Modelling the mechanics of narrowly contained soft tissues: the effects of specification of Poisson's ratio.

Many soft tissues are considered to be virtually incompressible. A number of recent analyses of the mechanics of these tissues have used Poisson's ratios in the range of 0.45 to 0.49 with little or no documentation, the apparent assumption being that a small change in Poisson's ratio will not significantly affect the results. We demonstrate here that the mechanics of a narrowly contained soft tissue are, instead, strongly sensitive to small changes in compressibility about the incompressible limit. Relevant practical examples include analysis of the mechanics of soft tissues within the sockets of artificial legs, pressure sore problems, and the calculation of strains within the soft tissues of a fracture gap.