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Scientific Articles   |    
Risk of Revision for Fixed Versus Mobile-Bearing Primary Total Knee Replacements
Robert S. Namba, MD1; Maria C.S. Inacio, MS2; Elizabeth W. Paxton, MA2; Christopher F. Ake, PhD2; Cunlin Wang, MD, PhD3; Thomas P. Gross, MD, MPH3; Danica Marinac-Dabic, MD, PhD3; Art Sedrakyan, MD, PhD4
1 Department of Orthopedic Surgery, Southern California Permanente Medical Group, Kaiser Permanente Orange County, 6670 Alton Parkway, Irvine, CA 92618
2 Department of Surgical Outcomes and Analysis, Kaiser Permanente, 3033 Bunker Hill Street, San Diego, CA 92109. E-mail address for M.C.S. Inacio: maria.cs.inacio@kp.org
3 Office of Surveillance and Biometrics, Center for Devices and Radiological Health, Food and Drug Administration, WO Building 66-Room 4110, 10903 New Hampshire Avenue, Silver Spring, MD 20993-0002
4 Weill Medical College of Cornell University, Cornell University, 402 East 67 Street, New York, NY 10065
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Investigation performed at the Department of Surgical Outcomes and Analysis, Kaiser Permanente, San Diego, California

A commentary by Paul Manner, MD, FRCSC, is linked to the online version of this article at jbjs.org.



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. None of the authors, or their institution(s), have had any financial relationship, in the thirty-six months prior to submission of this work, with any entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. Also, 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 Nov 07;94(21):1929-1935. doi: 10.2106/JBJS.K.01363
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Abstract

Background: 

Mobile-bearing total knee arthroplasty prostheses were developed to reduce wear and revision rates; however, these benefits remain unproven. The purposes of this study were to compare the short-term survivorship and to determine risk factors for revision of mobile-bearing and fixed-bearing total knee replacements.

Methods: 

A prospective cohort study of primary total knee arthroplasties performed from 2001 to 2009 was conducted with use of a community total joint replacement registry. Patient characteristics and procedure details were identified. Cox regression models were used. Bearing type was investigated as a risk factor for revision while adjusted for other risk factors such as age, American Society of Anesthesiologists (ASA) score, body mass index, sex, race, diagnosis, bilateral procedures, cruciate-retaining versus posterior-stabilized components, surgical approach, fixation, patellar resurfacing, hospital and surgeon volumes, and fellowship training.

Results: 

The study cohort consisted of 47,339 total knee arthroplasties, with 62.6% of the procedures in women. Fixed bearings were used in 41,908 knees (88.5%) and mobile bearings in 4830 (10.2%). Rotating-platform designs were used in all mobile-bearing total knee arthroplasties (3112 had a Rotating-Platform Press-Fit Condylar posterior-stabilized design; 1053, a Low Contact Stress [LCS] design; and 665, a Rotating-Platform Press-Fit Condylar cruciate-retaining design). Patients who received fixed-bearing total knee arthroplasty systems were older (mean age, 68.1 years) than those who received mobile-bearing total knee arthroplasty systems (mean age, 62.2 years); the difference was significant (p < 0.001). Overall, 515 knees (1.1%) were revised for reasons other than infection. The survival rate was 97.8% (95% confidence interval [CI], 97.4% to 98.0%) at 6.7 years. The adjusted risk of aseptic revision for the LCS total knee replacements was 2.01 times (95% CI, 1.41 to 2.86) higher than that for fixed-bearing total knee replacements (p < 0.001).There was no significant revision risk for the other mobile-bearing total knee arthroplasty systems. There was no association with surgeon and hospital case volumes and the risk of revision total knee arthroplasty.

Conclusions: 

Our study suggests the benefit of potential long-term wear reduction with the LCS implant may not be realized in a community-based setting, where a variety of surgical skills, surgical experience, and diverse patient demographic factors may affect early outcomes.

Level of Evidence: 

Therapeutic Level II. See Instructions for 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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