The Effects of Total Knee Arthroplasty on Physical Functioning in the Older Population

Arthritis & Rheumatism. 2008;58(10):3166-3171. 

Studies have shown that total knee arthroplasty (TKA), or total knee replacement, is safe and improves problems related to the knee, such as pain and range of motion. It is not as clear, however, if this type of surgery improves overall physical functioning. A new study, the first to examine the effects of total knee replacement on physical function using national data, found that the surgery was associated with significant improvements in elderly patients. The study is published in the October issue of Arthritis & Rheumatism ( ).

Led by Linda K. George of Duke University in Durham, N.C., researchers used data from the Medicare Current Beneficiary Survey and claims data collected between 1992 and 2003 to identify individuals who were at least 65 years old and had been diagnosed with osteoarthritis of the knee but had not yet undergone knee replacement surgery.

The study ultimately included 259 individuals who underwent a knee replacement during the study period and 1,816 individuals who did not have the surgery. The researchers evaluated physical functioning at three different levels using three scales that required differing levels of strength, mobility and stamina. These included a disability scale that assessed the ability to stoop/crouch, walk two to three blocks and lift weights up to 10 pounds; a scale that measured the ability to perform daily activities such as housework, preparing meals and shopping; and another daily activities scale that included bathing/showering, getting dressed, getting in and out of a chair, walking, and using the toilet.

The results showed that total knee replacement was associated with improvements in both basic and advanced activities of daily living. Those who had knee replacements improved significantly in their ability to bathe, do both light and heavy housework, shop, walk two to three blocks and lift weights up to 10 pounds. Those who did not undergo the surgery showed an overall decline in physical functioning. Although the results were based on participants' reports of how well they functioned, previous research strongly suggests that older adults accurately report their functional capabilities.

Rates of disability in the older population have been steadily declining since the 1980s. Experts typically attribute this decline to the long-term effects of public health measures introduced in the last century, rising levels of socioeconomic status, and better health habits. "Improvements in medical care are only rarely suggested as contributors to declining disability rates, although substantial research has reported the importance of improvements in health care for longevity." the authors note.

"Joint replacement is one likely way that medical care is contributing to declining rates of disability in the older population," the researchers conclude, adding that additional research examining the effects of medical procedures on disability should be a high priority.



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