Patellar luxation

Causes of patellar dislocation

The exact cause of patellar dislocation is not always known, but there are some factors that may increase the risk. These include:

• Genetic predisposition: Some dog breeds have a congenital malformation of the stifle socket or patellar tendon that causes the kneecap to slip out of place more easily. These breeds include the Chihuahua, Yorkshire Terrier, Poodle, Maltese and Boston Terrier.
• Trauma: An accident or injury to the knee can cause damage to the ligaments or cartilage that stabilize the kneecap. This can lead to loosening or displacement of the kneecap.
• Excess weight: Excess weight puts strain on the joints and can lead to wear and tear of the cartilage. This can affect the stability of the kneecap and increase the risk of patellar dislocation.

Symptoms of patellar luxation

Symptoms of patellar dislocation can vary depending on the severity and frequency of the incident. Some possible signs include:

• Limping or hopping on three legs: This is often the first and most noticeable symptom of patellar luxation. The dog tries to take the weight off the affected leg and lifts it when walking. Sometimes you can also see the dog trying to bring the kneecap back into position by stretching or shaking the leg.
• Pain or discomfort: The dog may show signs of pain or discomfort when the kneecap is dislocated. He may howl, growl or lick his knee. He may also be less active or playful than usual.
• Swelling or redness: The knee joint may be swollen or red when the kneecap is dislocated. This indicates inflammation or infection.
• Osteoarthritis: If patellar dislocation occurs frequently or chronically, this can lead to permanent damage to the cartilage and bone in the knee joint. This is known as osteoarthritis and is a degenerative joint disease that leads to pain, stiffness and restricted movement.

Diagnosis of patellar luxation

If you suspect that your dog is suffering from patellar luxation, you should take him to the vet as soon as possible. The vet will perform a physical examination and palpate the knee joint. He will try to manually push the kneecap out of position and feel how easily it snaps back into place. This is called a luxation test and helps the vet determine the degree of patellar luxation.

The vet will also take x-rays of the knee joint to assess the condition of the cartilage and bone. This will help him to rule out other possible causes for the limp and create a treatment plan.

Treatment of patellar dislocation

The treatment of patellar dislocation depends on the severity and incidence of the condition. In mild cases, conservative treatment may be sufficient, which includes the following:

• Painkillers and anti-inflammatory medications: These help to relieve the pain and inflammation in the knee joint. However, they should only be administered under the instruction of the vet as they can have side effects.
• Weight management: If the dog is overweight, he should go on a diet to reach his ideal weight. This will help to reduce stress on the joints and reduce the risk of patellar luxation.
• Physiotherapy: This involves exercises that strengthen the muscles and ligaments around the knee joint and improve mobility. The vet can show you how to do these exercises for your dog at home.
• Joint protection: This involves protecting the dog from activities that can strain or injure the knee joint, such as jumping, running or climbing stairs. You can also provide him with an orthopaedic bed or ramp to increase his comfort.

In severe cases or if conservative treatment is not effective, surgery may be necessary. Surgery aims to fix the kneecap back in its normal position and improve joint stability. There are different types of surgery that can be performed depending on the degree of patellar dislocation and the condition of the knee joint. These include:

• Deeper knee socket: this involves deepening the bony surface of the knee socket to create more space for the kneecap.
• Shortening or lengthening the patellar tendon: This involves shortening or lengthening the patellar tendon to align it in a straight line with the femur.
• Patellar tendon insertion offset: This involves moving the insertion point of the patellar tendon on the tibia to correct the direction of patellar pull.
• Stabilization of the ligaments: This involves tightening or loosening the ligaments that hold the kneecap in place.

The surgery is performed under general anesthesia and requires post-operative care and follow-up. The dog will need to wear a bandage or splint for a few weeks and limit its activity. He will also need regular visits to the vet to monitor his healing. The success rate of the surgery is high, but there are some possible complications, such as infection, bleeding or re-dislocation.