Biomaterial-based joint lubricants for osteoarthritis: emerging multifunctional designs and therapeutic strategies.

Osteoarthritis is a prevalent degenerative joint disease in which impaired lubrication can accelerate disease progression, making restoration of joint lubrication an important therapeutic avenue. This review summarizes emerging biomaterial-based joint lubricants and multifunctional designs that integrate lubrication with biological regulation and tissue regeneration. We highlight advances in hydrogels, microspheres, nanoparticles, and emulsions, focusing on material architectures, lubrication mechanisms, tribological performance, and biological functions including anti-inflammatory and antioxidative effects, drug delivery, and cartilage regeneration. We further discuss structure-function coupling that links interfacial lubrication to cellular responses and tissue repair, and outline key considerations for performance optimization and clinical translation. Finally, we propose an integrated lubrication-therapy-regeneration paradigm to guide the development of intelligent, responsive, and long-acting joint lubricants toward clinical application.