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

Authors

    • Department of Surgery, University Hospital Center Zagreb and School of MedicineUniversity of Zagreb
  • Slavko Davila
    • Department of Surgery, University Hospital Center Zagreb and School of MedicineUniversity of Zagreb
  • Toma Udilljak
    • Department of Technology, Faculty of Mechanical Engineering and Naval ArchitectureUniversity of Zagreb
  • Tomislav Staroveski
    • Department of Technology, Faculty of Mechanical Engineering and Naval ArchitectureUniversity of Zagreb
  • Danko Brezak
    • Department of Technology, Faculty of Mechanical Engineering and Naval ArchitectureUniversity of Zagreb
    • Department of Robotics and Production System Automation, Faculty of Mechanical Engineering and Naval ArchitectureUniversity of Zagreb
  • Slaven Babic
    • Department of TraumatologyClinical Hospital Center Sestre Milosrdnice
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