Optimizing the grain size distribution of allografts in bone impaction grafting

In bone impaction grafting, allografts in the form of bone chips are used for reconstruction of defects and to induce bone remodeling. Optimizing grain size distribution of this allograft material should help prevent implant subsidence by achieving higher primary stability of the graft. We evaluated the influence of grain size distribution on the mechanical stability of allograft material. Bone tissue was rinsed, and the grain size distribution of the allograft material was determined by performing a sieve analysis. Uniaxial compression tests were carried out before and after a standardized compaction procedure for samples with controlled grain size distribution and a control group. Allografts with controlled grain size distribution showed a yield limit almost twice as high as in the control group after a standardized compaction procedure. A better interlocking between bone particles was observed compared to the control group. Thus, grain size distribution has a major impact on the mechanical stability of bone grafts. By controlling the grain size distribution of allograft material, a tighter packing can be achieved and subsequently implant subsidence of implants could be avoided.