Abstract

The ideal suture implant should be noncapillary, biologically inert, have sufficient strength to hold during the healing process, good handling characteristics, easily sterilizable, nonallergic, noncorrosive, nontoxic, noncarcinogenic, nonteratogenic and inexpensive. It should not harbour bacteria and must be reabsorbed once it's not needed, it should handle easily, and hold securely when knotted. A basic understanding of the characteristics of the most common suture materials is needed, as this impacts on where and when they should appropriately be used. Some materials can be used in most circumstances; others are for specific purposes.

Introduction

Suture materials are foreign implants used in the body to aid the healing process. As such, they elicit a response, which may be detrimental to the healing process. The ideal suture implant should be noncapillary, biologically inert, have sufficient strength to hold during the healing process, good handling characteristics, easily sterilizable, nonallergic, noncorrosive, nontoxic, noncarcinogenic, nonteratogenic and inexpensive. It should not harbour bacteria and must be reabsorbed once it's not needed, it should handle easily, and hold securely when knotted.

Reabsorption can occur via one of two distinct mechanisms:

 Nonenzymatic hydrolysis - this occurs independent of inflammation and happens at a dependable rate according to the size and composition of the material. After hydrolysis, the particles can be phagocytosed. Examples are synthetic absorbable materials such as polyglycolic acid, polyglactin 910, polydioxanone, polyglyconate and polyglecaprone 25. The rate of absorption is not significantly affected by exposure to digestive enzymes or infection.

 Phagocytosis and enzymatic digestion - by monocytes after recognition of these agents as a foreign substance, rate of absorption significantly increased by inflammation and presence of digestive enzymes. Elicits an inflammatory response leading to possibly excessive scar tissue. Examples are surgical gut.

Suture Materials

Suture materials are categorized in 3 broad categories:

 Absorbable vs. nonabsorbable

 Organic vs. synthetic

 Monofilament vs. multifilament (braided)

It is important to have a basic understanding of the characteristics of the most common suture materials, as this impacts on where and when they should appropriately be used.

This should be used in conjunction with estimated healing times of tissue, as well as the expected rapidity of healing of the particular tissue where it will be used. Examples are fast healing tissue where minimal tension is expected, like oral mucosa vs. slow-healing tissue where lots of tension can be expected, like linea alba or tendon. The same material is not appropriate to be used in both cases, although there are materials which can be used successfully in both tissue types.

Sizes of material thickness according to U.S. Pharmacopeia (USP) or metric sizing in mm or part thereof increments.

The suture materials can be summarized in the following table:

Needles

Appropriate suture needle choice is important for optimal surgical outcomes. Surgical needles are described according to the geometric shape of the body and point, the taper ratios associated with the point section of the needle, and the method of suture attachment.

Geometric shape: straight, curved (5/8 ½, 3/8, ¼), overall length and arc length

 Straight to be used closer to the body surface, skin

 Curved in deeper and smaller surgical fields

Point section shape: blunt, taper or cutting (reverse and conventional)

 Blunt to be used in friable tissues

 Taper in delicate tissues such as git, fat, urinary bladder and muscle

 Cutting in tougher or fibrous tissue like skin, periosteum, and fascia

 Spatula or side cutting to be used most frequently in ocular surgery

Method of suture attachment: eyed or swaged on

 Eyed to be used passing large material in orthopaedic surgery

 Swaged most commonly used routinely, as much less traumatic when passing through tissue

 Needle tip should always penetrate tissue perpendicular to tissue plane being sutured

Staples

Supplied with technique specific applicators. Are a mechanical way of closing a wound and saves time. Stainless steel, titanium and absorbable staples are most frequently used. Can increase risk of wound complications in dogs though, including difficulty and discomfort during removal.

Adhesives

Cyanoacrylate (superglue) is supplied in a monomer form, which undergoes polymerization on contact moisture associated with skin wounds, leading to bonding.

Glue sloughs with skin cells as they die and are replaced. When applied the skin edges should be held in apposition, with no or very little tension present. It should not enter a wound, but form a bridge over the wound. If allowed into a wound, it will lead to a foreign body reaction, and the formaldehyde byproduct can be very toxic to tissues locally.

References

1.  Tobias KM, Johnston SA. Chapter 17: Suture Materials, tissue staplers, ligation devices and closure methods. In: Veterinary Surgery Small Animal.

2.  Slatter. Chapter 9: Biomaterials and surgical implants. In: Textbook of Small Animal Surgery. 3rd ed.