Introduction

Knee pain caused by osteoarthritis is a widespread and often painful problem that affects millions of people worldwide. While knee replacement surgery can be a solution for some, many prefer to try less invasive treatments first. One such approach is knee injections, which can help reduce pain and improve joint movement without the need for surgery.

This article compares three popular types of knee injections: Arthrosamid, hyaluronic acid, and corticosteroids. We’ll answer common questions about how effective they are, how long their effects last, and who might benefit most. With insights from experienced clinicians like Professor Paul Lee and the MSK Doctors team, this guide aims to help you understand your options and make informed decisions about your knee health.

How Do Arthrosamid, Hyaluronic Acid, and Corticosteroid Knee Injections Work?

Each of these injections targets knee pain in its own unique way.

Arthrosamid is a gel made of polyacrylamide — a synthetic substance that is safe and compatible with the body. When injected into the knee, it mixes with the surrounding tissues and acts like a cushion, providing ongoing shock absorption and lubrication. It essentially creates a soft scaffold in the joint that lessens irritation and protects the bones over time. Research describes Arthrosamid as "a useful alternative to hyaluronic acid for treating knee osteoarthritis," especially for those looking for longer-lasting relief.

Hyaluronic acid is a natural substance that your body normally produces to lubricate joints and absorb shocks. In osteoarthritis, the amount and quality of this natural fluid decline, which causes pain and stiffness. Injecting extra hyaluronic acid helps to restore the joint’s slippery surface, making movement easier and less painful. However, this treatment mainly hydrates the joint and does not change the joint’s physical structure.

Corticosteroids are very different — these are powerful anti-inflammatory medicines injected to rapidly reduce swelling and pain. They do not provide cushioning but help calm down inflammation during flare-ups. Corticosteroids work quickest but the effects usually last for only a short while.

Understanding these differences can make it clearer which injection might be most suitable, depending on individual needs.

Comparing Pain Relief: Which Knee Injection Lasts Longest?

One key question many people ask is: how long do these injections actually work?

Arthrosamid stands out for its longer-lasting benefits. Studies have shown that a single injection can relieve knee pain and improve joint function for at least a year, and in some cases even up to two years. One study found, "Statistically significant results at 2 years," indicating the treatment remains effective over time. Another noted that Arthrosamid users experienced a stable reduction in pain and symptoms long after treatment, while other injections showed a return of pain closer to baseline levels.

When directly compared to hyaluronic acid, Arthrosamid showed superior results in several groups, notably "patients under 70 years old, those with a normal body mass index, and those with moderate osteoarthritis severity." Overall, Arthrosamid "approached superiority to hyaluronic acid at 52 weeks," meaning it tended to work better over the long term for many patients.

Hyaluronic acid injections usually ease symptoms within a few weeks and offer relief lasting 3 to 12 months. Because the body naturally breaks down the injected acid over time, repeated treatments might be needed.

Corticosteroids provide rapid pain relief within days but usually only for several weeks or a few months. They are most helpful during sudden flare-ups but not ideal for ongoing management due to possible side effects if used too frequently.

It’s worth noting that while Arthrosamid offers promising longevity, a recent study concluded that “long-term superiority is limited," meaning it may be best viewed as part of a tailored treatment plan rather than a guaranteed cure.

Safety, Side Effects, and Who Should Consider Each Option?

Safety is an important factor when considering any treatment.

Arthrosamid is generally well tolerated. Most patients report only mild side effects like brief swelling or discomfort where the injection was given. Research confirms it has “no long-lasting adverse events reported.” Under the care of experienced clinicians like Professor Paul Lee and the MSK Doctors team, patients receive careful assessment and expert care to minimise any risks.

Hyaluronic acid injections also have a strong safety record, with side effects typically limited to mild, temporary joint soreness or swelling.

Corticosteroids, while effective, carry greater risks if used repeatedly. Possible side effects include damaging the cartilage within the joint, increasing infection risk, or accelerating joint wear. Therefore, corticosteroids are usually reserved for specific cases where quick inflammation relief is needed, rather than routine use.

Choosing the right injection depends on many factors including the severity of arthritis, personal health, and lifestyle. Professional assessment is essential to ensure treatment is safe and appropriate.

Cost, NHS Availability, and Other Practical Considerations

Cost and availability often influence treatment decisions.

Arthrosamid is mostly available privately and is not usually covered by the NHS. This means patients often pay out of pocket, though some clinics offer flexible payment plans. Private insurance coverage may be possible but is not guaranteed.

Hyaluronic acid injections are sometimes available on the NHS, usually under specific conditions and after specialist approval. Private clinics offer these injections more readily and often at a lower cost than Arthrosamid.

Corticosteroid injections are widely available on the NHS and are generally inexpensive, making them a common first-line treatment for rapid symptom control.

When deciding on treatment, consider the expertise of your clinic, waiting times, and the support available. Clinics like MSK Doctors provide comprehensive consultations and ongoing care to help ensure the best outcomes.

Expert Advice and Summary of Key Differences

Professor Paul Lee, a trusted expert in musculoskeletal medicine, stresses that there is no one-size-fits-all solution for knee injections. The choice depends on each patient’s unique situation and goals.

While Arthrosamid offers a longer-lasting cushioning effect, hyaluronic acid is a well-established option for lubricating damaged joints in mild to moderate cases. Corticosteroids remain valuable for quick relief during inflammatory flare-ups but should be used carefully.

Talk with experienced clinicians to discuss your symptoms, lifestyle, and preferences so they can tailor a treatment plan just for you.

Conclusion and Disclaimer

In summary, Arthrosamid, hyaluronic acid, and corticosteroid injections all play important roles in managing knee osteoarthritis pain. Arthrosamid tends to last longest by creating a cushioning scaffold in the joint. Hyaluronic acid improves lubrication and movement, while corticosteroids provide fast relief from inflammation.

If you’re considering knee injections, expert advice from specialists like Professor Paul Lee and the MSK Doctors team can help you choose the best approach for your needs.

For personalised medical advice, please consult a qualified healthcare professional.

References

Cole, A., Maulana, R. K., Whitehead, J. P., & Lee, P.Y.F. (2022). A Systematic Review of the Novel Compound Arthrosamid Polyacrylamide (PAAG) Hydrogel for Treatment of Knee Osteoarthritis. Medical Research Archives, 10(8). https://doi.org/10.18103/mra.v10i8.2950

Bliddal, H., Beier, J., Hartkopp, A., Conaghan, P. G., & Henriksen, M. (2023). Polyacrylamide hydrogel versus hyaluronic acid in knee osteoarthritis: A subgroup analysis of a randomized study. Orthopaedic Proceedings, 105-B(SUPP_13), 81–81. https://doi.org/10.1302/1358-992x.2023.13.081

Aykaç, B., Dinç, M., Nar, Ö. O., Karasu, R., & Bayrak, H. Ç. (2025). Comparative efficacy of polyacrylamide hydrogel versus hyaluronic acid and corticosteroids in knee osteoarthritis: A retrospective cohort study. Medicine, 104(38), e44655. https://doi.org/10.1097/md.0000000000044655