Considerations in the treatment of cervical ossification of the posterior longitudinal ligament.

Ossification of the posterior longitudinal ligament (OPLL), defined as pathological hypertrophy and prominent bony formation of the posterior longitudinal ligament, compresses the spinal cord and results in myelopathy.6,12 The first report of OPLL was made in 1839.16 Tsukimoto presented the first Japanese autopsy case of cervical OPLL in 196040 and Terayama et al. gave the disease its name.38 There is a geographical difference in the prevalence of OPLL. In Japan, the reported incidence ranges from 1.7 to 2.4% and includes asymptomatic cases. In non-Asians, it is 0.16%.19,31,41 OPLL tends to present in the fifth and sixth decades of life. It is most frequent in the cervical region and fewer than 10% are observed in the thoracic or lumbar region. There is an association between OPLL and ossification of yellow ligament (OYL) or ankylosing spondylotic hyperostosis. The precise etiology of OPLL remains obscure. Laboratory examinations return normal results, although an association with diabetes mellitus and generalized hyperostosis of the spinal ligaments such as diffuse idiopathic skeletal hyperostosis has been noted in patients with OPLL. Siblings of patients with OPLL who share an increased number of human leukocyte antigen haplotypes are at increased risk for developing OPLL, suggesting a genetic factor. An abnormality in the N-propeptide of the COL 11A2 gene that is related to Type II collagen has been reported in patients with OPLL.33