Diagnostic retrospective case series.
To evaluate cervical intersegmental motion in rheumatoid arthritis patients using specialized tracking software (QMA) and compare the findings with a previously published cohort of "normal" subjects.
Rheumatoid arthritis follows 3 patterns of cervical involvement, atlantoaxial subluxation, atlantoaxial impaction, and subaxial subluxation. Deformities present are sometimes considered "unstable" to the point where surgery can be recommended based on the interpretation of cervical radiographs.
Cervical flexion-extension radiographs of 99 subjects with rheumatoid arthritis were evaluated. Angular and translational segmental motions were determined at each level using specialized tracking software. Findings were compared with previously published normative data using the same device.
Relative to controls, patients with rheumatoid arthritis demonstrated significantly less overall sagittal motion. Segmental analysis at C1-C2 demonstrated a 10% prevalence of dynamic motion outside the 95% confidence interval for "normal" patients. In contrast, segmental analysis at C2-C7 demonstrated no intersegmental motion outside the 95% confidence interval for "normal" subjects.
In patients with rheumatoid arthritis, abnormal motion at C1-C2 was consistent with truly dynamic deformity and should be closely evaluated. Conversely, subaxial subluxations, although frequently present, were relatively fixed deformities and in most cases, may not represent an unstable condition.