We investigated changes in the biomechanical properties of the ligamentum flavum (L4/5) with age. The ligaments of young patients with herniations and elderly patients with lumbar canal stenosis (LCS) were studied. We used a very specific machine for tensile test: it can maintain the edges of the ligament; and the stress-strain curve is equal to that of the ligament itself that is separate from the bone. Comparison between the young and elderly showed no clear differential mechanical properties in the physiologic strain range and speed. This indicated that histological change does not influence ligament properties to a greet extent, and disc narrowing (major changes with age) causes ligament shortening and disfunctioning.
