External Fixation in Cats

External fixation in cats is primarily used to treat limb fractures and deformities. This is achieved using an external fixator, which is comprised of a “bridging” bar and several metal pins. These pins are threaded through the bone and fixed to the bridging bar, holding it in place during the recovery period. There are three main types of fixators: standard, circular, and hybrid. The type of fixator used will depend on the location and severity of the fracture or deformity. 

The procedure steps may vary based on the type of fixator used and the location of the fracture. The general procedure steps for fitting an external fixator are outlined below.

1. The surgeon will first perform a preoperative evaluation to ensure anesthetization is safe for the cat.
2. Anesthesia and analgesics are then administered intravenously. A catheter will also be placed, and the cat’s vital signs will be monitored throughout surgery.
3. The operative area is clipped and shaved.
4. The surgeon will then make an incision through the skin.
5. Using a special power tool, the surgeon will insert the pins into the bone, taking care not to damage any main nerves. The pins are then fixed to a bridging bar on either side using clamps. The process will be repeated as many times as needed.
6. The pins will be cut to an appropriate size.
7. Once the fixator is in place, the surgeon will make any necessary adjustments before suturing the initial incision.
8. An x-ray will be taken to ensure the pins have been placed in the optimal positions.
9. The surgeon will then apply an antibiotic ointment to the pins and skin prior to dressing it using gauze.
10. Sterile sponges will be packed around the pins before a compression bandage is placed. This bandage will be removed within two days following surgery.
11. The cat will then be hospitalized – usually for a maximum of two days, but sometimes longer – to ensure no immediate postoperative complications arise.

The efficacy of external fixation will depend on how well the pins are maintained after fixation. If owners do not practice proper and thorough pin care, the bone will not heal correctly. Infection is a common result of poor pin care. External fixation, provided that owners explicitly follow their veterinarian’s pin care instructions, is usually very effective in healing broken or fractured bones.

After the surgeon has fitted a fixator, it is crucial that owners follow all aftercare instructions. If these instructions are not followed carefully, the bone will not heal.

General Pin Care Instructions

• Administer analgesics one hour prior to cleaning the external fixator if the cat is showing any signs of pain.
• Clean all discharge from the external fixator, pins, and skin using cotton swabs or sponges and an appropriate antiseptic solution as recommended by your veterinarian or surgeon.
• Use an extra-strength (ideally triple) antibiotic ointment that is safe to use on animals. If you have any doubts, ask your veterinarian to recommend one.
• Pack small foam sponges around the pins. These should be packed tightly enough to compress the skin but not too tightly.
• Use bandage tape or vet wrap to secure each sponge, and cover sharp points with tape or vet wrap as well.

It is imperative that owners prevent the pin sites from getting infected. Infected pin sites are red and inflamed. Infected pin sites will cause pain and discomfort for the cat and will slow the healing process. Avoiding proper pin care can also result in damage to the pins. They may come loose or break, which will result in improper and delayed healing. If owners have any questions about pin care, they should contact their veterinary surgeon.

Antibiotics and analgesics will be prescribed to ward off infection and manage postoperative pain. Cats are generally required to undergo cage rest, but may engage in limited activity – no running, jumping, or climbing – in small rooms under the owner’s supervision as recommended by the surgeon. The veterinarian or surgeon may recommend hydrotherapy to promote limb function. Owners should monitor their cats at all times during the recovery period. When left alone, cats should be confined to a small crate or kennel. If the crate is made of wire, cats should not be able to catch the pins or fixator on the wire as this can damage the fixator and the bone.

After the fracture has healed, usually within three to four months provided no complications have occurred, the veterinarian or surgeon will remove the fixator and take an additional x-ray to ensure the fracture has healed.

The cost of external fixation will vary based on the type of fixator used and additional costs incurred. The average cost of external fixation, including preoperative and postoperative imaging, ranges from $2,000 to $2,700.

There are several complications associated with poor external fixator care. These include, but are not limited to:

• Infection
• Loose pins
• Pin migration
• Pins becoming bent
• Drainage
• Hemorrhage near the pin site

Some of these complications will warrant pin removal. Others will delay healing significantly. Drainage is the most common complication of external fixation. Excessive, prolonged drainage should be avoided, as this can cause severe infection and may result in pin damage.

Ensuring cats do not participate in activities that may cause severe fracture can prevent the need for external fixation. Some conditions, such as joint destabilization, are difficult to prevent.