RESUMO
OBJECTIVE: To investigate the relationship between ergonomic positions and electromyographic muscle activity during otologic drilling. STUDY DESIGN: Cross-over experimental trial. SETTING: Tertiary Academic Medical Center. METHODS: Surgeon participants were tasked with delicate eggshell drilling in 3 different seated positions: "neutral," "slouched," and "craned." Surface electromyography (sEMG) sensors recorded the amplitude and frequency of muscle activity. The joint analysis of spectrum and amplitude (JASA) method, which combines temporal trends in frequency and amplitude, was used to identify trials that exhibited patterns of fatigue. RESULTS: The sEMG amplitude and frequency responses demonstrated wide temporal changes. In a majority of experiments, amplitude increased over the course of the experiment, while frequency remained more stable. On analysis of variance testing, only the mean frequency of the deltoid differed significantly between postures (P = .02). Under the JASA framework, external carpi radialis and upper trapezius experienced fatigue in nearly half of the trials regardless of position (47% vs 49%). The upper trapezius demonstrated fatigue during 46% and 69% of the "craned" and "slouched" trials, respectively, compared to just 31% of the "neutral" trials. Fewer attendings demonstrated upper trapezius fatigue compared to trainees (33% vs 62%). Female surgeons experienced fatigue in more trials than male counterparts (73% vs 25%). CONCLUSION: This study highlights a first step in quantifying the relationship between operating postures and muscle fatigue. Results suggest that specific muscle groups are more susceptible to fatigue; gender and experience may also impact muscle activity.