How to stabilize a single level lesion of degenerative lumbar spondylolisthesis.

The purpose of this study was to compare the success rate of bony fusion and the clinical results of rigid instrumentation, nonrigid instrumentation, and no instrumentation for a single level lesion for degenerative lumbar spondylolisthesis. Thirty-three patients with degenerative spondylolisthesis of L4 who had undergone posterior decompression and posterolateral fusion with autogenous bone graft that included the facet joints had a single level stabilization with a newly designed syndesmoplasty using Leeds-Keio artificial ligaments (Group Leeds-Keio-nonrigid). Thirty-four patients with degenerative spondylolisthesis of L4 who had the same procedure were stabilized with the Steffee system (Group Steffee-rigid). Thirty-five patients who had the same decompression and bony fusion without instrumentation (Group Noninstrumented) were compared with the former two groups. Clinical results were correlated with the stage of bony fusion. The Steffee system was reliable for stabilizing intervertebral angular instability such as a preoperative intervertebral angle difference of more than 11 degrees in flexion and extension. In the patients who preoperatively had an angle difference of less than 10 degrees, no significant difference was seen between Group Leeds-Keio and Group Steffee. The authors concluded that nonrigid instrumentation can be used to achieve successful bony fusion in patients with degenerative spondylolisthesis, who have a preoperative angle difference less than 10 degrees, with excellent clinical results.