Morphologic analysis of tissue-expander shape using a biomechanical model.

Using a biomechanical model designed to reproduce the forces exerted by the soft tissues of the chest wall, the contours created by several currently available round as well as anatomically shaped tissue expanders were evaluated. Parameters that describe expander shape were defined, the most useful of which proved to be the point of maximal projection and the percentage of upper pole deformity. Direct comparison of seven different expanders with respect to these variables revealed the anatomically shaped expanders to offer improved contours over traditional round designs. Continuing modifications in expander design should focus on lowering the point of maximal projection and minimizing the upper pole deformity.