The alteration in mechanical properties of bone graft after the addition of hydroxyapatite bone graft substitutes

The problems of supply, cost, increasing demand and infection risk that are associated with the use of allograft are well known. The addition of bone graft substitutes, such as hydroxyapatite (HA) to allograft has various advantages in terms of extending supply and also providing more reliable mechanical properties. In this way HA can be used for both trauma and elective joint replacement surgery. The mixing of bone and HA to form an aggregate will result in mechanical properties different from those of the individual parts. However, at present the changes in material properties of such a mix have fully investigated and the optimum mixing ratio has not been characterized The acetabulum is subjected to mainly compressive forces during impaction grafting and subsequent walking. Therefore a compressive model of a uniaxial compression chamber was used to investigate the change in mechanical properties that occurs with the addition of HA in varying proportions to morcellised bone graft (MBG).