[Effects of tissue expansion on the ratio of length to width of random-pattern skin flaps].

A randomized controlled trial of 11 pairs of random-pattern skin flaps in pigs was observed. The flaps (5 x 16 cm) were divided into two groups: experimental group (EG)--the flaps were inflated with controlled expanders placed into subcutaneous tissue of the back of pigs; control group (CG)--the same expanders were placed into subcutaneous tissue of other side but not inflated. After the test period of 5 weeks, the results showed that the mean surviving length of flaps was 13.58 cm in EG and 9.40 cm in CG. The ratio of length to width was 2.72:1 in EG and 1.88:1 in CG. The differences between two groups were statistically significant (P less than 0.001). The result indicates that the random-pattern skin flaps inflated by expanders can be greatly increased the ratio of length to width. It is suggested that the increase of surviving length of the flaps in EG results from the increment of blood vessel and the enlargement of vessel diameter along the long axes of the flaps.