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 sagittal 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° 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° (range, 75° to 105°) with an average correction at final follow-up of 43° (range, 26° to 65°). Preoperative lumbar lordosis averaged 75° (range, 58° to 100°) and at final follow-up averaged 55° (range, 23° to 74°). 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° 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.