Features of skin elastogenesis when damaged with the pins of the distraction apparatus of external fixation

Introduction. Among disadvantages of transosseous distraction osteosynthesis is the eruption of the skin and soft tissues with pins, which leads to scar formation in the area of injury. One of the causes for scar formation in wound healing is a failure of elastogenesis. We aimed to study the features of the elastogenesis of the skin damaged with the pins of the distraction apparatus of external fixation at osteosynthesis stages. Materials and methods. The study was performed on 26 adult Wistar rats that underwent transosseous osteosynthesis of the femur with an external fixation device. The traction of the percutaneously drawn proximal pin was done by rotating the nut along the core part of the structure, simulating skin eruption during limb lengthening. Each 4 animals were removed from the experiment 5 days after the installation of the external device; 5 and 10 days after distraction; and 14 days after its fixation and 30 days after its deinstallation. The skin regenerate was examined in the damaged area. On histological slides, elastic fibers were detected using Tenzer–Unn staining, whereas elastogenesis was studied with descriptive light microscopy and morphometry. Results. We revealed a significant decrease in the content of elastic fibers in scar tissue formed in the area of skin damage with the pins in both early stages of the experiment, when extracellular matrix synthesis occurs, and its late stages when there is organotypic restructuring of the fibrous component of the skin regenerate. The content of the elastic component in the skin regenerate after 30 days without the apparatus was 1.61%, which is 6.4 times less than in the skin of intact rats. Conclusion. When the skin undergoes prolonged traction eruption with a pin, the epithelization of the wound is delayed, thus the duration of reparation phases changes. This leads to scar tissue formation with few destructured elastic fibers. Keywords: skin wound, transosseous distraction osteosynthesis, elastic fibers, scar tissue