In my recent article “Suture Basics For The Off-Grid Medic “, I gave some thoughts on suture materials, especially as they apply to closing skin lacerations. Your skin is your armor, and anything that breaches it can cause a life-threatening infection.
Although the decision to close a wound should never be automatic, simple skin lacerations can often be cleaned and closed successfully by the off-grid medic. Sutures are just one of a number of ways to accomplish this goal and allow acceleration of the healing process. Today, we’ll discuss the qualities of suture needles.
(Note: This article is for educational purposes only. If the medical system in your area is intact, seek it out to treat lacerations or other medical issues!)
Suture needles are made of a corrosion-resistant stainless steel alloy that is sometimes coated with silicone to permit easier tissue penetration.
A suture needle has three sections: the point, the midportion or body, and the swage. The swage is the “end” of the needle and is where the thread is attached. The midportion is usually curved at an arc, and the point is, well, pointy.
Before about 1920, suture needles had “eyes” and string was separate; the surgeon had to thread the eye of the needle. Since then, sutures became a single continuous unit. This process of connecting suture needle and string is called “swaging”.
Swaging dealt with a number of disadvantages associated with using separate needles and thread. In the old method, two lengths of string were formed on either side of the eye. Passage of a double strand of suture through tissue led to more tissue trauma and, perhaps, a higher risk of infection. Also, the suture string was more likely to become unthreaded or frayed.
THE IDEAL SUTURE NEEDLE
Suture needles perform based on a number of qualities, including strength and sharpness. The strength of a needle refers to its resistance to deformation during use, limiting the amount of trauma to tissue. Sharpness measures the ease of penetration into tissue and is dependent on factors involving not only the point, but the shape of the body of the needle.
Just as suture thread has ideal characteristics, the effective suture needle would be:
- Made of high-quality stainless steel
- The smallest diameter possible
- Stable in the grasp of the needle holder
- Capable of running suture material through tissue with minimal trauma
- Sharp enough to penetrate tissue with minimal resistance
- Sterile and corrosion-resistant to prevent introduction of microorganisms or foreign materials into the wound
- Rigid enough to go through tissue, but flexible enough to bend before breaking
Not all suture needles meet the above criteria, but will suffice for the basic needs of the medic.
There are a number of different needle types variations at the point, body, and swaged end:
Cutting Needles: The shape of the suture needle on cross-section may vary dependent on the particular need. The point of this shape to have more cutting edges. On cross section, it appears triangular. These needles are effective in penetrating thick, firm tissue, like skin.
There are two common types of cutting needles. “conventional” and “reverse”. Conventional cutting needles have the third edge of the “triangle” on the inner surface of the needle. Reverse cutting needles have the third edge of the triangle on the outer surface of the needle’s arc. The reverse edge is even stronger and able to penetrate tendons and other tough tissues, while decreasing the amount of trauma during the procedure.
Tapered Needles: These needles are round on cross-section and can pass through tissue by stretching more than cutting. A sharp tip at the point becomes round, oval, or square shape as you approach the swage. The taper-point needle minimizes trauma in delicate and easily-penetrated tissues such as organs or intestinal lining.
Blunt Needles: These don’t come to a sharp point, but are rounded at the end. These are best used for suturing liver, kidney, and other delicate organ tissue without causing excessive bleeding.
The body of a needle is important for interaction with the needle holder instrument and the ability to easily transfer penetrating force to the skin. A needle must be stable in the jaws of the needle holder to give maximum control and prevent bending.
The midportion comprises most of the needle’s length and is commonly curved into a 3/8 circle arc for skin or 1/2 circle for close spaces. Of course, other curvatures are available. Straight needles may be used if dealing with easy-to-reach tissues such as certain types of skin closures.
Next time, we’ll discuss the instruments you’ll use when closing a laceration with sutures.
Joe Alton MD
Learn more about different types of wound closure and the factors you should consider beforehand, pick up a copy of The Survival Medicine Handbook’s Third Edition, available at Amazon and an autographed copy at store.doomandbloom.net. You’ll be glad you did.