Studies on the Pathogenesis of Ossification of the Posterior Longitudinal Ligament

Abstract

To determine the induction mechanism of OPLL, using cultured cells derived from the human posterior longitudinal ligament of the spine, the ossification group and the non-ossification group were compared morphologically and biochemically.
The result seems to suggest that the non-ossification group consists chiefly of fibroblast-like cells, while the ossification group consists chiefly of osteogenic undifferentiated mesenchymal cells. The pathogenesis of OPLL is considered as follows. In the ossification group, the posterior longitudinal ligament is composed of high osteogenic potential cells, with a resulting general tendency of systemic ossification.
This systemic ligamentous ossifaication factor is a primary cause of OPLL. When localized anatomical stress and/or abnormalities of hormone and bone metabolism stimulate this ligament, which is in a high osteogenic activity, this may result in initial ossification which may develop into pathological OPLL.