Surgical suture is a medical device used to hold body tissues together after an injury
or surgery.
Application generally involves using a needle with an attached length of thread.
A number of different shapes, sizes, and thread materials have been developed over its millennia
of history.
History Through many millennia, various suture materials
were used, debated, and remained largely unchanged.
Needles were made of bone or metals such as silver, copper, and aluminium bronze wire.
Sutures were made of plant materials or animal material.
African cultures used thorns, and Indians used ant sutures by coaxing insects to bite
wound edges with their jaws and subsequently twisting off the insects' body to keep the
wound closed by the clenched jaws.
The earliest reports of surgical suture date back to 3000 BC in ancient Egypt, and the
oldest known suture is in a mummy from 1100 BC.
A detailed description of a wound suture and the suture materials used in it is by the
Indian sage and physician Sushruta, written in 500 BC.
The Greek "father of medicine" Hippocrates described suture techniques, as did the later
Roman Aulus Cornelius Celsus.
The 2nd-century Roman physician Galen described gut sutures.
In the 10th century the manufacturing process involved harvesting sheep intestines, the
so-called catgut suture, and was similar to that of strings for violins, guitar, and tennis
racquets.
Joseph Lister introduced great change in suturing technique when he endorsed the routine sterilization
of all suture threads.
He first attempted sterilization with the 1860s "carbolic catgut," and chromic catgut
followed two decades later.
Sterile catgut was finally achieved in 1906 with iodine treatment.
The next great leap came in the twentieth century.
The chemical industry drove production of the first synthetic thread in the early 1930s,
which exploded into production of numerous absorbable and non-absorbable synthetics.
The first synthetic absorbable was based on polyvinyl alcohol in 1931.
Polyesters were developed in the 1950s, and later the process of radiation sterilization
was established for catgut and polyester.
Polyglycolic acid was discovered in the 1960s and implemented in the 1970s.
Today, most sutures are made of synthetic polymer fibers.
Silk and, rarely, gut sutures are the only materials still in use from ancient times.
In fact, gut sutures have been banned in Europe and Japan owing to concerns regarding Bovine
Spongiform Encephalopathy.
Silk suture is still used, mainly to secure surgical drains.
Needles Eyed or reusable needles are needles with
holes or eyes which are supplied separate from their suture thread.
The suture must be threaded on site, as is done when sewing at home.
The advantage of this is that any thread and needle combination is possible to suit the
job at hand.
Swaged, or atraumatic, needles with sutures comprise a pre-packed eyeless needle attached
to a specific length of suture thread.
The suture manufacturer swages the suture thread to the eyeless atraumatic needle at
the factory.
The chief advantage of this is that the doctor or the nurse does not have to spend time threading
the suture on the needle, which may be difficult for very fine needles and sutures.
Also.
the suture end of a swaged needle is narrower than the needle body, eliminating drag from
the thread attachment site.
In eyed needles, the thread protrudes from the needle body on both sides, and at best
causes drag.
When passing through friable tissues, the eye needle and suture combination may thus
traumatise tissues more than a swaged needle, hence the designation of the latter as "atraumatic".
There are several shapes of surgical needles.
These include: Straight
1/4 circle 3/8 circle
1/2 circle.
Subtypes of this needle shape include, from larger to smaller size, CT, CT-1, CT-2 and
CT-3.
5/8 circle compound curve
half curved half curved at both ends of a straight segment
The ski and canoe needle design allows curved needles to be straight enough to be used in
laparoscopic surgery, where instruments are inserted into the abdominal cavity through
narrow cannulas.
Needles may also be classified by their point geometry; examples include:
taper cutting
reverse cutting trocar point or tapercut
blunt points for sewing friable tissues side cutting or spatula points for eye surgery
Finally, atraumatic needles may be permanently swaged to the suture or may be designed to
come off the suture with a sharp straight tug.
These "pop-offs" are commonly used for interrupted sutures, where each suture is only passed
once and then tied.
Sutures can withstand different amounts of force based on their size; this is quantified
by the U.S.P.
Needle Pull Specifications.
Thread Materials
Suture thread is made from numerous materials.
The original sutures were made from biological materials, such as catgut suture and silk.
Most modern sutures are synthetic, including the absorbables polyglycolic acid, polylactic
acid, Monocryl and polydioxanone as well as the non-absorbables nylon, polyester, PVDF
and polypropylene.
Newer still is the idea of coating sutures with antimicrobial substances to reduce the
chances of wound infection.
Sutures come in very specific sizes and may be either absorbable or non-absorbable.
Sutures must be strong enough to hold tissue securely but flexible enough to be knotted.
They must be hypoallergenic and avoid the "wick effect" that would allow fluids and
thus infection to penetrate the body along the suture tract.
Absorbability All sutures are classified as either absorbable
or non-absorbable depending on whether the body will naturally degrade and absorb the
suture material over time.
Absorbable suture materials include the original catgut as well as the newer synthetics polyglycolic
acid, polylactic acid, polydioxanone, and caprolactone.
They are broken down by various processes including hydrolysis and proteolytic enzymatic
degradation.
Depending on the material, the process can be from ten days to eight weeks.
They are used in patients who cannot return for suture removal, or in internal body tissues.
In both cases, they will hold the body tissues together long enough to allow healing, but
will disintegrate so that they do not leave foreign material or require further procedures.
Occasionally, absorbable sutures can cause inflammation and be rejected by the body rather
than absorbed.
Non-absorbable sutures are made of special silk or the synthetics polypropylene, polyester
or nylon.
Stainless steel wires are commonly used in orthopedic surgery and for sternal closure
in cardiac surgery.
These may or may not have coatings to enhance their performance characteristics.
Non-absorbable sutures are used either on skin wound closure, where the sutures can
be removed after a few weeks, or in stressful internal environments where absorbable sutures
will not suffice.
Examples include the heart or the bladder.
Non-absorbable sutures often cause less scarring because they provoke less immune response,
and thus are used where cosmetic outcome is important.
They must be removed after a certain time, or left permanently.
Sizes Suture sizes are defined by the United States
Pharmacopeia.
Sutures were originally manufactured ranging in size from #1 to #6, with #1 being the smallest.
A #4 suture would be roughly the diameter of a tennis racquet string.
The manufacturing techniques, derived at the beginning from the production of musical strings,
did not allow thinner diameters.
As the procedures improved, #0 was added to the suture diameters, and later, thinner and
thinner threads were manufactured, which were identified as #00 to #000000.
Modern sutures range from #5 to #11-0.
Atraumatic needles are manufactured in all shapes for most sizes.
The actual diameter of thread for a given U.S.P.
size differs depending on the suture material class.
Techniques
Placement Sutures are placed by mounting a needle with
attached suture into a needle holder.
The needle point is pressed into the flesh, advanced along the trajectory of the needle's
curve until it emerges, and pulled through.
The trailing thread is then tied into a knot, usually a square knot or surgeon's knot.
Ideally, sutures bring together the wound edges, without causing indenting or blanching
of the skin, since the blood supply may be impeded and thus increase infection and scarring.
Ideally, sutured skin roll slightly outward from the wound, and the depth and width of
the sutured flesh is roughly equal.
Placement varies based on the location, but the distance between each suture generally
is equal to the distance from the suture to the wound edge, in accordance with Jenkin's
Rule.
Many different techniques exist.
The most common is the simple interrupted stitch; it is indeed the simplest to perform
and is called "interrupted" because the suture thread is cut between each individual stitch.
The vertical and horizontal mattress stitch are also interrupted but are more complex
and specialized for everting the skin and distributing tension.
The running or continuous stitch is quicker but risks failing if the suture is cut in
just one place; the continuous locking stitch is in some ways a more secure version.
The chest drain stitch and corner stitch are variations of the horizontal mattress.
Other stitches or suturing techniques include: Purse-string suture, a continuous, circular
inverting suture which is made to secure apposition of the edges of a surgical or traumatic wound.
Figure 8 stitch Subcuticular stitch.
Layers In contrast to single layer suturing, two
layer suturing generally involves suturing at a deeper level of a tissue followed by
another layer of suturing at a more superficial level.
For example, Cesarean section can be performed with single or double layer suturing of the
uterine incision.
Removal Whereas some sutures are intended to be permanent,
and others in specialized cases may be kept in place for an extended period of many weeks,
as a rule sutures are a short term device to allow healing of a trauma or wound.
Different parts of the body heal at different speed.
Common time to remove stitches will vary: facial wounds 3–5 days; scalp wound 7–10
days; limbs 10–14 days; joints 14 days; trunk of the body 7–10 days.
Expansions A pledgeted suture is one that is supported
by a pledget, that is, a small flat non-absorbent pad normally composed of Polytetrafluoroethylene,
used as buttresses under sutures when there is a possibility of sutures tearing through
tissue.
Tissue adhesives In recent years, topical cyanoacrylate adhesives,
a.k.a.
medicinal grade super glue, have been used in combination with, or as an alternative
to, sutures in wound closure.
The adhesive remains liquid until exposed to water or water-containing substances/tissue,
after which it cures and forms a flexible film that bonds to the underlying surface.
The tissue adhesive has been shown to act as a barrier to microbial penetration as long
as the adhesive film remains intact.
Limitations of tissue adhesives include contraindications to use near the eyes and a mild learning curve
on correct usage.
They are also unsuitable for oozing or potentially contaminated wounds.
Cyanoacrylate is the generic name for cyanoacrylate based fast-acting glues such as methyl-2-cyanoacrylate,
ethyl-2-cyanoacrylate and n-butyl-cyanoacrylate.
Skin glues like Indermil and Histoacryl were the first medical grade tissue adhesives to
be used, and these are composed of n-butyl cyanoacrylate.
These worked well but had the disadvantage of having to be stored in the refrigerator,
were exothermic so they stung the patient, and the bond was brittle.
Nowadays, the longer chain polymer, 2-octyl cyanoacrylate, is the preferred medical grade
glue.
It is available under various trade names, such as LiquiBand, SurgiSeal, FloraSeal, and
Dermabond.
These have the advantages of being more flexible, making a stronger bond, and being easier to
use.
The longer side chain types, for example octyl and butyl forms, also reduce tissue reaction.
The use of common household super glue is not advisable.
See also Alexis Carrel
Barbed suture Chitin
Cyanoacrylate Knots
Ligature List of medical topics
Sewing Steri-Strip
Surgical staple References
External links Sutures_04_Introduction Introduction to Surgical
Sutures on Wikisurgery.