Comminuted Fractures in Cats
Dr. Nicholas Trout
A comminuted fracture is a splintered or fragmented break in the continuity of bone or cartilage. The fracture site consists of multiple pieces of bone, which can be small or large, grouped together or displaced within the traumatized tissue. Significant limb swelling when a pet returns from being missing
Comminuted fractures are associated with high-energy trauma such as being hit by a car or sustaining a gunshot injury. A lot of force and energy is required to fragment bone, and this energy also affects the surrounding soft tissues. Many comminuted fractures will also be described as open, where a piece of shattered bone pierces through the skin, causing contamination or infection.
There is no breed predisposition, but since vehicular trauma is the most common cause of comminuted fractures, young intact males are more commonly affected.
Most comminuted fractures are considered a severe orthopedic injury, which, unless treated, may lead to loss of limb function and could lead to spread of infection and even death. Many of these fractures are associated with other life threatening injuries.
What to Watch For
Not using a limb
Seeing a limb dangle in an awkward and unnatural position
In many cases, a history of trauma will be obvious, but your veterinarian will question you carefully about any other health problems prior to the accident. Given that most comminuted fractures occur secondary to major trauma, other vital systems will be assessed and stabilized first. After stabilization, additional tests may include:
Radiographs (x-rays) will be taken to diagnose the presence of the fracture. Chest x-rays may be obtained at the same time to ensure that there are no chest injuries that need to be addressed before possible anesthesia.
There are no laboratory tests specific to fractures, but blood may be obtained and tested prior to a general anesthesia.
While other life-threatening problems are being addressed, a temporary bandage may be applied to an injured limb. Once stabilized, treatment may include:
Any areas of skin, muscle and other soft tissue trauma is dressed and covered to prevent further contamination at the fracture site. Antibiotics may be started at this time, or a sampling for bacterial culture may be taken from the fracture site.
To repair a comminuted fracture, the ends of the bone must be opposed and the continuity of the bone restored as close to normal as possible. Given the amount of disruption to the normal bone anatomy in a comminuted fracture, this often requires open fixation, which means surgically exposing the bones by separating and, if necessary, cutting through muscle to visualize the fracture and to put it back together. This type of surgery obviously requires general anesthesia.
Splints and casts are usually inadequate types of repair for comminuted fractures due to their inability to restore the normal anatomy and the fact that many times they would conceal and impair treatment of concurrent soft tissue trauma.
External fixation describes the use of pins passed from outside the leg, through the skin and into the bones of the limb, ideally with at least three pins above and below the fracture. These pins can then connect to one another either by bars, rods, cement or rings. External fixators can be very useful for comminuted fractures of the tibia and radius.
Internal fixation describes the use of pins and wire, plate and screws with variations on these themes, placed via open reduction of the fracture. Plates and screws can be used for a variety of different fragments but offer exceptionally stable fixation and in some cases the ability to squeeze or compress the ends of the bone fragments together. These techniques are commonly applied in comminuted fracture repair.
Injectable analgesics (pain medications) may be given to your pet while being treated in the hospital and may be continued orally once your pet is discharged from the hospital.
Home Care and Prevention
External fixators must have the skin-pin interface cleaned daily where the pins pass through the skin toward the bone. Crusting and discharge is common at this location, but excessive swelling or discharge should be brought to your veterinarian's attention.
In cases of open fracture repair, there will be an incision that needs to be monitored for swelling, redness and discharge. Stitches or staples will need to be removed in 10 to 14 days.
Your pet will need to rest to allow the fracture to heal. This time frame will be less for younger animals (2 to 4 weeks) and longer for older animals (6 to 12 weeks or even more depending on the nature of the fracture).
Comminuted fractures can be difficult to repair and heal, given the damage to the blood supply to the bone and the possibility that bacteria have contaminated or infected the fracture site.
Follow up x-rays will be taken to ensure the fracture is healing and that there are no problems with the implants.
Since most fractures occur secondary to being hit by a car, cats should be kept indoors when possible.