title: Role of tissue undermining in the trapdoor effect of transposition flaps.
abstract: 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.
  
  
  CONCLUSIONS
  Tissue undermining may prevent the development of the trapdoor effect in transposition flaps.
authors.affiliation: Division of Dermatology, UCLA School of Medicine 90024.
authors.forename: A J
authors.initials: AJ
authors.lastname: Kaufman
authors.forename: K L
authors.initials: KL
authors.lastname: Kiene
authors.forename: R L
authors.initials: RL
authors.lastname: Moy
mesh_terms: D000818:Animals; D002921:Cicatrix / Q000209:etiology / Q000517:prevention & control; D006168:Guinea Pigs; D008297:Male; D011183:Postoperative Complications / Q000209:etiology* / Q000517:prevention & control; D011897:Random Allocation; D013524:Surgical Flaps / Q000009:adverse effects* / Q000379:methods; D013536:Suture Techniques