OBJECTIVETo investigate the role of transforming growth factor (TGF)-beta1 in degeneration of the ligamentum flavum in the lumbar spine.

METHODSThe degenerative ligamentum flavum was obtained during surgery from 8 patients with lumbar spinal stenosis (mean age 58.6 years), and 8 young patients (mean age 24.2 years) with acute lumbar disc herniation were included as normal controls. The thickness of the ligamentum flavum was measured on preoperative magnetic resonance images, and the mRNA expressions of type-I collagen and TGF-beta1 in the ligamentum flavum were detected using reverse transcriptase-polymerase chain reaction. The protein expression and localization of TGF-beta1 were investigated by Western blotting and immunohistochemical staining, respectively.

RESULTSThe thickness of the ligamentum flavum were 4.70-/+0.40 mm in the degenerative group and 2.50-/+0.36 mm in the control group, showing significant difference between the two groups (P<0.001). The type-I collagen mRNA expression in the degenerative group was significantly higher than that in the control group (P=0.007). The mRNA and protein expressions of TGF-beta1 were significantly higher in the degenerative group than in the control group (P=0.008 and 0.004, respectively). Immunohistochemistry showed that TGF protein was localized in the fibroblasts within the ligamentum flavum.

CONCLUSIONDegenerative ligamentum flavum shows hypertrophy and fibrosis, and TGF-beta1 overexpression may be associated with in the development and progression of ligamentum flavum degeneration in the lumbar spine.