Failure characteristics of various arthroscopically tied knots

The current study evaluated multiple arthroscopic knot configurations and compared their properties with open, hand-tied square knots. This is an experimental study done on a material testing system. Number 2 Ethibond Extra and Number 1 Polydioxanone sutures were used. Four types of sliding knot configurations were tested: the Duncan loop, the Tennessee Slider, the Savoie-Modified Roeder, and the Lieurance-Modified Roeder. Two types of nonsliding knots were tested: the Revo knot and a knot consisting of alternating half-hitches tied with the Sixth Finger Knot Pusher. Ten knots were tied of each configuration, using strict arthroscopic technique. Each knot was backed-up with four half-hitches using post switching technique. Knots were tied around two rings and then transferred wet to a materials testing machine. The knots were tested until ultimate failure, with note of clinical failure at 3 mm. Ethibond suture using the Revo knot, the Lieurance-Modified Roeder knot, and the Savoie-Modified Roeder knot were similar in strength to the square knot with comparable failure modes. Polydioxanone suture was more variable; the Revo knot, the Savoie-Modified Roeder, the Tennessee Slider, and the Duncan loop were comparable with hand-tied square knots. All of the open and arthroscopic suture loops tested in this study failed by the suture loops expanding to greater than 3 mm before ultimate failure occurred. The surgeon choosing arthroscopic repair techniques should be aware of the differences in suture material and the variation in knot strength afforded by different knot configurations.