Surface Electromyography as a Measure of Fatigue in Otologic Drilling

Introduction: Poor surgical ergonomics can lead to injury and reduced career longevity. However, the specific effects of different ergonomic positions on muscle activity have not been thoroughly studied. We utilized surface electromyography (sEMG) to quantify the relationship between ergonomic positioning and muscle activity during otologic drilling.

Methods: In a randomized, cross-over trial, 4 attending, 2 fellow, and 6 resident otolaryngology head and neck surgeons were asked to perform an eggshell drilling simulation in three different seated positions: ergonomically neutral, “slouched,” and “craning”. For every trial, we analyzed surface electromyography (sEMG) signals in four muscle groups: anterior deltoid, upper trapezius, biceps, and extensor carpi radialis (ECR) muscle groups. In accordance with previous literature, we utilized joint analysis of spectrum and amplitude (JASA), a method of combining temporal changes in frequency and amplitude, to identify fatiguing activities.

Results: The neutral position revealed lower muscle activation in the biceps (p = .038) and frequency in the deltoid (p = .043). The ECR and upper trapezius experienced fatigue in nearly half of the trials regardless of position (47% and 49% respectively). While posture did not affect fatigue in most muscle groups, the upper trapezius experienced fatigue during 58% of the trials in "craning" and "slouched" positions compared to 31% of the trials in the neutral position. Fewer attending surgeons demonstrated fatigue in the upper trapezius compared to trainees (40% and 62%, respectively). Additionally, female surgeons experienced fatigue in more trials than male counterparts (79% and 27%, respectively).

Conclusions: This study highlights an important first step in quantifying the relationship between different operating postures and muscle activity. The results suggest that specific muscle groups are more susceptible to fatigue, and gender and experience may also impact muscle activity. Future studies in a variety of contexts and procedures are needed to guide interventions and curricular changes in training programs.