Cements for bone defect filling

20 years ago, the use of bone cement in orthopaedic surgery meant referring only to a synthetic acrylic resin resulting from the polymerization of methyl methacrylate. The mechanical properties of these cements mean that they can be used to fix prostheses or fill vertebral defects. However, their physico-chemical characteristics remain far removed from the biological environment of their implantation site, which is why researchers and practitioners have been developing calcium phosphate (CaP)-based bone substitutes for several decades, whose chemical composition is close to that of bone and which can therefore also undergo the natural bone remodeling cycle.

Initially used as bioceramics, these bone substitutes in the form of self-curing in vivo cement fundamentally broaden therapeutic indications by enabling these bioactive substitutes to adapt perfectly to the bone defects to be filled. This has, however, presented new challenges for these bioactive biomaterials in terms of injectability, setting time and mechanical strength. These cements have already proved their worth in orthopedic and dental surgery, but some of their properties still need to be improved. A new challenge is to use these phosphocalcic cements as carriers of active ingredients to provide a therapeutic response in clinical contexts deemed critical (osteoporosis, infection, inflammation, irradiation...). After reviewing the general context of bone-filling cements, this article focuses on the phosphocalcic cements currently in use, as well as on new generations of these derivatives.