These three cases of spondylolisthesis in adults were probably caused by laminar fractures. In two of the patients there were bilateral defects or fractures, and in one a unilateral defect. In the two cases with bilateral laminar defects, the posterior arches were displaced and rotated in identical ways. The vertebral displacement or slipping was unusual in that it occurred in the vertebra below that with the laminar lesion. The spinal motions in all of the patients were comparatively free.
The treatment of choice in these cases would seem to be a spine fusion to prevent chronic pain and disability.