Surgical suture materials are used in the closure of most wound types. The ideal suture should allow the healing tissue to recover sufficiently to keep the wound closed together once they are removed or absorbed. The time it takes for a tissue to no longer require support from sutures will vary depending on tissue type:
- Days: Muscle, subcutaneous tissue or skin.
- Weeks to Months: Fascia or tendon.
- Months: Vascular prosthesis.
In this article, we shall look the classification of suture materials, suture size, and the components of the surgical needle.
Classification of Suture Materials
Broadly, sutures can be classified into absorbable and non-absorbable materials. They can be further sub-classified into synthetic or natural sutures, and monofilament or multifilament sutures.
It is worth noting that regardless of suture composition, the body will react to any suture as a foreign body, producing a foreign body reaction to varying degrees.
Absorbable vs Non-Absorbable
Absorbable sutures are broken down by the body via enzymatic reactions or hydrolysis. The time in which this absorption takes place varies between material, location of suture, and patient factors. Absorbable sutures are commonly used for deep tissues and tissues that heal rapidly, such as bowel, stomach, or bladder.
Non-absorbable sutures are used to provide long-term tissue support, remaining walled-off by the body’s inflammatory processes until removed. Non-absorbable sutures are commonly used for surface sutures and with tissues that heal slowly, such as fascia or tendons. Surface non-absorbable sutures require manual removal post-operatively.
Synthetic vs Natural
The absorbable and non-absorbable suture materials can be further categorised by their raw origin:
- Natural – made of natural fibres (e.g silk or catgut). They are less frequently used, as they tend to provoke a greater tissue reaction. However, suturing silk is still utilised regularly in the securing of surgical drains.
- Synthetic – comprised of man-made materials (e.g PDS or nylon). They tend to be more predictable than the natural sutures, particularly in their loss of tensile strength and absorption.
Monofilament vs Multifilament
Suture materials can also be sub-classified by their structure:
- Monofilament suture – a single stranded filament suture (e.g nylon, PDS or prolene) They have a lower infection risk but also have a poor knot security and ease of handling.
- Multifilament suture – made of several filaments that are twisted together (e.g braided silk or vicryl). They handle easier and hold their shape for good knot security, yet can harbour infections.
The diameter of the suture will affect its handling properties and tensile strength. The larger the size ascribed to the suture, the smaller the diameter is – for example a 7-0 suture is smaller than a 4-0 suture.
When choosing suture size, the smallest size possible should be chosen, taking into account the natural strength of the tissue.
The surgical needle allows the placement of the suture within the tissue, carrying the material through with minimal residual trauma. The ideal surgical needle should be rigid enough to resist distortion, yet flexible enough to bend before breaking.
Commonly, surgical needles are made from stainless steel. They are composed of a swaged end, a body/shaft, and a point:
- The swaged end connects the needle to the suture.
- The needle body or shaft is the region grasped by the needle holder, typically third of the way along from the swaged end.
- The needle point acts to pierce the tissue, beginning at the maximal point of the body and running to the end of the needle.
Surgical needles vary in their curvature and are described as proportion of a circle completed – the ¼, ⅜, ½, and ⅝ are the most common curvatures used.
- Suture materials can be classified in a variety of ways
- Choice of suture material is dependent on numerous factors, such as tissue type, infection risk, and personal preferences
- The surgical needle allows for the correct positioning of the suture material within a tissue