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Common Knee Problems in Dogs: Patellar Luxation

What Is Patella Luxation?

Patella luxation is one of the most common knee conditions found in many small-breed dogs and some larger breed dogs, too. The patella, or kneecap, is positioned at the front of the stifle joint—the knee joint in dogs and cats. It rides smoothly along a groove in the femur when the knee is functioning properly. This groove keeps the patella in place, allowing for the knee’s flexibility.

A luxating (dislocated) patella typically occurs when the femur’s groove is too shallow. This leads to the patella’s not staying where it should and can cause a weakening of the ligaments that keep the patella in place.

Dog Breeds Commonly Affected

Patellar Luxation Dog Breeds At Risk Chart

Chart was created by Embrace Pet Insurance; data is according to the Orthopedic Foundation for Animals.

Signs and Symptoms

Generally, patella luxation manifests in puppies between four and six months of age. Its appearance may not be readily observable—perhaps a skip in your dog’s step or your dog not letting one paw touch the ground. You might also see signs in the way your dog runs.

Four Grades of Patellar Luxations

The condition falls into one of the following four categories. This grading system describes the kneecap’s degree of luxation. Diagnosing a luxating patella is often simple, but grading the condition can be tricky: X-rays help determine the degree of damage that’s occurred. Grades III and IV typically require surgery.

Grade I: The patella can be luxated manually but won’t move out of the groove by itself. It will naturally return to its normal position if left alone.

Grade II: The patella might spontaneously luxate (or ride out of its groove) but can return to its normal position manually or when the pet straightens the stifle joint.

Grade III: The patella remains luxated most of the time but can manually be returned to its correct position.

Grade IV: The patella is permanently luxated and cannot be repositioned.


Severely affected dogs are best treated surgically. Because any instability in the knee joint could potentially lead to arthritis, some dogs with moderate lameness could also be helped by surgery.




Luxating patella is genetic. Ramps or steps might help lower the impact on your pet’s knees, but no proven way to prevent this condition exists.

You will, of course, want to maximize your dog’s comfort and minimize secondary issues related to patellar luxation. This means keeping your dog’s weight within the normal range. A leaner dog will likely have fewer complications, and an osteoarthritic one at a normal weight will suffer significantly less pain.

Consult with a Board-Certified Surgeon

If your primary care veterinarian diagnoses your pet with a Grade III or IV luxating patella, they will likely refer you to a board-certified surgeon for consultation and treatment. VSEC Thousand Oaks is fortunate to have two skilled and experienced surgeons on the team. If you would like to schedule a consultation with one, please call us at (805) 492-2436 or e-mail us at

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