Common knee osteoarthritis jab 'ineffective' - Study

AN injection commonly used to treat osteoarthritis in knees is hardly better than a placebo for relieving pain and increases the risk of harmful side effects, according to research.

Injections of hyaluronic acid have been prescribed since the 1970s, but despite previous research indicating the treatment is ineffective, its use has continued -- and even increased -- in some countries.

Knee osteoarthritis is a leading cause of disability among older people, the study said, citing 2020 research which found that more than 560 million people suffer from the condition worldwide.

It causes deterioration of the cartilage in knee joints, leading to pain and often difficulty walking.

Hyaluronic acid, a gel-like substance, has long been injected into the joint aiming to lubricate movement and decrease pain. The treatment is also known as viscosupplementation.

A meta-analysis published in the BMJ journal looked at 169 previous trials that compared the injections to a placebo -- or no treatment.

The researchers then whittled that down to 24 large placebo-controlled trials involving nearly 9,000 patients, in what is the largest review of the available data so far.

They found "strong conclusive evidence" that "viscosupplementation is associated with a clinically irrelevant reduction in pain intensity", the study said.

They also said the treatment is "associated with a higher incidence of serious adverse events", adding that it is "not only ineffective compared with a placebo but might also be seriously harmful".

- 'Don't need new trials' -

One of the study's authors, Bruno da Costa of the University of Toronto, and his team carried out a similar review of the available research in 2012 -- and found the same results.

"We don't need new trials," he told AFP, saying the latest results were conclusive.

He said that further research could be done into whether a sub-group of patients could benefit from the treatment -- but for the typical patient it should be considered at best as a last resort.

Since the team's 2012 research, several large-scale, industry-funded studies were carried out that found negative results about the treatment.

But those studies were never published, da Costa said.

"This is concerning, and perhaps mainly driven by commercial interests," he added.

Thursday's study suggested that more than 12,000 patients were unnecessarily subjected to the treatment between 2009 and 2021, given the compelling research already available at that point.

France's social security system stopped offering reimbursements for the treatment a few years ago, despite the opposition of specialists who prescribe the injections, companies that produce hyaluronic acid, and some patients' groups.

England's National Institute for Health and Care Excellence recommends against viscosupplementation.

In the United States, however, the treatment's use grew considerably from 2012 to 2018, the study said, with one in every seven patients with the condition receiving an injection. For many it was first treatment they were given.

The study also said that a quarter of the money that US Medicare spent on viscosupplementation in 2018 went towards treating infections in joints following an injection, one of the most common side effects.