Observations on the role of fracture mechanics in biology and medicine

Fracture mechanics has been of great benefit in the fields of biology and medicine. Biological materials have low fracture toughness and often fail by cracking, so the knowledge which has been developed for engineering materials can usefully be applied to study the failure of bone, cartilage and many other natural materials. Medical devices such as artificial joints and stents experience complex failure modes owing to their interactions with the human body: materials science and fracture mechanics experts have played an important role in the development and validation of new materials for these applications. It is also true that the fields of biology and medicine have been very good for fracture mechanics, presenting us with new and interesting challenges such as the inclusion of repair processes in theoretical models of fracture. This article describes some examples of work in this area, including the development of low modulus titanium alloys, the application of fracture concepts to study human bone and the wide range of biological materials which Nature has evolved for load-bearing applications.