Objective: To evaluate the long term results of an operation developed to decompress the roots at the stenotic level, preserve the midline structures, and not use instrumentation or fusion.

Design: A retrospective clinical and radiological review of consecutive patients operated on for spinal stenosis secondary to lumbar spondylosis.

Subjects: One hundred and sixty patients (eighty seven female and seventy three male) with a mean age at operation of sixty eight (range 40–90). Sixty one patients (38%) had a degenerative listhesis causing stenosis. The mean post operative follow-up was twenty two months (range two months to fourteen years).

Summary of background data: Lumbar spondylosis, commonly involving degenerative listhesis, is the commonest cause for spinal stenosis in the lumbar spine. Surgery offers the only permanent cure. The standard procedure remains a laminectomy with fixation and fusion in the presence of possible instability. The laminectomy destabilises the spine and the instrumented fusion makes it a much bigger operation in patients often not best placed to cope with it. There is a need, therefore, for an effective operation that does not compromise spinal stability.

Results: At six weeks one hundred and forty one patient (85%) reported relief of leg pain and a further nine patients were improved at three to six months. 52% of the patients reported a concomitant improvement in back pain. The results were sustained at follow-up.

The operation was not responsible for the development of a new spondylolisthesis. A minimal increase in an existing degenerative listhesis was seen in two patients only without compromise of their good results. There was no revision surgery at any of the operated levels.

Conclusions: The operation of segmental spinal decompression for degenerative lumbar spinal stenosis has been found to be effective, safe, and give good long term results, without compromising the existing spinal stability. Patient selection and attention to operative technique are essential.