Biomechanical Study of Lumbar Spine after Restoration of Resected Lamina

The biomechanical stability of the lumbar spine after lamino-facetectomy and the restoration of the resected lamina was investigated using fresh frozen human cadaveric lumbar spine specimens. Six pure moments of flexion-extension, right-left bending and right-left axial rotation were applied and intervertebral rotations were recorded. The neutral zone (NZ) and range of motion (ROM) under three conditions of intact, lamino facetectomy and after the restoration of the resected lamina were analyzed statistically to determine comparative biomechanical instability. NZ results showed no changes in any direction, with respect to the intact behavior, after the two procedures. The flexion/extension ROM increased significantly after the lamino-facetectomy, but not after the restoration of the resected lamina. The axial rotation ROM increased remarkably after the lamino-facetectomy and the increased ROM was not reduced completely by the restoration of the resected lamina. We concluded that the spinous process prevents hyperextensive instability of the lumbar spine and it is important to preserve the spinous process as well as facet joints in the decompressive surgeries of the lumbar spine.