Optimizing Assessment of Surgical Knot Tying Skill

Abstract

Knot tying is a fundamental surgical skill. Existing knot tying models assess tying efficiency and errors but do not address respect for tissue. Development of a model that assesses tissue displacement during knot tying may provide a good surrogate for respect for tissue, allow detection of expertise, and offer an improved training platform for skill acquisition. This study aimed to develop a novel, low-cost, knot tying board (KTB) that collects objective, automated metrics of knot displacement, and assesses knot displacement by level of surgical expertise. The novel KTB was developed in collaboration between engineering students and surgical educators. Joystick potentiometers were incorporated on 2 parallel rubber tubes to measure vertical and horizontal displacement while tying. Participants used a standardized technique to tie 1- and 2-handed knots. Differences in time and tubing displacement were compared among junior residents (postgraduate year 1-2), senior residents (postgraduate year 3-5), and attending surgeons; p < 0.05 was considered statistically significant. This study was conducted at the Indiana University Surgical Skills Center in Indianapolis, IN. Forty-seven residents and faculty participated in the study (26 juniors, 14 seniors, 7 attendings). KTB development required 100 hours and $70.00. The attending surgeons tied 2-handed knots faster and with significantly more vertical tubing displacement than residents. Senior residents tied knots significantly faster but with similar tubing displacement as juniors. Similar trends were found for 1-handed knots. A novel, low-cost KTB was developed to measure knot displacement as a surrogate for tissue handling. The new performance metric of vertical knot displacement proved more sensitive in detecting performance differences among groups compared with horizontal knot displacement. This board and its novel metrics may promote the development of robust knot tying skill by residents.