Changes in skin during distraction osteogenesis of the tibia in Sprague-Dawley rats: Verification of epidermal proliferation by immunohistochemical methods

To investigate the effect of bone lengthening by distraction osteogenesis, a pair of external fixators was placed in the right tibias of 40 Sprague-Dawley rats. Two weeks ( n = 10) and 12 months ( n = 10) after 25% lengthening, skin flaps were removed and prepared for the immunohistochemical measurement of bromodeoxyuridine ( BrdU) and staining with haematoxylin and eosin. The same procedures were done for the rest of 20 unlengthened tibias. At 2 weeks the number of cells labelled with BrdU, which indicate the extent of DNA synthesis, was 4.35 times ( p < 0.001) greater in the lengthened than the unlengthened skin. However, at 12 months, there was no difference. Haematoxylin and eosin staining showed no additional findings. Although the physical properties of the skin can accommodate a lengthened bone, our results suggest that distraction osteogenesis stimulates epidermal proliferation, which might lead to an increase in the amount of skin.