Background Few studies have compared rheumatoid arthritis (RA)-related disorders of the cervical and lumbar spine.
Objectives The objectives of this study were to examine the correlation between cervical and lumbar spinal instability in RA patients and to evaluate the associated risk factors.
Methods From a total of 1,663 patients registered in the Akita Orthopedic Group on Rheumatoid Arthritis (AORA), 128 patients [111 women, 17 men; mean age, 66 (41–84) years; mean disease duration, 14 (1–63) years] who underwent a radiographic examination were enrolled in this study. In the cervical spine, we defined instability as one of the following characteristics: (1) atlantodental interval (ADI) >3 mm, (2) Ranawat value <13 mm on a neutral plain radiograph, or (3) anteroposterior translation >3 mm at the subaxial cervical spine on an anteroposterior bending plain radiograph. In the lumbar spine, instability was defined as anteroposterior translation >3 mm on a neutral plain radiograph. The association between cervical and lumbar spinal instability was examined using Mantel-Haenszel statistics. The patients were classified into two groups: with cervical and/or lumbar spinal instability and without. The independent risk factors for cervical and/or lumbar spinal instability were then determined using multivariate logistic regression analysis.
Results Forty-three (33.6%) patients exhibited cervical spinal instability, and 47 (36.7%) patients exhibited lumbar spinal instability. Twenty-two patients (17.2%) exhibited both cervical and lumbar spinal instability. Instability of the lumbar spine was significantly greater in the group with cervical spinal instability than in the group without (OR: 2.46; 95% CI: 1.13–5.35). Cervical and/or lumbar spinal instability were significantly and independently associated with Steinbrocker's classification stage (OR: 1.62; 95% CI: 1.07–2.47) and disease duration (OR: 1.01; 95% CI: 1.00–1.01).
Conclusions Cervical and lumbar spinal instabilities in RA patients are correlated. Steinbrocker's classification stage and disease duration were independent risk factors for cervical and/or lumbar spinal instability in this study.
Disclosure of Interest None declared