Advances in the modification of injectable calcium-phosphate-based bone cements for clinical application

摘要

Autografts, allografts, and xenografts are the most widely used methods to enhance effective reconstruction of bone defects, but natural donor bone has some deficiencies, such as limited supply, excessive damage of transplant-supplied-parts, constrained growth and high complication rates.[1] Bioactive bone replacement materials provide an alternative for bone defect repair and regeneration. Augmented injectable bone scaffold material applied to bone replacement therapies in orthopedics and dentistry has generated much discussion in bone tissue engineering for bone defect repair. Injectable cement materials currently in clinical use and those under research can be classified into three main categories: polymethylmethacrylate (PMMA), calcium-phosphate-based bone cements (CPCs), and calcium-sulfate-based bone cements (CSCs). Of these, the chemical components of CPCs are most similar to the inorganic components of bones. CPCs mimic the mineral phase of bone to formulate a natural lattice for bone tissue to promote natural bone ingrowth and remodeling.[2] Furthermore, in comparison with the most widely used PMMA cements, CPCs have a lower exothermic reaction temperature and promote better osteointegration. For these reasons, they have become one of the most promising bone repair materials.[3] Nevertheless, CPCs have some limitations: (1) Their slow degradation rate and lack of macroporosity to promote the formation of new bone make their osteoinduction capacity insufficient for clinical needs.[4] Modification efforts include fabricating porousano structures and/or drug delivery CPC composites to promote bone growth; (2) Another drawback is that the mechanical strength of CPCs cannot match the strength of human cortical bone; thus, strength modification is another research direction.