Effect of temperature on the fracture toughness of compact bone

Bone is a composite composed mainly of organics, minerals, and water. Many researchers have studied effects such as crack velocity, density, orientation, storage media, porosity, and age on the fracture toughness (K(C), also called critical stress intensity factor) of compact bone. Most of these studies were conducted at room temperature. Considering that the body temperature of animals is greater than room temperature, and that bone has a large volumetric percentage of organics and water (generally, 55-65%), it is hypothesized that temperature has a significant effect on the fracture toughness of compact bone. Single-edge V-notched (SEVN) specimens were prepared to measure the fracture toughness of bovine femur and manatee rib in water at 0, 10, 23, 37, and 50 degrees C in four-point flexure. The fracture toughness values of bovine femur and manatee rib were found to decrease from 7.0 to 4.3MPam(1/2) and from 5.5 to 4.0MPam(1/2), respectively, as temperature increased over a temperature range of 50 degrees C. The results support the hypothesis that temperature has a significant effect on the fracture toughness of compact bone. Therefore, we suggest that study on fracture toughness of bone should be done at physiologically relevant temperatures.