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Randomized Clinical Trial of Rotating-Platform and Fixed-Bearing Total Knee Arthroplasty: No Clinically Detectable Differences at Five Years
Michael M. Kalisvaart, MD1; Mark W. Pagnano, MD1; Robert T. Trousdale, MD1; Michael J. Stuart, MD1; Arlen D. Hanssen, MD1
1 Department of Orthopedic Surgery, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905
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Investigation performed at the Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota



Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.

Copyright © 2012 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2012 Mar 21;94(6):481-489. doi: 10.2106/JBJS.K.00315
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Abstract

Background: 

For some surgeons, rotating-platform total knee designs are an intellectually appealing option to use for total knee arthroplasty because of the contention that they can self-align and accommodate small mismatches in the rotational position of the tibial and femoral components. We carried out a randomized clinical trial to determine if a posterior-stabilized, rotating-platform knee design provided better maximum knee flexion, better function, or better durability at five years of follow-up when compared with a fixed-bearing design.

Methods: 

This randomized clinical trial of 240 primary total knee arthroplasties involved a single type of distal femoral implant (posterior-stabilized) and three different types of tibial implant (all-polyethylene fixed-bearing, modular-metal-backed fixed-bearing, and rotating-platform). The three tibial implant groups were balanced dynamically with a computerized randomization process that accounted for patient age, sex, and body mass index; surgeon; and implant type. Patients returned for examination and radiographs at three months, one year, two years, and five years postoperatively.

Results: 

Knee range of motion was not significantly different among the all-polyethylene, modular-metal-backed, and rotating-platform tibial component groups at two years (mean, 111°, 111°, and 110°, respectively) or five years (mean, 110°, 109°, and 109°, respectively). Function, as measured with Knee Society scores, was not significantly different among the all-polyethylene, modular-metal-backed, and rotating-platform groups at two years (mean, 90, 91, and 91 points, respectively) or five years (mean, 88, 89, and 88 points, respectively). Stair-climbing scores were not significantly different among the three groups at two years (mean, 39, 40, and 39 points, respectively) or five years (mean, 37, 40, and 36 points, respectively). There were four revisions: one in the all-polyethylene group (patellar fracture), two in the modular-metal-backed group (aseptic loosening), and one in the rotating-platform group (deep infection).

Conclusions: 

In this randomized clinical trial, the rotating-platform total knee design was reliable and durable but did not provide better maximum knee flexion, better function, or better durability at five years postoperatively when compared with a posterior-stabilized, fixed-bearing design incorporating either an all-polyethylene or a modular-metal-backed tibial component.

Level of Evidence: 

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

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    References

    Accreditation Statement
    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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