title: A microscopic and biomechanical study of skin and soft tissue after repeated expansion.
abstract: BACKGROUND
  Conventional expansion inadequately restores damaged skin for patients with large areas of skin deficiency or who lack sources of normal skin. These patients require repeated skin expansions, but little is known about the outcomes of this procedure.
  
  
  OBJECTIVE
  To evaluate the microscopic changes and biomechanical properties of skin and soft tissue after repeated expansion.
  
  
  METHODS
  We prepared three groups of six pigs each: a conventional expansion group, a repeated expansion group, and a blank nonsurgical control group. We measured histology, ultrastructure, basic fibroblast growth factor (bFGF), stress-strain, stress relaxation, and stress strength.
  
  
  RESULTS
  Skin obtained after conventional expansion and repeated expansion was basically healthy, but the microscopic and biomechanical properties differed from those of nonexpanded skin, especially in the repeated expansion group.
  
  
  CONCLUSIONS
  Repeated skin expansion involves growth under stress, simultaneous injuries, and further repairs, with fibers showing more injury signs than cells. This article describes the microscopic changes and biomechanical properties that occur after repeated expansion.
authors.affiliation: Department of Aesthetic, Plastic and Burn Surgery, Shandong Provincial Hospital, Jinan City, Shangdong Province, China. huoran@medmail.com.cn
authors.forename: Ran
authors.initials: R
authors.lastname: Huo
authors.forename: Wang
authors.initials: W
authors.lastname: Yang
authors.forename: Li
authors.initials: L
authors.lastname: Shangbin
authors.forename: Leng
authors.initials: L
authors.lastname: Tingting
authors.forename: Zhao
authors.initials: Z
authors.lastname: Yang
authors.forename: Gao
authors.initials: G
authors.lastname: Feng
authors.forename: Yu
authors.initials: Y
authors.lastname: Qingping
authors.forename: Zhang
authors.initials: Z
authors.lastname: Wenhao
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005346:Fibroblast Growth Factors / Q000032:analysis; D008854:Microscopy, Electron; D019651:Plastic Surgery Procedures / Q000379:methods; D012867:Skin / Q000737:chemistry* / Q000166:cytology* / Q000648:ultrastructure; D013314:Stress, Mechanical; D013552:Swine; D015626:Tissue Expansion
chemical_list: D005346:Fibroblast Growth Factors