Drilling Technique Can Minimize Plunging

Purpose: Vibratory and acoustic feedback, drill sharpness, and material density have each been shown to influence the depth of plunging when drilling through bicortical bone. We hypothesized that drilling technique can also influence the depth of plunging. Methods: Six subjects of various training levels (PGY1 to 16-year experienced surgeon) were asked to drill through a cortical bone surrogate, third-generation Sawbones tube with similar density and compressive modulus of healthy cortical bone. Using a sharp 4.5-mm drill bit and System 6 drill, each participant drilled 30 holes wearing surgical gloves to mimic tactile feedback and using 3 different techniques (10 holes each). The techniques were single-handed smooth, single-handed bounce, and 2-handed smooth drilling. A 60 frame-per-second high-definition video recorder was placed a standard distance from the model and used to calculate the depth of plunging. Analysis of variance with Fisher PLSD post hoc was used to compare techniques (significance P < 0.05). Results: The average +/- SD plunge depths were 13.0 +/- 4.2 mm (range 6.2-26.8 mm) for single-handed smooth, 17.2 +/- 5.0 mm (range 8.0-28.8 mm) for single-handed bounce, and 10.6 +/- 3.5 mm (range 5.8-19.2) for 2-handed smooth techniques. Difference among all 3 groups reached statistical significance. Conclusion: Bounce technique had the greatest average depth and variance. The 2-handed technique demonstrated the least plunge and the lowest variance, indicating the highest degree of control. This study supports the use of a 2-handed technique for drilling when intraoperative circumstances permit.