Treatment of severe spondylolisthesis by anterior and posterior reduction and stabilization. A long-term follow-up study.

Twenty-two consecutive unselected patients who had severe spondylolisthesis were treated by a first-stage posterior decompression (Gill procedure) and a posterolateral arthrodesis, followed by halo-skeletal traction, and then by a second-stage anterior interbody arthrodesis, followed by immobilization in a cast. Nineteen patients had complete clinical and radiographic evaluation, with an average follow-up of five years (range, two to seven and one-half years). The slip angle averaged 71 degrees preoperatively, was corrected to an average of 31 degrees by reduction, and averaged 28 degrees at follow-up. The average preoperative percentage of slippage (98 per cent) did not change substantially. A pseudarthrosis developed in four patients, all of whom had a reoperation. The neurological deficits that had been present in ten patients preoperatively had completely resolved in all but one at follow-up. One patient had a cauda equina syndrome and two patients had a neuropathy of the root of the fifth lumbar nerve as a result of the reduction; complete recovery occurred in two patients and partial recovery, in one. Alignment in the sagittal plane was restored in seventeen patients, and the back pain and radicular symptoms were relieved in all patients except one who had had those symptoms preoperatively.