New knees are becoming old hat. For every 10, 000 Medicare enrollees, 62.1 have received a total knee arthroplasty (TKA) procedure. The number of procedures jumped 162%—to 243, 802—from 1991 to 2010 and the per capita rate rose 99%. This is according to an analysis of fee-for-service Medicare records by Peter Cram, M.D., MBA, of the University of Iowa in Iowa City and reported by Crystal Phend of MedPage Today.
While patients stayed for shorter and shorter periods of time in the hospital, that cost saving was offset by rising readmissions and complications in revision procedures, particularly those related to wound infections, Cram and his associates reported in their article in the September 26 issue of the Journal of the American Medical Association.
“This growth is likely driven by a combination of factors including an expansion in the types of patients considered likely to benefit from a TKA, an aging population, and an increasing prevalence of certain conditions that predispose patients to osteoarthritis, most notably obesity, ” they wrote.
According to Phend, Cram’s group analyzed the records of 3.3 million Medicare Part A beneficiaries ages 65 and older who had a primary knee replacement and 318, 563 who had a revision procedure. They found that the trends in utilization from 1991 to 2010 showed a 162% increase in the total volume of primary procedures from 93, 230 to 243, 802; a 106% rise in revision TKA volume, from 9, 650 to 19, 871; and a 99% increase in the per capita rate of primary knee replacement from 31.2 to 62.1 per 10, 000 Medicare enrollees. Finally, there was a 59% increase in per capita revision procedures, from 3.2 to 5.1 per 10, 000 Medicare enrollees.
The researchers questioned whether the growth in TKAs reflected the fact that it was an “appropriate use of a highly effective procedure or overuse of a highly reimbursed procedure for which indications still depend on clinical judgment.” In other words—was the procedure urged on the patient by the doctors? “It is likely that both factors are at play, ” they wrote.
Patients’ hospital length of stay fell from an average of 8 days for a primary knee replacement in the 1991-1994 time period to 4 days in 2007-2010 and from 9 days to 5 for revision procedures over the same time period. The authors speculated that the shortening length of stay reflected changes in the payment system that provided a powerful incentive for hospitals to speedily discharge patients to their homes or skilled nursing facilities.
Phend reported that revision procedures were associated with a more than doubling in readmission rates for wound infection from 1% to 3% and more than a 100% increase in readmissions for hemorrhage, sepsis, and heart attack. Patients who returned to the hospital soon after their procedure tended to be older, male, black and sicker with comorbidities.
The researchers discovered that centers that did more knee replacements were associated with lower readmission rates for both primary and revision procedures. Surprisingly, a significant percentage of TKAs were performed by surgeons doing fewer than 12 cases a year.
Reflecting this fact, the researchers wrote, “Careful consideration should be given to whether the majority of these cases should be shifted toward high-volume centers, which often have the infrastructure and the experience needed to develop the highly coordinated care pathways necessary to optimize the quality outcomes and efficiency of the episode of care for complex patients.”
