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The Knee Arthroplasty Trial (KAT)Design Features, Baseline Characteristics, and Two-Year Functional Outcomes After Alternative Approaches to Knee Replacement

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Membership of the KAT Trial Group (in alphabetical order): Project Management Group: Marion Campbell (Aberdeen), Nick Fiddian (Bournemouth), Ray Fitzpatrick (Oxford), Adrian Grant (Aberdeen), Alastair Gray (Oxford), Richard Morris (London), David Murray (Co-Chair: Oxford), and David Rowley (Co-Chair: Dundee). Additional members of the writing committee: Linda Johnston (Dundee), Graeme MacLennan (Aberdeen), Kirsty McCormack (Aberdeen), Craig Ramsay (Aberdeen), and Allan Walker (Aberdeen).
Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from the NIHR Health Technology Assessment Programme (Project Number 95/10/01); Howmedica Osteonics; Zimmer; DePuy, a Johnson and Johnson company; Corin Medical; Smith and Nephew Healthcare. Biomet Merck; and Wright Cremascoli. 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. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
Disclaimer: The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the funding bodies.

The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2009 Jan 01;91(1):134-141. doi: 10.2106/JBJS.G.01074
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Background: The aim of continued development of total knee replacement systems has been the further improvement of the quality of life and increasing the duration of prosthetic survival. Our goal was to evaluate the effects of several design features, including metal backing of the tibial component, patellar resurfacing, and a mobile bearing between the tibial and femoral components, on the function and survival of the implant.

Methods: A pragmatic, multicenter, randomized, controlled trial involving 116 surgeons in thirty-four centers in the United Kingdom was performed; 2352 participants were randomly allocated to be treated with or without a metal backing of the tibial component (409), with or without patellar resurfacing (1715), and/or with or without a mobile bearing (539). Randomization to more than one comparison was allowed. The primary outcome measures were the Oxford Knee Score (OKS), Short Form-12, EuroQol-5D, and the need for additional surgery. The results up to two years postoperatively are reported.

Results: Functional status and quality-of-life scores were low at baseline but improved markedly across all trial groups following knee replacement (mean overall OKS, 17.98 points at baseline and 34.82 points at two years). Most of the change was observed at three months after the surgery. Six percent of the patients had additional knee surgery within two years. There was no evidence of differences in clinical, functional, or quality-of-life measures between the randomized groups at two years.

Conclusions: Patients have substantial improvement following total knee replacement. This is the first adequately powered randomized controlled trial, of which we are aware, in which the effects of metal backing, patellar resurfacing, and a mobile bearing were investigated. We found no evidence of an effect of these variants on the rate of early complications or on functional recovery up to two years after total knee replacement.

Level of Evidence: Therapeutic Level I. 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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