OBJECTIVE ASSESSMENT OF ENDOSCOPIC KNOT QUALITY

BACKGROUND: Studies of the surgeon's skill and the ergonomics of task performance in endoscopic surgery can be based on knot-tying tasks, Th e aim of this study was to establish an objective method for assessing the quality of surgical knots for use in such studies. METHODS: In al l, 2,700 surgeon's endoscopic knots were studied. Each knot was distra cted using a tensiometer, and a computerized system analyzed force-ext ension curves, The breaking force was taken as an index of knot streng th while the force integrated over the slope of the curve reflected kn ot tightening, A knot quality score (KQS) was obtained from the produc t of the knot-breaking force and the integrated force expressed as a p ercentage of the product for the untied ligature. RESULTS: The mean br eaking force (24 Newton +/- 2.5) and integrated force (7.4 Newton +/- 2.8) for broken knots were 71% and 35%, respectively, of those for unt ied ligature. The integrated force yielded a narrower range of variabi lity for untied ligature (SD 3.5% of mean) than for knots (SD 37% of m ean), The KQS was higher for broken (25.3% +/- 10.3%) than slipped kno ts (7.1% +/- 5.1%), CONCLUSION: The KQS provides a reliable assessment of knot security and reflects the strength and degree of tightening o f the knot. (C) 1997 by Excerpta Medica, Inc.