusion starting short of the proximal vertebra in the measured kyphosis. Distal junctional kyphosis developed in patients whose fusion ended short of the first lordotic segment. CONCLUSIONS: This procedure appeared to yield good results when proper levels of fusion were selected and correction > 50% was not attempted.