Range of motion and patient satisfaction with traditional and high-flexion rotating-platform knees

Although a high degree of flexion is necessary for some activities of daily living, most total knee arthroplasty implants are designed to provide only up to 120° of flexion. Some new designs claim to provide greater flexion. In this retrospective study, we evaluated the Sigma rotating-platform high-flex knee against the traditional Sigma rotating-platform knee (DePuy, Warsaw, IN). There were 153 knees evaluated. We matched the subjects primarily on preoperative flexion and had 64 matched pairs. We also evaluated the knees based on their preoperative flexion, either <120° or ≥120°. In comparing the two implants, there were no significant differences in the patients' overall satisfaction, flexion gained or lost, or the need for further surgery. This study was approved by an institutional review board.