FATIGUE OF HAPEX~(TM) - A STRUCTURAL BONE REPLACEMENT MATERIAL

摘要

The fatigue behaviour of hydroxyapatite polyethylene (HAPEX~(TM)) has been studied. Both isotropic and hydrostatically extruded HAPEX~(TM) have been subjected to fatigue testing at 37 deg C in physiological saline. The effect of hydrostatic extrusion (HE) is to increase the mechanical properties of HAPEX~(TM) and while the isotropic material eventually fractured the HE HAPEX~(TM) did not fracture, but underwent creep and lost stiffness. S-N curves have been constructed for both materials. In biaxial loading the effect of increasing phase angle is to increase the fatigue life. The effect of fatigue is to gradually debond the interface between the hydroxyapatite and the polyethylene seen by widening hysteresis loops before failure and from fractography.