Efficacy of novel polyacrylamide hydrogel injection for osteoarthritis.

BACKGROUND: 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.

RESULTS: 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.

CONCLUSION: 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.