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Equipment / Instruments

Unit 11: Sutures & Other Materials

Topic 7: Healing and Suture Selection

Tissue reaction

As we have seen, tissues respond to the presence of suture materials as they do to any foreign body, and their presence may therefore effect the process of wound healing.

The chemical properties of the suture material may significantly influence the degree and type of reaction to the material. Catgut is recognised as causing an intense inflammatory reaction relative to inert materials such as polypropylene or steel.

The actual size and surface area of the material will influence not only the reaction to the suture but will also increase the trauma inflicted on the tissues during its placement. Trauma may also be increased by the passage of an uncoated multifilament suture due to "tissue drag". Increasing the gauge of the material will also increase the size of the knot significantly and increase tissue reactions and the risk of infection at the surgery site.

It is generally accepted that the smallest size of material
which is adequate for the indication to which it is applied should be used.

The effect of the suture pattern by everting, inverting or approximating tissues has been recognised to influence the healing processes. Excessive tension of the suture material in the wound may increase the risk of suture cut-out or cause trauma to the tissues within the suture.

These factors will influence the ability of bacteria to adhere to the material and the ability of bacteria to multiply in devitalised tissues

High capillarity of a suture material may increase the incidence of infection because they allow bacteria to invade the interstices and can act as a "wick" along which serum and bacteria can migrate. Braided suture materials will also absorb more fluid than monofilamentous materials, and cause more tissue drag and trauma during placement. Monofilament sutures are less conducive to the development of infection. Various coatings of suture materials have been used to reduce the capillarity and the effect of the braided material on wicking and absorption of fluid.

To minimise the chances of infection in the face of contamination, it is therefore important to minimise the degree of surgical trauma, use monofilament materials such as polypropylene, nylon, PDS, and Maxon (although Dexon and Vicryl are also reported to be well tolerated in contaminated wounds), avoid tissue tension and use the minimal number and size of sutures possible

Some suture materials such as Nylon and polyglycolic acid are also known to degrade in a way that releases bactericidal factors into the wound.

Ehicon have recently released Vicryl Plus which is a triclosan coated polyglactin 910 suture in an effort to reduce surgical site infections.

The presence of foreign bodies such as suture materials within the lumen of the urinary or biliary tract may act as a focus on which calculi may form. Non-absorbable materials such as silk and polyester should never be used in these systems.

Biomechanical properties

It has been suggested that the biomechanical properties of the suture material should match that of the tissues as closely as possible. It is well recognised that a compliance mismatch between sutured tissues in the arterial system which undergoes continual loading and stresses will result in a tissue reaction which is characterised by the proliferation of smooth muscle cells invading into the intima and production of excessive collagen deposition and luminal narrowing.