POLYACRYLAMIDE HYDROGEL FOR KNEE OSTEOARTHRITIS: 4-YEAR RESULTS FROM A PROSPECTIVE STUDY

Henning Bliddal(1), Jannie Beier(2), Andreas Hartkopp(3), Philip Conaghan(4), Marius Henriksen(5)

(1)The Parker Institute, Bispebjerg-Frederiksberg Hospital, University of Copenhagen, Copenhagen, Denmark, (2)Rheumatology Odense, Odense, Denmark, (3)A2 Rheumatology and Sports Medicine, Holte, Denmark, (4)Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds & NIHR Leeds Biomedical Research Centre, Leeds, United Kingdom, (5)The Parker Institute, Bispebjerg- Frederiksberg Hospital, University of Copenhagen, Copenhagen, Copenhagen, Denmark

Introduction

Polyacrylamide hydrogel (iPAAG1), is CE marked for treating symptomatic knee osteoarthritis (OA), meeting the need for an effective, long-lasting, and safe non-surgical option. This study evaluates the efficacy and safety of a single 6 ml intra-articular injection of iPAAG in participants with moderate to severe knee OA over a 5-year post-treatment period, presenting data from the 4-year follow up.

Method

This prospective multicentre study (3 sites in Denmark) involved 49 participants (31 females) with an average age of 70 (range 44 – 86 years). They received a single 6 mL iPAAG injection. All participants provided informed consent and re-consented to continue after 1 year. The study followed GCP principles and was approved by Danish health authorities and local Health Research Ethics committees. Twenty-seven participants completed the 4-year follow-up.

The study evaluated WOMAC pain, stiffness, function, and Patient Global Assessment (PGA) of disease impact. Changes from baseline were analysed using a mixed model for repeated measurement (MMRM). Sensitivity analyses were applied on the extension data, where the MMRM analysis was repeated only including patients in the extension phase and an ANCOVA model was used, replacing missing values at 4-years with baseline values (BOCF).

Results

The planned MMRM analysis (n=49) revealed a statistically significant decrease in WOMAC pain subscale scores (-22.0; 95%CI: -29.5; -14.4) from baseline to 4-years. Analysis of the extension phase (n=27) showed similar results (-21.8; 95%CI: -29.0; -14.6) compared to the initial analysis. Furthermore, BOCF analysis indicated a statistically significant reduction in WOMAC pain subscale scores from baseline (-13.0 units). Four new adverse events were reported between the 3-year and 4-year visits; none were related to treatment.

Conclusions

This study shows that single injections of 6 ml intra-articular iPAAG were well tolerated and continued to provide clinically important effectiveness at 4-years after treatment.

Acknowledgements