SUTURE MATERIALS

Surgical sutures

Ideal suture should be:

• Easy to handle
• Have minimally reaction in tissue
• Inhibits bacterial growth
• Holds securely when knotted
• Resist shrinking in tissue
• Is noncapillary, nonallergenic, noncarcinogenic and nonferromagnetic
• Absorbs with minimal reaction after tissue has healed

NOTE: Such an ideal suture does not exist.

CHARACTERISTICS OF SUTURES

• Suture size

The smallest diameter suture that will adequately hold the mending wounded tissue should be used in order to minimize trauma as the suture passed through the tissue. And also to reduce the amount of foreign material left in the wound. A suture should not be stronger than the sutured tissue.

The most commonly used standard for suture size is the USP (United States Pharmacopoeia), which denotes dimension from 10-0 the smallest and 7 the largest.

• Flexibility

The flexibility of suture is determined by its torsional stiffness and diameter, which influence its handling and use.

• Surface characteristic

The surface characteristics of suture influence the ease with which is pulled through tissues (i.e., the amount of friction or ″drag″) and the amount of trauma caused.

• Capillarity

Capillarity is the process by which fluid and bacteria are carried into the interstices of multifilament fibers. Capillary suture materials should not be used in contaminated or infected sites. Coating reduces capillarity of some sutures.

• Knot tensile strength

Knot tensile strength is measured by the force that suture strand can withstand before it breaks when knotted.

• Relatively knot security

The knot-holding capacity of suture material is the strength required to untie or break a defined knot by loading the part of the suture that forms the loop.

Sutures material may be classified:

• According to their origin:

a) organic

b) synthetic

c) metallic

• According to their behavior in tissue:

a) absorbable (phagocytized or hydrolyzed)

b) nonabsorbable

• According to their structure

a) monofilament

b) multifilament

► Monofilament vs. Multifilament ◄

Monofilament sutures:

Monofilament sutures are made of a single strand of material.

Advantage

• have less tissue drag than multifilament suture,

• do not have interstices that may harbor bacteria.

Disadvantage

o with thicker threads the wiriness that is a characteristic of all monofilament threads impairs handling and in particular renders knot-tying more difficult,

o care should be used in handling because nicking or damaging them with forceps or needle holder weakens them and predispose them to breakage.

Multifilament suture

Multifilament sutures are made of several strands of suture that are twisted or braided together.

Advantage

• are more pliable and flexible than monofilament sutures,

• results in considerably better knot holding security.

Disadvantage

• the longitudinal orientation of the individual filaments within the thread results in relatively high capillarity, but the capillarity of braided threads is less than that of twisted threads.

• have a rough surface that impairs passage through tissue.

Multifilament threads are generally coated. The coating smoothes out the irregular surface and thus facilitates passage through tissue without impairing knot-holding security. Coated multifilament threads are less stiff and wiry than monofilament threads. The coating also reduces capillarity.

►some types of the suture materials (table 1) ◄

Surgical needles

Surgical needles are divided in two groups:

• Traumatic needles
• Atraumatic needles

Traumatic needles (picture 1) - are needles with holes or eyes which are supplied to the hospital separate from their suture thread. In traumatic needles with eyes, the thread comes out of the needle's hole on both sides. When passing through the tissues, this type of suture rips the tissue to a certain extent, thus the name traumatic.

Picture 1. Traumatic needles

Atraumatic needles with sutures (picture 2) - comprise an eyeless needle attached to a specific length of suture thread. Important thing is that the suture end of a swaged needle is smaller than the needle body.

With attached suture thread

Picture 2. Atraumatic needle

Needles shapes:

• Straight – skin, nervs, GI tract, tendons, blood vessels, etc.

• Halfcurved – skin (rarely used one),

• Curved – according to curve degree are divided:

• 1/4 circle – eye, microsurgery,
• 3/8 circle – used for the most body structures,
• 1/2 circle - used for the most body structures,
• 5/8 circle – urinary and reproductive system.

• Combine needle – anterior segment of the eye.

Straight needle Halfcurved neddle

Combine needle

1/4 circle 3/8 circle 1/2 circle 5/8 circle

Point and body shape:

• Taper – taper point and round or quadrangular body (cross section) – aponeurosis, muscles, nerves, peritoneum, blood vessels, valves.
• Blunt - blunt point and flat body (cross section) – bowels, kidney, spleen, liver.
• Triangular – triangular point and flat or quadrangular body (cross section). If the cutting side of triangular is upward this type of needle is called conventional (skin, sternum), and if it’s downward reverse cutting (fascia, ligaments, skin, tendons).
• Tapercut - small triangular cutting point and flat body (cross section) – fascia, ligaments, uterus, oral cavity and etc.

Taper Blunt

Conventional Reverse cutting

Tapercut

REFERENCES:

1. http://www.ethicalagents.co.nz/pages/Apr%2005%205.htm
2. Ethicon – wound closure manual, Ethicon INC. a Johnson-Johnson company