 When non-surgical treatment is ineffective, decompression including laminectomy and medial facetectomy and fusion of the spinal segments with moderatesevere lumbar spinal stenosis has been used to stabilize the motion segment and to alleviate the patients clinical symptoms. Spinal fusion surgery using metal instrumentation is designed to stop motion at a painful, unstable spinal segment by permanently fusing the segment. While fusion may decrease pain generated at the treated segment, the procedure also eliminate motion at the implanted level and transfers and thus increases loads on the adjacent segments. 