Anatomical characteristics of nonuniform settlement of the C 2 lateral mass and its association with atlantoaxial osteoarthritis
10.3760/cma.j.cn121113-20250107-00023
- VernacularTitle:枢椎侧块关节面不均匀沉降的解剖特征及其与寰枢椎骨关节炎的相关性
- Author:
Chao TANG
1
;
Qing WANG
;
Ying ZHANG
;
Yehui LIAO
;
Qiang TANG
;
Sizhen YANG
;
Hao QIU
;
Dejun ZHONG
;
Tongwei CHU
Author Information
1. 陆军军医大学第二附属医院（新桥医院）骨科，重庆 400037
- Publication Type:Journal Article
- Keywords:
Axis, cervical vertebra;
Atlanto-axial joint;
Osteoarthritis;
Finite element analysis;
Nonuniform settlement
- From:
Chinese Journal of Orthopaedics
2025;45(9):531-541
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the anatomical characteristics of the atlantoaxial joint associated with nonuniform settlement of the C 2 lateral mass (C 2LM-NUS) and its correlation with atlantoaxial osteoarthritis. Methods:A retrospective analysis was conducted on clinical and imaging data of 522 hospitalized patients (288 males, 234 females; mean age 60.8±11.2 years; range 18-83 years) who underwent CT scans of the head/neck or cervical spine at the Second Affiliated Hospital of Army Medical University between January 1, 2022 and December 31, 2022. Multiplanar reconstruction of CT data was performed to measure the settlement of the C 2 lateral mass (C 2LMS). Patients with a difference in bilateral C 2LMS (d-C 2LMS) >1.4 mm were classified into the C 2LM-NUS group (137 cases; 71 males, 66 females; mean age 63.3±11.6 years), while the normal group included 385 patients (217 males, 168 females; mean age 59.9±11.0 years). Imaging parameters of the atlantoaxial joint were measured, including the C 1, 2 coronal inclination angle (C 1, 2 CI), atlanto-dental interval (ADI), lateral atlanto-dental interval (LADI), coronal deviation angle of the odontoid (Od-CDA), and C 1, 2 relative rotation angle (C 1, 2 RRA). Osteoarthritis prevalence was recorded. A normal C 0-C 3 finite element (FE) model was constructed using CT data from a 48-year-old female in the normal group. A C 2LM-NUS FE model was developed based on anatomical differences between the C 2LM-NUS and normal groups, and stress distribution on the C 2 lateral mass articular surface was analyzed under flexion-extension, lateral bending, and axial rotation torques. Results:The C 2LM-NUS group exhibited asymmetric atlantoaxial joint morphology, with bilateral differences in C 1, 2CI and LADI of 8.5°(5.8°, 11.3°) and 0.8(0.1, 1.4) mm, respectively, significantly greater than those in the normal group [1.7°(0.8°, 2.7°) and 0.2(0.1, 0.5) mm, P<0.05]. Od-CDA and C 1, 2RRA were 3.9°(2.0°, 5.4°) and 7.2°(5.0°, 10.0°) in the C 2LM-NUS group, exceeding the normal group's values [0°(0°, 1.0°) and 0°(0°, 5.5°), P<0.05]. The prevalence of C 2LM-NUS was 37.8% in the atlantoaxial osteoarthritis group, significantly higher than in the non-osteoarthritis group (22.8%, P<0.05). Significant differences were observed in age (68.3±9.4 vs. 58.6±10.8 years), sex distribution (50/69 vs. 238/165), and C 1, 2RRA [5.6°(0°, 8.2°) vs. 3.8°(0°, 6.2°)] between the osteoarthritis and non-osteoarthritis groups ( P<0.05). After adjusting for age, sex, and C 1, 2RRA, binary logistic regression identified C 2LM-NUS as an independent risk factor for atlantoaxial osteoarthritis [ OR=2.024, 95% CI (1.300, 3.150), P<0.001]. FE analysis demonstrated a reduced C 1, 2 range of motion in the C 2LM-NUS model, with elevated stress concentrations on the settled side lateral mass during simulated flexion-extension, lateral bending, and rotation. Conclusions:The study indicated that C 2LM-NUS is associated with asymmetric anatomical changes in the atlantoaxial joint, increasing the risk of osteoarthritis. Stress concentration on the C 2 lateral mass articular surface, caused by C 2LM-NUS, is a biomechanical contributor to this heightened risk.
