Evaluation of a tensiometer to provide objective feedback in knot-tying performance

Training and assessment methods for knot tying by medical students or residents have traditionally been subjective. Objective methods for evaluating creation of a tied knot should include assessing the strength and quality of the knotted suture. The purpose of this study was to evaluate the use of a tensiometer as a feedback device for improving knot-tying performance. Twelve medical students with no knot-tying experience were selected to perform three-throw instrument ties with 00 silk suture. Students were randomly assigned to perform between 10 and 20 baseline knots and then received one of four feedback training conditions followed by 10 completion knots. Subjects were timed, and all knots were pulled in the tensiometer to assess for strength and slippage. Differences between baseline and completed knots for each subject were analyzed with an unpaired t test. Subjects receiving both subjective and tensiometer feedback demonstrated the greatest improvements in knot quality score (KQS) and slip percentage (Subject 1: 0.15 +/- 0.9 vs 0.21 +/- 0.05, P < 0.04, 75% vs 60%, P = NS; Subject 2: 0.22 +/- 0.10 vs 0.29 +/- 0.05, P < 0.02, 33% vs 0%, P < 0.05; Subject 3: 0.10 +/- 0.07 vs 0.25 +/- 0.07, P < 0.0001, 60% vs 10%, P < 0.01). Objective assessment of knot-tying performance is possible using the tensiometer device. Introduction of the tensiometer during the learning phase produced improved KQS and slip percentage in most students regardless of the number of baseline knots tied. Greatest improvements in performance were seen when the tensiometer was used in combination with subjective instruction.