Efficacy of novel polyacrylamide hydrogel injection for osteoarthritis

Osteoarthritis (OA) affects 7.6% of the population, with the knee being the most commonly involved joint. Although many patients ultimately require total knee replacement, effective symptom control can delay or even avoid surgery. Intra-articular corticosteroids provide short-term relief but may have detrimental long-term effects on cartilage. Arthrosamid® is the only non‑absorbable, biocompatible polyacrylamide hydrogel licensed for intra‑articular use in knee OA. Comprising 97.5% water and 2.5% cross‑linked polyacrylamide, it represents a novel and potentially therapeutic option. This article reviews the current evidence for polyacrylamide hydrogel in knee OA.

Four case series reported improvements in mean WOMAC scores following polyacrylamide hydrogel, with significant reductions in pain (-15.7 to -20.8), stiffness (-12.1 to -17.5) and physical function (-9.4 to -18) over 6 months to 3 years. A comparative cohort study found no significant differences between polyacrylamide hydrogel, corticosteroid and hyaluronic acid at 3 months. Greater improvement was observed at 6 months with polyacrylamide hydrogel compared with corticosteroid (median 47.5 vs. 57, P = 0.008). A randomised controlled trial reported no significant differences between polyacrylamide hydrogel and hyaluronic acid. Biomarker studies demonstrated increased anti-inflammatory mediators at 3 months post-injection. Most common adverse event was transient pain (16%), with no serious complications reported.

The study findings suggest that polyacrylamide hydrogel improves knee OA symptoms. However, limitations in study quality, mechanistic understanding and long-term evidence preclude recommending routine clinical use, and it should therefore be used cautiously. Further evaluation in well-designed clinical studies is required to establish its safety, clinical effectiveness and cost-effectiveness.