Symptomatic adjacent segment disease after single-lever anterior cervical discectomy and fusion: Incidence and risk factors.

The purpose of this study was to determine the incidence and risk factors of symptomatic adjacent segment disease (ASD) following single-lever anterior cervical discectomy and fusion (ACDF) for cervical degenerative diseases.From January 2000 to December 2010, a total of 582 patients with cervical radiculopathy and myelopathy who had undergone single-lever ACDF surgery in the authors' institution were reviewed retrospectively. Patients who had a revision surgery for symptomatic ASD were selected for this study. The authors analyzed the incidence for ASD after single-lever ACDF. And univariate analysis and logistic regression analysis were performed to identify the risk factors of ASD.Among the 582 patients, 36 patients received subsequent surgical management for ASD after initial single-lever ACDF for an overall prevalence of 6.2%. The average onset time of ASD was 8.5 (2-15) years. The univariate analysis showed that there were no significant differences in sex, duration of disease, BMI, DM, smoking, operative levels, and follow-up period (P > .05) between the 2 groups with and without ASD. There were statistically significant differences in age at the time of operation (χ = 4.361, P = .037), and developmental canal stenosis (χ = 4.181, P = .041) between patients with and without ASD. The variables of age at the time of operation and developmental canal stenosis were included in a logistic regression model. The logistic regression analysis revealed that age at the time of operation ≤50 years (P = .045, OR = 3.015, 95% CI = 1.024-8.882) and developmental canal stenosis (P = .042, OR = 2.797, 95% CI = 1.039-7.527) were the risk factors for ASD after single-lever ACDF.In the present study, the incidence of symptomatic ASD after single-lever ACDF was 6.2%. And the age at the time of operation ≤50 years and developmental canal stenosis were the risk factors for ASD. The patients ≤50 years old at the time of operation or with developmental canal stenosis are more likely to develop ASD after surgery, and the risk of reoperation will increase.