Comparison of the Efficacy of Intra-Articular Polyacrylamide Hydrogel and the Cross-Linked Hyaluronic Acid/Chondroitin Sulfate Combination in Treating Advanced-Stage Knee Osteoarthritis

Background and Objectives: Polyacrylamide hydrogel (PAAG) is still underresearched, and few human studies have validated its efficacy in knee osteoarthritis (OA), particularly in advanced stages. The aim of this study was to compare the efficacy of intra-articular PAAG with that of the widely used cross-linked chondroitin sulfate/hyaluronic acid (HA/CS) combination in treating knee OA in a retrospective trial. Materials and Methods: A total of 127 patients diagnosed with grade 3 or 4 knee OA according to the Kellgren–Lawrence scale were included. The first group received an intra-articular injection of the cross-linked HA (60 mg)/CS (90 mg) combination, whereas the second group was administered 6 mL of PAAG. The outcome measures, which were assessed at baseline, 3 months, and 12 months, were knee pain severity measured with the visual analog scale (VAS), range of motion (ROM), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale score, and the Pittsburgh Sleep Quality Index (PSQI). Results: At three months, the PAAG group demonstrated significantly lower pain and WOMAC scores than the HA/CS group, while ROM and sleep quality scores were not significantly different at either 3 or 12 months. Within-group comparisons revealed significant reductions in pain, WOMAC, and sleep scores in both groups over time, but no significant improvement in ROM was detected in either group. Conclusions: Compared with HA/CS injection, intra-articular PAAG injection significantly improved the VAS and WOMAC scores in advanced knee OA patients at three months. However, the outcomes for all the parameters were similar in the two groups at 12 months.