Comparative efficacy of polyacrylamide hydrogel versus hyaluronic acid and corticosteroids in knee osteoarthritis: A retrospective cohort study

Abstract

This study investigates whether intra-articular polyacrylamide hydrogel (iPAAG) provides superior outcomes compared to conventional injections, namely hyaluronic acid (HA) and corticosteroid, in managing knee osteoarthritis (KOA). This retrospective cohort study included primary KOA patients (Kellgren-Lawrence grade II-IV) treated between January 2023 and December 2024 with 1 of 3 intra-articular injections: iPAAG (6 mL Arthrosamid), HA (2 mL, 60 mg Artroaid), and Steroid (40 mg methylprednisolone acetate, Arhropan). Outcomes were assessed at baseline, 3, 6, and 12 months. Primary outcomes were the Visual Analog Scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index. Clinically meaningful improvements were evaluated using minimal clinically important difference (MCID) and patient acceptable symptom state thresholds. A total of 150 patients (n = 50 per group) were included. The groups were comparable at baseline in median age (HA: 66; Steroid: 69.5; iPAAG: 69.5; P = .104), sex (female: 72%, 62%, 66%; P = .566), median body mass index (30.4, 30.6, 30.7 kg/m2; P = .716), and Kellgren-Lawrence distribution (P = .765). Baseline median VAS was 7, dropping to 3 in all groups at 3 months (P < .001). At 6 months, they rose to 4 (HA), 5 (Steroid), and 4 (iPAAG) (P < .001). By 12 months, VAS returned to baseline in HA and Steroid, while iPAAG remained slightly improved (P = .219). iPAAG outperformed Steroid at 6 months (P < .001), but not HA (P = 1.000). No significance at 12 months (P = .128). Baseline median Western Ontario and McMaster Universities Osteoarthritis Index scores were 49.5 (HA), 59.5 (Steroid), and 57 (iPAAG), improving at 3 months to 42.5, 48.5, and 45 (P < .001). At 6 months, scores were 45, 57, and 47.5 (P < .001). At 12 months, HA and Steroid returned to baseline, while iPAAG remained stable (P = .979). iPAAG was better than Steroid at 6 months (P = .008), but not HA (P = .066). Although overall differences at 12 months were significant (P = .044), pairwise comparisons were not. iPAAG showed the highest patient acceptable symptom state rates (72%, 54%, and 42% at 3, 6, and 12 months), and greatest minimal clinically important difference achievement at 3 and 6 months, though without significant intergroup differences (P > .05). iPAAG offers comparable short-term efficacy and modest advantage at 6 months. However, long-term superiority is limited. It may be a complementary option in individualized osteoarthritis management. Further prospective studies are needed to define its optimal use.

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