Background: Conventional expansion inadequately restores damaged skin for patients with large areas of skin deficiency or who lack sources of normal skin. These patients require repeated skin expansions, but little is known about the outcomes of this procedure.
Objective: To evaluate the microscopic changes and biomechanical properties of skin and soft tissue after repeated expansion.
Materials and methods: We prepared three groups of six pigs each: a conventional expansion group, a repeated expansion group, and a blank nonsurgical control group. We measured histology, ultrastructure, basic fibroblast growth factor (bFGF), stress-strain, stress relaxation, and stress strength.
Results: Skin obtained after conventional expansion and repeated expansion was basically healthy, but the microscopic and biomechanical properties differed from those of nonexpanded skin, especially in the repeated expansion group.
Conclusion: Repeated skin expansion involves growth under stress, simultaneous injuries, and further repairs, with fibers showing more injury signs than cells. This article describes the microscopic changes and biomechanical properties that occur after repeated expansion.