Hydrogel composite scaffold repairs knee cartilage defects: a systematic review.

Currently, the incidence of cartilage defects in knee joints owing to different causes is increasing every year, and surgery is the most common treatment strategy. In general, tissue engineering materials that mimic the structural, mechanical, and biological properties of natural bone have been widely used, with hydrogels being particularly prominent due to their good biocompatibility as well as adjustable mechanical properties. However, the inherent limitations of monolithic materials in mimicking the complex zonal organization of articular cartilage have driven significant progress in composite scaffold engineering. Herein, we briefly outline the structure of the knee joint and several common surgical approaches for knee cartilage defects. We also discuss the physical properties, functions, and preparation methods of common hydrogel composite scaffolds according to their different types. Finally, we review their application in knee cartilage defects and summarize and discuss their future prospects.