International Orthopaedics

, Volume 36, Issue 7, pp 1449–1456

Temperature changes during cortical bone drilling with a newly designed step drill and an internally cooled drill

  • Goran Augustin
  • Slavko Davila
  • Toma Udilljak
  • Tomislav Staroveski
  • Danko Brezak
  • Slaven Babic
Original Paper

DOI: 10.1007/s00264-012-1491-z

Cite this article as:
Augustin, G., Davila, S., Udilljak, T. et al. International Orthopaedics (SICOT) (2012) 36: 1449. doi:10.1007/s00264-012-1491-z

Abstract

Purpose

Bone drilling causes an increase in bone temperature, and a temperature above 47°C is critical because it causes thermal bone necrosis. Thermal osteonecrosis is common with the drill diameter of ≥4.5 mm without cooling. The aim of this study was to determine the increase of bone temperature during drilling using newly contructed two-step and internally cooled drills.

Methods

An experiment was set up according to a central composite design. An internally cooled drill (3.4 mm and 4.5 mm) and a two-step drill (2.5/3.4 and 3.4/4.5 mm) were used in combination with feed rates of (0.02, 0.04, 0.10, 0.16 and 0.18 mm/rev) and cutting speeds (1.18, 10.68, 33.61, 56.55 and 66.05 m/min) with and without cooling with water of 24°C. Bone temperatures were measured with thermocouples. Drilling was performed on pig diaphyses with a three-axis mini milling machine.

Results

Bone temperatures in all combinations of parameters with internal cooling were below the critical 47°C (p = 0.05). The highest temperatures were detected using a 4.5-mm drill (40.5°C). A statistically significant effect other than cooling was found with the drill diameter and feed. A drill diameter of 3.4 mm with internal cooling developed a maximum temperature of 38.5°C and without cooling 46.3°C. For the same conditions a drill with diameter of 4.5 mm reached temperatures of 40.5°C and 55.7°C, respectively. The effect of feed rate is inversely proportional to the increase in bone temperature. With the feed rate 0.16 mm/rev, temperature was below critical even using the 4.5-mm drill (46.4°C, p = 0.05). Using the 3.4-mm drill all temperatures were below critical (46.2°C, p = 0.05). The two-step drill compared to a standard drill with the same diameter did not show statistical differences in maximum bone temperatures for all combinations of parameters (p = 0.05).

Conclusions

A two-step drill does not have any advantages over a standard twist drill of the same diameter. An internally cooled drill causes a significantly smaller increase of bone temperature during drilling with water of 24°C. An internally cooled drill is currently the 'ideal' drill for traumatology/orthopaedics because it produces the smallest increase in bone drilling temperature. If internal cooling is used the regulation of other drilling parameters is of no importance.

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Goran Augustin
    • 1
  • Slavko Davila
    • 1
  • Toma Udilljak
    • 2
  • Tomislav Staroveski
    • 2
  • Danko Brezak
    • 2
    • 4
  • Slaven Babic
    • 3
  1. 1.Department of Surgery, University Hospital Center Zagreb and School of MedicineUniversity of ZagrebZagrebCroatia
  2. 2.Department of Technology, Faculty of Mechanical Engineering and Naval ArchitectureUniversity of ZagrebZagrebCroatia
  3. 3.Department of TraumatologyClinical Hospital Center Sestre MilosrdniceZagrebCroatia
  4. 4.Department of Robotics and Production System Automation, Faculty of Mechanical Engineering and Naval ArchitectureUniversity of ZagrebZagrebCroatia