VALIDATION OF A FINITE ELEMENT MODEL OF THE MECHANICAL PERFORMANCE OF SURGICAL KNOTS OF VARYING TOPOLOGY

Abstract

Background Knot tying is considered a basic surgical skill, however, there is no consensus on the best technique. Suture breakage and slippage are failure modes during surgical repair and are related to stress concentrations which cannot be easily established with physical testing. Few computational models exist that describe the effect of knot topology on the failure mechanism. The purpose of this study was to implement the finite element

method to analyze the mechanical behavior of surgical sutures according to number of throws and to validate the model against experiments. Methods Experiments and models of monofilament and multifilament sutures were conducted. Multiple throw knots were tested to failure in a laboratory setting and with corresponding finite element models. Gross loads were compared when the knot reached a localized material yield stress in the model or when failure occurred in laboratory tests that have the same suture topology.

Results The results of laboratory tests and corresponding finite element models of single throw knots were compared and found to be well correlated and consistent with existing literature in strength prediction and failure location. Moreover, single throw knots have reduced failure strengths relative to non-knotted suture approximately by 120 N for both monofilament and multifilament sutures, respectively.