Restoration of range of motion (ROM) after total knee arthroplasty (TKA) greatly affects post-operative results. We analyzed various actors, including implant systems, to identify those factors affecting ROM in TKA.

645 knees of 418 patients who received TKA from the same operator between June 1990 and May 1999 were analyzed. Knees were sorted according to patient (age, sex, body mass index, symptom duration, pre-operative ROM, and deformity), disease (osteoarthritis, rheumatoid arthritis, and osteonecrosis), implant (implant system, and thickness of spacer), operation (preservation or resection of the posterior cruciate ligament (PCL), and lateral release or not). Post-operative ROM was evaluated with a minimum 3 years of follow-up.

Within 1 year after TKA, BMI, symptom duration, pre-opeative deformity, pre-operative ROM, and lateral release were found to significantly (p-value<0.05) affect post-operative ROM. At 2 years after TKA, BMI, pre-operative deformity, and pre-operative ROM were found to significantly affect post-operative ROM. At 3 years after TKA, post-operative ROM was significantly better for a wider pre-op. (p<0.0001), and in patients without lateral release (p<0.018). Underlying disease, the implant system used, and PCL treatment showed no significant difference.

A better pre-operative ROM and no lateral release of the retinacular ligament showed a better post-operative ROM at 3 years after TKRA.