Knee replacement surgery keeps one active even after 20 years: Study

By Dr. Ananya Mandal, MDFeb 20 2011

A latest study has shown that patients with artificial knees were still functional after 20 years, even jogging or playing tennis. The researchers looked at people who had knee replacements between 1975 and 1989 in the state of Indiana and noted that they lived for another 20 years maintained an active lifestyle. All reported at least “moderate” activity.

Study author Dr. John B. Meding said, “The whole point of having a total joint replacement is to maintain a functional knee that allows patients to maintain a good deal of activity for a long time…This shows it lasts 20 years or more after the [operation]…If you get a good knee and treat it well, and are blessed to live long enough, even after 20 years you can maintain this level of activity.” Meding is an orthopedic surgeon at the Center for Hips and Knee Surgery at St. Frances Hospital Mooresville, in Mooresville, Ind.

The results were presented on Thursday at the annual meeting of the American Association of Orthopedic Surgeons held from Feb. 15 to 19 in San Diego. Although experts warn that the findings are preliminary the study has generated interest. Knee replacement surgery, also called knee arthroplasty, is done to relieve pain and restore normal use of the joint, usually for people afflicted by severe arthritis. There are between 300,000 and 500,000 knee replacement surgeries done annually in the United States, said Dr. Howard Luks, an orthopedic surgeon at Westchester Medical Center in New York.

For this study the team involved 1,757 patients who had knee replacements at St. Frances during the time span examined, 128 were still living after their 20-year follow-up. The average age at the time of the procedure was about 64. The vast majority of patients in the study had osteoarthritis (82 percent) and most of them were females (78 percent). They were examined for knee flexibility, walking distance, ability to climb stairs and level of pain. All but two patients could use stairs, only three were housebound, and 95 could walk at least five blocks. Many (82) were able to walk indefinitely, and 81 were pain-free. Against doctors’ advice, 22 participated in hard-impact sports - such as jogging, volleyball and tennis - some with both knees replaced.

“Although aging may cause a gradual decline in physical activity after TKR, improved functional outcomes continue over the long term. Our results indicate that this group of patients demonstrates remarkable functional capacity over 20 years after the index arthroplasty,” the authors write.

Dr. Luks, chief of sports medicine at the facility added that this study is important for younger patients and those in their late 50s who are considering a knee replacement but are hesitant because they worry it will wear out. “Until this time, I have been telling my patients the surgery is good for 15 to 20 years, but this is showing good to excellent results that can last 20 years and beyond…Now I can tell patients there is early evidence showing it can last more than 20 years…but I can’t say it’s beyond a reasonable doubt,” said Luks.