Suture Selection and Knot Tying Demonstration

Knot tying is a fundamental skill in the surgical field, essential for securing sutures, ligating vessels, and creating secure anastomoses. The art of knot tying requires precision, dexterity, and a thorough understanding of suture materials and techniques. This text aims to provide a comprehensive overview of surgical knot tying, drawing from the presented video.

Surgical sutures serve a crucial role in wound management by approximating tissues, allowing the healing process to occur effectively. Sutures can be categorized based on their structure (braided or monofilament), absorbability (non-absorbable or absorbable), and origin (natural or synthetic).^1,2 Braided sutures, composed of multiple strands woven together, are often easier to tie and hold knots better, making them suitable for ligating vessels. Monofilament sutures, with their smooth surface, minimize tissue drag and are preferred for vascular anastomoses. Natural sutures like surgical gut and silk were traditionally used but have largely been replaced by synthetic sutures due to better biocompatibility and predictable degradation rates. Common synthetic absorbable sutures include poliglecaprone (Monocryl), polyglactin (Vicryl), and polydioxanone (PDS). Non-absorbable synthetics include nylon, polypropylene (Prolene), and polyester (Ethibond). Non-absorbable sutures, such as silk (braided) or nylon, are used in tissues requiring prolonged healing, while absorbable sutures, like Vicryl (braided) or Monocryl (monofilament), are used for rapidly healing tissues like intestinal mucosa.

Some sutures have coatings to improve handling and knot security. For example, Vicryl Plus has a polyglactin/calcium stearate coating, while Prolene is coated with polydioxanone to improve smoothness.

Mass absorption and strength retention for various suture materials can be seen in Table 1.

Table 1. Tensile strengths and mass absorption rates of different widespread suture materials.⁸

Sutures are sized using a numerical system, with larger numbers indicating thicker sutures (e.g., 0, 1, 2). However, when followed by a zero (e.g., 2-0, 3-0), the numbers indicate smaller suture diameters, with more zeroes signifying a finer suture.

The square knot (two overhand knots in succession with opposite orientations) is the most common surgical knot. Other knots used include the surgeon's knot (one extra throw on the first part of the square knot to prevent slipping) and the slip knot.^3–5

The two-handed knot tying technique involves creating a square knot, consisting of two throws in opposite directions. This method can be performed right-handed or left-handed and requires equal tension on both strands to ensure a flat, secure knot. Practicing with gloves and colored suture materials aids in visualizing the knot formation.

The one-handed knot tying technique is useful in situations where one hand is required for retraction or instrument manipulation. In this method, one hand serves as the post, holding the suture taut, while the other hand performs the knot tying motions. The process involves creating a cross with the suture, pinching and rotating the hand to form the first throw, followed by the "karate chop" motion and stealing the suture from the adjacent finger to create the second throw.^6,7

The presented video offers a comprehensive and detailed explanation of surgical knot tying techniques, emphasizing the importance of proper suture material selection, sizing, and knot tying methods. The clear visual demonstrations and step-by-step instructions make it an invaluable resource for surgical trainees and practicing surgeons alike. By mastering these fundamental skills, surgeons can achieve secure wound closure and healing, and ultimately enhance patient outcomes.