Steroid induced osteonecrosis of femoral head (SONFH) is a progressive and refractory orthopedic disease, which has a great impact on the physical and mental health of patients, but the pathogenesis of SONFH is still unclear. Exosomes are extracellular lipid structural vesicles with a diameter of 30-120 nm that can be produced by most types of cells. The vesicles can reflect the physiological characteristics of the source cells, and transfer bioactive substances to target cells to affect cell activities. Exosomes derived from different mesenchymal stem cells (MSCs) play an important role in the development of SONFH and many other aspects. In addition, the current research also suggests that exosomes are expected to become an important tool for diagnosis and treatment of SONFH, and even to guide the early clinical use of glucocorticoids, but more high-quality research and evidence based medicine are needed. Focusing on the research progress in the treatment of SONFH by exosomes from different MSCs, the research progress in the role of exosomes from other different sources and exosomes in the diagnosis of SONFH is expounded, in order to provide a new idea for the diagnosis and treatment of SONFH.

BACKGROUND:In recent years,with the development of biological scaffold materials and bioprinting technology,tissue-engineered bone has become a research hotspot in bone defect repair. OBJECTIVE:To summarize the current treatment methods for bone defects,summarize the biomaterials and bioprinting technology for preparing tissue-engineered bone scaffolds,and explore the application of biomaterials and printing technology in tissue engineering and the current challenges. METHODS:Search terms were"bone defect,tissue engineering,biomaterials,3D printing technology,4D printing technology,bioprinting,biological scaffold,bone repair"in Chinese and English.Relevant documents published from January 1,2009 to December 1,2022 were retrieved on CNKI,PubMed and Web of Science databases.After being screened by the first author,high-quality references were added.A total of 93 articles were included for review. RESULTS AND CONCLUSION:The main treatment methods for bone defects include bone transplantation,membrane-guided regeneration,gene therapy,bone tissue engineering,etc.The best treatment method is still uncertain.Bone tissue engineering technology is a new technology for the treatment of bone defects.It has become the focus of current research by constructing three-dimensional structures that can promote the proliferation and differentiation of osteoblasts and enhance the ability of bone formation.Biological scaffold materials are diverse,with their characteristics,advantages and disadvantages.A single biological material cannot meet the demand for tissue-engineered bone for the scaffold.Usually,multiple materials are combined to complement each other,which is to meet the demand for mechanical properties while taking into account the biological properties of the scaffold.Bioprinting technology can adjust the pore of the scaffold,build a complex spatial structure,and is more conducive to cell adhesion,proliferation and differentiation.The emerging 4D printing technology introduces"time"as the fourth dimension to make the prepared scaffold dynamic.With the synchronous development of smart materials,4D printing technology provides the possibility of efficient repair of bone defects in the future.