TGFB1 and spinal stenosis: Recent reports have suggested that increased concentrations of transforming growth factor-beta 1 (TGF-β1) or tissue inhibitors of metalloproteinases (TIMPs) might be associated with ligamentum flavum hypertrophy in patients with spinal stenosis.17-20) It is well known that MMPs can degrade elastin and collagen components within the various connective tissues of the body.6-8) Based on this, we hypothesized that MMPs might also play a role on the histologic changes that occur in the ligamentum flavum of spinal stenosis patients.