We studied the various drill bits available for engineering purposes, and compared them with standard orthopaedic drill bits, using continuous temperature recording at 0.5 mm, 1.0 mm and 1.5 mm from the edge of a 2.5 mm hole as it was drilled in fresh cadaver human tibia.

We found that some commercially available drill bits performed better than their orthopaedic equivalents, producing significantly less thermal injury to the surrounding bone and halving the force required for cortical penetration. Our work suggests that the optimal bit for orthopaedic purposes should have a split point and a quick helix. Theoretical knowledge of cutting technology predicts that the addition of a parabolic flute will further reduce thermal damage. Further work is being done on other drill sizes used in orthopaedic practice and on new custom-designed bits.

In this study, we discuss 68 cases in which peripheral nerve trunks were inadvertently divided by surgeons. Most of these accidents occurred in the course of planned operations. Delay in diagnosis and in effecting repair was common. We list the nerves particularly at risk and the operations in which special care is needed. We recommend steps to secure prompt diagnosis and early treatment.