The Pathogenesis of Ossification of the Posterior Longitudinal Ligament and Ossification of the Ligamentum Flavum with Special Reference to Bone Morphogenetic Proteins and Transforming Growth Factor-βs

Abstract

Listen

Translate article

Both ankylosing spinal hyperostosis (ASH) [1] and diffuse idiopathic skeletal hyperostosis (DISH) [2] are well-known conditions in which hyperostosis is associated with ossification of the ligaments of the spine. Patients with ASH or DISH often develop ossification of the posterior longitudinal ligament (OPLL) [3,4] and/or ossification of the ligamentum flavum (OLF) [5,6], causing serious neurological complications. Protrusion of the thickened, hypertrophied, and ossified ligaments into the spinal canal leads to compression and deformation of the contiguous spinal cord and nerve roots, which cause myelopathy and radiculopathy. Patients with OPLL or OLF occasionally suffer from severe neurological deficits such as motor weakness, sensory disturbance, and urinary incontinence. Decompressive surgeries, anterior or posterior, with or without resection of the ossified ligaments and with or without spinal fusion, do not always produce a satisfactory result (see chapters by E. Taketomi et al., K. Hirabayashi et al., and K. Abumi et al., this volume). No therapeutic agent is known to prevent the development or growth of OPLL and OLF.