The healing process for fractured tibia bones of sheep studied by neutron diffraction

Neutron diffraction has shown directly that the long bones of animals have the c axes of their apatite crystals preferentially oriented to withstand stresses. When a sheep tibia is fractured and allowed to heal, the jointing material is initially randomly arranged, but a return of some orientation occurs after a few months. This orientation increases slowly with time. The growth of callus bone around the outside of the fracture becomes overshadowed by the appearance of poorly oriented internal bone. After 22 months, the end of this experiment, the process of bone restoration is still far from complete and it is evident that data after longer periods of time would be desirable. The current state of the structure at 22 months is shown in more detail by a two-dimensional neutron scan over a thin vertical section of bone cut through the centre of the fractured tibia.