Chapter 4: Table of Contents
- 4.1 Suture Materials
- 4.2 Knots
- 4.3 Miller’s Knot
- 4.4 Modified Miller’s Knot
- 4.5 Hand Ties
- 4.6 Ligatures and Suture Patterns
- 4.7 Circumferential Ligature
- 4.8 Cruciate Pattern
- 4.9 Cushing Pattern
- 4.10 Ford Interlocking Pattern
- 4.11 Intradermal Pattern
- 4.12 Lembert Pattern
- 4.13 Mattress Suture Patterns
- 4.14 Modified Transfixing Ligature
- 4.15 Purse-String and finger trap
- 4.16 Simple Continuous Pattern
- 4.17 Simple Interrupted Pattern
- 4.18 Skin Staples
- 4.19 Subcutaneous closure & How to bury a knot
- 4.20 Suture Material and Patterns Quiz
Suture materials can be classified into two broad categories: Absorbable & Non-absorbable
Suture is considered to be absorbable if it loses its tensile strength by 60 days after implantation. The material may not be completely absorbed at this point, but it will have lost the majority of its initial tensile strength. Absorbable sutures are generally chosen to appose and ligate tissue that will be inaccessible after implantation.
A suture material is considered nonabsorbable if it does not lose a significant amount of its tensile strength within the first 60 days after implantation. Many nonabsorbable sutures take years to lose all of their tensile strength, and others lose 100 percent of their tensile strength within 6 months (multifilament nylon). Nonabsorbable sutures are typically chosen to appose tissue that will heal slowly or for tissue in which the suture can be removed non-invasively after healing.
Three characteristics of suture materials are important to consider when choosing the proper suture for repair: 1) Initial tensile strength 2) Knot security 3) Suture handling.
1. Initial tensile strength:
Initial tensile strength is the strength of the suture at the time it is implanted. This strength must be similar to that of the tissue in which it is used. The surgeon must therefore consider how long a tissue will require to heal, and the forces exerted on the tissue (and therefore the sutures) during healing. Suture materials lose strength during implantation due to manipulation and knotting and after implantation due to tissue degradation while it is healing.
2. Knot security:
Knot security is also an important factor to consider when choosing suture materials. Knot security tends to improve as the diameter of the suture material decreases. However, suture size should be based on the tissue to be sutured and the size of the animal rather than knot security and suture of too small a diameter will not be as strong in larger patients. Too large a suture will lead to excessive tissue reaction since inflammatory reaction increases with the increasing suture size. The number of throws required to make a secure knot also varies with each suture material and pattern (interrupted vs continuous). Remember that there are two throws in a square knot. In general, a minimum of three throws is required to form a secure knot when using an interrupted pattern (more throws are required for many suture materials). When performing a simple continuous pattern, one extra throw (minimum of four throws) must be placed at the beginning of the suture line and two at the end (minimum of 5 throws). The overall relative strength of suture is based on both its initial tensile strength and knot security.
3. Suture handling:
Suture handling properties are also of interest. Multifilament suture materials tend to be easier to flex, manipulate and knot compared to monofilament materials. Larger diameter suture has been found to be more rigid than smaller diameter suture material. Silk tends to be considered as having the best handling properties compared to other suture materials. Handling features might be most important when choosing the ideal suture material for fine, coordinated procedures such as microvascular surgery.
One should remember that use of suture material is essential but it implies that foreign material is implanted in the tissues. The foreign material will cause various degrees of inflammation and tissue reaction and it may promote infection or slow tissue healing. Non-absorbable materials are typically less reactive than absorbable suture materials but will potentially remain in the tissues permanently. Suture knots are usually more reactive than the remainder of the suture line because of the larger amount of suture concentrated in a specific area. The knot will also be larger as the suture size or the number of throws increases. Furthermore, multifilament materials are more likely to predispose to infection than monofilaments as they can harbour bacteria in their interstices.
A table summarizing the pertinent information for each suture material presented in this site is available as a pdf (see below).
Suture Chart PDF