Hip endoprosthesis stabilization with a porous low modulus stem coating: factors influencing stabilization

A polytetrafluoroethylene/vitreous carbon porous material has been investigated as an alternative to acrylic for hip endoprosthesis fixation. This material, which is mechanically fused to the endoprosthesis stem, has been shown to promote soft-tissue ingrowth. In 29 patients receiving a porous-coated Thompson endoprosthesis, stabilization of the porous-coated stem as observed by acceptable clinical results occurred in only about 50%. Stabilization of porous-coated endoprostheses is unsatisfactory for the following reasons: lack of press-fit, inadequate prosthetic design, infection, and technical difficulties. The major cause of 40% failure in this series was an initially inadequate press-fit.