Patellar Luxation in Dogs

Patellar luxation, often called a dislocating kneecap, is a common orthopedic condition in dogs. It occurs when the patella (kneecap) slips out of its normal groove at the end of the femur (thigh bone). This can lead to discomfort, pain, and difficulty walking or using the affected leg. Cases range from mild, with occasional dislocations, to severe, with the kneecap permanently out of place.

Understanding Patellar Luxation

The patella sits within the quadriceps tendon and acts as a pulley for the quadriceps muscle, which extends the knee joint. When the patella luxates, it moves out of its groove—either toward the inside of the leg (medial patellar luxation, or MPL) or toward the outside (lateral patellar luxation, or LPL).

• MPL is more common, especially in small and toy breeds.
• LPL is less common and occurs more often in larger breeds.

Causes of Patellar Luxation

Several factors can contribute to this condition:

• Genetics: Small breeds are especially prone to MPL.
• Bone Structure: A shallow femoral groove can increase risk.
• Trauma: Injury to the knee joint may cause or worsen luxation.
• Obesity: Excess weight places added stress on the knee.

Signs to Watch For

Symptoms vary depending on severity and may include:

• Intermittent limping or a “skipping” gait
• Stiffness or difficulty rising
• Pain when using the leg
• Bowlegged stance in chronic cases
• Persistent lameness in severe cases

Diagnosis

A veterinarian will perform a physical exam to assess kneecap movement and stability. Radiographs (X-rays) may be taken to evaluate the knee’s anatomy and check for arthritis. Patellar luxation is graded on a scale of I to IV, with Grade I being the mildest and Grade IV the most severe.

Treatment Options

Treatment depends on the grade and severity of the luxation.

Non-Surgical (Conservative) Management

For mild cases (Grade I or II), especially in small or less active dogs, management may include:

• Weight control
• Joint supplements
• Anti-inflammatory medications
• Controlled exercise
• Physical rehabilitation

Surgical Treatment

Surgery is often recommended for Grade II luxations with ongoing symptoms, and for all Grade III or IV luxations. The goal is to correct the underlying cause and prevent complications like arthritis. Common surgical techniques include:

• Trochleoplasty: Deepening the femoral groove.
• Tibial Tuberosity Transposition: Repositioning the patellar ligament attachment.
• Lateral Imbrication: Tightening soft tissues to stabilize the kneecap.
• Osteotomies: Reshaping bones to correct alignment.

Some specialty hospitals may also perform extracapsular lateral suture stabilization—a surgery more commonly used for cranial cruciate ligament (CCL) injuries—combined with lateral imbrication in certain small dogs where MPL is linked to limb angle abnormalities.

Recovery and Prognosis

• Post-Surgery: Most dogs require 6–8 weeks of strict rest.
• Aftercare: Includes pain control, antibiotics (if prescribed), and incision monitoring.
• Rehabilitation: Strongly recommended to restore mobility and strength.
• Outcome: Surgery has a high success rate, and many dogs return to normal activity. Early surgical intervention can slow arthritis development.

Dogs with mild luxation may not require surgery but should be monitored for changes. Left untreated, patellar luxation can cause chronic pain and arthritis over time.