Acetaminophen is the most commonly used pain reliever for knee osteoarthritis, but it is not as effective as ibuprofen, naproxen and other over-the-counter pain medications, according to a new study being published in the Annals of Internal Medicine.
Knee osteoarthritis (OA) is a common and progressive joint disease affecting over 250 million people worldwide. Nearly 40 percent of Americans over the age of 45 have some degree of knee OA, and those numbers are expected to grow as the population ages.
“This increased prevalence of knee OA will lead to many persons living with chronic pain. To improve quality of life and minimize disability, these patients will need effective pain control. However, it is not necessarily clear which therapies work best for OA pain,” wrote Lisa Mandl, MD, of Hospital for Special Surgery in New York and Elena Losina, PhD, of Brigham and Women’s Hospital in Boston in an editorial also published in Annals of Internal Medicine.
“One reason for therapeutic uncertainty is that more than half of OA pain studies and over 80% of those funded by the industry are less than 6 months in duration. Osteoarthritis is a chronic disease, and results from short randomized, controlled trials may not necessarily reflect long-term responses.”
Another deficiency in research is that there are few head-to-head studies comparing the many oral nonsteroidal anti-inflammatory drugs (NSAIDs) and injectable therapies that are used to treat knee OA.
In effort to find which treatments work best, researchers at Tufts Medical School and Brown University School of Public Health conducted a systematic evidence review (a study of studies) of 137 published clinical trials that compared two or more of the following in knee OA patients: acetaminophen, diclofenac, ibuprofen, naproxen, celecoxib, corticosteroid injections, hyaluronic acid injections, oral placebo, and placebo injections.
After three months of treatment, all oral medications were found to be significantly better than oral placebo for relieving pain from knee OA. But acetaminophen was shown to be the least effective option. Naproxen, ibuprofen, diclofenac, and celecoxib were all significantly better than acetaminophen at relieving pain.
Corticosteroid and hyaluronic acid injections proved to be the most effective treatment for knee OA pain. Even placebo injections were better than oral NSAIDs, suggesting a placebo effect in the delivery method.
“One striking aspect of our results is that IA therapies (injections) were the most effective treatments for knee OA pain. This result is especially salient for hyaluronic acid, which is a treatment generally considered by expert panels to be minimally effective,” the authors wrote.
“This observation raises many important philosophical and therapeutic questions about the extent to which this benefit is attributable to a true placebo response or physiologic effects after injecting a fluid by means of a needle into the knee joint.”
Injections and medications are not the only ways to relieve pain from knee OA. A combination of diet and exercise was found to be more effective than drugs in reducing knee pain in obese patients, according to research published in JAMA. Nearly 40 percent of the patients enrolled in an intensive weight loss and exercise program had little or no knee pain after 18 months. They also had better mobility, joint function and quality of life.
Even just going for a long walk or joining a dance class can be beneficial. Two recent studies found that both activities can significantly reduce pain and improve mobility in older adults with knee OA.