Abstract

Long-term fixation of both components of a total hip prosthesis has been a never-ending problem facing replacing surgeons. Even the less frequent use of methyl-methacrylate cement does not seem to have reduced the tendency of femoral components to loosen after perhaps a decade or even less of use. The case is argued that the present methods of attempting long-term fixation both of socket and stem are doomed to ultimate failure be they never so sophosticated nor cunning. The reason is that a locus of pathology is created in the immediate vicinity of the intruder; "gate post"; in the case of the stem. Pathology engenders change and instability, clinically demonstrated by loosening. A new method of fixation is described. It has been used in over 8000 instances spread over seven years without failure. The problem of joining "living to dead material" is accepted and solved in a novel way. The dead material i.e. the metal prosthesis is coated with another dead material i.e. calcium hydroxyapatite ceramic, but this latter material has the capacity of being animated. Once animated, hydroxyapatite ceramic becomes "osteotropic", not to say osteogenic. Placed in a situation that simulates a fresh fracture, union by first intention, primary bone healing, takes place with surprising speed. Local conditions are contrived so as to encourage and accelerate bony union, this is achieved by the design of the prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)