Adjacent level degeneration after anterior cervical fusion: a clinical review.

Anterior cervical discectomy and corpectomy for the treatment of cervical spondylosis,cervical disc herniation, and ossification of the posterior longitudinal ligament enjoy favorable rates of fusion and successful clinical outcomes. Although the complications from these procedures have been well described, the pathogenesis and clinical development of adjacent segment degeneration (ASD) are not fully understood. The definition of symptomatic ASD is the development of radicular or myelopathic signs and symptoms referable to a motion segment adjacent to prior cervical arthrodesis. The incidence, pathogenesis, prevalence, and potential treatment strategies for symptomatic ASD are discussed in this article.