Biomechanical behavior of lumbar spine following laminotomy and laminectomy

摘要

The surgical approach to decompress the lumbar canal in cases of spinal stenosis or a diffuse herniated disc involves either a wide bilateral laminectomy or a bilateral laminotomy. The biomechanical advantage of laminotomy over the more traditional laminectomy is the preservation of the posterior ligamentous tissues of the spine that are important in maintaining the stability of the spine. Clinically, the pathology in spinal canal stenosis is usually posterolateral, and only very rarely directly posterior. Therefore, decompression can be more effectively achieved by a laminotomy and medial facetectomy, while still preserving the uninvolved spinous process and interspinous ligaments. Posterior ligaments of the spine have been the subjects of several in vitro biomechanical studies [1-6]. Mechanical distraction tests of the interspinous ligament have been performed, either through sequential dissections of the posterior ligament complex or isolated bone-ligament-bone specimens to determine the role of interspinous ligament. Contribution of the interspinous and supraspinous ligaments in maintaining segmental stability of the spine has also been studied. All these studies suggest that interspinous and supraspinous ligaments play an important role in restricting spinal motion, especially in flexion. However, there have been no previous studies that directly compare the amount of destabilization between the laminotomy and laminectomy procedures. More importantly, the increases in mechanical stresses on the intervertebral disc resulting from the two procedures have not been previously quantified.