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