Polyacrylamide Gel versus Hyaluronic Acid and Steroids in Knee Osteoarthritis: An Evidence-Based Comparison

Knee osteoarthritis (OA) is a very common problem that develops when the cartilage protecting our knee joints slowly wears away. This can lead to pain, stiffness, and trouble moving—often making everyday activities much more difficult. The main goal of treatment for knee OA is to reduce pain and keep people moving comfortably for as long as possible. One proven approach is injecting relief-providing substances directly into the knee . Traditionally, doctors have relied on hyaluronic acid and steroids for these injections, but a newer option— polyacrylamide gel (PAAG)—has recently been added to the mix. In this article, we’ll compare PAAG to these established treatments and break down what current evidence says about how well they work, how safe they are, and what they offer for people with knee OA .

How Do PAAG, Hyaluronic Acid, and Steroids Work?

Polyacrylamide gel (PAAG) is a synthetic substance, mostly made up of water and polyacrylamide molecules. When it’s injected into the knee, PAAG acts like a cushion—filling gaps in the joint and absorbing shocks. Imagine PAAG as a little shock absorber inside your knee, easing pressure on the damaged areas and reducing pain. Unlike some other treatments, PAAG doesn’t work by changing the body’s chemistry or triggering a biological response. Instead, it simply provides long-term mechanical support directly at the problem spot.

Hyaluronic acid is quite different. It’s a natural substance found in our joint fluid that lubricates and cushions the joint. When osteoarthritis develops, our knees have less hyaluronic acid, making movement painful and stiff. By injecting hyaluronic acid back into the knee, we restore some of that lost lubrication—helping the joint move more smoothly and comfortably. Hyaluronic acid may also reduce inflammation slightly, which can further ease symptoms.

Steroids , on the other hand, are powerful anti-inflammatory drugs. They provide fast relief by reducing swelling and inflammation in the knee joint . However, steroids don’t actually cushion the joint or rebuild cartilage. Their main strength is rapid, short-term pain control during flare-ups. Steroid injections need to be used carefully, as repeated use can carry risks, including possible damage to the joint if overused.

Comparing Effectiveness and Safety

Research suggests that PAAG can provide significant and lasting pain relief in knee OA. In a recent clinical study, patients experienced improved symptoms that lasted for up to two years, especially those who were older, did not have diabetes, and had milder forms of knee OA. The gel’s cushioning effect seems to last longer than steroid injections, and at least matches hyaluronic acid in improving joint comfort and function. Since PAAG doesn’t react chemically within the body, side effects are rare and usually mild.

Hyaluronic acid injections are a well-established treatment, and many people with mild to moderate knee OA find that they help relieve pain and improve mobility. Not everyone experiences dramatic improvement, but the side effects tend to be minor—such as brief swelling or soreness where the shot was given.

Steroid injections excel at quickly calming intense pain and inflammation. However, their effect usually fades after a few weeks to a few months. Because repeated use can damage cartilage or raise other health concerns, doctors are cautious about how often steroids are used.

Importantly, not every treatment is right for every patient. For instance, PAAG seems to work best for people who are older, have milder OA, and don’t have certain other health problems like diabetes. It stands out for its longer-lasting mechanical support and safety, while steroids are mostly useful for short-term symptom relief. Deciding on the best option depends on your health needs and the specific features of your knee OA.

What Does This Mean for Patients and Doctors?

Choosing among PAAG, hyaluronic acid , and steroids means weighing each treatment’s strengths and possible downsides, while also considering what's most important to the patient—such as long-lasting relief versus quick fix, or minimizing the number of injections.

PAAG might be an especially good choice for patients wanting ongoing support from fewer injections, as well as those interested in a treatment that doesn’t rely on animal or biological sources. It’s practical, safe, and may become increasingly cost-effective.

Hyaluronic acid remains a reliable option, especially for those with less severe OA who benefit from both its lubrication and its mild anti-inflammatory effects. Steroids are generally reserved for quick relief during sudden flare-ups or waves of inflammation.

Research on PAAG is still active, and future studies are expected to clarify which patients benefit most, how long the effects last, and whether PAAG works even better when paired with other treatments. Cost, patient satisfaction, and long-term results will all shape how widely PAAG is adopted.

In Summary

Polyacrylamide gel is a promising new addition to the treatment options for knee osteoarthritis . By acting as an internal shock absorber, PAAG offers effective and longer-lasting symptom relief, with a strong record of safety so far. While traditional choices like hyaluronic acid and steroid injections are still important tools, PAAG’s unique benefits make it an attractive option to discuss with your healthcare provider. As research progresses, we’ll know more about how to use PAAG most effectively and help more people with knee osteoarthritis stay active and comfortable.

References

Gao, H. C. K., Akhtar, M., Creedon, C., Nar, Ö. O., Verma, T., & Lee, P. Y. F. (2025). Polyacrylamide hydrogel injections in knee osteoarthritis: A PROMs-based 24 month cohort study. Journal of Clinical Orthopaedics and Trauma. https://doi.org/10.1016/j.jcot.2025.103136