Using skin staplers in veterinary practice

Skin staplers have gained increasing acceptance in veterinary surgery over the past decade. Their popularity is due to several factors, including:

• Increased affordability; simplicity of use;

• The security of a simple interrupted skin suture pattern;

• Significant reduction in surgery time;

• A decrease in anesthesia time; and

• Relative ease of removal

Overview of skin staplers

There are a number of companies currently marketing skin staplers for human and veterinary use. There are two basic stainless steel staple sizes that can be purchased: the regular staple (width range from 4.8 to 6.1mm) and the wide staple (width range from 6.5mm to 7.0mm). The length of staple legs varies with individual manufacturers.

Photo 1: Various stapler designs, including fixed and rotating head units. The fixed-head skin staplers are more economical and quite suitable for veterinary use. Note the various grips available.

Most companies sell disposable staplers containing 35 staplers per unit. Although there are several designs on the market, many units have a clear plastic window to visualize the number of staples remaining. A compressible palm grip is more popular than a finger "trigger" to apply the staples into the tissue (Photo 1). All units have a simple arrow or pointer at the tip of the stapler, allowing the clinician to center the stapler directly over the apposed skin margins (Photo 2). Today, most skin staples are extruded in a rectangular shape. As the staple wire is bent against the central anvil, the chisel-pointed tips are directly aligned as they pass through the dermis (Photos 3A and B).

Photo 2: Stapler with a clear plastic window to assess the number of staples remaining in the unit. Note the black guide arrow for alignment over the skin incision.

In skin closure, it is my opinion that the wide staple is the best size to use in the dog and cat. Skin staplers are purchased in sterile pouches for immediate use; incompletely used staplers can be resterilized either with ethylene oxide or the Sterrad Sterilizer (Advanced Sterilization Products, Inc.). The current plastic components in these devices generally cannot tolerate the extreme temperatures generated in the autoclave.

Photo 3A: Staple undergoing deformation as it is forced against the central "anvil"

Many surgeons commonly apply skin staples after an incision is apposed with an intradermal suture pattern. In cases where an intradermal pattern is not necessary or advisable, standard thumb forceps can be used to align, grasp, and slightly elevate the apposed skin borders during application of the staples.

Most veterinary practices used fixed-head staplers based on their significantly lower cost, in comparison to staplers with a rotating head for easier positioning in contoured areas of the body. Several factors are considered prior to the purchase of a stapler, including the cost, overall handling properties, and staple security in the skin. A paper, reviewing various stapler features, outlined the various advantages and disadvantages of six staple models in 1997. Currently, I favor the Davis and Geck Appose ULC 35W. This is the standard skin stapler currently used at the Angell Memorial Animal Hospital.

Photo 3B: Upon competion of the application, the staple disengages from the stapler as the plunger retracts. Again, note the black guide arrow used for alignment of the skin incision.

Problems associated with skin staple applications

The "learning curve" for the application and removal of staples is low. The primary problem initially faced by the veterinarian is how much pressure to apply for proper engagement of the staple. Insufficient pressure will result in a staple that stands above the skin without substantial engagement of the dermis. Excessive downward pressure can embed the staple. With tissue swelling, the embedded staple can cut into the skin and make removal difficult and painful to the patient. Because various staplers have different handling features, veterinarians need to adjust the amount of pressure to apply for a given model.

Photo 4A: Example of a skin staple remover. All skin staple removers have a similar design.

Improper alignment of the stapler with the apposed skin margins will result in a staple which does not properly engage one cutaneous border, necessitating its removal. Proper alignment of the "arrow or pointer guide" with the incision line can minimize this problem. These "guide arrows" and their visualization during application differ between manufacturers.

Most staples are extracted with the staple removers provided by the manufacturer. Staple removers grasp and crimp the external staple bar outwards, as the scissors-like handle is closed. The staple remover is lifted to free the staple from the skin surface(Photos 4A and 4B. For removal of one or two aberrant staples, mosquito hemostats can be inserted beneath a skin staple; gently opening the hemostat will spread the staple points apart and the staple can be lifted from the skin.

Photo 4B: The lower "double bar" jaw is slipped beneath the body of the skin staple. Closure of the handles compresses the upper bar against the staple, splaying the staple ends. The closed staple remover is immediately lifted to extract the staple.

Skin staples generally do not engage thin skin particularly well. The thin dermis creates staple instability, thereby allowing the staples to tilt and pivot perpendicular to the skin surface. As a result, the staples do not properly align the skin and their subsequent removal can be difficult. Oftentimes, a mosquito hemostat must be used to grasp the displaced staple. The veterinarian then must elevate and rotate the staple so that a remover or second hemostat can be used to free it from the skin. A second problem has been noted with stapling thin skin (eg, lower abdominal skin in cats, small dogs): rotation of the staple can enable the thin skin to stretch through a gap present between the chisel points of the staple. Dehiscence can be rather immediate (and dramatic) when this occurs along a major segment of a stapled incision. Veterinarians should examine the staples of a given manufacturer closely, to determine the staple shape is uniform and a significant gap is not present in the bent staple (Photo 5).

Photo 5: Close up view of a wide staple. Surgeons should examine the staple gap located between the chisel points. Large gaps increase the likelihood of wound dehiscence, primarily when staples are used on thin skin.

The author has noted that application of a surgical cyanoacrylate glue, over the length of a stapled incision, is very effective in improving the stability and security of skin staples. The glue forms a rigid bond to the staple and outer skin surface, thereby minimizing staple movement. In about one week, the glue has largely fragmented and does not impair the subsequent removal of the staples. The glue also adds an additional "footprint" of security to the stapled incision, further reducing the likelihood of dehiscence.

It is the author's experience that skin staples are not particularly reliable for closing wounds under mild to moderate incisional tension, compared to hand-sutured wounds. Under this situation, a vertical mattress suture pattern, alternated with a simple interrupted suture pattern is preferred. An intradermal suture pattern can give additional support to these problematic wounds. Surgical (cyanoacrylate) glues also can be used in conjunction with conventional suture patterns for additional security.

Photo 6A: Graft application to the inner thigh of a cat. Skin staples greatly facilitated graft alignment and security to the recipient bed.

"Quick closure" and reinforcement

Skin staples can be used to reinforce a conventional wound closure in danger of dehiscence, or incisions where small gaps are noted. In those cases in which the patient has removed skin sutures, the wound can be lightly prepared with an antiseptic solution, followed by the immediate application of skin staples. In many cases, little or no sedation is required to apply a few supportive staples to the "incision at risk."

Skin graft application

Skin staples are a simple and effective method of securing sheet or meshed skin grafts to wounds, especially defects involving the extremities. The prepared graft is applied to the wound, with the graft overlapping the skin bordering the defect by about 1 cm. Graft tension is adjusted as opposing sides of the wound are stapled in an alternate fashion (Photo 6A).

Photo 6B: Staple application to the nonadherent dressing. The dressing was stapled over the graft, thereby preventing its displacement postoperatively. This entire area was then covered with a heavily padded bandage and external aluminum bar (Spica Bandage) to prevent graft motion.

Applying wound dressings

Dressings applied to wounds are occasionally displaced as a result of motion. Ointments or discharge from the wound also can serve as a lubricant, facilitating movement of the contact dressing. Medicated or protective dressings can be effectively secured to a problematic area with skin staples. The author has found this technique particularly useful for coverage of skin grafts. Staples also can be used to secure individual (secondary bandage) bandage layers together for stronger, more cohesive coverage of a given body region (Photo 6B).

Securing drainage tubes

Closed vacuum drainage systems are comprised of a reservoir to collect body fluids by means of a fenestrated tube placed into the wound or body cavity prior to skin closure. The external tube (nonfenestrated) segment in turn is connected to the reservoir. Strips of surgical tape, applied as small "butterfly" bands to the external tubing, can support its span between the wound and collection reservoir. Skin staples are a simple method of securing the tape strips to the external skin (Photo 7).

Photo 7: Closed vacuum drainage system was inserted into a surgical wound after removal of a vaginal leiomyoma. The external drainage tube was secured to the side of the patient with tape bands and skin staples. The free end of the tube was then attached to the reservoir, secured to the trunk of the patient with adhesive tape.

Skin staples as radiopaque markers

After removal of a malignant tumor scheduled for future radiation therapy, metallic vascular clips or stainless steel sutures can be applied to the musculofascial tissues surrounding the surgical site. After skin closure, these retained radiopaque markers enable the radiation therapist to better determine the area requiring adjunctive radiation treatment. The author has found that stainless steel skin staples are easier to apply and attached securely to the musculofascial tissues for this purpose. Their biocompatible stainless steel composition permits their burial beneath the skin with minimal risk of tissue reaction.

Intestinal anastomosis

The use of the smaller, regular-sized staple has been advocated for small intestinal anastomosis. The author has no experience with this specific technique, and cannot comment on its reliability. However, there are other surgical stapling devices, and technique variations that have been proven to be effective both in human and veterinary surgery.

Suggested Reading

• Waldron, D.R.: Skin and fascia staple closure. Vet. Clin. No. Amer. 24:413-423, 1994.

• Smeak, D.D.; Crocker, C.: Fixed-head skin staplers: features and performance. Compend. Contin. Ed. Pract. Vet. 19:1358-1368, 1997.

• Coolman, B.R.; Ehrhart, N.; Pijanowski,G.; et al.: Comparison of skin staples with sutures for anastomosis of small intestine in dogs. Vet. Surg. 298:293-302, 2000.