OBJECTIVETo investigate the correlation of pathology, bone morphogentic protein (BMP) expression, CT value with the ossification of thoracic ligamentum flavum (TOLF) to afford the evidence to choose appropriate treatment methods.

METHODSTwenty-three patients aged 35 - 65 years old had TOLF in my hospital as case. Their courses of disease were 2 months to 9 years. The values of blood calcium, blood phosphorus and AKP in them were normal. The 5 peoples aged 21 - 35 years old who presented fracture of thoracic but not the ligamentum flavum ossification were selected as control. We excluded those who have DISH, ankylosing spondylitis, fluorosis and other disease related with TOLF. The lesion locus were scanned and mensurated by CT. The pathology characteristics were classified into immature ossification and mature ossification by general observation, histology examination. BMP were measured by the immunohistochemical (IHC) staining techniques.

RESULTSThe CT value was significantly higher in the case group (547.2 +/- 131.4) than controlled group (137.7 +/- 10.6) (t = 6.922, P = 0.000). Further, the CT value in the mature ossification (702.9 +/- 17.7) was significantly higher than the immature (480.5 +/- 180.2) (t = 5.623, P = 0.000). In addition, BMP both expressed negative in the mature ossification and the controlled group, but positive in the immature ossification. BMP expression was significantly different between the immature ossification and the mature (chi2 = 70.000, P = 0.000).

CONCLUSIONSThe CT values, pathological types and BMP expression results are similar to evaluate the ossification degrees of ligamentum flavum, and then could be indirectly judged the maturation degrees of TOLF by CT to confirm the treatment methods before operation.