A Medical Device Daily

More than 10 million Americans are afflicted with osteoarthritis, a type of arthritis caused by the breakdown and eventual loss of cartilage. Left unchecked the disease becomes increasingly painful and gradually decreases mobility and quality of life.

A recent study by researchers at Duke University (Durham, North Carolina) indicates that patients with osteoarthritis of the knee who undergo a total knee replacement along with other forms of treatment such as medication and physical therapy are able to have a much stronger sense of mobility, than those who go untreated from osteoarthritis, no matter what their age is.

"Our motivation for the study was to show that while you have many, many, many, clinical trials that establish efficacy of the knee replacements, there are few that show the benefits, over time, of having such a procedure completed," said Linda George, PhD, professor of sociology and associate director of the Duke Center for the Study of Aging. "Those who didn't use the knee replacements declined even further," she told Medical Device Daily.

The knee implants used came from a "hodge podge" of different companies, George said.

George led the study, which was published in this month's edition of Arthritis & Rheumatism and supported by a grant from The Institute for Health Technology Studies (Washington); its co-authors are Frank Sloan, PhD, and David Ruiz, Jr.

National data for the study was taken from the Medicare Current Beneficiary Survey, a randomly selected group of Medicare beneficiaries who represent 96% of the U.S. population, age 65 and older.

The Duke researchers looked at 259 patients who received total knee replacement and 1,816 patients who did not. They found that those who underwent the procedure performed better on three separate forms of measurement, representing different levels of strength and mobility that included heavy to light housework, walking a few blocks and lifting weights up to 10 pounds.

The study showed that patients who received total knee replacement improved over time, whereas physical functioning declined in those who did not. Patients who were disabled at the time of surgery transitioned out of disability within one year of the procedure.

According to the National Institutes of Health, only 13% of men and 9% of women who could benefit from the procedure choose to receive it. George speculated this could be due to the fact that total knee replacement is an invasive treatment with an intense rehabilitation period.

"This may explain why physicians are less likely to present the total knee replacement as an option to those patients 85 years of age and older, and why there may be some reluctance among patients," she said.

"One of the things we also wanted to look at is the cost effectiveness of the knee replacement," she said.

According to the study findings, reimbursement for the surgical procedure (averaging $4,000-$6,000) proves less costly than the long-term cost of healthcare for the disabled health economists estimating savings associated with a year of a disability-free life at nearly $50,000. And the Duke researchers said it is cost-effective compared to the related healthcare costs incurred by disabled patients, such as hospital stays, nursing homes and home healthcare.

The study went on to show that older patients who received the procedure were twice as likely as those who did not to show improved physical mobility.

The study's findings, the researchers said, should help doctors and patients make more informed decisions when considering the procedure.

"We found that patients improved on all levels, which is important because it shows that the procedure allows individuals to remain independent, take care of themselves and ultimately improve their quality of life," George said. "Physicians should feel confident in recommending the procedure to patients who are eligible."

Since the patients observed were Medicare service recipient, the group was limited by not looking at patients who were younger than 65.

In time, George said, she hopes to correct this and assemble a broader patient population list. "We'd sure like to look at younger patients but we haven't found a data set," she said.

A possible alternative would be to look at insurance companies, but those agencies keep records on "medical utilization" of the device and don't go into detail about recovery from the disability, George said. Medicare has the only database that goes into detail about both.