Survivorship Analysis of Clinical Adjacent-Segment Pathology After Single-Level Cervical Fusion

BACKGROUND Clinical adjacent-segment pathology (CASP) is an important problem after anterior cervical surgery. The purpose of this study was to predict prevalence of CASP and determine the possible risk factors for CASP after single-level anterior cervical discectomy and fusion surgery. MATERIAL AND METHODS We retrospectively reviewed a series of patients who underwent single-level cervical discectomy and fusion surgery (ACDF). Both basic and radiographic data of patients were collected. Life-table method and Kaplan-Meier analysis were used to calculate prevalence of CASP and disease-free survival rate. Cox analysis was performed to determine the predictive factors for it. RESULTS A total of 256 patients were included in this study. The mean length of follow-up was 70.64 months. Among them, 31 patients were diagnosed as having CASP during follow-up. Nineteen of them were at the cephalad adjacent segment, and the other 12 were at the caudal segment. After ACDF procedures, 10.01% of patients developed new symptoms of CASP within 5 years, and the incidence increased to 23.89% after 10 years. The incidence rate of CASP was an average of 2.46% per year. Multivariate Cox regression analysis showed that congenital stenosis (hazard ratio [HR], 3.250; 95% confidence interval [CI], 1.538-6.867) and degeneration of adjacent segment (HR, 2.681; 95% CI, 1.259-5.709) were correlated with the incidence of CASP. CONCLUSIONS Patients with congenital stenosis and pre-existing degenerative changes of adjacent segments had a higher risk of developing CASP after single-level anterior cervical discectomy and fusion.