Anisotropic pore structure of surgical implants achieved by pressing sponge titanium powder with a punch with elastic polyurethane facing
This article describes the need to improve functional characteristics of porous implants by forming an anisotropic pore structure with high porosity and enlarged pore sizes at the surface and by provision accreting of bone tissues to the pore surface at a considerable depth. In order to achieve this effect we have suggested pressing the implants made of sponge titanium powder in a closed steel matrix by means of a steel punch with elastic polyurethane facing, which shapes the functional surface of such implants. It has been found that the implants produced with such a punch possess an increased porosity in the surface layer. The porosity ranges from 60 to 80% at the depth of 0.8-1.0 of particle diameter from the outer surface and up to 35-50% in the remaining volume of porous implants, wherein the average pore size in the surface layer is 2-4 times more than inside. Besides, the use of elastic facing to a much greater extent preserves a developed particle surface structure of sponge titanium powder in the surface layer, which provides accreting of bone tissues to the entire pore surface of the implant, both in its internal volume and on the entire outer functional surface.