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Predictors of Functional Outcome Two Years Following Revision Hip Arthroplasty
Aileen M. Davis, PhD1; Zoe Agnidis, MScPT2; Elizabeth Badley, PhD3; Alex Kiss, PhD4; James P. Waddell, MD, FRCSC5; Allan E. Gross, MD, FRCSC2
1 Toronto Western Hospital, MP 11-322, 399 Bathurst Street, Toronto, ON M5T 2S8, Canada. E-mail address: adavis@uhnresearch.ca
2 Department of Orthopaedic Surgery, Mount Sinai Hospital, 600 University Avenue, Suite 476A, Toronto, ON M5G 1X5, Canada. E-mail address for Z. Agnidis: zoe.agnidis@utoronto.ca. E-mail address for A.E. Gross: allan.gross@utoronto.ca
3 Arthritis Community Research and Evaluation Unit, University Health Network, Toronto Western Hospital, 399 Bathurst Street, Toronto, ON M5T 2S8, Canada. E-mail address for E. Badley: badley@uhnres.utoronto.ca
4 Sunnybrook and Women's College Health Sciences Centre, 2075 Bayview Avenue, G Wing, 1st Floor, Room 144, Toronto, ON M4N 3M5, Canada. E-mail address for A. Kiss: kiss@ices.on.ca
5 University of Toronto, St. Michael's Hospital, 30 Bond Street, Room 5013, Bond Wing, Toronto, ON M5B 1W8, Canada. E-mail address for J.P. Waddell: waddellj@smh.toronto.on.ca
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A commentary is available with the electronic versions of this article, on our web site (www.jbjs.org) and on our quarterly CD-ROM (call our subscription department, at 781-449-9780, to order the CD-ROM).
Note: The following surgeons enrolled patients in this study: J. Roderick Davey, Toronto Western Hospital of University Health Network; Jeffrey Gollish, Sunnybrook and Women's College Hospital; Allan E. Gross, Mount Sinai Hospital; Caroline Hutchinson, formerly of Mount Sinai Hospital; Hans Kreder, Sunnybrook and Women's College Hospital; Nizar Mahomed, Toronto Western Hospital of University Health Network; Emil Schemitisch, St. Michael's Hospital; and, James Waddell, St. Michael's Hospital. The authors also acknowledge the contributions of Dr. Khaled Saleh and Dr. Amiram Gafni to this study.
In support of their research for or preparation of this manuscript, one or more of the authors received an Operating Grant (No. 98/0012) from The Arthritis Society (Canada). A.M. Davis is supported by a Health Career Award from the Canadian Institutes of Health Research. None of the authors 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, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.
Investigation performed at Mount Sinai Hospital, Toronto Western Hospital—University Health Network, Sunnybrook and Women's College Health Sciences Centre, and St. Michael's Hospital, Toronto, Ontario, Canada

The Journal of Bone and Joint Surgery, Incorporated
J Bone Joint Surg Am, 2006 Apr 01;88(4):685-691. doi: 10.2106/JBJS.E.00150
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Background: Little is known about factors that might predict functional outcome following revision hip arthroplasty. The purpose of this study was to identify predictors of pain and physical function at two years following revision total hip arthroplasty and to evaluate whether the time that the patient waited for the surgery and whether the patient had complications were significant predictors of outcome.

Methods: One hundred and twenty-six patients (126 hips) were entered prospectively into the study when their name was placed on the waiting list for surgery. Baseline measures included demographic factors, comorbidities, and the responses to the Short Form-36 (SF-36) and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) questionnaires. Follow-up was carried out at six-month intervals while the patient was waiting for the surgery; within one week prior to the surgery; and at six, twelve, and twenty-four months after the surgery. Patient age and gender, the preoperative WOMAC pain and function scores, the physical and mental component scores of the SF-36, comorbidities, the number of revisions, bilateral joint replacement, and the severity of the revision were evaluated as possible predictors of ultimate pain and function as measured with the WOMAC instrument.

Results: The mean age of the patients was 68.6 years. Improvement in WOMAC pain and function scores plateaued at six months. The mean pain score (and standard deviation) improved from 9.4 ± 4.1 points preoperatively to 3.9 ± 3.9 points at six months postoperatively, and the mean function score improved from 35.4 ± 14.1 to 19.1 ± 13.2 points. Preoperative pain (p = 0.002) and comorbidity (p = 0.02) were significant predictors of pain at two years. There was a trend toward preoperative function predicting function at twenty-four months (p = 0.07). There was no significant deterioration in the WOMAC pain or function score while the patients waited for surgery. Twenty-eight patients had complications. When the time that the patient waited for the surgery and complications were added to the models, only complications were found to be predictive of outcome (p = 0.04 for pain and p = 0.05 for function). Four patients required repeat revision during the follow-up period.

Conclusions: Patients with better preoperative pain scores and fewer comorbidities have better outcomes following revision total hip arthroplasty. Although the time that the patient waited for the revision was not predictive of the ultimate WOMAC pain and function scores, we believe that performing revision arthroplasty before the patient has substantial functional compromise potentially improves the outcome.

Level of Evidence: Prognostic Level I. See Instructions to Authors for a complete description of levels of evidence.

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    Aileen M. Davis, Ph.D.
    Posted on June 02, 2006
    Dr. Davis et al respond to Dr El Masry et al
    Outcomes and Population Health, ACREU, Toronto Western Research Institute

    We thank Mahomed A. El Masry and colleagues for their comments and wish to respond to them.

    In order to report the number of participants on combination therapy, the paper data collection sheets would have to be retrieved from storage at great cost as the electronic database does not capture these data.

    El Masry et al correctly indicate that the post-operative pain scores may be confounded by a change in medications. Given that many individuals undergoing joint arthroplasty and, hence, revision arthroplasty have arthritis in multiple joints, it is possible that medication changes related to arthritis as opposed to the surgery were made over a two year period. People may experience problems in another joint or have had some injury that resulted in a medication change and/or affected their WOMAC scores. The WOMAC does specify that the patient is to respond based on their hip in an attempt to prevent this problem. However, we are also aware that questions are starting to be raised as to whether individuals can cognitively separate their experiences so as to ensure that responses are isolated to an individual joint.

    Thank you for the opportunity to respond.

    Mohamed A El Masry
    Posted on May 01, 2006
    Predictors of Functional Outcome Two Years Following Revision Hip Arthroplasty
    Leeds General Infirmary

    To the Editor:

    We read with interest the paper “Predictors of Functional Outcome Two Years Following Revision Hip Arthroplasty". In presenting their results, the authors mentioned that the majority of patients (88 out of 126, 70%) were using Non Steroidal anti-inflammatory medications (NSAIDs) and/or pain medication. In other words, they consider NSAIDs as a non-pain medication. This is a point of contention as NSAIDs are part of the analgesic ladder i.e. a non-narcotic drug (1). In addition, the authors have not been clear about the number of patients being on combination therapy as table II clearly showed all patients to be on monotherapy only.

    Secondly, they compared the preoperative and postoperative analgesic requirements and found a significant difference of 49% and 28% (p<0.001) respectively. This figure only compared patients taking pain medication pre- and post-operatively and not NSAID. However, table II showed a proportional increase in the use of NSAIDs preoperatively (26 patients; 21%) compared to postoperatively (55 patients, 44%) which was not commented on by the authors. We can only assume that the patients have been prescribed a NSAID rather than a narcotic / non-narcotic drug throughout their postoperative course for an unknown reason. Hence, the post –operative pain scores may be confounded by this particular factor.


    1. http://bnf.org/bnf/bnf/51/3457.htm

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