What is a Tibial Tuberosity Avulsion Fracture in a dog or cat?

Tibial tuberosity avulsion fracture usually occurs in younger dogs due to the area of the tibia not being fully fused to the rest of the bone. Puppies diagnosed with this type of fracture usually have had some sort of trauma such as falling from a couch or bed and landing with the knee flexed. This can tear the bone fragment from its normal position. If left untreated, a tibial tuberosity avulsion fracture can result in poor function of the knee joint or the entire leg.

Tibial tuberosity avulsion fractures occursin young animals, usually between 4-8 months of age. Young puppies or kittens of any breed can be susceptible to tibial tuberosity avulsion fractures. Small breed dogs, especially toy breeds of any age can also have a tibial tuberosity avulsion fracture occur if they fall or jump off of furniture or steps.

The tibial tuberosity attaches the patella to the tibia with a strong tendon of the quadriceps muscle group. A fracture of the tibial tuberosity can result in an avulsion fracture and pull the quadriceps muscles. An avulsion fracture happens when a bone has been broken and a fragment of the bone is being separated by the pull of an attached muscle or tendon. The tibial tuberosity serves as the insertion point of the quadriceps muscles through the patellar ligament, and avulsion results from contraction of the muscle while the stifle is flexed and the foot is firmly on the ground. This mechanism, for example, could easily occur during jumping, running and in a fall.

What are the symptoms of Tibial Tuberosity Avulsion Fractures in Dogs?

Dogs, especially puppies, can come up with bumps and bruises from any number of causes. However, if you notice that your puppy or young dog has taken a spill and is not acting like his normal self, call your veterinarian for an assessment. Any of the following symptoms should be taken seriously and your dog should immediately see a veterinarian.

  • Sudden onset of lameness on a hind leg
  • Refusing to bear weight on a hind leg
  • Pain in the joint or leg on a hind leg
  • Swelling around the front of the knee joint on a hind leg

How did my dog or puppy get a Tibial Tuberosity Avulsion Fracture?

Tibial tuberosity avulsion fractures are caused by some form of trauma. They can be difficult to prevent, however, some preventative measures can be taken such as not allowing puppies or small dogs on furniture unsupervised.

Be careful not to drop puppies or small breeds of dogs when holding them and never allow them to jump on or off furniture. If you have a lot of steps in your home, pick your puppy up and carry them up or down the stairs.

How does a vet diagnose a Tibial Tuberosity Avulsion Fracture in a dog?

When you take your dog in for an examination by your veterinarian, provide as much information as possible including medical history and if you witnessed falls or stumbles. Your veterinarian will perform a physical exam and an orthopedic evaluation to determine the extent of damage that has been done.

Your veterinarian will palpate the injured leg. The leg will be painful to your dog when it is flexed or extended. Swelling may be present and the patella may be higher than usual since it is no longer attached firmly to the tibia.

X-rays and other imaging scans will give a definitive diagnosis. Both legs will be x-rayed so a comparison can be made and the exact displacement of the bone fragment can be found.

In most instances, the tibial tuberosity avulsion fracture is the only medical problem, therefore, blood work will only be needed in the event of surgery. Any dog undergoing general anesthetic should have blood work completed to ensure that they are healthy enough to undergo surgery.

What are my dog or cat’s treatment options for a Tibial Tuberosity Avulsion Fracture?

Generally, for a tibial tuberosity avulsion fracture, surgery is the best treatment. Some veterinarians may opt to rest the leg if the avulsion fraction does not look severe to give the swelling a chance to subside. Casting the leg may also be an option if the displacement is minimal.

Surgery will entail putting the bone back into its correct position to keep the quadriceps muscles from continuing to pull the bone fragment out of place. Your dog will be placed under anesthesia and pins and/or wire will be used to correct the fracture.

Surgery:

Open reduction and internal fixation technique.

  • A longitudinal incision is made just medial to the patella, the patellar ligament, and the tibial tuberosity.
  • The blood clot and fibrin clot is removed from the original location of the tuberosity. Fracture is reduced and anchored in place with three Kirschner wires.

After the bone has been put back into place x-rays will be taken to ensure that the realignment of the bone is correct.

What can I expect after a dog or cat has a Tibial Tuberosity Avulsion Fracture surgery?

Post surgery care will be required and some veterinarians will expect your dog to remain at the hospital overnight or for a few days for close monitoring. A padded bandage on the leg will be required to keep the incision site clean. Anti-inflammatory medications and antibiotics may be prescribed as well as pain medications.

During recovery from surgery, swelling or redness need to be watched for and any abnormal drainage from the incision site to ensure that the wound is healing properly. If you notice anything unusual, contact your veterinarian immediately. Stitches or staples will be removed about 10 – 14 days following surgery. Exercise should be kept minimal for about 6 weeks following surgery. Your veterinarian will give you detailed instructions that need to be followed exactly to ensure that your dog fully heals from the tibial tuberosity avulsion fracture and the consequential surgery.


Post-operative care / rehab after tibial tuberosity avulsion fracture surgery on a dog or cat

Week 1:

  • 1. Provide pain management with NSAID’s the first five days 2. If a padded bandage was applied, it should be removed after five days
  • 3. Apply an ice-pack to the stifle for 10 to 15 minutes two to four times a day for the first 24 to 36 hours after surgery if no bandage is applied
  • 4. If inflammation has resolved after 72 hours, apply a hot-pack to the stifle for 10 to 15 minutes two or three times a day if no bandage is applied
  • 5. Perform passive range of motion exercise (gently flex and extend the knee); 10 slow repetitions three times a day
  • 6. Precede and follow the passive range of motion exercise with massage of the quadriceps muscles (large muscles above the kneecap)
  • 7. Begin slow leash walks of less than 10 minutes three times a day
  • 8. Schedule a recheck to evaluate range of motion and percent weight bearing
  • 9. If your pet is very rambunctious we may place an off weight bearing bandage for two weeks

Week 2:

  • 1. Apply a hot pack to the stifle for 10 to 15 minutes two or three times a day until the swelling has resolved
  • 2. Stop passive range of motion exercise if your pet is using the leg correctly
  • 3. Increase the slow leash walks to 10 to 20 minutes three times a day
  • 4. Continue massage
  • 5. Schedule a check-up with your veterinarian 2 weeks after surgery to remove any sutures and evaluate range of motion and percent weight bearing
  • 6. Most patients should be walking normally by 2 weeks, but every pet is different and some may take longer

Week 3:

  • 1. Increase the slow leash walks to 20 to 30 minutes two or three times daily
  • 2. Have your pet perform 10 repetitions of sit-stand exercises three times a day
  • 3. Have your pet perform 10 to 15 repetitions of figure-of-eight walks two or three times a day, circling to the right and left
  • 4. Recheck 3 weeks after surgery if your pet is not walking normally or improving week to week.
  • 5. If your pet is 4 months or under at the time of surgery, a radiograph should be taken around 3-4 weeks after surgery to evaluate the growth plate and remove the tension band wire if one was utilized.

Week 4:                                          

  • At this point, your pet’s healing should be complete and should gradually return to full activity by the end of 6 weeks.
  • Your pet in 4-6 weeks after surgery to have a final radiograph to evaluate healing and the growth plate function.
  • The surgeon may recommend removing the tension band wire at this time if your pet is very young and the growth plate is still open.