In the present study we evaluated radiographically involvement of the ankle joint and its relationship to destruction of the subtalar joint in rheumatoid arthritis (RA).
An inception cohort of 103 patients with seropositive RA was followed over a period of 20 years. Follow-up examinations were conducted after onset, 1, 3, 8, 15, and 20 years from entry. A total of 83 patients attended the 15-year and 68 patients the 20-year follow-up. Radiographic evaluation was performed using a lateral weight-bearing ankle radiograph. A simplified grading was applied for the talocrural joint, in which the ankles (patients) were divided into three groups: no changes, minor changes and major changes. In the end-point analysis the last radiograph was assigned. Subtalar destruction was recorded (Larsen grade > or = 2). Severity of RA in different groups was evaluated using the Larsen score of 0-100 of hands and feet. Difference between patient groups was evaluated using Cuzick's test.
At the endpoint major changes of the ankles were detected in seven patients (7%) only, minor changes were observed in 17 patients (16%). The first minor involvement of the ankle was observed at the three-year follow-up in two patients. First major changes were detected at the 15-year follow-up in three ankles of two patients. Subtalar pathology preceded that of TC joint in all ankles with major changes. In 17 patients with minor changes, simultaneous subtalar pathology was observed in all but two ankles, while preceding subtalar involvement was radiographically manifest in 13 of 21 ankles. The means of Larsen scores of 0-100 were in the three ankle grading groups 40, 54 and 63, respectively. Cuzick's test for the trend was highly significant (P < 0.001). No reconstructive surgery was performed on the ankle joint during the follow-up, whereas the subtalar joint complex was fused cumulatively in 12 patients.
The ankle joint is involved in a late stage of RA and is usually affected only in the patients with severe disease. Subtalar pathology precedes the changes in the talocrural joint almost regularly.