Role of tissue undermining in the trapdoor effect of transposition flaps.

BACKGROUND

The trapdoor or pincushioning effect is a frequent complication of transposition flaps. Several explanations have been proposed for its occurrence, including lymphatic or venous obstruction, scar hypertrophy, excessive subcutaneous fat or flap tissue, and scar contracture.

OBJECTIVE

To study the effects of tissue undermining and scar contracture using a guinea pig animal model.

METHODS

Circular wounds on the dorsal surface of guinea pigs were repaired with transposition flaps. Half of the recipient beds were undermined widely and half were not undermined. Animals were observed for evidence of the trapdoor phenomenon.

RESULTS

Only animals in the group without undermining demonstrated evidence of the trapdoor effect.

CONCLUSION

Tissue undermining may prevent the development of the trapdoor effect in transposition flaps.