title: Risk of injury to vascular-nerve bundle after calcaneal fracture: comparison among three techniques.
abstract: OBJECTIVE
  To ascertain whether the number of screws or pins placed in the calcaneus might increase the risk of injury when three different techniques for treating calcaneal fractures.
  
  
  METHODS
  126 radiographs of patients who suffered displaced calcaneal fractures were retrospectively analyzed. Three surgical techniques were analyzed on an interobserver basis: 31 radiographs of patients treated using plates that were not specific for the calcaneus, 48 using specific plates and 47 using an external fixator. The risk of injury to the anatomical structures in relation to each Kirschner wire or screw was determined using a graded system in accordance with the Licht classification. The total risk of injury to the anatomical structures through placement of more than one wire/screw was quantified using the additive law of probabilities for the product, for independent events.
  
  
  RESULTS
  All of the models presented high explanatory power for the risk evaluated, since the coefficient of determination values (R (2)) were greater than 98.6 for all the models. Therefore, the set of variables studied explained more than 98.6% of the variations in the risks of injury to arteries, veins or nerves and can be classified as excellent models for prevention of injuries.
  
  
  CONCLUSIONS
  The risk of injury to arteries, veins or nerves is not defined by the total number of pins/screws. The region and the number of pins/screws in each region define and determine the best distribution of the risk.
authors.affiliation: Universidade Federal Fluminense, Niterói, RJ, Brazil.
authors.forename: Pedro José
authors.initials: PJ
authors.lastname: Labronici
authors.affiliation: "Prof. Dr. Donato D'Ângelo" Orthopedics and Traumatology Service, Hospital Santa Teresa, Petrópolis, RJ, Brazil.
authors.forename: Vitor Rodrigues
authors.initials: VR
authors.lastname: Reder
authors.affiliation: "Prof. Dr. Donato D'Ângelo" Orthopedics and Traumatology Service, Hospital Santa Teresa, Petrópolis, RJ, Brazil.
authors.forename: Guilherme Ferreira
authors.initials: GF
authors.lastname: de Araujo Marins Filho
authors.affiliation: Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Robinson Esteves Santos
authors.initials: RE
authors.lastname: Pires
authors.affiliation: Department of Orthopedics and Traumatology, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, Brazil.
authors.forename: Hélio Jorge Alvachian
authors.initials: HJ
authors.lastname: Fernandes
authors.affiliation: Santa Casa de São Paulo, Pavilhão Fernandinho Simonsen, São Paulo, SP, Brazil.
authors.forename: Marcelo Tomanik
authors.initials: MT
authors.lastname: Mercadante
keywords: Bone screws; Calcaneus/injuries; Operative surgical procedures/methods; Orthopedic pins