Fig. 8.

In regions in the gap where compressive strains are small to moderate, bone healing can occur, which has the effect of increasing the gap's properties (e.g., elastic modulus). In turn, that will stiffen the gap, thereby decreasing implant micromotion (under the same applied force level) as well as the strain. However, the degree of bone regeneration in the gap depends on a “race” between local damage accumulation in locations with initially high strain vs. bone regeneration in locations with low/moderate strain (as explained in the text). Note that the color bars denoting strain magnitude are different A–C; strains are much larger in A than in B and C because the modulus values for the gap region increase from 0.05 MPa, 1 MPa, and 5 MPa in A, B, and C respectively. For the same magnitude of axial force on the implant (D), the axial micromotion of the implant decreases substantially as the elastic modulus of the interfacial gap increases. Likewise, the magnitude of the peak strains in the gap decreases with increasing modulus of the interfacial gap.