Ossification of the posterior longitudinal ligament: Etiology, prevalence, progression, and surgical strategies

Abstract

Ossification of the posterior longitudinal ligament (OPLL) is characterized by replacement of the ligamentous tissue by ectopic new bone formation. OPLL often causes narrowing of the spinal canal and has been recognized as a cause of cervical myelopathy and/or radiculopathy. Although a clear inheritance of OPLL has not been identified, there is a strong genetic background for OPLL. A recent genome-wide association study using all Japan cohort reported that there were 6 susceptible loci for OPLL. In addition, there were several studies to seek the biomarkers of OPLL. OPLL is frequently found in the cervical spine. However, 53.4% had OPLL not only in the cervical spine, but also in other spinal regions in patients with cervical OPLL. Further, 65.2% with cervical OPLL had ossification of the ligamentum flavum (OLF) especially at the levels of the thoracic and the lumbar spine. There is no effective conservative treatment. Surgical decompression is considered in patients with severe and/or progressive myelopathy. Early surgical decompression of the spinal cord is recommended in patients with apparent myelopathy. Operative methods are divided into two procedures, anterior decompressive surgery and posterior decompressive surgery. The choice of the surgical procedure is determined according to several factors, such as local pathology of OPLL and spinal alignment.