Incidence of elbow involvement in rheumatoid arthritis. A 15 year endpointstudy

Objective. To evaluate the incidence of involvement and cause of destructio n of humeroulnar (HU) and humeroradial (HR) joints in a prospectively follo wed cohort of 74 patients with seropositive and erosive rheumatoid arthriti s (RA). Methods. At the 15 year followup standard anteroposterior and lateral radio graphs of 148 elbow joints were evaluated. and the grade of destruction was assessed by the Larsen method. Results. Erosive involvement (Larsen grade 2) was observed in 75/148 (51%) elbows in 45/74 (61%) patients; 30 patients had bilateral and 15 unilateral involvement. The incidence of mild erosions (Larsen grade 2) was 49/148 (3 3%), and severe erosions (Larsen 3-5) 26/148 (18%). The 13 most severely in volved (Larsen grade 4-5) joints were seen in 8 (11%) patients. Erosions we re most often observed on the capitellum (64 joints) and the lateral epicon dyle (58 joints) of the humerus (AP view) or on the olecranon of the ulna ( 52 joints). The Larsen score (0-100) for peripheral joints correlated signi ficantly with the elbow joint Larsen grade on both sides: right, r = 0.53 ( 95% CI 0.34 to 0.68); left, r = 0.53 (95% CI 0.34 to 0.68). Conclusion. After 15 years more than half of the elbows and almost 2 of 3 p atients with RA showed definite involvement of the elbow joint. Erosions we re most often located on the capitellum and the lateral epicondyle of the h umerus or the olecranon of the ulna. Severe destruction was most often bila teral.