Injectable hydrogel-based strategies for osteoarthritis: Anti-inflammatory, antioxidative, and cartilage regenerative approaches

Osteoarthritis (OA) is a progressive degenerative joint disease characterized by chronic inflammation, oxidative stress imbalance, and cartilage destruction. Current treatments mainly provide symptomatic relief and have limited capacity to restore cartilage structure and function. Injectable hydrogels have emerged as promising therapeutic platforms for OA due to their localized delivery capability, tunable properties, and biocompatibility. This review summarizes recent advances in injectable hydrogel-based strategies for OA treatment from three perspectives: inflammatory regulation, oxidative stress modulation, and cartilage repair/regeneration. We first discuss how injectable hydrogels regulate the inflammatory microenvironment through sustained delivery of anti-inflammatory agents, immune modulators, and responsive release systems. We then highlight their roles in controlling oxidative stress by scavenging reactive oxygen species and restoring redox homeostasis. Furthermore, we summarize regenerative strategies based on extracellular matrix mimicry, stem cell regulation, growth factor delivery, and tissue reconstruction. Recent developments in multifunctional and stimuli-responsive hydrogels are also discussed, including their potential for targeted therapy and lubrication restoration. Finally, current challenges related to mechanical adaptation, long-term biosafety, scalable fabrication, and clinical translation are addressed. This review provides a comprehensive perspective on the design principles and therapeutic potential of injectable hydrogels for disease-modifying OA treatment.