Increasing Use of Total Knee Replacement and Revision Surgery

Abstract

IN THIS ISSUE OF JAMA, CRAM AND COLLEAGUES 1 report detailed analysis of primary and revision total knee replacement (TKR) performed on more than 3.2 million Medicare beneficiaries from 1991 to 2010. This analysis confirms and quantifies several important findings. First, the use of primary and revision TKRs in Medicare beneficiaries has increased both in absolute volume from 93 230 procedures in 1991 to 226 177 procedures in 2010 and in per capita usage. Second, the pattern of care has changed substantially. Between 1991 and 2010, length of hospital stay for primary TKR decreased from 7.9 to 3.5 days and revision TKR from 8.9 to 5.0 days. However, 30-day all-cause readmission rates after primary TKR increased from 4.2% in the years 1991-1994 to 5.0% in the years 2007-2010 and after revision TKR increased from 6.1% in the years 1991-1994 to 8.9% in the years 2007-2010. A clear change in the pattern of discharge status also occurred with a shift initially to a more institutionalized setting, and recently to a discharge to home with home care services (ie, discharges to patients’ homes decreased from 67.5% in the years 19911994 to 39.9% in the years 1999-2001 then increased to 56.2% in years 2007-2010). In addition to the increase in readmissions, the data demonstrated an important increase in infection rates for revision cases, increasing from 1.4% in the years 1991-1994 to 3.0% in the years 2007-2010. The first question to consider is what is driving the increased utilization. While there are different contributing factors, more importantly this report may be describing only the surface of what is expected to be a profound increase in knee arthroplasty over the next 30 years. By 2030, the demand for TKR in the United States is projected to be as high as 3.48 million procedures annually. Cram et al address only Medicare beneficiaries, but the number of younger individuals (and those without Medicare) undergoing knee replacement is also expected to continue to increase. This is particularly true considering the development of newer arthroplasty procedures used to treat degenerative arthritis in younger patients, such as bicompartmental and unicondylar knee replacements, which have been shown in select studies to be the most rapidly increasing arthroplasty treatment in this younger population. These projections will make TKR a key driver of health care cost, which makes this procedure worthy of careful consideration. This is particularly challenging given the magnitude of the predicted increase and because, as the authors discuss, many studies have demonstrated that TKR is a cost-effective procedure that may improve patients’ activity and health-related quality of life. Although health benefits are difficult to quantify, this expenditure could potentially decrease the allocation of health care resources used by patients having knee replacement over the remainder of their lifetime. Consequently, the ideal number of knee replacements that should be performed per capita is unknown. Although the study by Cram et al suggests that recent stabilization in rates of TKR procedures appears to have occurred, the authors suggest several explanations for the per capita increase, including expansion of indications and the increased prevalence of obesity, which combined with the increase in the number of patients eligible for Medicare has led to the significant increases in utilization reported. Another factor is the increased demand for an active lifestyle in this age group. Furthermore, increased efforts are needed to identify and address predisposing modifiable factors, such as obesity that lead to the need for knee replacement, and to advance efforts at early intervention strategies to treat mild arthritis and to prevent progression of the disease obviating the need for eventual arthroplasty. The cost of TKR over the next 20 years will be driven by the absolute number of primary procedures performed, the increasing number of more costly revision procedures, and