Total ankle arthroplasty for deformity of the foot in patients with rheumatoid arthritis using the TNK ankle system: clinical results of 21 cases

We report the results of total ankle arthroplasty (TAA) of 21 ankle joints performed on 19 patients with rheumatoid arthritis (RA) using the Japanese TNK ankle system. The clinical evaluation for an average follow-up period of 33.8 months was based on the ankle analysis system. The total score, pain score, range of motion, and walking ability significantly improved postoperatively compared with the preoperative period. These parameters also showed significantly different values between the preoperative and the follow-up periods. However, the range of motion significantly improved postoperatively. In the evaluation of TAA using the TNK ankle system, a radiolucent line of about 1 mm was detected, but there was no dislocation or sinking of the tibial and talar prostheses. There were no severe complications except for two cases with a delayed wound healing and one with a deep infection. These results suggest that if the talocrural joint only was destroyed and the neighboring joints (subtalar or talonavicular) had fibrous fusion, or the patient had relatively fewer activities in daily life or was an elderly person, TAA using the TNK ankle system was effective for the treatment of painful and disabling ankle joints in patients with RA in the middle of the follow-up period.