Implantable metallic open-celled lattice/polyethylene composite material

Abstract

A method for making a composite material for implantation in the body which is able to act as a matrix for the biological ingrowth of bone and is suitable as a bearing surface. The method consists of compression molding the implant by forming to net shape the first material to its desired end device and inserting it into a mold cavity. Polyethylene in is then placed onto the first material, and the mold is subjected to heat and pressure for specific time durations. The end result is polyethylene which is fully interdigitated into the first material to a desired depth which is controlled by temperature, pressure and time constraints. The present method creates an interface between the first material and the polyethylene which is securely fixed and does not allow micro and macro motion between the two materials. The compression molding process optimizes the mechanical and wear properties of the polyethylene, and enables the new material to provide a smooth and frictionless bearing surface on one side of the composite material. The opposite side of the composite material is porous and thus allows for biological ingrowth of new bone or cement interdigitation. The first material provides structural stability, yet allows flexibility and load transfer to improve biological interface characteristics and a more normal bony remodeling that are lacking in other acetabular cups. An acetabular cup constructed with the composite material is also disclosed.