Ankylosis, or spontaneous bone fusion, of the small joints of the hand is a rare event in patients with rheumatoid arthritis (RA), being observed in 0.8% of them on conventional radiographs. It is associated with long-lasting and severe disease. In other settings, such as fracture healing, bone fusion is a reparative process. The aim of this paper is the study of the frequency of wrist ankylosis in patients with RA in comparison with other arthritides; to correlate ankylosis with disease activity.
A total of 94 patients affected by RA, 71 patients with different rheumatic conditions and 42 controls with no joint disease or with slight hand osteoarthritis were studied. DAS-28 CRP was calculated in patients with RA and psoriatic arthritis. MRI of the clinically most involved wrist was performed with a 0.2 T, extremity-dedicated MRI system.
Of RA patients, 10/94 (10.6%) showed ankylosis in comparison with 2/113 (1.8%) controls (p=0.015). RA patients with ankylosis had longer disease duration (p=0.019) but similar disease activity.
MRI-defined bone ankylosis is frequent in RA. It is not limited to seronegative spondyloarthritides and may be part of the bone damage observed in RA.