[Reoperations after surgical treatment of lumbar stenosis]

PURPOSE THE STUDY: The aim of this study was to determine the causes of failure following surgical treatment of lumbar spinal stenosis, indications for redo surgery and factors influencing the final result.

Between 1975 and 1992, 38 patients were reoperated after a surgical treatment of lumbar spinal stenosis. The mean follow-up was 34 months. All of these patients had had at least one previous lumbar spinal operation. Second operation was performed 35 months on average following the previous surgery. CLINICAL EVALUATION: The grading scale used in this review assessed walking ability, radicular pain at rest and at exersion, back pain, motor deficit and sphincter dysfunction. Patients were evaluated before and after the 2 surgeries and at last follow-up. Radiological study was done from CT-scan, MRI, myelograms, static and dynamic standard X-rays before the first surgery and following the revision surgery.

According to our grading scale the final result was very good for 36 per cent of the patients, good for 24 per cent, fair for 24 per cent and poor for 16 per cent. The main causes of failure were post-operative destabilization and incomplete neurological decompression. In 56 per cent of our cases initial nerve roots decompression was incomplete: disc excision without bone resection in case of lumbar stenosis associated with disc herniation, incomplete lateral release, decompression of the symptomatic nerve roots only and not of all of them that were compressed. In these cases revision surgery was comprised by a new decompression. In 25 per cent of our cases post-operative destabilization was the cause of failure. During the previous surgery bone resection had been extensive: total bilateral facetectomy without fusion, wide laminectomy extended into the pars inter-articularis, resulting in isthmic fracture. Revision surgery was a posterolateral fusion with or without instrumentation generally associated with a new decompression. Two patients were reoperated on without evidence of inadequate decompression or destabilization. Result was poor in both. Final results were statistically better when the cause of revision surgery was a post-operative destabilization and when redo surgery was performed on surgically untouched levels.

Final results were disappointed since only 60 per cent were good or very good results. Revision surgery should be avoided, by using pre-operative planning of the neural decompression, and by adding a fusion if a wide bone resection is necessary.