Development of adjacent segment disease following multilevel anterior cervical discectomy and fusion surgery

Abstract

BACKGROUND: Cervical spondylosis, a degenerative disease of the spine, is a common medical condition that results in significant morbidity, loss of function, and financial burden on the healthcare system in the United States. The disease ranges in severity from axial pain, which is among the most common medical complaints encountered in healthcare, to severe neurological symptoms such a myelopathy and radiculopathy, which may require surgical intervention. Anterior cervical discectomy and fusion (ACDF) has been established as a gold standard for safe and effective surgical treatment of cervical spondylotic myelopathy (CSM) and/or radiculopathy. However, there are significant complications that are associated with surgical intervention, including the development of pathology at the spinal levels adjacent to the fusion level(s), known, as adjacent segment disease (ASD). LITERATURE REVIEW: ASD has been studied in ACDF surgery, however there are a limited number of large studies that evaluate the correlation between the number of fused spinal levels and the rate of development of symptomatic and radiographic ASD. Mechanisms for the pathogenesis of ASD have been proposed and some are supported by in vitro cadaveric studies, but there is not yet conclusive and strong in vivo evidence in the literature. PROJECT PROPOSAL: This retrospective cohort study will be comparing rates of ASD development following short segment (one and two-level), and long segment (three or more levels) ACDF in patients with a minimum of three years of follow-up. Patients are evaluated for ASD via review of electronic medical records, including operative reports, outpatient and hospital charts, and evaluation of imaging studies. Images are assessed for radiographic ASD using the Kellgren-Lawrence criteria, and these results are subsetquently evaluated for correlation with symptomatic ASD. This study aims at investigating the incidence rates and relative risk of developing ASD and evaluate for statistically significant difference using chi-square analysis. CONCLUSION: More research is still needed to confirm the mechanism of pathogenesis of ASD and determine the effect that length of fusion construct has on the incidence of this disease. Further information will help guide physicians in their clinical decision making in the surgical treatment of patients with ACDF and those that subsequently develop ASD.