Carbon-metal graded composites for permanent osseous attachment of non-porous metals

Abstract

The recently devised REPLAMINEFORM process for imparting controlled pore microstructures to metals, ceramics, and plastics now makes it possible to join materials which differ greatly in chemical, physical, mechanical, or biological properties, by means of composite bonding at the interface. A solution to the long-standing problem of attaching metal to bone is proposed as one application. The join would be accomplished with a porous carbon intermediary permitting a transition from solid, non-porous metal to metal-carbon composite to carbon-bone composite to bone. As a result, advantage can be taken of the superior biocompatibility qualities of carbon which is otherwise of limited value for implant purposes because of its poor strength characteristics. Additional advantages include reduction or elimination of problems arising from metal corrosion or toxicity, and the formation of a much more desirable stress distribution pattern. A carbon-composite intermediate will minimize the poor match of mechanical properties at a bone-metal interface, thus preventing the development of large stress concentrations which cause tissue necrosis, bone resorption, deterioration of implant attachment, and other adverse effects.