Fatigue life of compact bone—I effects of stress amplitude, temperature and density

Abstract

Fatigue tests to failure of compact adult bovine bone specimens were conducted at five stress amplitudes (65–108 MN/m 2) and four temperature levels (21–45°C) which span the physiologic range of bone temperature in the human foot. After testing, determinations were made of specimen density and microstructure and fracture surfaces were examined by scanning electron microscopy. The test results demonstrated highly significant ( P < 0·01) negative correlations between fatigue life and stress amplitude and between fatigue life and temperature. A highly significant positive correlation between fatigue life and bone density was also shown. The microstructure studies indicated that primary compact bone has a longer fatigue life than secondary Haversian bone. A multiple regression analysis was used to derive an equation for fatigue life as a function of stress amplitude, temperature and bone density. This statistically derived equation correlates well with previous fatigue studies of human compact bone.