title: How Safe Is High-Speed Burring in Spine Surgery? An In Vitro Study on the Effect of Rotational Speed and Heat Generation in the Bovine Spine.
abstract: METHODS
  In vitro animal cadaveric study.
  
  
  OBJECTIVE
  To identify the appropriate rotational speed and safe bone distance from neural tissue during bone burring in spinal surgery.
  
  
  BACKGROUND
  Bone burring is a common step in spinal surgery. Unwanted frictional heat produced during bone burring may result in thermal injury to the bone and adjacent neural structure. One of the important parameters influencing the bone temperature rise during bone burring is rotational speed.
  
  
  METHODS
  This laboratory-based animal study used bovine spine bones, and the tests were conducted using a steel round burr. The bone temperature was measured simultaneously with thermocouple at the distances of 1 mm, 3 mm, and 5 mm from the burring site during the burring process. The bone burring was done with 4 different rotational speeds of 35,000 revolutions per minute (rpm), 45,000 rpm, 65,000 rpm, and 75,000 rpm.
  
  
  RESULTS
  This study showed that increasing the rotational speed significantly elevated bone temperature. The threshold temperature of 47°C was reached when bone was burred for 10 seconds, with a rotational speed of 45,000 rpm. The mean bone temperature measured at a distance 1 mm from the burring site for all 4 rotational speeds was always higher than that measured at a distance of 3 mm and 5 mm and this difference was statistically significant (P < 0.001). There was no significant difference between the mean bone temperature measured at a distance of 3 mm and 5 mm (P > 0.05).
  
  
  CONCLUSIONS
  Taking 47°C as the threshold temperature for causing significant impairment to the regenerative capacity of bone, a rotational speed of lower than 45,000 rpm is preferable so as to minimize thermal injury to bone tissue. We also concluded that a 3-mm distance between the site of burring and the neural tissue is a safe distance.
  
  
  METHODS
  N/A.
authors.affiliation: From the Spine and Spinal Cord Rehabilitation Unit, Department of Orthopaedics, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia.
authors.forename: Taran Singh Pall
authors.initials: TS
authors.lastname: Singh
authors.forename: Abdul Halim
authors.initials: AH
authors.lastname: Yusoff
authors.forename: Yap Keat
authors.initials: YK
authors.lastname: Chian
mesh_terms: D000818:Animals; D001831:Body Temperature; D002056:Burns / Q000209:etiology / Q000517:prevention & control; D002417:Cattle; D017276:Friction; D006358:Hot Temperature; D019637:Orthopedic Procedures / Q000009:adverse effects*; D059348:Peripheral Nerve Injuries / Q000209:etiology / Q000517:prevention & control; D012399:Rotation; D013124:Spinal Injuries / Q000209:etiology / Q000517:prevention & control; D013131:Spine / Q000601:surgery*