Comparison between standard and high-flexion posterior-stabilized rotating-platform mobile-bearing total knee arthroplasties: a randomized controlled study

Abstract

Background: A high-flexion posterior-stabilized rotating-platform mobile-bearing prosthesis was designed in an attempt to improve the range of motion after total knee arthroplasty without compromising the theoretical advantages of the posterior-stabilized rotating-platform mobile-bearing system. The aim of this study was to compare the outcomes of standard and high-flexion posterior-stabilized rotating-platform mobile-bearing total knee arthroplasties.

Methods: One hundred and seventy knees were randomly allocated to receive either a standard (n = 85) or a high-flexion (n = 85) posterior-stabilized rotating-platform mobile-bearing prosthesis and were followed prospectively for a minimum of two years. Ranges of motion, functional outcomes determined with use of standard scoring systems, and radiographic measurements were assessed. In addition, patients' abilities to perform activities requiring deep knee flexion and patient satisfaction were evaluated with use of questionnaires.

Results: The average postoperative maximal flexion was 130° for the knees with the standard design and 128° for those with the high-flexion design, and the difference was not significant. The two prosthetic designs also did not differ significantly with regard to the Knee Society scores; Hospital for Special Surgery (HSS) scores; or the scores on the pain, stiffness, and function subscales of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). In addition, the numbers of knees able to perform deep-flexion-related activities and the rates of patient satisfaction were similar in the two study groups.

Conclusions: This prospective randomized study revealed no significant differences between standard and high-flexion posterior-stabilized rotating-platform mobile-bearing total knee prostheses in terms of clinical or radiographic outcomes or range of motion at a minimum of two years postoperatively.