Arthrosamid®

Arthrosamid® for Knee Osteoarthritis

Overview

Arthrosamid is a hydrogel injection designed to provide long-term relief for people experiencing pain due to knee osteoarthritis (OA). Unlike traditional injections, Arthrosamid remains in the joint, acting as a cushion and reducing irritation, which can improve movement and reduce discomfort over months and even years. It is supported by increasing research on safety and effectiveness.

Although originally introduced and studied in Denmark, trials are now ongoing within the UK in NHS hospitals at Royal Berkshire Foundation Trust and Robert Jones and Agnes Hunt Orthopaedic and District NHS Trust to evaluate benefit and cost-effectiveness.

Who Might Benefit?

Arthrosamid may be suitable for individuals who:

  • Have knee osteoarthritis causing pain, swelling, or restricted movement
  • Have tried non-surgical treatments such as physiotherapy, exercise, weight loss, pain medications, knee braces, and other injection treatments, but still experience persistent symptoms

It is not recommended for people who are:

  • Pregnant or breastfeeding
  • Experiencing infection in or around the knee
  • Scheduled for knee replacement within the next six months
  • Allergic to the medications used in the procedure

How Arthrosamid Works

The hydrogel integrates with the lining of the knee joint (the synovium) and helps:

  • Reduce inflammation
  • Support smoother movement and improved joint function

This mechanism can lead to lasting relief, with some patients maintaining benefits for up to 4 years.

Assessment and Suitability

Before the injection, a clinical assessment is conducted to ensure the knee is suitable for Arthrosamid and to allow you to discuss the benefits and potential risks of the treatment. This will include reviewing imaging such as X-rays, ultrasound scans or MRI images taken within the last year. Your clinician will also discuss your medical history, current medications, and any allergies.

The Procedure

  • Antibiotic prophylaxis: To minimise infection risk, patients are prescribed a single dose of antibiotics 1–2 hours before the injection.
  • Ultrasound guidance: The injection is performed under ultrasound by a consultant in sport and exercise medicine to ensure precise placement.
  • Local anaesthetic: A local anaesthetic is administered to numb the injection area.
  • Injection: Arthrosamid is delivered directly into the knee joint over several minutes.
  • Post-procedure care: A dressing is applied, and you will be observed for 20 minutes to ensure there are no immediate reactions.

Patients are generally advised to avoid strenuous activity for 10–14 days and not to drive immediately after the injection.

Expected Benefits

  • Pain relief usually begins to appear within 4-6 weeks, with continued improvement over 6 months
  • Improvement in knee function and mobility
  • Long-lasting effects compared to other injectable treatments, which may require repeated administration

Potential Risks and Side Effects

Arthrosamid is generally well-tolerated. Possible reactions include:

  • Mild immediate post-injection pain or swelling
  • Occasionally an initial flare-up of discomfort before benefit takes effect
  • Rare risk of infection or allergic reactions
  • Very rarely, pseudo-sepsis (severe inflammation requiring medical assessment)

Your clinician will discuss all potential risks in detail before treatment.

Follow-Up

Most patients only require a single Arthrosamid injection. Follow-up visits or online assessments may be used to monitor progress.

Contact Information

If you have questions or wish to book an assessment, please contact Pure Sports Medicine.

References

  1. Bliddal, H., et al. (2024a). Effectiveness and safety of polyacrylamide hydrogel injection for knee osteoarthritis: results from a 12-month follow up of an open-label study. Journal of Orthopaedic Surgery and Research, 19, 274.
  2. Bliddal, H., et al. (2024b). Polyacrylamide gel versus hyaluronic acid for the treatment of knee osteoarthritis: a randomised controlled study. Clinical and Experimental Rheumatology, 42(9), 1729–1735.
  3. Cole A et al. A Systematic Review of the the Novel Compound Arthrosamid Polyacrylamide (PAAG) Hydrogel for Treatment of Knee Osteoarthritis. Medical Research Archives
  4. Bliddal, H.., et al. (2025) 10-Year Follow-Up After Intra-Articular Injections of 2.5% Polyacrylamide Hydrogel for Knee Osteoarthritis. Presented at WCO-IOF-ESCEO 2025. 
  5. Bliddal, H., et al. (2025) A Prospective Study of Polyacrylamide Hydrogel Injection for Knee Osteoarthritis: Results From 5 Years After Treatment. Presented at WCO-IOF-ESCEO 2025.
  6. Bliddal, H., et al. (2024) Polyacrylamide hydrogel for knee osteoarthritis: Four-year results from a prospective study. Orthop Procs. 2024;106-B(SUPP_18):106.