Effects of interfacial debonding on fatigue damage of cemented hip prostheses

Abstract

Clinical studies on retrieved cement mantles have pointed out that the cemented hip prostheses failed after long‐term use due to debonding at the cement‐stem interface and local fractures in the cement mantles. These were linked to fatigue damages of cement mantles proved by fatigue experiments. In this paper, a numerical approach based on finite element analysis and continuum damage mechanics is proposed to investigate the fatigue behavior of cement mantles during gait cycles. Results reveal that the major sites for failure initiation are at the proximal medial regions and at the distal prostheses tip. Such fatigue failures not only result in the corruption of cementstem interfaces, but also greatly affect the stress distribution and damage rate of the proximal cement mantles in subsequent loading cycles. The interfacial debonding rate increases from 2.5% to 15% with gait loadings from five to twenty million cycles. Meanwhile, owing to the partial debonding of interface, the cement stresses on the remaining regions increase by 91% to 871% when compared with those generated with a fully bonded interface, which in turn accelerates the fatigue damage accumulation rate of the cement mantle from 5.99 % to 21.5%.