title: Mathematical guide to minimize donor size in full-thickness skin grafting.
abstract: BACKGROUND
  Full-thickness skin grafting is a common repair option in dermatologic surgery. Generally, a 3:1 ellipse is designed for the donor area. This results in occasional large donor site defects. A new formula to guide donor site design would potentially create smaller donor defects.
  
  
  OBJECTIVE
  To design a mathematical formula to facilitate smaller donor incisions.
  
  
  METHODS
  A geometric analysis was undertaken to design a practical formula to create smaller defects. This strategy was then used in a case series of 23 patients with large (average 11 cm in diameter) defects [This sentence was corrected after online publication on June 29, 2009: (average 16 x 11 cm) changed to read (average 11 cm in diameter).]. A geometrical analysis was used to design the best way to divide donor grafts to minimize tissue loss.
  
  
  RESULTS
  A formula called for the diameter of the primary defect to be multiplied by 3/2 and 2/3 to design a donor ellipse length and width, respectively. The resulting graft was divided into two equal sizes, using a tangential acute angle. The width and the area of the donor were significantly smaller, so the donor site was repaired using a shorter and faster repair.
  
  
  CONCLUSIONS
  Skin graft harvest may be accomplished using a smaller donor graft than previously described using the formula reported here. This will probably reduce surgical morbidity, time, and expense. The authors have indicated no significant interest with commercial supporters.
authors.affiliation: Department of Dermatologic Surgery, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, JiangsuProvince, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Mei
authors.initials: M
authors.lastname: Cai
authors.forename: Yu-Le
authors.initials: YL
authors.lastname: Wu
authors.forename: Guo-Cheng
authors.initials: GC
authors.lastname: Zhang
mesh_terms: D034861:Abdominal Wall / Q000601:surgery*; D000368:Aged; D001706:Biopsy; D001913:Bowen's Disease / Q000473:pathology / Q000601:surgery*; D006801:Humans; D008297:Male; D008432:Mathematical Computing; D012878:Skin Neoplasms / Q000473:pathology / Q000601:surgery*; D016038:Skin Transplantation / Q000379:methods*; D013536:Suture Techniques; D014019:Tissue Donors