Incidence of elbow involvement in rheumatoid arthritis. A 15 year endpoint study

To evaluate the incidence of involvement and cause of destruction of humeroulnar (HU) and humeroradial (HR) joints in a prospectively followed cohort of 74 patients with seropositive and erosive rheumatoid arthritis (RA).

At the 15 year followup standard anteroposterior and lateral radiographs of 148 elbow joints were evaluated, and the grade of destruction was assessed by the Larsen method.

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 (33%), and severe erosions (Larsen 3-5) 26/148 (18%). The 13 most severely involved (Larsen grade 4-5) joints were seen in 8 (11%) patients. Erosions were most often observed on the capitellum (64 joints) and the lateral epicondyle (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 significantly 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).

After 15 years more than half of the elbows and almost 2 of 3 patients with RA showed definite involvement of the elbow joint. Erosions were most often located on the capitellum and the lateral epicondyle of the humerus or the olecranon of the ulna. Severe destruction was most often bilateral.