The influence of loading conditions on the life-times in fatigue testing of bone cements

The fatigue behaviour of bone cement was investigated with respect to the influence of loading conditions. The tests were performed under simulated physiological conditions using a testing arrangement in accordance with ISO. A pure load-controlled and pure displacementcontrolled cycling procedure were compared. It is demonstrated that load control is much more critical and leads to decisively shorter life-times, or remarkably lower long-term strengths. In consequence, in order to determine reliable material properties for life-time predictions and safety assessments, it is necessary to measure the fatigue behaviour under load control as this corresponds to the normal physiological situation.