Impactability and time-dependent mechanical properties of porous titanium particles for application in impaction grafting.

Aims: Impaction grafting with bone particles is a successful technique to restore bone stock loss during hip revision surgery. Allograft shortage is expected within the near future. This study investigates the feasibility of porous titanium particles (TiP) to replace bone particles (BoP) and to compare mechanical properties of TiP and a commercially available porous ceramic bone graft extender (CeP). Impactability and time-dependent mechanical properties (stability and stiffness during physiologic loading (0.1-2.5 MPa)) were assessed by standardized impaction and a confined compression test. Loaded samples were used for particle release analysis. Findings: TiP were more impactable than BoP and created a stable, highly entangled macroporous construct. CeP were crushed during impaction, resulting in non-cohesive specimens of small ceramic particles. TiP showed very little deformation at the end of physiological loading. Impacted TiP were stiffer than BoP but more elastic than CeP. TiP generated a low volume of microparticles (0.2% of original TiP weight) with a bimodal size distribution (diameter range, 7-2000 μm). Conclusion: TiP are impactable and create a stable, elastic and highly entangled, macroporous layer. Further in-vitro testing and biological studies are warranted to verify whether the promising results are maintained with THA reconstructions.