Severe spondylolisthesis. Reduction and internal fixation.

The authors have developed and algorithm for management of spondylolysis and spondylolisthesis. Since March 1983, 15 patients with an average age of 20 years and with greater than 50% anterior displacement have been treated. The mean follow-up period is 24 months. Before surgery the average anterior displacement was 72%, the average delta angle at L5-S1 representing kyphosis was 73 degrees, and the average lumbar lordosis from L1 to L5 was 64 degrees. An anterior release and fusion was combined with a posterior reduction and instrumentation using the internal fixator. Correction of the anterior displacement averaged 46%, while the kyphosis was corrected a mean of 20 degrees and the lordosis a mean of 12 degrees. The L4 segment was preserved in 13 cases and the L4-L5 angle was improved by a mean of 7 degrees. Postoperative pain and function were improved in all cases. Neurologic complications occurred in four patients, three permanent and one temporary. Hardware failure occurred in two patients, and reoperation has been required in one. Further follow-up evaluation of this technique is required.