Stresses in a simplified two dimensional model of a normal foot : a preliminary analysis

The loss of motor functions of the foot muscles in leprosy or diabetes changes the pattern of internal stresses in the foot skeleton. This may provoke local foci of relatively high stresses. In those cases where osteoporosis and cystic degeneration has weakened the mechanical strength of the bones, these excessive stresses may eventually lead to a local break down of bone. Afinite element analysis of a foot model indicates those regions of high stresses. Before proceeding the analysis of stresses in the foot of a leprosy patient, it is essential that an estimate is made of the stress patterns in a normal foot. The foot is a complex structure with a number of bone segments, cartilages, ligaments and muscles. But, it is difficult to represent all the complex geometries and muscles in the first model. Therefore, in this paper, a simplified two-dimensional model of the foot is chosen and the predominant muscle forces acting (as per literature) are taken into consideration. The simplified model is used to study the regions of high stresses during three simulated, quasi-static equilibrium positions: mid-stance, heel strike and push off positions. The result of this analysis can serve as guidance in devising a model with next-higher level of complexity.