By Kendra Freeman, DVM, MS, DACVS (Large Animal/Small Animal)

If you were opening your own hospital, starting a surgical service, or asked to select suture material to have available, would you know where to start? The options for selecting a suture may seem almost endless. Many factors are to be considered, including material handling, memory, tensile strength, and cost. While there is no one-size-fits-all answer to the best suture, answering the following questions can help ensure the best and most appropriate selection for your operating room.

How long does the suture need to be present?

Is the tissue being sutured rapidly healing, like the urinary bladder? Will it heal over the next several months, like the linea alba? Is the tissue very slow to heal and may need the support of a suture for many months, like a tendon or ligament injury?

Tensile strength is a measure of a suture material's ability to resist breakage.¹ For absorbable suture materials, the tensile strength decreases significantly within 60-90 days after placement in the body. Some absorbable sutures lose tensile strength rapidly, while others do so more slowly.¹

The bladder is one of the most rapidly healing tissues in the body. It regains >75 percent tensile strength in about 14 days after surgery.¹ Because this healing is so rapid, a suture that loses its tensile strength quickly is appropriate. Rapidly absorbable sutures include glycomer 631 and poliglecaprone 25. These sutures lose ~50 percent of their strength in 14-21 days.^2,3

The linea alba is the aponeurosis of the external and internal abdominal oblique and transverse abdominal muscles.¹ In general, this type of healthy fascia regains approximately 50 percent tensile strength in three months.¹ Rapidly absorbing sutures, such as glycomer 631 or poliglecaprone 25, may lose too much tensile strength to provide appropriate support before the fascia heals or regains substantial strength. Suture material that is slower to lose tensile strength over 30-60 days may be more appropriate for this tissue. This may include polydioxanone, polyglyconate, and polyglycolic acid.

Closure and repair of very slow-healing tissue or tissue under tension, such as tendons and ligaments, may benefit from suture material that takes >60 days to lose significant tensile strength. This type of suture material is considered non-absorbable and may include nylon, silk, polypropylene, and polyester. A potential disadvantage of this type of suture is infection or suture reaction may be challenging to resolve without removing the suture material.

What type of environment will the suture be placed in?

If moisture or wicking may be present in the tissue, a multifilament or braided suture material is best avoided. While braided materials, such as polyglactin 910, polyglycolic acid, and lactomer 9-1, may offer great knot security, wicking of moisture may lead to seroma, contamination, draining tracts, etc.^4,5 Full-thickness closure of the bladder mucosa or gastrointestinal tract is better accomplished with a monofilament suture to avoid such potential complications.

The presence of bacteria at a surgical site may affect a suture's tensile strength. The presence of Proteus mirabilis bacteria in the urine may rapidly speed the degradation of the suture, with many suture materials disintegrating within seven days.²

How comfortable is the suture material to use?

A suture that maintains its shape after removal from the suture packet is said to have memory. This is more common in monofilament suture material compared to multifilament suture. Sutures with memory tend to be stiffer, can be more challenging to handle, and may have less knot security.¹ An ideal suture material to handle would have little to no memory and minimal tissue drag when placed (Figure 1).

How many different suture sizes do I need?

The types of surgical procedures and range of patient sizes will help determine the variety of suture sizes appropriate to stock in your hospital. A feline-only practice performing limited soft tissue surgeries (ovariohysterectomy, castration, cystotomy, etc.) may only need two to three sizes of sutures .

A small-animal specialty practice offering a wide variety of procedures, or even a mixed-animal practice, will need a wide range of suture materials and sizes available. The general principle is to use the smallest suture strong enough for the tissue. This allows for less suture material to be present, which may potentially contribute to inflammation and tissue reaction. Although very little data is available on appropriate suture size, 3-0 or 4-0 suture is generally appropriate for the gastrointestinal tract and urinary bladder.

2-0 or 0 suture is appropriate for the linea alba in medium- to large-size animals. Be reminded even with a limited selection of suture sizes, the appropriate suture material is still needed in appropriate sizes.

Which needle is best?

Most of us are likely using sutures with swaged needles. Although needles can be purchased straight or curved, curved ones are more versatile and easier to handle for most situations. This is where options can seem almost endless when selecting your ideal suture. Curved needles range from 5/8 to ¼ of a circle and come in a variety of thicknesses. The preferred amount of curve of the needle can be the surgeon's preference and may depend somewhat on the target tissue in which the suture will be placed.

Basic needle points include taper, cutting, and reverse cutting. Slender, taper point needles are appropriate for delicate tissue, such as urinary bladders and urethra, for perineal urethrostomies.

A large needle, possibly with a cutting or reverse cutting point, is helpful for thicker, sturdier tissue, such as fascia. It can be challenging to find your preferred combination of curved needle, size of needle and suture for different situations (Figure 2).

How much does a suture cost?

Although pricing should not be the main deciding factor for suture selection, it is often taken into consideration. Suture equivalents are often available from multiple manufacturers. The price differences may be in suture length, needle types available, and presence of suture memory. It is reasonable to have a preferred suture, although being aware of equivalent alternatives is advised in case of supply issues.

The options of needle and suture combination can be overwhelming. If starting from scratch, it may take some trial and error to find the suture type that you feel handles the easiest, is attached to a needle that is comfortable to use, and versatile for different situations. A huge variety of suture and needle types may not be necessary in your hospital; however, the options available need to be appropriate for the tissue in which they will be placed.

Kendra Freeman, DVM, MS, DACVS (Large Animal/Small Animal), is a graduate of the Colorado State University and maintains dual certification with the American College of Veterinary Surgeons. Dr. Freeman is an associate surgeon in Albuquerque, N.Mex. Her caseload consists of orthopedics, general soft tissue, and sports medicine cases, with occasional returns to her roots in large-animal lameness and surgery.

References

1. Tobias, K. M., & Johnston, S. A. (2017). Veterinary surgery: small animal. Suture Material, Tissue Staplers, Ligation Devices and Closure Methods.
2. Greenberg CB, Davidson EB, Bellmer DD, Morton RJ, Payton ME. Evaluation of the tensile strengths of four monofilament absorbable suture materials after immersion in canine urine with or without bacteria. Am J Vet Res. 2004 Jun;65(6):847-53.
3. SCHILLER, T.D., STONE, E.A. and GUPTA, B.S. (1993), In Vitro Loss of Tensile Strength and Elasticity of Five Absorbable Suture Materials in Sterile and Infected Canine Urine. Veterinary Surgery, 22: 208-212.
4. Fossum, T.W. (2007) Small Animal Surgery. 3rd Edition, Elsevier, Mosby, 57-78.
5. Grigg TR, Liewehr FR, Patton WR, Buxton TB, McPherson JC. Effect of the wicking behavior of multifilament sutures. J Endod. 2004 Sep;30(9):649-52.