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Scientific Articles   |    
Improved Fixation in Cementless Unicompartmental Knee ReplacementFive-Year Results of a Randomized Controlled Trial
H. Pandit, DPhil, FRCS(Orth)1; A.D. Liddle, BSc, MRCS1; B.J.L. Kendrick, BSc, FRCS(Orth)1; C. Jenkins, MSc2; A.J. Price, DPhil, FRCS(Orth)1; H.S. Gill, DPhil3; C.A.F. Dodd, FRCS2; D.W. Murray, MD, FRCS(Orth)1
1 Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Windmill Road, Headington, Oxford OX3 7LD, United Kingdom. E-mail address for D.W. Murray: david.murray@ndorms.ox.ac.uk
2 Nuffield Orthopaedic Centre, Windmill Road, Headington, Oxford OX3 7HE, United Kingdom
3 University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
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Investigation performed at Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, and the Nuffield Orthopaedic Centre, Oxford, United Kingdom



Disclosure: One or more 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 an aspect of this work. In addition, 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 © 2013 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2013 Aug 07;95(15):1365-1372. doi: 10.2106/JBJS.L.01005
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Abstract

Background: 

When used for appropriate indications, unicompartmental knee replacement is associated with fewer complications, faster recovery, and better function than total knee replacement. However, joint registries demonstrate a higher revision rate for unicompartmental knee replacement. Currently, most unicompartmental knee replacements are cemented; common reasons for revision include aseptic loosening and pain. These problems could potentially be addressed by using cementless implants, with coatings designed to improve fixation. The objectives of this study were to compare the quality of fixation as well as clinical outcomes of cemented and cementless unicompartmental knee replacements at five years of follow-up.

Methods: 

A randomized controlled trial was established with sixty-three knees (sixty-two patients) receiving either cemented (thirty-two patients) or cementless Oxford unicompartmental knee replacements (thirty patients). Fixation was assessed with fluoroscopic radiographs aligned to the bone-implant interface at one and five years. Outcome scores, including the Oxford Knee Score, Knee Society objective and functional scores, and Tegner Activity Score, were collected preoperatively and at six months and one, two, and five years postoperatively. At each postoperative time point, these were recorded as absolute scores and change from the preoperative score.

Results: 

Four patients died during the study period. There were no revisions. Mean operative time was nine minutes shorter in the cementless group (p = 0.049). At five years, there was no significant difference in any outcome measure except the Knee Society functional score and the change in the Knee Society functional score, which were significantly better in the cementless group (p = 0.003 for both). There were significantly more tibial radiolucencies in the cemented group (twenty of thirty knees versus two of twenty-seven knees; p < 0.001). There were nine complete radiolucencies in the cemented group and none in the cementless group (p = 0.01).

Conclusions: 

Cementless fixation provides improved fixation at five years compared with cemented fixation in mobile-bearing unicompartmental knee replacements, maintaining equivalent or superior clinical outcomes with a shorter operative time and no increase in complications.

Level of Evidence: 

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

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    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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