Assessment of surgical trainees' quality of knot-tying

This study aimed to assess surgical trainees' knot tying technique and determine the type and security of knots created.

Twenty-five participants were requested to tie 40 knots each, using Vicryl 2-0 and Prolene 2-0 sutures. With each suture material, the participants tied: in series 1, 4 knots as they would normally do during surgery; in series 2, 4 knots with 3 throws, 4 knots with 4 throws, 4 knots with 5 throws, and 4 knots with 6 throws. All knots were tested for tensile strength using a tensiometer. Knots with tensile strength of less than 5 N were considered dangerous.

Of the 25 participants, 2 created square knots consistently, 2 created a mixture of square and slip knots, and 21 created only slip knots. Square knots accounted for only 12.8% of all the knots. The incidence of knot slipping under tension was significantly lower with square knots (p < 0.001). Square knots had significantly higher tensile strength than slip knots (p < 0.001). For Vicryl, 4-throw square knots were superior to 6-throw slip knots (p < 0.001). For Prolene, 3-throw square knots were superior to 6-throw slip knots (p = 0.035). Some 12.6% of Vicryl knots and 5.6% of Prolene knots were dangerous and all of these were slip knots with up to 6 throws. Three out of 12 participants who thought they had created square knots actually created square knots and the rest produced slip knots. The participants' surgical experience did not have any correlation with their knot security (r = -0.044, p = 0.833).

Knot tying is often executed with technical errors resulting in slip knots with less than optimal security and high incidence of dangerous knots. Tensiometry testing could be used as an objective assessment tool for knot-tying competency for surgical trainees.