Bio-inspired Multi-layer structure artificial joint for In vivo wear resistant

Severe osteoarthritis often necessitates artificial joint replacement, yet conventional designs remain challenged by mismatched mechanics with native bone, metal ion release, and wear-induced inflammation. Here, we introduce a cartilage-inspired biomimetic artificial joint (BAJ) engineered with a polyether-ether-ketone (PEEK) substrate and a hydrogel (κ-carrageenan/polyacrylamide) cartilage layer. Distinct from existing implants, the BAJ integrates a gradient structure in which deeper layers provide robust load-bearing capacity, while the lubricating surface layer ensures ultra-low friction. This architecture enables a sliding friction coefficient as low as 0.004, withstanding more than 1.27 million friction cycles and an exceptionally low mass wear rate of 7.1 × 10^{− 7} mg/cycle. Cellular assays and in vivo subcutaneous implantation confirmed outstanding biocompatibility, while long-term wear tests in Beagle temporomandibular joints demonstrated remarkable durability over nine months without systemic toxicity. By harnessing a biomimetic gradient design, this study offers a transformative strategy for next-generation artificial joints, capable of mitigating severe inflammation and extending implant longevity.