Over a third of the total knee replacements in the U.S. are inappropriate, according to researchers who found that many patients had pain and other symptoms that were too mild to justify having the surgery. Over 600,000 knee replacements are performed annually in the U.S.
During the surgery, doctors replace a diseased or damaged joint with metal or plastic components that allow for continued motion of the knee. Postoperative pain can be severe and recovery periods last 6 weeks or longer, often with extensive physical therapy.
Osteoarthritis, a degenerative joint disease that causes pain and swelling in the knee, is the leading reason why people have the surgery. But some experts believe the procedure is over-utilized and too often recommended by doctors.
In the past 15 years, the number of total knee replacements (TKR) has grown significantly, with studies showing an annual increase of nearly 100% in surgeries between 1991 and 2010. The number of Medicare-covered TKR surgeries grew by 162% annually over the same period.
“To my knowledge, ours is the first U.S. study to compare validated appropriateness criteria with actual cases of knee replacement surgery,” said lead author Dr. Daniel Riddle from the Department of Physical Therapy at Virginia Commonwealth University.
Riddle and his colleagues evaluated 175 knee replacement patients who were enrolled in the Osteoarthritis Initiative — a 5-year study funded by the National Institutes of Health. They used an evaluation system developed by Escobar et al. along with the Western Ontario and McMaster Universities Arthritis Index (WOMAC) Pain and Physical Function scales.
They found that only 44% of the knee replacement surgeries could be classified as appropriate, with 22% rated inconclusive and 34% deemed inappropriate.
A rating of ‘‘inconclusive’’ indicates that the expected benefits and harms to the patient are roughly equal. An “inappropriate’’ rating indicates the expected harms outweigh the expected benefits.
“Our finding that one third of knee replacements were inappropriate was higher than expected and linked to variation in knee pain OA severity and functional loss. These data highlight the need to develop patient selection criteria in the U.S.,” said Riddle.
The study is being published in Arthritis & Rheumatology, a journal of the American College of Rheumatology.
“The implication that fewer than half of TKRs performed in the U.S. are appropriate and that fully one third are inappropriate raises serious concern about overutilization,” wrote Dr. Jeffery Katz in an editorial also published in Arthritis & Rheumatology.
Katz, a professor at the Orthopedic and Arthritis Center for Outcomes Research at Brigham and Women’s Hospital in Boston, said he was concerned that doctors were offering TKR surgeries to patients who had mild pain and little loss of function in their knees.
“We cannot be sure that TKR will improve such patients at all. I have similar, substantial reservations about performing TKR subjects with no joint space narrowing at all,” he wrote.
“As a community of providers, we implore our patients and the public at large to engage in exercise and physical activity in order to delay functional decline and to preserve and augment functional status. We must consider whether it is advisable and affordable to use costly technology such as TKR in the same fashion.”
Costs can vary depending on the surgeon and insurance coverage, but the average hospital charge for TKR surgery in the U.S. is about $50,000.
A recent study in Germany found that arthroscopic knee surgery provides no benefit to patients with osteoarthritis, and does not relieve pain any better than physical therapy or over-the-counter pain medications.
Arthroscopy of the knee is a procedure in which a surgeon inserts a thin tube with a camera through a small incision in the skin to view the inside of the knee. The surgeon removes damaged cartilage and loose bone by flushing the knee joint with saline solution.
Osteoarthritis is the most common form of arthritis, and affects more than 27 million Americans and over 100 million people worldwide. Osteoarthritis of the knee is more prevalent and severe in women, elderly and the obese.