Feb. 17, 2011 (San Diego) -- Knee replacement patients tend to remain active 20 years after their surgery, despite some age-related declines, according to a new survey of 128 patients.
"If you have a good knee replacement and are blessed with good health, you have an excellent chance of walking as much as you want and doing activities such as swimming, golfing, and riding a bike, into your 80s," researcher John B. Meding, MD, tells WebMD.
He is presenting his findings this week at the annual meeting of the American Academy of Orthopaedic Surgeons (AAOS) in San Diego.
The study, based on evaluations of patients cared for by Meding's group practice in Mooresville, Ind., was launched because of patient concerns about how well they will function several years after the original surgery and whether they will need revision surgery.
The activity level of the patients, evaluated 20 years or more after the surgery, surprised Meding. He says the activity level was higher than he expected.
Knee Replacement Study: Details
Meding and his colleagues first identified 1,757 total knee replacement surgeries done at their practice. All had a type of surgery known as primary cruciate-retaining surgery. Meding says he wanted to study just one type of knee replacement approach to minimize differences from surgery type.
From that pool, the researchers looked at 128 patients still living at the 20-year follow-up. In this group there were 171 knee replacements, done at an average age of about 64.
The researchers evaluated the patients with standard measures that looked at how well they could do everyday activities, such as climb stairs and walk.
''There were only three patients who were what we would consider housebound," Meding says. ''Seventy percent (95 patients) could walk at least five blocks."
"Half thought their walking was unlimited," he says. ''All but one patient could negotiate stairs." Some needed help to do so, such as using rails, he says.
The researchers also evaluated 62 of the patients who had 98 knee replacements using another measure, the UCLA activity score. ''You would expect people in their 80s to have a UCLA score of 5 to 6," he tells WebMD. "The average UCLA activity score was 8.3 out of 10. This was rather amazing. We were expecting much lower scores."
About 581,000 knee replacements are done annually in the U.S., according to the AAOS, often after the knee is severely damaged by arthritis or injury.
Meding's group, the Joint Replacement Surgeons of Indiana, reports receiving research funding for other studies from Zimmer and BioMet, makers of joint replacement technologies. The recent study was not funded.
Knee Replacement: Another View
''Total knee replacements have been shown repeatedly to be cost-effective treatments that improve the quality of life for people," says Neil J. Cobelli, MD, chair of orthopaedic surgery for Montefiore Medical Center and professor of surgery at Albert Einstein College of Medicine in New York.
He reviewed the study findings for WebMD. The study confirms those facts and adds information, he says. "Now we are seeing that effectiveness continues for a long time,'' he says."Roughly 90% of knee replacements done after 60 years of age last a lifetime."
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.