Expansive Suspension Laminoplasty Using a Spinous Process-Splitting Approach for Lumbar Spinal Stenosis: Surgical Technique and Outcomes Over 8 Years of Follow-up.

Abstract

To maximize the benefits of posterior decompression for severe multilevel lumbar spinal stenosis, we refined the expansive laminoplasty technique using a spinous process-splitting approach. This study tests the hypothesis that the surgical benefit of adequate decompression with posterior element preservation is maintained in the long term, over 8 years of follow-up. Fifty-eight patients were followed up yearly for 8 years. Eight patients having nonlumbar spine surgery or Parkinson disease were excluded. The noninferiority of the 8-year versus peak-year outcomes was tested, with margins of 5 points for the Oswestry disability index and 1 point for the numeric rating scales (NRSs). In the 50 patients available for follow-up, the peak values of the mean improvements from baseline within the first 7 years were 35.8, 5.7, 5.9, and 2.8 points for the Oswestry disability index, low back pain NRS, leg pain NRS, and leg numbness NRS, respectively. The 95% lower confidence limits for the differences between the mean improvements from baseline at 8 years and the peak year were within the noninferiority margins for each scale. Our technique was associated with substantial improvement from baseline for each scale. The initial improvements in function and symptoms were maintained for 8 years.