Cervical spine instability in axial spondyloarthritis: prevalence, patterns, and predictive factors in a high-risk cohort

OBJECTIVE: Although axial spondyloarthritis (axSpA) is an inflammatory disease primarily affecting the spine, studies investigating cervical spine instability (CSI) are limited, and no research has comprehensively evaluated all forms of CSI. This study aimed to determine the frequency and associated factors of CSI in axSpA patients. METHOD: This retrospective cross-sectional study, conducted in a single tertiary rheumatology unit, included adult axSpA patients with inflammatory back pain duration of > 10 years and receiving biological or targeted synthetic therapy. Patients with any concomitant disease that could affect the spine were excluded. CSI lesions were assessed using lateral neutral, full extension, full flexion, and open-mouth anteroposterior cervical radiographs. Radiographs were evaluated by two blinded rheumatologists. RESULTS: In total, 159 axSpA cases (ankylosing spondylitis: 89.3%; non-radiographic axSpA: 10.7%) were included in the study; 57.9% were male, mean age was 47 years, and mean disease duration was 17 years. A total of 33 CSI lesions was detected in 31 patients (19.5%); the most common was anterior atlantoaxial subluxation (54.5%), followed by subaxial (33.3%) and vertical subluxation (6.1%). In univariate logistic regression analysis; disease duration (p = 0.004), age at first symptom (p = 0.02), uveitis (p = 0.049), and sacroiliitis stage (p = 0.039) were associated with CSI. In multivariate analysis, disease duration was identified as a potential independent predictor of CSI (p = 0.027). CONCLUSION: These results highlight the need for increased clinical awareness of CSI in axSpA, and support consideration of cervical imaging in patients with prolonged disease duration, severe sacroiliitis, or uveitis.