An implantable medical device includes a porous metal foam or foam-like structure having pores defined by metal struts or webs wherein the porous structure has directionally controlled pore characteristics. The pore characteristics controlled include one or more of the metal structure porosity, pore...http://www.google.co.uk/patents/US7578851?utm_source=gb-gplus-sharePatent US7578851 - Gradient porous implant
