To Improve Your Surgical Drilling Skills, Make Use of Your Index Fingers
Authors: Langeveld Aernout R. J. , Rustenburg Christine M. E. , Hoozemans Marco J. M. , Burger Bart J. , Meuffels Duncan E. 
Published: November 2018

Abstract

Background
Surgery has greatly benefited from various technologic advancements over the past decades. Surgery remains, however, mostly manual labor performed by well-trained surgeons. Little research has focused on improving osseous drilling techniques. The objective of this study was to compare the accuracy and precision of different orthopaedic drilling techniques involving the use of both index fingers.

Questions/purposes
(1) Does the shooting grip technique and aiming at the contralateral index finger improve accuracy and precision in drilling? (2) Is the effect of drilling technique on accuracy and precision affected by the experience level of the performer?

Methods
This study included 36 participants from two Dutch training hospitals who were subdivided into three groups (N = 12 per group) based on their surgical experience (that is, no experience, residents, and surgeons). The participants had no further experience with drilling outside the hospital nor were there other potential confounding variables that could influence the test outcomes. Participants were instructed to drill toward a target exit point on a synthetic bone model. There were four conditions: (1) clenched grip without aiming; (2) shooting grip without aiming; (3) clenched grip with aiming at the contralateral index finger; and (4) shooting grip aiming at the contralateral index finger. Participants were only used to a clenched grip without aiming in clinical practice. Each participant had to drill five times per technique per test, and the test was repeated after 4 weeks. Accuracy was defined as the systematic error of all measurements and was calculated as the mean of the five distances between the five exit points and the target exit point, whereas precision was defined as the random error of all measurements and calculated as the SD of those five distances. Accuracy and precision were analyzed using mixed-design analyses of variance.

Results
Accuracy was highest when using a clenched grip with aiming at the index finger (mean 4.0 mm, SD 1.1) compared with a clenched grip without aiming (mean 5.0 mm, SD 1.2, p = 0.004) and a shooting grip without aiming (mean 4.9 mm, SD 1.4, p = 0.015). The shooting grip with aiming at the index finger (mean 4.1 mm, SD 1.2) was also more accurate than a clenched grip without aiming (p = 0.006) and a shooting grip without aiming (p = 0.014). Shooting grip with aiming at the opposite index finger (median 2.0 mm, interquartile range [IQR] 1.2) showed the best precision and outperformed a clenched grip without aiming (median 2.9 mm, IQR 1.1, p = 0.016), but was not different than the shooting grip without aiming (median 2.2 mm, IQR 1.4) or the clenched grip with aiming (median 2.4 mm, IQR 1.3). The accuracy of surgeons (mean 4.1 mm, SD 1.1) was higher than the inexperienced group (mean 5.0 mm, SD 1.1, p = 0.012). The same applied for precision (median 2.2 mm, IQR 1.0 versus median 2.8 mm, IQR 1.4, p = 0.008).

Conclusions
A shooting grip combined with aiming toward the index finger of the opposite hand had better accuracy and precision compared with a clenched grip alone. Based on this study, experience does matter, because the orthopaedic surgeons outperformed the less experienced participants. Based on our study, we advise surgeons to aim at the index finger of the opposite hand when possible and to align the ipsilateral index finger to the drill bit.

Level of Evidence
Level II, therapeutic study.