Hardly any treatment for knee osteoarthritis is as controversial as the injection of hyaluronic acid into the joint (viscosupplementation). While some guidelines advise against it, professional societies for bone and joint diseases see a benefit for selected patients. An expert consensus by the European society ESCEO, published in Aging Clinical and Experimental Research in 2026, attempts to provide clarity.
Why hyaluronic acid in the joint?
In healthy joints, hyaluronic acid keeps the synovial fluid viscous and lubricating. In osteoarthritis, its amount and molecular size decrease. The injection is intended to improve “lubrication” and relieve pain; anti-inflammatory effects are also being discussed.
For whom can it be useful?
The ESCEO working group – which included patients as well as rheumatologists, orthopaedic surgeons and rehabilitation specialists – names in particular:
- people with symptomatic knee osteoarthritis in the early to moderate stage (Kellgren-Lawrence grade 2–3),
- symptoms outside an acute inflammatory phase,
- as an active component of an overall treatment plan – together with exercise therapy, weight reduction and analgesics where appropriate – not as a standard therapy for everyone.
Advanced age alone is not a reason for exclusion. However, people over 70, with severe obesity, with advanced osteoarthritis or with osteoarthritis behind the kneecap may respond less well.
What does the evidence say?
- An umbrella review from 2025 found a significant benefit in 20 of 22 systematic reviews.
- A network meta-analysis of 74 trials with more than 13,000 participants showed no significant systemic safety problems. The most common side effect was temporary pain or inflammatory reactions at the injection site (8.5 %).
- Some meta-analyses had previously reported a slightly increased risk of serious events; according to the consensus, however, a causal relationship has not been demonstrated.
- According to a meta-analysis of cohort studies summarised in American Family Physician (November 2025), the injections delayed knee replacement by an average of around 299 days. Such observational data are, however, susceptible to bias.
Why do the guidelines contradict each other?
Professional societies such as ESCEO, OARSI, EULAR and PANLAR support the injections for selected patients. Guidelines with a primary care focus, such as those of the UK’s NICE and the American College of Rheumatology, tend to advise against them. One reason: depending on which studies are included – for example only very large trials – the average effect turns out smaller. The products also differ greatly in molecular size, cross-linking and additives.
What patients should know
- In Germany, hyaluronic acid injections are generally a self-pay service (IGeL).
- The effect sets in more slowly than with corticosteroids but can last longer.
- Before planned joint replacement surgery, a sufficient interval after the last injection should be observed (risk of infection).
- Exercise and muscle strengthening remain the foundation of all osteoarthritis treatment.
Note: This article is for general information only and does not replace medical advice. Talk to your orthopaedic specialist about the treatment that is right for you.
