title: Working volume: validity evidence for a motion-based metric of surgical efficiency.
abstract: BACKGROUND
  The aim of this study was to evaluate working volume as a potential assessment metric for open surgical tasks.
  
  
  METHODS
  Surgical attendings (n = 6), residents (n = 4), and medical students (n = 5) performed a suturing task on simulated connective tissue (foam), artery (rubber balloon), and friable tissue (tissue paper). Using a motion tracking system, effective working volume was calculated for each hand. Repeated measures analysis of variance assessed differences in working volume by experience level, dominant and/or nondominant hand, and tissue type.
  
  
  RESULTS
  Analysis revealed a linear relationship between experience and working volume. Attendings had the smallest working volume, and students had the largest (P = .01). The 3-way interaction of experience level, hand, and material type showed attendings and residents maintained a similar working volume for dominant and nondominant hands for all tasks. In contrast, medical students' nondominant hand covered larger working volumes for the balloon and tissue paper materials (P < .05).
  
  
  CONCLUSIONS
  This study provides validity evidence for the use of working volume as a metric for open surgical skills. Working volume may provide a means for assessing surgical efficiency and the operative learning curve.
authors.affiliation: Department of Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave, K6/135 CSC, Madison, WI, 53792, USA. Electronic address: ad'angelo@uwhealth.org.
authors.forename: Anne-Lise D
authors.initials: AL
authors.lastname: D'Angelo
authors.affiliation: Department of Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave, K6/135 CSC, Madison, WI, 53792, USA; Department of Kinesiology, School of Education, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Drew N
authors.initials: DN
authors.lastname: Rutherford
authors.affiliation: Department of Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave, K6/135 CSC, Madison, WI, 53792, USA.
authors.forename: Rebecca D
authors.initials: RD
authors.lastname: Ray
authors.affiliation: Department of Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave, K6/135 CSC, Madison, WI, 53792, USA; Department of Electrical and Computer Engineering, College of Engineering, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Shlomi
authors.initials: S
authors.lastname: Laufer
authors.affiliation: Department of Kinesiology, School of Education, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mason
authors.affiliation: Department of Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave, K6/135 CSC, Madison, WI, 53792, USA.
authors.forename: Carla M
authors.initials: CM
authors.lastname: Pugh
mesh_terms: D002983:Clinical Competence; D004501:Education, Medical; D004526:Efficiency; D007839:Functional Laterality; D006801:Humans; D059032:Learning Curve; D000066908:Simulation Training; D013536:Suture Techniques / Q000193:education*; D013996:Time and Motion Studies
keywords: Education; Motion tracking; Skills assessment; Surgery; Technical skills; Working volume