[Evaluation of the risk of vertebral displacement after surgical treatment of a lumbar stenosis].

The author has operated on 83 cases of spinal stenosis between 1977 and 1984. In seven cases a secondary spondylolisthesis developed early. The extent of the displacement was moderate and it was painful in only two cases. In five instances it was entirely related to the surgical procedure and in two others was an aggravation of a pre-existing displacement. Most of the cases were situated at the L4/5 level and developed in narrowed discs and in cases of excessive lumbar lordosis. The lesion appeared after extensive laminectomy and arthrectomy, and sometimes after more limited procedures. It is concluded that, in spines at risk, postero-lateral arthrodesis should be associated with posterior enlargement of the canal. The danger of a painful post-operative displacement is less troublesome than failure after too limited a decompression.