DURHAM, North Carolina—Senior citizens who undergo total knee arthroplasty (TKA) show long-term, significant improvements in physical functioning and motor skills, of the type likely to help them stay out of nursing homes, according to a new study in the July 2009 issue of Medical Care.¹

"Knee replacements are effective in treating patients with advanced osteoarthritis, contributing to reduced disability and improved quality of life for these individuals,” said lead researcher Frank Sloan, PhD, the McMahon professor of health policy and management and professor of economics at Duke University in Durham, NC. “Such findings are extremely important for the broader context of discussions about healthcare reform, cost-containment, device quality, and patient safety."

Adults aged 65 and older who underwent total knee replacement showed a 17.5% increase in mobility, a 39.3% improvement in motor skills, and a 46.9% decrease in limitations in activities of daily living such as bathing and dressing oneself, when compared to their counterparts who did not have TKA, the study showed. The study followed patients for 4 years. Most other studies in the literature assess such outcomes over a shorter period of time, the researchers note. Moreover, those studies that did have similar follow-up periods did not include control groups.

The new study culled data on 2,272 people from the Health and Retirement Study (HRS) and linked it to Medicare claims from 1994 through 2006. Of these, 516 individuals underwent total knee arthroplasty and 1,756 did not. Researchers used propensity score matching to generate 515 pairs of treated and untreated individuals. Subjects were matched on baseline functional status, other health conditions, socioeconomic characteristics, and time before TKA or diagnosis. Each pair was followed for up to 4 years.

Study strengths include solid matching and long follow-up  

“We are looking at a pretty well-matched control group,” said Sloan. “Some of the studies just follow [TKA] patients, so we don’t know how patients would have done if they had not gotten knee replacement.”

Therein lies one of the major strengths of this study, he told MSKreport.com. “We have pretty good matching of treatment and controls.”

“We are now in a situation where we can say that TKA preserves certain key function of daily living and we know that limits on activities of daily living lead to nursing home use,” he says. “Keeping people functioning independently is very desirable outcome and that is probably also true for cost-containment.”

References

1. Sloan FA, Ruiz, Jr. D, Platt A. Changes in functional status among persons over age sixty-five undergoing total knee arthroplasty. Medical Care. 2009; 47:742-748.