Unstable lumbar spine without hypermobility in postlaminectomy cases. Mechanism of symptoms and effect of spinal fusion with and without spinal instrumentation.

The morbid conditions of unstable lumbar spine that are not associated with hypermobility in postlaminectomy cases were studied. The dura and the nerve roots with adhesion could be affected by minimal movement of the spine, which seemed to be the mechanism of symptoms of instability without hypermobility. The effects of spinal instrumentation on this particular instability were studied. The spinal instrumentation provides instantaneous rigid fixation, and maintains it until fusion is obtained, which might prevent adhesion, new bone formation, and re-stenosis. Spinal instrumentation seemed to be the effective treatment for this particular instability.