Fracture healing, the diamond concept under the scope: hydroxyapatite and the hexagon.

Bone healing after a fracture has many intercalated steps that depend on the host, type of injury, and often the orthopedist. The diamond concept since 2007 has outlined 4 main facets that have to be considered as a model by the treating surgeon at the time of injury and when nonunion develops: osteogenic cells, osteoconductive scaffolds, osteoinduction, and the biomechanical environment. All of these foment fracture healing in optimal circumstances. Yet, this work proposes other facets, such as osteoimmunology and vascularity, to be considered as well in the model. These are as important as the original four, though their correlation to the original work has been less noted until more recent literature. The mindset of the orthopedist must thoroughly analyze all these facets and many more when dealing with nonunion. This work presents, probably the most significant ones, parting from the original 4-corner diamond model and expanding it to a more representative hexagon integrated model. Metaphorically, just like the strongest inorganic constituent of the bone: hydroxyapatite.