A CADAVERIC STUDY ON THE STABILITY OF LUMBAR SEGMENT AFTER PARTIAL LAMINOTOMY AND FACETECTOMY WITH INTACT POSTERIOR LIGAMENTS

This study aimed to biomechanically investigate a change in the stabil ity of decompressed segments in the degenerative lumbar spine. Cyclic loading tests to the cadaveric spinal unit were conducted in compressi ve and bending directions with a stepwise resection of the posterior e lements such as wide fenestration (partial laminotomy), unilateral and bilateral facetectomy with the intact supra- and interspinous ligamen ts and spinous process. Flexion stability did not decrease significant ly, and may reflect the fact that the aforementioned ligamentous struc tures were preserved throughout the resection process. After wide fene stration, the loss of compression stiffness amounted to only half that of bilateral facetectomy, and extension stiffness dropped to this sam e level. Lateral bending stiffness was maintained until unilateral fac etectomy was performed. We recommend restricted decompression surgerie s for a single-level central stenosis in the degenerative lumbar spine .