Effects of unilateral endoscopic facetectomy on spinal stability.

There are various definitions for spinal instability and its exact clinical usefulness is uncertain. Facetectomy has been considered a potential source of instability via conventional approaches. Studies have suggested that if the ligament structure of the spine is maintained then instability may not occur with an endoscopic facetectomy. This study is a prospective analysis of 10 patients who underwent unilateral endoscopic facetectomy for the treatment of severe foraminal stenosis to determine whether endoscopic facetectomies result in instability. The patients underwent pre and postsurgical x-rays that were evaluated via a specialized computer program that determined whether or not there was any altered mobility between the 2 sets of x-rays. These were compared with controls to determine whether instability was present. Of the 10 endoscopic facetectomy patients, none had any statistically significant change in sagittal rotational or translational motion when compared to controls. Thus, endoscopic removal of a unilateral facet joint does not necessarily cause spinal instability possibly because of the reduction in tissue damage associated with an endoscopic approach and the maintenance of the ligament structure of the spine.