Comparison of the efficacy of intra-articular polyacrylamide hydrogels versus cross-linked hyaluronic acid/chondroitin sulfate combination for the treatment of advanced-stage knee osteoarthritis

Background Polyacrylamide hydrogel (PAAG) remains a novel molecule, and few human studies have validated its efficacy in knee OA, particularly in advanced stages. The aim of this study was to compare the efficacy of intra-articular polyacrylamide hydrogel (PAAG), a novel molecule, with that of the widely used cross-linked chondroitin sulfate/hyaluronic acid (HA/CS) combination in the treatment of knee osteoarthritis (OA) in a retrospective trial. Methods A total of 127 patients diagnosed with grade 3 or 4 knee OA according to the Kellgren-Lawrence scale were included. Patients’ age, education level, and body mass index (BMI) were recorded. The first group received an intra-articular injection of a cross-linked HA (60 mg)/CS (90 mg) combination, whereas the second group was administered 6 ml of PAAG. Both groups received a single injection. The outcome measures, which were assessed at baseline, 3 months, and 12 months, included knee pain severity measured by the visual analogue scale, range of motion (ROM), WOMAC scale score, and Pittsburgh Sleep Quality Index (PSQI). Results At 3 months, the PAAG group demonstrated significantly lower pain and WOMAC scores than did the HA/CS group. However, no significant differences in pain or WOMAC scores were observed between the groups at 12 months. The 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. Conclusion Compared with HA/CS injection, intra-articular PAAG injection significantly improved the VAS and WOMAC scores in advanced knee OA patients at 3 months. However, the outcomes for all the parameters were similar between the groups at 12 months.