Images from Waves - photoelastic modelling of bones

Background This paper cites the development of the principles of photoelastic stress analysis, contemporary to the life of Samuel Haughton. Subsequent studies of bone and joint replacements are discussed, with reference to hypotheses regarding bone, including the coincidence of trabecular structure with principal stresses. Issues regarding assumptions of homogeneous and isotropic properties in photoelastic modelling are acknowledged. Aim Awareness of photoelastic methods is often through the visual appeal of the coloured fringe patterns. The aim of this paper is to complement this awareness by demonstration of the quantitative analyses that may be conducted through biomechanical examples. Methods Examples of new pseudo three-dimensional model analyses are presented together with a method for photoelastic study of cancellous bone, which entails novel procedures for preparation of replicate models and for optical evaluation of fringes. Conclusion Photoelastic analysis offers novel solutions to studies in biomechanics, which are facilitated by contemporary modelling materials.