As we go around the country teaching the art of suturing pig’s feet to aspiring survival medics and porcine podiatrists, we are often asked about how to choose appropriate suture needles and material for different types of injuries.  There are a wide variety of choices and, today, we’ll discuss what is available and what is most effective for different types of wounds.

How to Suture a Wound

First, let’s identify some of the qualities of the optimal suture.  The suture should:

• Be sterile
• Be easily worked with
• Be strong enough to hold wound edges together while they heal
• Be unlikely to cause infection, tissue reaction or scar formation
• Be reliable in its everyday use with every type of wound

It is rare, if not impossible, to find a single suture type that meets all of the above criteria, but there are many that will serve to allow adequate healing if chosen properly.

In the United States and many other countries, a standard classification of suture has been in place since the 1930s.  This classification identified stitches by type of material and the size of the “thread”.  Suture diameters most commonly used in humans (and pigs, I would think) is measured in zeroes, much like buckshot.  2-0 (00) suture, for example, is thicker than 5-0 (00000) suture. The more zeroes, the finer the “thread”.

In addition to size, sutures are classified as absorbable and non-absorbable.  An absorbable suture is one that will break down spontaneously over time but not before the tissue has had sufficient time to heal.  Absorbable sutures have the advantage of not requiring removal after healing has taken place. This type of suture is commonly used in deep layers, such as muscle, fat, organs, etc.  A classic example of this is “catgut”, actually made from the intestines of sheep or cows. Although still in use, “catgut” and other natural sutures have been replaced by synthetic material for many circumstances, such as the popular “Vicryl”, “Dexon”, and “Monocryl”.

Nonabsorbable sutures are those that retain their character for a very long time, and will stay in the body until removed.  As such, normal immune response will cause the development of scar tissue around these sutures.  Nonabsorbable sutures are commonly used in skin closures and include monofilaments (such as “Nylon”) and braided multifilaments (such as ”Surgical Silk”; yes, made by silkworms and covered with beeswax or silicone).  Monofilaments like Nylon are useful because of less likelihood of harboring bacteria, whereas braided multifilaments have nooks and crannies for these organisms to hide.  In trade, braided Silk is somewhat easier to handle than Nylon for many.  I recommend Nylon in most survival situations, with 2-0 Nylon ideal for those new to the suturing skill.  This size “thread” is easy to handle and useful for medics to learn surgical knot-tying.

The size of the “thread” you’ll use depends on the area of the body being repaired. Slowly healing tissues such as skin and tendons require nonabsorbable sutures; wounds in rapidly healing areas such as the inside of the cheek and vagina (childbirth) are best repaired with absorbables.  In survival situations, cosmetic results are less important, but surgeons generally use smaller sutures in delicate areas such as areas on the head and face.  5-0 or 6-0 Nylon would normally be the choice here, but require more skill in handling.  Skin sutures should be placed about 1/2 inch or so apart in survival settings (as long as the skin will close).  This will allow drainage while keeping the wound together.  Areas over joints or other moving parts should be closer together.

Deeper lacerations that involve the fat and muscle should be closed in layers to eliminate what we call “dead space”.  Dead spaces are areas not closely approximated under the skin that serve as locations for inflammatory fluid (and bacteria) to accumulate; therefore, infections may occur that could become life-threatening.  Fat, interestingly, does not heal together but should still be approximated for this very reason.  It is important to tie knots tight enough to hold the tissue together but not so tight as to prevent good circulation in the tissue (which will prevent healing).  Approximate, don’t strangulate!

How long skin sutures remain in place before removal is dependent on the body part repaired.  Face wounds are usually removed relatively soon (5 days) compared to, say, a forearm wound (7-10 days).  Thicker skins, such as the sole of the foot should stay in somewhat longer.   Sutures placed over the knee or other joints should remain in place 14-21 days.

Remember that the act of suturing is more traumatic than using butterfly closures, Steri-Strips, surgical glue, and others due to the fact that you are making more punctures in an area of skin already injured.  Each extra “hole” you create could allow the entry of bacteria into the wound.  We’ve discussed this in our book “The Doom and Bloom™ Survival Medicine Handbook” and in other articles at www.doomandbloom.net. Learning to identify which wounds should be closed and which should be left open is much more important than the just learning to throw a stitch.

One relevant point:  When you practice suturing on your pig’s foot, you are learning a skill, not a trade.  The practice of medicine without a license is illegal and punishable by law; as long as modern medical care exists, seek it out.

In a future article, we’ll discuss different needle types and when to use each one.

Dr. Bones