A clinical study of degenerative spondylolisthesis. Radiographic analysis and choice of treatment.

Surgical treatment of degenerative spondylolisthesis in 27 patients by means of anterior lumbar interbody fusion and in 14 patients by means of posterior decompression yielded average degrees of recovery of 77% and 56%, respectively. Preoperative analysis of myelograms, and computed tomographies after myelography indicated that anterior shifting of the inferior articular process of the slipping vertebra was the main factor responsible for compression of the nervous tissue in the early stages of degenerative spondylolisthesis. Patients in these stages should be treated by anterior lumbar interbody fusion. In the later stages of degenerative spondylolisthesis, osteophytes on the superior articular processes of the lower vertebra were an additional factor in compression, and patients should be treated by posterior decompression. Computed tomographies after myelography provided the key images for identifying pathologic processes in degenerative spondylolisthesis and selecting appropriate surgical procedures.