Biorheological characteristics of skin after expansion

This study investigated the changes in biorheological characteristics of skin after expansion. Expanders were implanted into the back of eight adult dogs, and after an eight-week expansion the expanded and the non-expanded control skins were transferred to an adjacent site. The expanded specimens and their controls were obtained at 3, 6, 12 and 24 weeks after transfer, and their biorheological characteristics and histological changes were studied. The characteristics of the stress-relaxation, the stress-strain relationship and tensile strength of the expanded and control specimens were measured. The tests demonstrated that during the initial stage after transfer, the biorheological properties of experimental specimens differed significantly from those of their controls. However, the differences between expanded and control specimens began to lessen gradually with increasing recovery time. When the recovery time reached 24 weeks or longer, the experimental skin exhibited the same mechanical properties as the control skin. Histological examination of expanded specimens showed thickened epidermis and thinned dermis. But there were no significant histological differences between expanded skins and their controls after 24 weeks.