Computer-aided analysis of Z-plasties.

Various Z-plasties were evaluated with a mathematical analytical method called the finite-element method. The lengthening and shortening effects on the skin proved to depend on the tip angle. Serial Z-plasties diminished the stress concentration after pairs of flaps had been transposed. Subdivided Z-plasties proved to be the most effective for lengthening. The finite-element method provided a good simulation of Z-plasties on a skin with complex properties. The lengthening and shortening effects on anisotropic skin were influenced not by the degree but by the direction of the anisotropy, whereas the total force required for transposing the two flaps was vice versa. The finite-element method was found to be useful for finding analytical solutions for biomechanical skin problems.