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Scientific Articles   |    
Computer-Assisted Techniques Versus Conventional Guides for Component Alignment in Total Knee ArthroplastyA Randomized Controlled Trial
William G. Blakeney, MBBS1; Riaz J.K. Khan, MBBS, BSc(Hons), FRCS(Tr&Orth), FRACS2; Simon J. Wall, MBBS, BSc(Hons), FRCS(Tr&Orth)1
1 Department of Orthopedic Surgery, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009, Australia
2 University of Western Australia, Perth, WA 6009, Australia
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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 the authors of this work are available with the online version of this article at jbjs.org.

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Investigation performed at Sir Charles Gairdner Hospital, Nedlands, and Hollywood Private Hospital, Perth, Western Australia, Australia

Copyright © 2011 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2011 Aug 03;93(15):1377-1384. doi: 10.2106/JBJS.I.01321
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Abstract

Background: 

Optimal alignment of the prosthesis in total knee arthroplasty results in improved patient outcomes. The goal of this study was to determine the most accurate technique for component alignment in total knee arthroplasty by comparing computer-assisted surgery with two conventional techniques involving use of an intramedullary guide for the femur and either an intramedullary or an extramedullary guide for the tibia.

Methods: 

One hundred and seven patients were randomized prior to surgery to one of three arms: computer-assisted surgery for both the femur and the tibia (the computer-assisted surgery group), intramedullary guides for both the femur and the tibia (the intramedullary guide group), and an intramedullary guide for the femur and an extramedullary guide for the tibia (the extramedullary guide group). Measurements of alignment on hip-to-ankle radiographs and computed tomography (CT) scans made three months after surgery were evaluated. The operative times and complications were compared among the three groups.

Results: 

The coronal tibiofemoral angle demonstrated, on average, less malalignment in the computer-assisted surgery group (1.91°) than in the extramedullary (3.22°) and intramedullary (2.59°) groups (p = 0.007). The coronal tibiofemoral angle was >3° of varus or valgus deviation in 19% (seven) of the thirty-six patients treated with computer-assisted surgery compared with 38% (thirteen) of the thirty-four in the extramedullary guide group and 36% (thirteen) of the thirty-six in the intramedullary guide group (p = 0.022). The increase in accuracy with computer-assisted surgery came at a cost of increased operative time. The operative time for the computer-assisted surgery group averaged 107 minutes compared with eighty-three and eighty minutes, respectively, for the surgery with the extramedullary and intramedullary guides (p < 0.0001). There was no significant difference in any of the outcomes between the intramedullary and extramedullary guide groups.

Conclusions: 

This study provides evidence that the implant alignment with computer-assisted total knee arthroplasty, as measured with radiography and computed tomography, is significantly improved compared with that associated with conventional surgery with intramedullary or extramedullary guides. This finding adds to the body of evidence showing an improved radiographic outcome with computer-assisted surgery compared with that following conventional total knee arthroplasty.

Level of Evidence: 

Therapeutic Level I. See Instructions to 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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    Bertrand P. Kaper M.D.
    Posted on September 26, 2011
    Does CAS truly improve component position and alignment?
    Orthopaedic Specialists of Central Arizona

    I read with interest the article by Blakeney et al, 'Computer-Assisted Techniques Versus Conventional Guides for Component Alignment in Total Knee Arthroplasty'. At the present time, any objective addition to the body of knowledge of the proposed benefit of CAS in the setting of total joint arthroplasty is a benefit to us all.My concern with the conclusions of this article, however, center on the claim that alignment was 'significantly improved' in the CAS TKA group. The authors assessed component alignment based on eight different measurements, as outlined in Table I. Of these eight measurements, however, only one (Coronal tibiofemoral angle) achieved statistical significance- none of the other seven ANOVA p-values were even close to p<0.05. Given this reality, it would seem that analysis of the data would only allow one to conclude that minimal improvement of alignment can be expected with CAS technique.With the statistically significant increase in operative time cited by the authors, one must be able to stepback and question the true benefit of the addition of CAS in the setting of total knee arthroplasty.

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