title: The relevance of threaded external skeletal fixation pin insertion speed in canine bone with and without predrilling.
abstract: OBJECTIVE
  The effects of insertion speed in revolutions per minute (RPM) and pilot hole predrilling for placement of threaded external skeletal fixation pins on temperature and morphological damage in cortical bone were evaluated. The null hypothesis states that insertion speed and predrilling will have no significant effect on temperature and morphological damage.
  
  
  METHODS
  Fixation pins were inserted into cadaveric canine femurs at speeds of 700 RPM and 150 RPM, with and without pre-drilling. Temperature was measured at each cortex 0.5 mm and 3.0 mm from each insertion site. Samples were examined grossly and by scanning electron microscopy for evidence of morphological damage. Data were analysed for maximum temperature, temperature increase, sites above thermal necrosis thresholds, microcracks, thread quality and gross damage.
  
  
  RESULTS
  Predrilling had a significant effect on maximum temperature, temperature increase, sites exceeding necrosis thresholds, microcracks, thread quality and gross damage. Speed of insertion had no significant effect on any of the measured parameters following predrilling, but had a significant effect on thread quality without predrilling.
  
  
  CONCLUSIONS
  Our results fail to reject the null hypothesis concerning insertion speed, which had no significant effect on thermal damage, and minimal effect on morphological damage, which was negated by predrilling. Our results reject the null hypothesis concerning predrilling and support the practice of predrilling fixation pin insertion sites.
authors.affiliation: Jackson T. Walker, DVM, 1 BVMTH, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, United States, Phone: +1 405 744 7000, Fax: +1 405 744 6265, E-mail: jackson.walker@okstate.edu.
authors.forename: J T
authors.initials: JT
authors.lastname: Walker
authors.forename: M C
authors.initials: MC
authors.lastname: Rochat
authors.forename: T A
authors.initials: TA
authors.lastname: Snider
authors.forename: M E
authors.initials: ME
authors.lastname: Payton
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001858:Bone Nails / Q000662:veterinary*; D001842:Bone and Bones / Q000502:physiology*; D002102:Cadaver; D004285:Dogs; D016267:External Fixators / Q000662:veterinary*
keywords: Fixation pins; insertion speed; osteonecrosis; predrill