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Comparison Between Standard and High-Flexion Posterior-Stabilized Rotating-Platform Mobile-Bearing Total Knee ArthroplastiesA Randomized Controlled Study
Won Chul Choi, MD1; Sahnghoon Lee, MD, PhD1; Sang Cheol Seong, MD, PhD1; Jong Hun Jung, MD1; Myung Chul Lee, MD, PhD1
1 Department of Orthopaedic Surgery, Seoul National University Hospital, 101 Daehang-ro, Jongno-gu, Seoul 110-744, South Korea. E-mail address for M.C. Lee: leemc@snu.ac.kr
View Disclosures and Other Information
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

A commentary by Ronald Delanois, MD, Michael A. Mont, MD, and Ormonde M. Mahoney, MD, is available at www.jbjs.org/commentary and is linked to the online version of this article.
Investigation performed at the Department of Orthopaedic Surgery, Seoul National University Hospital, Seoul, South Korea

Copyright © 2010 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2010 Nov 17;92(16):2634-2642. doi: 10.2106/JBJS.I.01122
A commentary by Michael A. Mont, MD, is available here
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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.


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.


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.


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.

Level of Evidence: 

Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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