A mouse model for studying rapid intraoperative methods of skin closure and wound healing

We re-examine the adequacy of an albino (hairless) mouse dorsal distally based skin flap model by determining elastic modulus and by assessing viability after application of rapid intermittent stretch to facilitate wound closure.

Modulus of elasticity was determined with materials testing. Viability was accessed by laser Doppler flowmetry and by quantifying marginal tissue necrosis (mm2) at 5 days. Effective length gained and tension relieved were measured by subjecting flaps to simple undermining plus 3-10 g of initial tension (linear stretch) using a skin hook. Immediate hemispherical stretch was applied with an implanted subcutaneous silicone balloon (Rapid Intraoperative Tissue Expansion or RITE) at 1 or 2 cycles of 3-8 min and 6-12 ml for each cycle. Flaps subjected to simple and extensive undermining with or without application of initial linear stretch served as postoperative controls.

The elastic modulus of 9.85 (1.02) N/mm2 approximated the skin of the human face. Flowmetry demonstrated that all flaps were adequately perfused. Stretching significantly decreased flap tension and increased flap length over simple undermining alone. It drastically improved flap viability by provoking a 50-75% decline in 5-day necrosis. The benefits were dependent upon the initial linear tension applied, but independent of the timing, cycling, and volume selected for RITE and the flap dimensions at closure.

Results demonstrate that the albino (hairless) mouse dorsal distally based skin flap is a reliable model for studying wound closure and that rapid intermittent stretching in this model facilitates closure and wound healing.