Geometric Determinants of Full Thickness Wound Healing in Adult Male Yucatan Miniature Swine
White, D., Brandt, C., Madsen, T., Hanks, C., Brown, L., Stricker-Krongrad, A., Liu, J., Bouchard, G.F.
Our objective was to obtain quantitative data regarding the relationships between wound healing rates vs. initial size and shape of full thickness wounds.
Each of 3 adult male Yucatan miniature swine had 9 full-thickness paraspinous wounds created. The wounds for each animal were comprised of all combinations of 3 sizes (10, 20 and 30 cm2) with 3 shapes (square, circle and equilateral triangle –apex pointing to spine). Dressing changes were performed 3 times per week for 7 weeks, and then weekly until termination. During dressing changes, all wounds were photographed and planimetric measurements of perimeters, total wound areas and areas of epithelialization were obtained.
Time to complete healing was determined by clinical observation and photographic documentation. Although larger wounds took longer to heal than smaller ones, there was no appreciable association with wound shape, e.g. average healing times for 10 cm2 wounds were 33, 35 and 33 days for circles, squares and triangles respectively.
Absolute wound healing rates were calculated using planimetric data. There was a strong correlation between healing rate and initial wound area. Mean healing rates were 2.1, 2.6 and 3.3 cm2 per week for 10, 20 and 30 cm2 wounds, respectively. These differences did not appear to be affected by wound shape.
Results for the outcome of linear healing rate were determined from changes in planimetric measurements of area and perimeter using the following calculations:
Linear Healing Distance (cm):
Change in Area from Day X to Day Y (cm2)
Mean of Day X and Day Y Perimeters (cm)
Linear Healing Rate = Linear Healing Distance per unit of time (day, week, etc.)
Conclusions: Linear healing rates in adult Yucatan MS were largely unaffected by initial wound size or wound shape. This confirms the appropriateness of this test system for further preclinical wound healing studies.