We describe a modified technique of micro-decompression of the lumbar spine involving the use of an operating microscope, a malleable retractor and a high-speed burr, which allows decompression to be performed on both sides of the spine through a unilateral, hemi-laminectomy approach. The first 100 patients to be treated with this technique have been evaluated prospectively using a visual analogue score for sciatica and back pain, the MacNab criteria for patient satisfaction, and functional assessment with the Oswestry Disability Index. After a period of follow-up from 12 months to six years and four months, sciatica had improved in 90 patients and back pain in 84 patients. Their result was graded as good or excellent by 82 patients according to the MacNab criteria, and 75 patients had subjective improvement in their walking distance. Late instability developed in four patients. Lumbar micro-decompression has proved to be safe, with few complications. Postoperative instability requiring fusion was uncommon, and less than using traditional approaches in published series.
Bilateral decompression of spinal stenosis may induce instability which compromises outcome. In an attempt to overcome this problem, bilateral decompression can be carried out through a unilateral approach. The ipsilateral side is decompressed by hemi-laminectomy with undercutting partial facetectomy and the contra-lateral side is treated by careful excavation beneath the spinous processes and laminae with preservation of the laminae, posterior ligament complexes and paraspinal muscles. This is achieved with the aid of an operating microscope or loupe and headlight. Previous reports contain little information about outcome and complications. We reviewed 30 patients with bilateral spinal stenosis, but without significant spondylolisthesis who were decompressed bilaterally from a unilateral approach by a single surgeon during a calendar year. They represented a third of our annual operations for spinal stenosis. Thirty patients had 45 levels decompressed. Female to male ratio was 2:1 and average age was 66 years. The average duration of preoperative symptoms was 1.6 years. The mean follow up period was 30 weeks (12 weeks to one year). Assessment was carried out using the Oswestry Disability Index, pre- and post-operative visual analogue pain scores for leg pain and back pain, walking distance and MacNab criteria of patient outcome.
Whilst the technique is safe, and effective, a longer randomised controlled study is needed to demonstrate any real advantage over traditional approaches.
