Range of Motion of Standard and High-Flexion Posterior Cruciate-Retaining Total Knee Prostheses: A Prospective Randomized Study.

Background: The main goals of total knee arthroplasty are pain relief and improvement in function and the range of motion. The purpose of this study was to compare the ranges of motion of the knees of patients treated with a standard posterior cruciate-retaining total knee prosthesis in one knee and a high-flexion posterior cruciate-retaining total knee prosthesis in the other. Methods: Fifty-four patients (mean age, 69.7 years) received a standard posterior cruciate-retaining total knee pros- thesis in one knee and a high-flexion posterior cruciate-retaining total knee prosthesis in the contralateral knee. Five patients were men, and forty-nine were women. At a mean of three years postoperatively, the patients were assessed clinically and radiographically with the knee-rating systems of the Knee Society and the Hospital for Special Surgery and with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. Results: The mean postoperative Knee Society and Hospital for Special Surgery knee scores were 93.7 and 89 points, respectively, for the knees with a standard posterior cruciate-retaining prosthesis, and they were 93.9 and 90 points, respectively, for the knees with a high-flexion posterior cruciate-retaining prosthesis. The mean postoperative WOMAC score was 22 points. Postoperatively, the mean ranges of motion without and with weight-bearing were 131° (range, 900 to 150°) and 115° (range, 75° to 145°), respectively, in the knees with a standard prosthesis and 133° (range, 900 to 150°) and 118° (range, 750 to 145°), respectively, in those with a high-flexion prosthesis. Patient satisfaction and radiographic results were similar in the two groups. No knee had aseptic loosening, revision, or osteolysis. Conclusions: After a minimum duration of follow-up three years, we found no significant differences between the two groups with regard to the range of knee motion or the clinical or radiographic parameters. Level of Evidence: Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]