A comprehensive systematic review of marketed bone grafts for load-bearing critical-sized bone defects

Treatment of critical-sized bone defects typically involves implantation of a bone graft. Various types of bone grafts are nowadays marketed, categorized by their origin as allografts, xenografts, or synthetic grafts. Despite their widespread use, a comprehensive understanding of their morphology and mechanical response remains elusive. Controlling these characteristics for promoting bone growth and ensuring mechanical resistance remains challenging, especially in load-bearing districts. This study aims to systematically review existing literature to delineate the principal morpho-mechanical characteristics of marketed bone grafts designed for load-bearing applications. Furthermore, the obtained data are organized and deeply discussed to find out the relationship between different graft characteristics. Among 196 documents identified through PRISMA guidelines, encompassing scientific papers and 510(k) documents, it was observed that a majority of marketed bone grafts exhibited porosity akin to bone (>60%) and mechanical properties resembling those of low-bone volume fraction trabecular bone. The present review underscores the dearth of information regarding the morpho-mechanical characteristics of bone grafts and the incomparability of data derived from different studies, due to the absence of suitable standards and guidelines. The need for new standards and complete and transparent morpho-mechanical characterization of marketed bone grafts is finally emphasized. Such an approach would enhance the comparability of data, aiding surgeons in selecting the optimal device to meet patient's needs.