Application progress of bioactive polymers and composite materials in bone tissue engineering

Bone is the second largest tissue in the world requiring transplantation, and bone grafts and bone replacement materials are used in at least 4 million operations every year. The limitations of traditional treatment methods have affected the current treatment options, and bone defects caused by trauma, cancer, infection and arthritis have been increasing, and the demand for bone grafts in clinical treatment has also continued to rise. Autologous grafts and allografts are common methods for clinical treatment of bone defects, but chronic inflammation, disease transmission and immune rejection have hindered their development. In addition, metal stents are also the most commonly used implants. However, there are also problems such as stress shielding, infection and inflammation that lead researchers to expect new material stents to replace it. Therefore, the development of biologically active and self-adaptively deployable and filled three-dimensional scaffolds to promote bone regeneration has become a focus of bone tissue engineering. In recent years, manufacturing methods including 4D printing shape memory materials have been used to create new methods to replace traditional bone grafts. This article mainly reviews the types of traditional polymer materials and new shape memory polymer materials, the main manufacturing methods of scaffolds, mechanical properties, biocompatibility, and the latest applications in the field of bone tissue engineering, and summarizes the 4D in bone tissue engineering. The importance of printing technology, current challenges and future development directions