Ergonomics in percutaneous nephrolithotomy: a comparative analysis of musculoeskeletical and mental workload in prone vs. supine positions with two lithotripters-a pilot study.

Purpose: Percutaneous nephrolithotomy (PCNL) is a common technique in the surgical management of renal lithiasis, but it also represents a significant workload for surgeons. Factors such as the patient's position and the type of lithotripter used influence the physical and mental load on the surgeon. The study aimed to identify stressors related to PCNL by comparing the physical and mental workload experienced by urologists during PCNL under different patient positions and using two lithotripters.

Methods: Four expert endourologists were evaluated when simulating PCNL at four different conditions: prone and supine, using the Lithoclast Master (LM) or Lithoclast Trilogy (LT) devices. Physical load was measured using electromyography, while mental load was analyzed by measuring the heart rate variation (HRV). After each simulation, cylindrical grip strength was evaluated using a Jamar dynamometer, and the Surgery Task Load Index (SURG-TLX) questionnaire was applied.

Results: Differences in muscle activation were observed, with greater activation in the LT-Prone position, where the erector spinae reached 27.7%. This was reflected in increased mental, physical, and temporal demands. Similarly, overactivation of the wrist extensor, averaging 229%, was related to back muscle fatigue, when compared to low activation (10%). No significant differences were found in grip strength, while a greater HRV was observed with LT in both positions.

Conclusion: We observed differences in physical and mental fatigue related to patient position, the lithotripter used and the surgeon's muscle activation. This pilot study gives insights into conditions that should be considered to enhance urologist performance and prevent injuries during PCNL.