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Cover of Total Knee Replacement

Total Knee Replacement

Evidence Reports/Technology Assessments, No. 86

Investigators: , MD, , MD, MSc, FRCSC, , MD, MPH, , PhD, , BA, , MS, and , BS.

Rockville (MD): Agency for Healthcare Research and Quality (US); .
Report No.: 04-E006-2ISBN-10: 1-58763-097-4

Structured Abstract


The projected growth in the population with arthritis is likely to expand the future demand for elective arthroplasty. At present, there is no strong empirical base for the indicators in current use for what criteria should be used to identify potential candidates for Total Knee Arthroplasty (TKA); nor is there professional consensus around such indications. An NIH consensus conference has been planned to address these questions. This report summarizes the literature as part of the background for that conference.


A systematic review of the literature was undertaken to address four questions: 1. What are the current indications for, and outcomes from, primary total knee replacement? 2. How do specific characteristics of the patient, material and design of the prosthesis, and surgical factors, affect the short-term and long-term outcomes of primary total knee replacement? 3. Are there important perioperative interventions that influence outcomes? 4. What are the indications, approaches, and outcomes for revision total knee replacement? 5. What factors explain disparities in the utilization of total knee replacement in different populations? 6. What are the directions for future research?

Data Sources:

The primary TKA literature search was performed by the National Library of Medicine, which searched PubMed from 1995 to April 2003. The access search was done using PubMed and covering the period from 1990 through April 2003. The literature search on revisions was done in two stages. A prior Medline search covering the period from 1996 through 2000 was the basis for a meta-analysis. An updated search using PubMed covered 2001 through April 2003.

Study Selection:

The nature of this topic required heavy reliance on observational studies. The major criteria for identifying studies for inclusion in the indications for TKA search required that they address primary TKAs, have at least pre and post surgery data using at least one of four standard functional measures (Knee Society [KS] score, Hospital for Special Surgery [HSS] score, WOMAC, or SF-36), have a sample size of at least 100 total knee replacements, be published in English, and utilize tricompartment TKA. Sixty-two studies met the full inclusion criteria. The selection of studies on access required that they examine the relationship of at least gender or race to the performance of primary TKAs. Six articles were included. The same inclusion criteria applied to primary TKAs were applied to the update of the TKA revision study. Fourteen articles met the criteria.

Data Extraction:

Data were abstracted by trained abstractors using a standardized abstraction tool that had been pilot tested and reviewed by the Technical Expert Panel. For the indicators search, the original abstractions were reviewed to assure reliability. All articles meeting the inclusion criteria were independently re-reviewed by each of the three principals. Information related to study and patient characteristics, baseline and followup functional status measures, perioperative complications, and revision rates were extracted using a standardized abstraction tool that had been pilot tested. The access data was abstracted by a subset of the original abstractors using another standardized tool. The TKA revision update was abstracted by an abstractor and one principal using a modification of the primary TKA tool.

Data Synthesis:

Both TKA and total knee arthroplasty revision (TKAR) are associated with improved function. The strongest evidence exists over a followup period of up to two years, but the studies that extend to five and even ten years of followup show positive results as well. The average age of patients undergoing TKA in these reports was 70 years with few over aged 85. Two-thirds were female, one third were considered obese, and nearly 90% had osteoarthritis. No studies provided data on racial/ethnic status. The mean effect size (expressed as numbers of standard deviations) is considered large in magnitude and varies from 1.6 to 3.9 depending on the functional measure used and the duration of followup. There is no evidence that age, gender, or obesity are strong predictors of functional outcomes. Patients with rheumatoid arthritis show more improvement than those with osteoarthritis, but this may be related to their poorer functional scores at the time of treatment and hence the potential for more improvement. The revision rate through five or more years is 2.0% of knees and 2.1% of patients. Complications as defined by the investigator occurred in 5.4% of patients and 7.6% of knees. Patients with rheumatoid arthritis show more improvement than those with osteoarthritis. With regard to access, nonwhites receive TKAs less often than whites despite higher rates of osteoarthritis. Women receive TKAs more often than men, but the pattern is not as consistent as with race. TKA revisions are associated with consistent improvement in function on an order of magnitude similar to primary TKAs.


In general, the outcomes research on TKAs emphasizes before and after studies that are variations on case series of various techniques and prostheses with little attention to the role of other factors or to attrition. Although demographic and clinical factors are recorded, they are rarely used in the analysis. A consistent body of evidence suggests substantial improvement in function associated with TKA and TKAR. The follow-up periods vary but the mean is greater than five years. More informed decision making about indicators for TKAs will require stronger research designs. These need to be planned as prospective studies with multivariate analysis. Such analyses will require larger samples and more consistent and comprehensive data collection than was found in this review.


Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services.1 Contract No. 290-02-0009, Task Order #2. Prepared by: Minnesota Evidence-based Practice Center, Minneapolis, Minnesota.

Suggested citation:

Kane RL, Saleh KJ, Wilt TJ, Bershadsky B, Cross WW III, MacDonald RM, Rutks I. Total Knee Replacement. Evidence Report/Technology Assessment No. 86 (Prepared by the Minnesota Evidence-based Practice Center, Minneapolis, MN). AHRQ Publication No. 04-E006-2. Rockville, MD: Agency for Healthcare Research and Quality. December 2003.

This report may be used, in whole or in part, as the basis for development of clinical practice guidelines and other quality enhancement tools, or a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

AHRQ is the lead Federal agency charged with supporting research designed to improve the quality of health care, reduce its cost, address patient safety and medical errors, and broaden access to essential services. AHRQ sponsors and conducts research that provides evidence-based information on health care outcomes; quality; and cost, use, and access. The information helps health care decisionmakers—patients and clinicians, health system leaders, and policymakers—make more informed decisions and improve the quality of health care services.

The authors of this report are responsible for its content. Statements in the report should not be construed as endorsement by the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services of a particular drug, device, test, treatment, or other clinical service.


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Bookshelf ID: NBK37123


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