title: Real-time objective assessment of knot quality with a portable tensiometer is superior to execution time for assessment of laparoscopic knot-tying performance.
abstract: OBJECTIVE
  Laparoscopic intracorporeal knot tying is a difficult skill to acquire. Currently, time to complete a knot is the most commonly used metric to assess the acquisition of this skill; however, without a measure of knot quality, time is a poor indicator of skills mastery. Others have shown that knot quality can be accurately assessed with a tensiometer, but obtaining this type of assessment has typically been cumbersome. We investigated a new method of real-time assessment of knot quality that allows for more practical use of knot quality as a performance metric.
  
  
  METHODS
  Eleven experienced endoscopic surgeons tied 100 intracorporeal knots in a standard box trainer. Each of the knots was immediately tested using the InSpec 2200 benchtop tensiometer (INSTRON, Canton MA) where a knot quality score (KQS) is generated based on the load handling properties of the knotted suture. The execution time was also recorded for each knot.
  
  
  RESULTS
  The assessment of all knots ended with one of two end points: knots that slipped (n=48) or knots that held until the suture broke (n=52). Knots that slip are generally of poorer quality than those that held. Execution time did not correlate with knot-quality score (r=0.009, P=.9), and the mean execution time did not differ significantly between slipped and held knots (65 vs 68 seconds, P=.8). No completion time criteria were able to accurately predict slipped versus held knots. The mean KQS difference between held and slipped knots was highly significant (24 vs 12, P<.0001). A knot with a KQS exceeding 20 was nearly 10 times more likely to hold than slip.
  
  
  CONCLUSIONS
  Time to complete a knot is a poor metric for the objective assessment of intracorporeal knot-tying performance in the absence of a measure of knot quality. Real-time evaluation of the knot quality can accurately distinguish well-tied knots from poorly tied knots. This mode of assessment should be incorporated into training curriculum for surgical knot tying.
authors.affiliation: Emory Simulation Training and Robotics (E*STAR) Lab, Endosurgery Unit, Department of Surgery, Emory University School of Medicine, Atlanta, GA, USA. eritter@usuhs.mil
authors.forename: E Matt
authors.initials: EM
authors.lastname: Ritter
authors.forename: David A
authors.initials: DA
authors.lastname: McClusky
authors.forename: A G
authors.initials: AG
authors.lastname: Gallagher
authors.forename: C Daniel
authors.initials: CD
authors.lastname: Smith
mesh_terms: D001696:Biomechanical Phenomena; D002983:Clinical Competence; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D010535:Laparoscopy / Q000379:methods*; D008297:Male; D008365:Manometry; D012680:Sensitivity and Specificity; D013536:Suture Techniques; D013537:Sutures; D013647:Task Performance and Analysis; D013718:Tensile Strength; D013997:Time Factors