Scientific Article   |    
Validity and Responsiveness of the Knee Society Clinical Rating System in Comparisonwith the SF-36 and WOMAC
Elizabeth A. Lingard, BPhty, MPhil, MPH; Jeffrey N. Katz, MD, MS; R. John Wright, MD; Elizabeth A. Wright, PhD; Clement B. Sledge, MD
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Elizabeth A. Lingard, BPhty, MPhil, MPH
Department of Trauma and Orthopaedic Surgery, The Medical School, University of Newcastle upon Tyne NE2 4HH, England

Jeffrey N. Katz, MD, MS
Elizabeth A. Wright, PhD
Robert Brigham Multipurpose Arthritis and Musculoskeletal Diseases Center, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115

R. John Wright, MD
Clement B. Sledge, MD
Department of Orthopedic Research, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115

The Kinemax Outcomes Group included participants from three countries. In the United Kingdom, the participants included William Gillespie, Colin Howie, Ian Annan, Alastair Gibson, and Judith Lane, Princess Margaret Rose Hospital, Edinburgh; Ian Pinder, David Weir, Nigel Brewster, and Karen Bettinson, Freeman Hospital, Newcastle upon Tyne; Maurice Needhoff and Roz Jackson, King’s Mill Centre, Mansfield; Tim Wilton and Peter Howard, Derbyshire Royal Infirmary, Derby; Ian Forster, Paul Szyprt, Chris Moran, David Whitaker, Mike Bullock, and Zena Hinchcliffe, Queen’s Medical Centre, Nottingham; and Ian Learmonth, John Newman, Chris Ackroyd, George Langkamer, Robert Spencer, Mark Shannon, Evert Smith, John Dixon, and Sarah Whitehouse, Avon Orthopedic Centre, Bristol. In the United States, the participants included Clement Sledge, Frederick Ewald, Robert Poss, John Wright, Scott Martin, John Kwon, and Yvette Valderamma, Brigham and Women’s Hospital, Boston; Steven Harwin and Michael Lichardi, Beth Israel Medical Center, New York; Mark Mehlhoff, Linda Weiler, and Tom Cahalan, Iowa Medical Clinic, Cedar Rapids; and Richard Cronk and Allyson Sandago, Neuromuscular and Joint Center, Corvallis. In Australia, the participants included Stephen Rackemann and Emma McLaughlin, The Knee Centre, Gold Coast, and Peter Lewis, Robert Bauze, Gordon Morrison, Tom Stevenson, and Jane Clasohm, Queen Elizabeth Hospital, Adelaide.

In support of their research or preparation of this manuscript, one or more of the authors received grants or outside funding from Stryker/Howmedica, Rutherford, New Jersey, and Limerick, Ireland, and National Institutes of Health Grant AR36308. In addition, one or more of the authors received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity (Stryker/Howmedica). 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.

J Bone Joint Surg Am, 2001 Dec 01;83(12):1856-1864
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Background: The aim of this study was to validate the Knee Society Clinical Rating System (knee and function scores) and to compare its responsiveness with that of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the Medical Outcomes Study Short Form-36 (SF-36).

Methods: Patients were recruited as part of a prospective observational study of the outcomes of primary total knee arthroplasty for the treatment of osteoarthritis in four centers in the United States, six centers in the United Kingdom, and two centers in Australia. Independent research assistants at each site collected the Knee Society clinical data. The WOMAC, SF-36, patient satisfaction, and demographic data were obtained with self-administered questionnaires.

Results: A total of 862 eligible patients were recruited, and complete preoperative and twelve-month data were available for 697 (80.9%) of them. The mean age was seventy years (range, thirty-eight to ninety years), and the majority of the patients (58.9%) were women. Low correlations were found among the items of both the knee and the function score at both assessment times. The Knee Society pain and function scores had moderate-to-strong correlations with the corresponding pain and function domains of the WOMAC and SF-36 (r = 0.31 to 0.72). Measurement of the standardized response mean showed the Knee Society knee score to be more responsive (standardized response mean, 2.2) than the WOMAC (standardized response means, 2.0 for pain and 1.4 for function) and the SF-36 (standardized response means, 1.0 for bodily pain and 1.1 for physical functioning). The Knee Society function score was the least responsive measure (standardized response mean, 0.8). Correlation of changes in scores at twelve months with patient reports of satisfaction and improvement in health status showed the WOMAC and SF-36 to be more responsive than the Knee Society scores.

Conclusions: There is a poor correlation among the items of the Knee Society Clinical Rating System, but the rating system has adequate convergent construct validity. The WOMAC and SF-36 are more responsive measures of outcome of total knee arthroplasty. As they are less labor-intensive for researchers to use and as use of these instruments removes observer bias from the study design, they are preferable for knee arthroplasty outcome studies.

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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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