Wound contraction is the biologic sequence to the open wound secondary to skin loss from burn, trauma, or surgery. For example, contraction is a force so powerful that active flexion and extension of the digits cannot overcome the contractile force after a third degree volar hand burn. However, full-thickness cryosurgical destruction of skin neoplasm can give excellent aesthetic results without wound contraction.
In rats, the healing process of a full-thickness cryosurgical wound differs from that of a burn wound. Whereas burn wound heals by wound contraction, cryosurgical wound heals without wound contraction and absence of contraction presumed due to it’s lack of myofibroblasts, the cells reportedly associated with wound contraction.
Myofibroblasts share electron microscopic appearance, pharmacological reactivity and immunological cross-reaction with smooth muscle cells. The binding of antismooth muscle antibodies to the fibroblastis of granulation tissue is important support for the myofibroblasts theory. The immunoperoxidase-staning technique permits the identification of individual myofibroblasts by light microscopy and quantification of myofibrolasts over time in an experimental healing wound.
We studied the rate of contraction, histologic appearance and quantification of myofibroblasts in the healing process following injuries in the rat skin produced by burning and freezing.
Histologically, the degree of tissue destruction by the two types of thermal injury was similar.
Following both injuries, the appearance of myofibroblast was similar in the healing process, although contraction did not appear to participate in the healing process of freeze injuries. Under the polarized light optics microscope, the granulation tissue of burn wound showed no birefringence but that of freeze wound showed a distinct dermal-like pattern of birefringence.
This study shows that the condition of the residual matrix following injury seems to be a determinant factor of wound contraction and may explain the apparent difference in contraction between the two injuries.
Residual connective tissue matrix persists following freeze injuries and acts like an internal splint.
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