Optimizing the design of a barbed suture for flexor tendon repair using extended finite element analysis -

Abstract

Conventional surgeries for flexor tendon repair involve tying the ends of the suture in at least a single knot. Knots give rise to several complications at the repair site, from delaying wound healing, to constriction of blood flow and formation of scars. In addition, they present probable failure regions due to increased stress concentrations. To strengthen such critical locations, one approach is to use multiple suture strands. However, applying higher stresses on the tendon results in stiffer tissues that have reduced gliding ability. A promising solution implements sutures with protruding barbs that anchor themselves into the tissue; eliminating the need for a knot. The use of barbed sutures for flexor tendon repair offers several advantages over traditional knotted techniques. When barbs are inserted into the tendon, grip is achieved at multiple points. Consequently, the load is dispersed along the entire length of the suture decreasing the possibility of slippage. Furthermore, since knots are no longer required, regions with increased mass and volume of suture material are eliminated; hence, inflammation is reduced and healing of the wound is accelerated. The purpose of this study is to propose an enhanced barbed suture geometry such that it is capable of withstanding higher stresses, in an attempt to eliminate knots in tenorrhaphies and minimize the number of suture strands used. It is believed that the rigidity of the barb, as well as its ability to anchor surrounding tissue can be manipulated by the suture’s geometry via three factors: cross-sectional configuration, cut angle and cut depth. Inspired by the geometry of flexor tendons, an elliptical, rather than a circular, cross-section was investigated. The mechanical behavior of five different aspect ratios (ρ= 1-3, 1-2, 1, 2, 3), three different cut angles (150º, 154º, 160º) and three different cut depths (0.07mm, 0.12mm, 0.18mm) was studied via extended finite element analysis using ABAQUS, for two different loading con