An injection commonly used to treat osteoarthritis of the knees is little better than a placebo at relieving pain but increases the risk of harmful side effects, a study found Thursday.
Injections of hyaluronic acid have been used for the disease since the 1970s, but the new study adds to growing doubts about the treatment.
Osteoarthritis of the knee is a leading cause of disability in older people, according to the study, citing research from 2020 that found more than 560 million people suffer from the condition worldwide.
It causes deterioration of the cartilage in the knee joints, leading to pain and often difficulty in walking. Hyaluronic acid, a gel-like substance, has long been injected into the joint for the purpose of lubricating movement and decreasing pain. The treatment is also known as viscosupplementation.
A meta-analysis published in the journal BMJ looked at 169 previous trials comparing injections with placebo – or no treatment.
The researchers then narrowed that down to 24 large trials involving nearly 9,000 patients, the largest review of data available to date.
They found “strong conclusive evidence” that “viscosupplementation is associated with a clinically irrelevant reduction in pain intensity,” according to the study.
They also said the treatment is “associated with a higher incidence of serious adverse events”, adding that it is “not only ineffective compared to a placebo, but could also be seriously harmful”.
The study did not rule out the possibility that certain types of patients might benefit from the treatment.
But he said “the results do not support widespread use of viscosupplementation for the treatment of osteoarthritis of the knee.”
More than 12,000 patients were likely subjected to the treatment unnecessarily between 2009 and 2021, given the research already available on the subject at that time, according to the study.
Hyaluronic acid injections have come under intense scrutiny in several countries in recent years.
French social security stopped offering reimbursement for the treatment a few years ago, despite opposition from specialists who prescribe the injections, companies that produce hyaluronic acid and certain patient associations.
The National Institute for Health and Care Excellence in England has guidelines advising against viscosupplementation.
However, in the United States, use of the treatment increased significantly from 2012 to 2018, according to the study, with one in seven patients with the disease receiving an injection.
He added that a quarter of the money spent by Medicare in the United States on viscosupplementation in 2018 was actually for the treatment of joint infections after an injection, one of the most common side effects.