Multilevel Lumbar Spinal Stenosis Decompression Midterm Outcome Using a Modified Hinge Osteotomy Technique

Study Design: A prospective cohort study was carried out looking at the functional outcome and post procedure translational segmental instability after multi-level lumbar decompression using a hinge osteotomy technique. Objective: The hinge osteotomy technique involves unilateral subperiosteal muscle dissection with osteotomy of the base of the spinous processes, thereby preserving the integrity of the posterior elements. The objective of this study was to show the results of this technique clinically and radiologically. Methods: Between February 2005 and February 2007, 120 patients (51 male and 69 female) diagnosed with degenerative and/or congenital lumbar stenosis with a mean age of 64 years, underwent central and bilateral canal decompression using the hinge osteotomy technique. A mean of 2 segments (range 2 to 4) was decompressed. All patients were followed for a minimum of 3 years. Five outcome measures were used-visual analog scale for leg pain, Likert scale for functional status, symptom specific well-being score, general well-being score, and oswestry disability index score. The outcomes measures were recorded preoperatively, and at 6 months and 3 years postoperatively. Successful surgical outcome was defined as an improvement in at least 4 of 5 outcome measures. Results: One hundred and eight patients (90%) had a successful surgical outcome. There was a statistically significant improvement in all outcome criteria (P < 0.001), when measured at the 6-month postoperative mark as compared with preoperatively, with further marginal significant improvement (P < 0.05) at 3 years post surgery. There was no evidence of progressive lumbar segmental instability at 3 years postoperatively. Conclusions: Decompression of multi-level lumbar spine stenosis using the unilateral approach with the hinge osteotomy technique is a safe approach for multi-level stenosis, with good outcome and no evidence of significant segmental translational spinal instability.