The effect of initial mechanical fixation between porous implant and an artificial bone model material was studied. Fibre-reinforced composites made of non-woven E-glass fibre tissue and non-resorbable polymer with different degree of porosity were embedded into gypsum which was used as a substitute material for bone. Penetration of gypsum into the porous structure of the composite simulated bone ingrowth and mechanical interlocking between bone and the implant.
Selected composite sample groups embedded in gypsum were tested also with pins in order to model the situation of implant fixation with surgical screws. A push-out test was performed to analyse the shear strength of the interface between mechanically interlocking gypsum and the composite. Fractures occurred inside the gypsum resulted from lower compressive strength than the composite. Increase in the composite porosity revealed a significant rise of push-out forces. Pins did not affect measured push-out force values.
J Mech Behav Biomed Mater 2011;4:1797-1804.