SCIENTIFIC PAPER Range of Motion after Total Knee Replacement in Patients with Valgus Knee Deformity: Comparison of Patients with Rheumatoid Arthritis and Degenerative Osteoarthritis

Objective: To ascertain whether the range of motion after total knee replacement for patients with rheumatoid arthritis or degenerative osteoarthritis with valgus knee deformity is affected by the pathology causing valgus deformity and preoperative range of motion. Patients and Methods: The range of motion of 23 knees of 19 patients with valgus knee deformity of more than 10° undergoing total knee replacement was reviewed. The patients had either rheumatoid arthritis or degenerative osteoarthritis. Preoperative and postoperative differences in tibial-femoral alignment, flexion deformity, and maximum flexion were compared between the 2 patient groups. Results: Ten knees had rheumatoid arthritis and 13 had degenerative osteoarthritis. Duration of follow-up ranged from 6 to 49 months. Based on a similar pattern of preoperative deformity, patients with rheumatoid arthritis had better correction in flexion deformity and less loss of flexion range compared with patients with osteoarthritis after total knee replacement. Patients with a mobile knee preoperatively tended to lose some range of motion after total knee replacement and the loss was significantly greater for patients with osteoarthritis. Conclusion: The range of motion following total knee replacement for patients with valgus knee deformity is affected both by the preoperative range of motion and by the aetiology of the valgus deformity.