title: Comparative assessment of surgeons' task performance and surgical ergonomics associated with conventional and modified flank positions: a simulation study.
abstract: BACKGROUND
  Flank position is extensively used in retroperitoneoscopic urological practice. Most surgeons follow the patients' position in open approaches. However, surgical ergonomics of the conventional position in the retroperitoneoscopic surgery is poor. We introduce a modified position and evaluated task performance and surgical ergonomics of both positions with simulated surgical tasks.
  
  
  METHODS
  Twenty-one novice surgeons were recruited to perform four tasks: bead transfer, ring transfer, continuous suturing, and cutting a circle. The conventional position was simulated by setting an endo-surgical simulator parallel to the long axis of a surgical desk. The modified position was simulated by rotating the simulator 30° with respect to the long axis of the desk. The outcome measurements include task performance measures, kinematic measures for body alignment, surface electromyography, relative loading between feet, and subjective ratings of fatigue.
  
  
  RESULTS
  We observed significant improvements in both task performance and surgical ergonomics parameters under the modified position. For all four tasks, subjects finished tasks faster with higher accuracy (p < 0.005 or < 0.001). For ergonomics part: (1) The angle between the upper body and the head was decreased by 7.4 ± 1.7°; (2) The EMG amplitude collected from shoulders and left lumber was significantly lower (p < 0.05); (3) Relative loading between feet was more balanced (p < 0.001); (4) Manual-action muscles and postural muscles are rated less fatiguing according to the questionnaire (p < 0.05).
  
  
  CONCLUSIONS
  Conventional position of patient in retroperitoneoscopic upper urinary tract surgery is associated with poor surgical ergonomics. With a simulated surgery, we demonstrated that our modified position could significantly improve task performance and surgical ergonomics. Further studies are still warranted to validate these benefits for both patients and surgeons.
authors.affiliation: Urology Department and Institute of Urology, Peking University First Hospital, Peking University, Beijing, 100034, China, dantefanbmu@126.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Fan
authors.forename: Gaiqing
authors.initials: G
authors.lastname: Kong
authors.forename: Yisen
authors.initials: Y
authors.lastname: Meng
authors.forename: Shutao
authors.initials: S
authors.lastname: Tan
authors.forename: Kunlin
authors.initials: K
authors.lastname: Wei
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Jin
mesh_terms: D001696:Biomechanical Phenomena; D002983:Clinical Competence / Q000592:standards*; D003198:Computer Simulation; D004502:Education, Medical, Continuing; D006804:Ergonomics / Q000379:methods*; D006801:Humans; D056888:Patient Positioning; D066231:Surgeons / Q000592:standards*; D013520:Urologic Surgical Procedures / Q000193:education*