After each test, this loop was rotated slightly around the four pulleys to test a fresh portion of the suture material. Each end hung down and was knotted securely to the cord of the load distributing frame, creating a circular loop of suture material and cord. The selected suture material was threaded over one small pulley, knotted around the rod below the washer using the test ligature and then threaded over the other small pulley. To test the properties of a constrictor knot, he designed a horizontal test bench to measure the force required to pull a rod through a ligature, using friction as an indirect measure of tension. This study evaluated the constrictor knot for use in surgery and compared it with other ligature knots.īefore this study was initiated, one of the authors (HT) tested the constrictor knot’s ability to restrict flow in plastic tubing and also used it as a ligature for such procedures as pedicle ligation in canine ovariohysterectomy.

We found no study that examined either the constrictor knot or the stability of the critical first part of a ligature knot. However, these studies all considered the completed knot. Leitch et al bench tested several knots for their ability to attenuate flow through a plastic tube. In the knotting world, the constrictor knot is the pre-eminent binding knot. This critical risk was the subject of this study. Despite this, slipping may occur prior to the addition of the lock, particularly during an instrument tie. In practice, ligatures are locked with additional overhand knots. This study examined the ability of a ligature to be tightened and then remain tight. Ligature failures are reported, sometimes with critical consequences (eg after pulmonary resection and laparoscopic cholecystectomy in humans, or following pedicle ligation in canine or equine hysterectomy).

Constrictor knot pdf