title: Effect of feed rate and drill speed on temperatures in equine cortical bone.
abstract: OBJECTIVE
  To examine the amount of heat generated in equine cortical bone by a 6.2-mm drill, using low- and high-speed and controlled feed rate drilling.
  
  
  METHODS
  10 metacarpal bones harvested from five 2-year-old draft-type horses.
  
  
  METHODS
  Drilling on metacarpal bones was done using a machine shop mill with which the feed rate and drill speed could be precisely controlled. Bones were drilled, using 6 combinations of feed rate (1, 2, and 3 mm advance/s) and drill speed (317 and 1,242 revolutions/min [rpm], with maximal temperatures recorded by thermocouples placed 1, 1.5, and 2 mm from the drill. Maximal temperatures were evaluated for the effect of feed rate, drill speed, cortical thickness, and distance from the drill, using linear regression analysis.
  
  
  RESULTS
  Increasing feed rate from 1 to 2 and from 2 to 3 mm/s significantly decreased mean maximal temperature. Increasing drill speed from 317 to 1242 rpm significantly increased mean maximal temperature. Increasing cortical thickness significantly increased mean maximal temperature, and increasing the distance from the drill hole significantly decreased mean maximal temperatures.
  
  
  CONCLUSIONS
  On the basis of our results, we recommend using low drill speeds while applying sufficient axial force to advance the drill as rapidly as possible through the bone.
  
  
  CONCLUSIONS
  Results of using this in vitro model suggest that temperatures at the drill-bone interface may be sufficiently high to result in significant thermal necrosis when drilling equine cortical bone.
authors.affiliation: Department of Veterinary Anesthesiology, Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada.
authors.forename: A R
authors.initials: AR
authors.lastname: Toews
authors.forename: J V
authors.initials: JV
authors.lastname: Bailey
authors.forename: H G
authors.initials: HG
authors.lastname: Townsend
authors.forename: S M
authors.initials: SM
authors.lastname: Barber
mesh_terms: D000818:Animals; D005592:Fracture Fixation / Q000379:methods / Q000662:veterinary*; D017102:Fracture Healing; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary*; D006736:Horses / Q000293:injuries / Q000601:surgery*; D006358:Hot Temperature / Q000009:adverse effects; D016014:Linear Models; D008663:Metacarpus / Q000502:physiology / Q000601:surgery*