Presented by: Erin Kim BS
Case Western Reserve University School of Medicine

Introduction

Musculoskeletal complaints and orthopedic problems are common among urologists, with higher rates reported by female urologists and those with greater ureteroscopy (URS) case loads. Ergonomics during URS has not been well studied, particularly as related to gender. We aimed to assess differences in muscle activation and mental workload during simulated URS based on gender as well as surgeon position and ureteroscope type.

Materials

Urology trainees and staff at our institution were recruited. Subject variables (including gender and glove size) were collected. Surface electromyography (EMG) was measured in muscle groups of the ureteroscope driving upper extremity and back. The maximum voluntary contraction (MVC) was measured for each muscle 3 times, followed by EMG measurements during 3 simulated flexible URS tasks in randomized order: navigation, basketing, and dusting. Subjects were evaluated while sitting vs. standing and with single-use vs. reusable ureteroscopes. The root-mean-square of the EMG signal was calculated for each muscle in each condition and then normalized to the mean MVC for each subject to produce %MVC. Mean %MVC in each muscle was compared between men and women for different conditions. Mental workload was assessed using the National Aeronautics and Space Administration Task Load Index (NASA-TLX). Paired Wilcoxon rank-sum tests and multivariate linear regressions were conducted to associate %MVC of muscle groups with trial conditions and gender.

Results

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Greater %MVC was recorded in women vs. men in the forearm flexor, forearm extensor, biceps, and triceps in all conditions, with the greatest difference displayed in the forearm flexor across all positions and ureteroscope types (Figure). Even when evaluating by task, deltoid and trapezius did not differ between men and women.  With the reusable ureteroscope, an increase of 1 in glove size decreased forearm flexor MVC by 6.69%. Women reported higher mental workload per NASA-TLX scores for all comparisons (p<0.01).

Conclusion

Surgeon ergonomics, based on muscle activation and mental workload, during URS may vary between men and women regardless of position or ureteroscope type and should be further investigated. Ureteroscope design could be optimized for smaller hand sizes to reduce muscle strain and risk of injury.

Funding

Cleveland Clinic Research Program Committee and Glickman Urological Kidney Institute

Co-Authors

Alec Sun, BS
Case Western Reserve University School of Medicine

Juan Sebastian Rodriguez-Alvarez, MD
Cleveland Clinic Glickman and Urological Kidney Institute

Louisa Ho, MD
Cleveland Clinic Glickman and Urological Kidney Institute

Kyle O'Laughlin, MS
Cleveland Clinic Lerner Research Institute Department of Biomedical Engineering

Smita De, MD, PhD
Cleveland Clinic Glickman and Urological Kidney Institute