Rationale, biomechanics, and surgical indications for Graf ligamentoplasty.

Graf ligamentoplasty stabilizes the unstable segment through coaptation of bilateral facet joints. Intervertebral disc height should be preserved to avoid postoperative neuroforaminal stenosis. Biomechanically and clinically, this procedure has the potential to treat "flexion instability" but cannot correct vertebral slippage or scoliotic deformity. Surgical indication or patient selection is the key to successful ligamentoplasty. The surgical indication is degenerative lumbar disorder with less than 25% of vertebral slip, minimal disc space narrowing, and coronal facet tropism. In the long-term, Graf ligamentoplasty may reduce the risk of adjacent-segment deterioration compared with spinal fusion.