Flexion Dysfunction of Atlanto-occipital Joint as a Risk Factor for Cervical Spondylosis

Abstract

BACKGROUND: There exist varied craniocervical flexion angles from the teenagers to the elderly. To our best knowledge, there is no prior study to examine the role of range of motion (ROM) of the atlanto-occipital joint in the pathogenesis of cervical spondylosis (CS). The purpose of this study was to investigate the association between atlanto-occipital radiographic alignment in flexion and CS.METHODS: 232 CS patients, including 45 patients who accepted surgical treatment, were retrospectively reviewed. The angle between McGregor’s line and C1 line (O-C1 angle) was evaluated on images taken in flexion (F-OC) and neutral positions (N-OC) independently. The relationship between the FOC (FOC=F-OC—N-OC) and Neck Disability Index (NDI) was examined, and the involvement of the FOC in the onset of CS was analyzed. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cut-off for detecting an increased risk of CS.RESULTS: The FOC showed a significant correlation with NDI(P<0.05). The mean FOC was significantly lower in the CS groups than in the control group (P<0.001). Logistic regression analysis showed involvement of the FOC in the onset of CS, and the threshold value according to receiver operating characteristic curve analysis was 4.2 degree, with the odds ratio of 8.2 (95% CI:6.4–10.0; P<0.001). CONCLUSION: Stiff atlanto-occipital joint, represented by low FOC, is an independent risk factor in the incidence of CS compared with healthy individuals. This parameter can help spine surgeons to identify these people to implement appropriate preventive and management steps.