Objective assessment of endoscopic knot quality

background Studies of the surgeonʹs skill and the ergonomics of task performance in endoscopic surgery can be based on knot-tying tasks. The aim of this study was to establish an objective method for assessing the quality of surgical knots for use in such studies. methods In all, 2,700 surgeonʹs endoscopic knots were studied. Each knot was distracted using a tensiometer, and a computerized system analyzed force-extension curves. The breaking force was taken as an index of knot strength while the force integrated over the slope of the curve reflected knot tightening. A knot quality score (KQS) was obtained from the product of the knot-breaking force and the integrated force expressed as a percentage of the product for the untied ligature. results The mean breaking force (24 Newton ± 2.5) and integrated force (7.4 Newton ± 2.8) for broken knots were 71% and 35%, respectively, of those for united ligature. The integrated force yielded a narrower range of variability for untied ligature (SD 3.5% of mean) than for knots (SD 37% of mean). The KQS was higher for broken (25.3% ± 10.3%) than slipped knots (7.1% ± 5.1%). conclusion The KQS provides a reliable assessment of knot security and reflects the strength and degree of tightening of the knot.