Analysis of factors affecting range of motion after Total Knee Arthroplasty

Abstract

This study was done to analyze the various factors affecting range of motion in total knee Arthroplasty. Various factors such as age, sex, body mass index, disease, different prosthesis and designs, pre- op factors such as pre-op flexion, fixed flexion deformity, coronal plane deformity, were assessed to find out its effect on post-op range of motion. Post-op factors such as coronal plane alignment, joint line position change, change in antero-posterior diameter of femoral component and extension lag were assessed and its co-relation to post-op range of motion. One of the important aspect of the study was the surgeon was a single surgeon and hence surgeon factors remained a constant. A total of 75 knees were operated were studied upon, 8 were rheumatoid and 67 were primary osteoarthritis of the knee joint, with a minimum follow up period of 2 years. The average pre-op flexion was 87.678 and the average post-op flexion was 105.538. 86.15% of our patients had more than 100 degrees of flexion. 69.2% of our patients with a average pre-op flexion of less than 90 degrees had an average post-op flexion of 103.763. 30.8% of patients with average pre-op flexion between 90- 100 degrees had a average post-op flexion range of motion of 109.55. Patients with pre-op fixed flexion deformity had a post-op range of motion of 97.5 degrees. The average post-op flexion range of motion in 10 of our obese patients was 95 degrees, and in the non-obese group it was 107.454. The 8 patients with rheumatoid arthritis had an average post-op flexion of 96.25 degrees, wheareas the patients in the osteoarthritis group had an average post-operative flexion of 107.462 degrees. Post-op flexion with change in joint line postion was not significant. Patellar resurfacing was not done in any of the patients.