Polyacrylamide Hydrogel Injection for Knee Osteoarthritis: A 6 Months Prospective Study

Objective: Intra-Articular (IA) injection of polyacrylamide hydrogel (PAAG) is a possible treatment for symptomatic Osteoarthritis (OA) of the knee. This study evaluated the efficacy and safety of a single injection of 6 ml intra-articular PAAG over 26 weeks. Methods: Open-label study in patients with symptomatic and radiographically confirmed knee OA . Primary outcome was change in WOMAC pain after 13 weeks. Secondary outcomes were WOMAC stiffness and function subscales, Patient Global Assessment of disease impact (PGA) and proportion of OMERACT-OARSI responders. Follow-up time points were 4, 13 and 26 weeks. Results: 49 patients (31 females) received PAAG, with 48 patients completing the 13 and 46 the 26 weeks assessments. Mean change in WOMAC pain after 13 weeks was -18.3 points [95% CI-23.4 to -13.3]; P<.0001 and at 26 weeks -20.8 points [95% CI -26.3 to -15.3]; P<0.0001 with similar benefits for WOMAC stiffness, physical function, and PGA. After 13 weeks 64.6% were OMERACT-OARSI responders and this was maintained at 26 weeks.. During the 13 weeks, 18 patients reported 23 adverse events, 13 of which were related to PAAG, none severe. Two serious adverse events, atrial fibrillation and gastrointestinal pain, were assessed as ‘not related’ to PAAG. Conclusions: PAAG can be delivered in a single 6 ml injection and this non-randomized trial in patients with knee OA demonstrated beneficial clinical effects at 13 and 26 weeks. No serious adverse events were seen with PAAG. These encouraging results need to be confirmed in controlled studies

Effectiveness and safety of polyacrylamide hydrogel injection for knee osteoarthritis: results from a 12-month follow up of an open-label study

Objective: There are few effective osteoarthritis (OA) therapies. A novel injectable polyacrylamide hydrogel (iPAAG) previously demonstrated efficacy and safety up to week 26 in an open-label study of knee OA. Here we report longer-term effectiveness and safety data. Methods: This multi-centre, open-label study included patients with symptomatic and radiographic knee OA. Primary outcome was WOMAC pain (0–100 scale) at 13 weeks, and patients continued to 26 weeks before entering a further 26-week extension phase. Secondary efficacy outcomes included WOMAC stiffness and function subscales, Patient Global Assessment (PGA) and proportion of OMERACT-OARSI responders. Safety outcomes were adverse events (AEs). Results: 49 participants (31 women, mean age 70) received an ultrasound-guided, intra-articular injection of 6 ml iPAAG; 46 completed the extension phase to 52 weeks. There was a significant reduction in the WOMAC pain score from baseline to 52 weeks (− 17.7 points (95% CI − 23.1; − 12.4); p < 0.0001). Similar sustained improvements were observed for WOMAC stiffness (11.0 points; 95% CI − 17.0; − 4.9), physical function (18.0 points; 95% CI − 19.1; − 10.6), and PGA (16.3 points; 95% CI − 23.1; − 9.4). At 52 weeks 62.2% of patients were OMERACT-OARSI responders. From 26 to 52 weeks, 8 adverse effects (AE), including 1 serious AE (cerebrovascular accident) were reported in 5 subjects. None of the new adverse events were thought to be device related. Conclusion: This open-label study suggests persistent benefits and safety of iPAAG through 52 weeks after a single injection. Trial registration: Clinicaltrials.gov NCT04179552

Polyacrylamide gel versus hyaluronic acid for the treatment of knee osteoarthritis: a randomised controlled study

Objectives: To assess non-inferiority of intra-articular injectable polyacrylamide hydrogel (iPAAG) to hyaluronic acid (HA) on symptomatic benefit in individuals with knee osteoarthritis (OA). Methods: This randomised, controlled, multi-centre trial recruited adults with symptomatic and radiographic knee OA from 3 clinical rheumatology sites in Denmark; two private clinics and one public hospital department. Participants were randomised 1:1 to receive a single intra-articular 6 mL injection of either HA or iPAAG on an outpatient basis. Primary outcome was change from baseline in WOMAC pain subscale after 26 weeks. Secondary outcomes were changes from baseline in WOMAC stiffness and physical function subscales, patients’ global assessment of disease impact, EuroQoL-5D-5L, and proportion of positive OMERACT-OARSI responders after 26 and 52 weeks. Results: 239 adults were randomised: 120 to HA and 119 to iPAAG. For the primary outcome, the least squares mean changes in WOMAC pain were -14.8 (95% CI: -18.0 to -11.7) for HA and -18.5 (95% CI: -21.7 to -15.4) for iPAAG; group difference: 3.7 (95% CI: -0.7 to 8.1). The lower boundary of the 95% CI respected the pre-specified non-inferiority margin of 9 WOMAC pain points. No statistically significant differences were observed for the secondary outcomes. For HA, 9 participants (7.6%) reported 13 adverse device effects (ADEs). For iPAAG, 35 participants (28.9%) reported 41 ADEs. All ADEs were mild/moderate, with no serious ADEs reported. Conclusions: iPAAG was found to be as effective and safe as HA for treatment of knee OA symptoms for at least 1 year after a single injection