Ceramic Bone Substitutes in Orthopaedic Surgery: Standards, Trends and Future Perspectives.

In contrast to other tissues and organs, bone and its marrow have been successfully transplanted to promote bone healing for more than 100 years. Nevertheless, the amount of autologous bone grafts is limited and associated with relevant donor site morbidity. Therefore, intensive efforts have been made to develop adequate bone substitute materials. In combination with regenerative strategies including the application of bone marrow /mononuclear stroma cells, growth factors, cytokines (VEGF, PDGF, BMP2 etc.) as well as extracellular vesicles (EVs), bone substitutes (BS) may augment, supplement or even replace autologous bone grafts. BS provide a three-dimensional network that allows guided cellular migration, proliferation, differentiation, and mineralisation. In accordance with bionic principles, defined CaP-based BS have shown promising clinical results and are frequently applied in daily orthopaedic practice. In recent years and with better understanding, new technologies have been introduced in this area. These trends include ex vivo coating strategies for BS, the implementation of AI in BS design and planning, the combination with growth factors such as NELL-1 or P-15, the consideration of osteoimmunologic aspects, and the application of new material composites. In this study, we provide an overview and update to well-established standards and innovations in the field of ceramic BS and discuss findings reported in the literature.