RT Journal A1 Lyman S, Marx RG, Bach PB T1 COst-effectiveness analysis of an established, effective procedure JF Archives of Internal Medicine JO Archives of Internal Medicine YR 2009 FD June 22 VO 169 IS 12 SP 1102 OP 1103 DO 10.1001/archinternmed.2009.144 UL http://dx.doi.org/10.1001/archinternmed.2009.144 AB The number of total knee arthroplasty (TKA) procedures performed in the United States has been rising rapidly. In 2006, approximately 500 000 TKAs were performed, incurring direct medical costs of roughly $11 billion (our unpublished estimate). Use of this procedure is expected to continue to rise due to both the obesity epidemic and the aging of the population. One study estimates that 3.5 million TKAs will be performed annually by the year 2030.1 The increasing use of this procedure has prompted an increased interest in its evaluation. For instance, national TKA registries now exist in Australia, Denmark, Norway, and Sweden. The US Food and Drug Administration (FDA) has begun exploring the possibility of a national TKA registry to help to evaluate the potential strengths and weaknesses of different implant designs.2