Types of Sutures | Suture Materials

What are the different types of sutures and how are they classified?

1. Absorbable and Non-absorbable suture materials

We can basically classify sutures into two types– those which are absorbable and will break down harmlessly in the body over time without intervention and those which are non-absorbable and must be manually removed if they are not left indefinitely. The selection of suture varies on the duration of the support required,  the patient particulars, cost and choice of the Surgeons.

Sutures may be placed internally or externally and they need to be removed or left indefinitely. Often, materials which lie on the exterior of the body can be removed within minutes, and without re-opening the wound. As a result, absorbable materials are often used internally; non-absorbable externally.

Certain Sutures may need to be placed in a stressful environment, for example the heart (constant pressure and movement) or the bladder (adverse chemical presence) may require specialized or stronger materials to perform their role; usually such materials are either specially treated, or made of special polymers, and are often non-absorbable to reduce the risk of degradation.

Types of Absorbable sutures materials include :

Polyglycolic Acid, Polyglactin 910 , Catgut, Poliglecaprone 25 and Polydioxanone.

Types of Non-Absorbable sutures materials include :

Polypropylene sutures, Nylon (poylamide), Polyester, PVDF, PTFE, Silk, UHMWPE and stainless steel.

2. Monofilament, Multifilament and Barb Sutures

We can classify Suture materials on the basis of material structure i.e. monofilament, multifilament or braided and barb structure (knotless wound closure devices).

Braided sutures provide better knot security whereas monofilament sutures provide better passage through tissues. In general, Monofilament sutures elicit lower tissue reaction compared to braided sutures.

Multifilaments are usually braided or twisted and often coated with materials like silicon, wax, PTFE, polycaprolactone, calcium stearate etc.

Barb sutures are monofilaments that have barbs or projections on the surface that can penetrate the tissues and hold them without necessitating the need for knots.

Monofilament sutures include:

Polypropylene sutures, Catgut, Nylon, PVDF, PTFE, Stainless steel, Poliglecaprone and Polydioxanone.

Multifilament or braided sutures include:

PGA sutures, Polyglactin 910, Silk, UHMWPE and polyester materials.

Barb sutures are usually available in:

Polydioxanone, Poliglecaprone and polypropylene materials.

View Suture Materials Chart for properties of different suture materials.

3. Classification of sutures based on size (diameter)

Surgical Sutures and ligatures are available in a number of sizes i.e. based on the diameter of the thread. United States Pharmacopeia’s classification of sutures into various sizes is widely accepted across the world. The ideal suture should allow the healing tissue to recover sufficiently to keep the wound closed together once they are removed or absorbed. The diameter of the suture will affect its handling properties and tensile strength.

The following U.S.P. and metric suture sizes chart shows the diameter range for collagen and synthetic materials.

4. Synthetic and Natural Suture materials

Surgical sutures can also be divided into two types on the basis of raw material origin i.e. natural and synthetic. Synthetic fiber or synthetic fibre are fibers made by humans through chemical synthesis, as opposed to natural fibers that are directly derived from living organisms, such as plants or fur from animals. They are the result of extensive research by scientists to improve upon naturally occurring animal and plant fibers.

Natural sutures include silk and catgut whereas most of the other sutures are synthetic in nature.

5. Types of sutures based on coatings – Coated and Un-Coated

Some types of sutures are available with specialized coatings on the surface to enhance properties like knotting, easy passage through tissue and reduce tissue reaction. Normally, coating is applied to braided rather than monofilament sutures. It is easier to coat braided sutures compared to monofilaments. There are various coating technologies which embed a thin layer of substance on the surface of the suture material to change the material properties. Coating may be achieved by dip method, brushing, roll coating, spraying, spin coating, flow coating, etc.

Coating materials like chromium salt, silicon, wax, PTFE, polycaprolactone, calcium stearate. Polymeric coating materials are known to be more bio-compatible than conventional coating materials like chromium salts, beeswax, paraffin, gelatin etc. There are new functional coatings like antibacterial or antimicrobial coating given to both monofilament and multifilament sutures, stem cell coating for improving healing properties. Antimicrobial coatings like chlorhexidine, triclosan, silver ion may be given to any suture as a surface coating in addition to the regular coating materials to reduce the incidence of surgical site infection and help wound healing.

Coated sutures include:

PGA, Catgut Chromic, Polyglactin 910, Silk, Polyester, Poliglecaprone and Polydioxanone .

Un-coated sutures include:

Polypropylene, Nylon, PVDF, UHMWPE, Stainless steel and PTFE.

6. Classification of sutures based on usage

Sutures are also classified into various types based on the usage or application. We can classify them based on usage into general, cardiovascular, orthopaedic, dental, gynaec, veterinary, cosmetic or ophthalmic sutures, etc. A variety of materials may be used for a particular application based on the requirements. However, the sizes, length, needle profiles, etc., will be with a small change for a particular application.

Watch a video showing how sutures are manufactured by Dolphin Sutures on YouTube