[Long-term results of decompressive surgery without fusion for degenerative spondylolisthesis]

The long-term results of decompressive surgery for degenerative spondylolisthesis with symptomatic lumbar spinal stenosis were evaluated retrospectively with regard to the postoperative progression of slippage and clinical symptoms.

The study included 53 patients who underwent surgery, and for whom follow-up of at least 5 years was conducted. Spondylolisthesis was diagnosed based on the presence of sagittal vertebral translation greater than 3mm on lateral radiographs. The patients were divided into two groups:Group I:37 patients undergoing bilateral laminotomy, and Group II:16 patients undergoing laminectomy. The clinical results were evaluated according to McCulloch's classification and the Japanese Orthopaedic Association(JOA)score.

The mean pre-and postoperative JOA scores were 14.6 and 22.9 in Group I and 14.7 and 21.0 in Group II, respectively. The JOA scores improved soon after surgery, after which the scores declined gradually in both groups. The recovery rate was 63.0% in Group I and 43.7% in Group II. The average amount of pre- and postoperative slippage was 7.3mm and 6.9mm in Group I and 6.2mm and 6.9mm in Group II, respectively. In Group I, the slippage progressed within the first year, after which the degree of slippage slowly decreased to lower values than those observed preoperatively, whereas slippage progressed for 5 years before declining in Group II. No correlations were observed between progression of slippage and clinical outcomes in either group.

Laminotomy produces satisfactory long-term results both clinically and radiographically in patients with degenerative spondylolisthesis.