Factors associated with cervical instability in cervical myelopathy patients

OBJECTIVE Cervical instability may influence the development and progression of cervical spondylotic myelopathy (CSM). This study aimed to investigate the prevalence of cervical instability in patients with CSM and identify associated factors. METHODS The authors examined the clinical and radiological characteristics of 167 patients aged 40–80 years diagnosed with CSM who required hospitalization between June 2022 and June 2024. Cervical spine radiography was used to evaluate cervical instability, which was defined as a ≥ 3-mm translational motion between adjacent vertebrae on flexion-extension views. Factors potentially associated with cervical instability were compared between patients with and without instability and further investigated using multivariate logistic regression. RESULTS The mean patient age was 57.7 ± 10.3 years, and 115 patients (68.9%) were men. Cervical instability was identified in 72 patients (43.1%). Multivariate logistic regression identified cervical facet joint degeneration, a difference between the T1 slope and cervical lordosis, and visual analog scale score for neck pain as significantly associated factors for cervical instability. CONCLUSIONS This study revealed a high prevalence (43.1%) of cervical instability among patients with CSM and identified significantly associated factors. Spine surgeons should pay special attention to these factors in the surgical decision-making process.