Abstract
Introduction and aims: Surgical decompression for lumbar stenosis entails a risk of iatrogenic instability. Consequently, laminectomy has been largely superseded by the more conservative procedure of fenestration, but the decompression may be compromised. We describe an additional technique of undercutting laminectomy, which conserves stability while maximising decompression, and the results are presented.
Method: Forty-nine patients with lumbar spinal stenosis were treated by fenestration, medial facetectomy and removal with curved osteotomes of the ventral aspect of the lamina superior to the involved facets together with the attached ligamentum flavum. The results were assessed at a mean follow-up period of three years and four months using walking distance and a pain analogue scale as outcome measures, and surgical complications were recorded. The radiological results were assessed in 25 patients by measurement on MRI scan of the spinal canal cross-sectional area pre- and post-operatively.
Results: Ten patients had undercutting laminectomy at one level, 19 at two levels, 14 at three levels and four at four levels. Medical co-morbidity was present in most patients; 11 were ASA 1, 25 ASA2 and 11 ASA 3. Pre-operatively, all patients reported leg pain or numbness and 20 patients reported back pain. All but one had limited walking distance, the mean being 564 metres (range 5m–8000m). Post-operatively the mean pain score was 3.3 and the mean walking distance 762 metres. Forty-one patients said they felt the operation had been worthwhile and six said they did not. Surgical complications occurred in five patients, consisting of dural tear in four patients (repaired with no sequelae) and a wound haematoma requiring drainage in one patient. The mean spinal canal cross-sectional area at the level of maximal stenosis pre-operatively was 28mm2 and postoperatively was 75mm2, giving a mean increase of 133%. No patients had any evidence of iatrogenic instability as judged by the development of degenerative spondylolisthesis or scoliosis.
Conclusion: The technique described achieves excellent decompression of the stenotic lumbar canal as measured radiologically, while largely preserving the facet joints. In relation to published reports on fenestration and medial facetectomy alone, the clinical results are at least as good.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
One or more of the authors are receiving or have received material benefits or support from a commercial source.
