Follow-up study of medial facetectomies and posterolateral fusion with instrumentation in unstable degenerative spondylolisthesis.

From 1978 to 1983, 54 consecutive patients with unstable degenerative spondylolisthesis were treated by medial facetectomies and posterolateral fusion with combined distraction and compression rod instrumentation. The average period of follow-up observation was 30 months. Twenty-five patients had a combination of disc herniation or instability, excluding olisthesis. Single-level fusion was performed in 29 patients, two-level in 23, and three-level in two. Preoperative low-back pain in 87.0% and sciatica in 66.7% were reduced to 7.5% and 5.6%, respectively, at follow-up treatment. Preoperative neurogenic intermittent claudication in 63.0% and neurogenic bladder in 11.1% disappeared completely in all patients at follow-up examination. The solid fusion rate was 96.3%. Difference between the values of %-slip and slip-angle before surgery and those at follow-up examination was not statistically significant. Rod breakage occurred in two patients with pseudarthrosis. The overall clinical results were satisfactory relief of clinical symptoms and regression of physical signs, with a high rate of solid fusion.