The role of shear micromotion on bone ingrowth into a three-dimensional porous scaffold predicted by a mechanoregulatary finite element model.

One factor that could affect the success of bone ingrowth in total knee replacements is the mechanical environment at the bone-implant interface. We applied a mechanoregulatory model to predict the evolution of tissue formation and ingrowth for two scaffold porosities and a range of loads. When the compressive motion was applied across the gap, low levels of shear displacement improved bone formation by transmitting strain deeper into the scaffold. Ingrowth scaffolds with higher porosity are more tolerant to shear micromotion because their compliance leads to a mechanical environment that promotes tissue differentiation into the scaffold, resulting in greater interface stiffness.