WOUND CONTRACTION IN AN EXPERIMENTAL PORCINE MODEL

Wound contraction is thought to be independent of site, and circular f ull-thickness skin wounds are thought not to contract completely. To v erify these statements four circular full-thickness skin wounds were c reated on each side of eight pigs and randomised to treatment with eit her split-thickness skin grafts, or healing by secondary intention und er a hydrocolloid dressing. Time to healing, contraction, and final sc ar shape were evaluated. The median healing time was 12 days (range 6- 18) in the grafted wounds and 30 days (range 15-45) in the secondarily healing wounds. There were significant differences in healing time be tween the different sites on the pigs. In the secondarily healing grou p, medial-caudal wounds healed in 21 (15-21) days compared with latera l wounds which healed in 36 (21-45) days (p < 0.005), while no differe nces were found in the grafted group. There was a clear relationship b etween site and contractility and shape of the scars in both treatment groups. Scars located on the lateral-caudal aspect of the pig were pr edominantly round and contracted only slightly. Scars located on the l ateral aspect of the pig tended to be oval. Contraction was greatest i n the medial scars and least in the lateral scars. Median contraction was 33% (range -2-63) in skin grafted wounds and 64% (range 42-82) in secondarily healed wounds. This randomised experiment showed that exte nt of wound contraction is dependent of site, and that circular wounds do heal with contraction.