title: Postural instability does not necessarily correlate to poor performance: case in point.
abstract: BACKGROUND
  It is very important for surgeons who perform minimally invasive surgery (MIS) to maintain proper postural stability, which kinematic research can determine. Previous studies in surgical ergonomics have shown that postural stability is correlated to instrument type, task difficulty, and skill level. What should also be considered is that surgeons may strategically change stance or joint movement to achieve better surgical outcomes while potentially subjecting themselves to greater risk. Background information about subjects, e.g., joint impairment, should be considered an important surgical ergonomic element. Such information can lead to more realistic and accurate conclusions about postural stability and joint kinematics.
  
  
  METHODS
  A highly experienced and skilled right-handed surgeon developing carpal tunnel syndrome in both wrists was recruited into a small (6 subjects) performance study of pegboard transfer and circle-cutting tasks from the Fundamentals of Laparoscopic Surgery (FLS) skill set. Joint kinematics and postural data were collected using two associated force plates and a motion capture system of 12 digital, high-resolution, high-speed, infrared cameras.
  
  
  RESULTS
  Each task was completed in less than 90 s. In pegboard transfer, the subject increased shoulder abduction angle to align his hand and forearm and minimize wrist flexion. When circle-cutting required excessive wrist flexion, the subject maintained his lower body position and stance while twisting his torso, a strategy that appeared to stabilize tangential direction related to cutting while maintaining a fixed orientation of forearm, wrist, and hand. In another circle-cutting trial, the subject changed his stance primarily by shifting foot position as necessary to obtain better scissor approach angles. These compensatory, strategic movements caused an increase in overall postural sway but did not represent postural instability.
  
  
  CONCLUSIONS
  This case study indicated that poor joint kinematics or postural stability does not necessarily correlate to poor performance. Instead, they may indicate positive compensatory or strategic movements.
authors.affiliation: Division of General Surgery, Department of Surgery, School of Medicine, University of Maryland, Baltimore, MD, USA.
authors.forename: Gyusung
authors.initials: G
authors.lastname: Lee
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Kavic
authors.forename: Ivan M
authors.initials: IM
authors.lastname: George
authors.forename: Adrian E
authors.initials: AE
authors.lastname: Park
mesh_terms: D001696:Biomechanical Phenomena; D002349:Carpal Tunnel Syndrome / Q000503:physiopathology / Q000517:prevention & control*; D013502:General Surgery; D006801:Humans; D010535:Laparoscopy / Q000379:methods*; D008297:Male; D009784:Occupational Diseases / Q000503:physiopathology / Q000517:prevention & control*; D004856:Postural Balance; D013647:Task Performance and Analysis