Viscosupplementation (Gel Shots) For Your Knees?

Picture from whichmedicaldevice.com

Many of our patients have been asked to do a hyaluronic acid injection when told that their knees were "worn out" due to osteoarthritis.

Hyaluronic acid injections (also commonly known as gel shots) are thought to help with restoring the joint fluid (synovial fluid) composition to help with lubricating and providing shock absorption to the joint. They are often suggested for patients with mild to moderate osteoarthritis to alleviate pain, reduce friction and hopefully delay surgery (total knee replacement).

The following paper is a *systematic review and meta-analysis of the largest collection of randomised trials of whether hyaluronic injections are helpful for knee osteoarthritis.

169 trials involving 21,163 patients were first identified through searches from Medline, Embase and Cochrane Register of Controlled trials. Only randomised trials with more than 100 participants per group comparing viscosupplementation with placebo or no intervention were accepted. Patients were usually given a single course of 2 to 6 injections.

Of these, 24 large, placebo controlled trials (8997 randomised patients) were included in the main analysis found that viscosupplementation (or using hyaluronic acid injections) offered a small but strong conclusive reduction in pain intensity compared with a placebo injection. 

This translated to a margin of 5 mm on a 100 mm visual analogue pain scale (or half a point on a scale of 0-10). That's a really tiny pain reduction in my opinion.

However, based on 15 large, placebo controlled trials (6463 patients), viscosupplementation was associated with a statistically significant higher risk of serious adverse events compared to a placebo.

Serious adverse events were defined as resulting in hospital admission, prolonged hospital stay, persistent or major disability, congenital abnormality of offspring, life threatening events or death.

Hence, the authors of this systematic review concluded that the findings do not support the use of viscosupplementation for the treatment of knee osteoarthritis.

Still keen on getting a hyaluronic acid injection? Mark Philippoussis (nicknamed "The Scud" after the scud missile), was a former professional tennis player known for his awesome serve. He famously used hyaluronic acid injections every 6 months for his knees to enable him to keep playing after 3 knee operations. 

But he was a former professional who was a finalist in the 1998 US Tennis Open and 2003 Wimbledon Tennis tournament.

Reference

Pereira TV, Juni P, Saadat P et al (2022). Viscusupplementation For Knee osteoarthritis: Systematic Review And Meta-analysis. BMJ. 378: e069722. DOI: 10.1136/bmj-2022-06972

*A systematic review meta analysis is a search aided by computer looking for all randomized and clinically controlled studies while a meta-analysis means using statistics to combine the data derived from a systematic review.