Imaging study of lumbar posterior marginal intraosseous node. An analysis of 36 cases.

Clinical, radiological and CT manifestations of 36 patients with lumbar posterior marginal intraosseous cartilaginous node (LPMN) were analysed. Of the 36 patients, 27 were male and 9 female, most of them were young adults. The posteroinferior margin of L4 was the commonest site and the posterosuperior margin might also be involved. Two patients had multiple lesions. Typical radiological findings included a defect in the posteroinferior (or posterosuperior) margin of the affected vertebral body and behind the defect a bony ridge protruding into the spinal canal. CT scan showed a cartilaginous node in the posterior zone of the vertebral plate. It is suggested that LPMN was the result of disc material herniating into the posterior aspect of vertebral body through ruptured cartilaginous end-plate during the adolescence, similar to that of the limbus vertebra. Hyperflexion and hyperextension of the spine probably play an important role in the pathogenesis. The existence of LPMN favours posterior disc herniation in the same disco-vertebral junction.