Ossification of the Posterior Longitudinal Ligament

Ossification of the posterior longitudinal ligament (OPLL) is characterized by heterotopic bone formation in spinal ligaments through endochondral mechanisms. Although the etiology remains obscure, the pathogenesis of OPLL appears to involve inheritance of OPLL-related HLA genes in patients with this genetic predisposition. Onset of symptoms is often insidious except in patients who present after a trauma. Imaging evaluation usually will include magnetic resonance imaging and computed tomography (CT), with CT providing the most information about the extent of OPLL. Operative treatment for myelopathy from OPLL is often indicated. Operations for OPLL may be divided into two types, anterior and posterior approaches. Evidence suggesting better outcomes after anterior approaches for OPLL have increasingly led surgeons to favor that approach when feasible. In a patient where the OPLL is limited to three or fewer vertebral segments, an anterior decompression should be considered. Patients with OPLL that is continuous and involves more than three levels should be considered for a posterior decompression or a combined anterior and posterior decompression and reconstruction.