Luxating Patella in Dogs

Luxating patella is a common orthopedic condition that can occur in dogs. In fact, according to the American College of Veterinary Surgeons, (ACVS), the condition occurs in about seven percent of all puppies.

The patella is the kneecap, and if it moves out of its correct alignment, the condition is referred to as luxating patella. Normally, the patella sits in the grove called the tibial crest. This position allows the kneecap to move up and down when the knee is bent. The action of the patella helps guide the movement of the muscles in the lower leg called the quadriceps.

But in some dogs, the patella luxates, which means it moves outside the grove. This dislocation of the patella from its correct position causes the leg to lock up.

Causes of Patellar Luxation

In some instances, luxating patella can develop as the result of an injury, such as trauma to the knee. But in other cases, the cause of the condition is not known. It may occur due to a congenital defect.

Congenital defects, which may contribute to luxating patella are thought to involve skeletal abnormalities, such as a long patella ligament, malformation of the tibia and hip dysplasia.

According to the Colorado State University, luxating patella is more common in smaller breeds under 30 pounds including:

When the condition does occur in larger dogs, it tends to be more common in the following breeds:

Symptoms

Depending on the grade, some dogs may not have any symptoms. When symptoms do occur, they may include limping and lameness, which may come and go. Lameness refers to a disturbance in gait or stance. Lameness may occur because of pain or abnormal anatomy. Dogs with luxating patella may also skip when they run.

According to the Orthopedic Foundation for Animals, one of the most common symptoms is a knock-knee stance. In some cases, your dog may also yelp in pain, especially when the dislocation initially occurs.

Some dogs may shake or hold up their affected leg to lengthen the quadriceps, which helps the patella return to the correct anatomical position. Usually, the more severe the grade of the disorder, the more likely your dog is to have symptoms. For example, dogs who only have symptoms occasionally, may start to have more frequent and consistent symptoms as the condition progresses.

In more severe cases, complications of luxating patella can develop. The pain can become more severe, which limits activity. The cartilage of the knee can wear away resulting in osteoarthritis. Inflammation can also occur, which may breakdown the ligament.

Another potential complication in severe cases is rupture of the cranial cruciate ligament. The dislocation of the patella can lead to changes in the way the knee moves, which stresses the ligament.

Diagnosis

Diagnosis sometimes occurs after a routine visit to the vet. During a physical exam, the veterinarian may discover the condition. In other instances, symptoms may be present, which prompt a trip to the vet. The veterinarian will perform an exam and can often diagnose the condition after feeling the unstable kneecap. In some cases, additional tests may be performed preoperatively if surgery is recommended.

X-rays of the knee and possibly the pelvis to determine the extent of the disease and whether hip dysplasia is present may be done. X-rays are generally quick and are painless for your pup. A CT scan is also sometimes used. A CT can provide three dimensional images of the leg and may be helpful, especially if surgery is performed.

Once a diagnosis is made, the condition is usually classified into one of four grades based on the severity. The grades include the following:

Grade 1: The patella may be manually moved out of the grove. But it returns to its normal position without intervention.
Grade 2: The patella may spontaneously slip out of the grove occasionally or can be manually luxated, but it can be manipulated back into position.
Grade 3: The patella remains out of the grove most of the time, but it can be manipulated back into position.
Grade 4: The patella is out of the grove all the time and it cannot be manipulated back into position.

Treatment of Patellar Luxation

Not all dogs will who have luxating patella will require treatment. Dogs who do not have any symptoms may just be monitored. Some dogs, especially small dogs, may live a normal life and function fully without treatment.

In other instances, medical management of luxating patella classified as grade one may be an option for dogs who have symptoms. Medical management involves non-surgical approaches to treating the condition.

Medical management may include non-steroidal medication, which treats inflammation and pain. Keeping your dog at a healthy weight to decrease strain on the knee is also recommended. Physical exercises to strengthen the quadriceps may also be an option.

In dogs who have more advanced disease and are classified as having grade two, three and four luxating patella, surgery may be the best treatment option. There are a few different surgical approaches, which may be used. One procedure is referred to as trochlear modification. The procedure involves creating a deeper groove in the femur to hold the patella in place better.

Another surgical approach involves repositioning the patellar ligament and attaching it to the tibia crest on the opposite of the luxation. Keep in mind, if there is underlying damage to the knee due to arthritis, luxating patella surgery does not reverse arthritic changes.

How well a dog responds to treatment may depend on the severity of the disease and the age at diagnosis. Recovery from surgery may also vary based on the type of procedure. In most cases, a dog will use the affected leg well after about six to eight weeks.

Prognosis for most dogs with luxating patella is good. But there are potential risks to surgery. Although anesthesia is usually safe, there is a possibility of complications from the anesthetic. With most surgeries, there is also a risk of infection. If your dog is too active during the recovery time, it’s also possible the repair can breakdown. Following your vet’s post-operative instructions decreases the chances of complications.

How Much Is Luxating Patella Surgery for Dogs?

The cost of surgery to correct your dog’s luxating patella depends on the severity of the condition, age and size of your dog and where you live. Veterinary surgery costs vary widely depending on the cost of living in your zip code. With that said here is the average cost for knee surgery for dogs.

Luxating Patella Dog Surgery Cost: $1,500 to $3,000

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Incidence by Dog Breed

Each dog breed has unique genetic makeup that causes them to be more or less susceptible to patellar luxation. You can learn more from the Orthopedic Foundation for Animals or visit the American College of Veterinary Surgeons to learn more about luxating patella dog surgery.

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