Mechanical properties of skin graft wounds

In female Wistar rats the mechanical strength development of the wound between a skin graft and the neighbouring intact skin (graft wound) was compared with that of ordinary incisional wounds after 4, 7, 14 and 21 days of healing. In one group of rats a 35 x 20 mm skin graft including the subcutaneous muscle was raised and replaced in situ on the left side of the back and a 35 mm incisional wound was made on the right side. In another group a 35 mm incisional wound was made on the right side of the back only. After 4 days the maximum load, maximum stiffness and relative failure energy of the graft wounds were 49, 43 and 40% less respectively than those of the incisional wounds from the same animals and after 7 days the maximum load and maximum stiffness of the graft wounds were reduced by 26 and 29%. However, after 14 and 21 days no differences in mechanical properties were found between these two types of wounds. Compared with the incisional wound from rats without graft the maximum load, maximum stiffness and relative failure energy of the graft wound were reduced by 57, 58 and 44% after 4 days, 59, 62 and 54% after 7 days, 37, 38 and 29% after 14 days and for maximum load and maximum stiffness a reduction of 33 and 31% was found after 21 days of healing.