A luxating patella, a condition where a dog's kneecap shifts out of its usual place, is unfortunately a common occurrence among our canine companions. It's a challenge that can affect dogs of all breeds, though it tends to trouble small or toy breeds like Chihuahuas, Yorkshire Terriers and Pomeranians more frequently.

Luxating Patella in Dogs

When your furry friend experiences this ailment, it can be an emotional rollercoaster. Sometimes, all it takes to ease their discomfort is a regimen of physical therapy and medication, but in more severe cases where pain becomes a constant companion, surgery may become a necessary path to relief.

Let's delve into how this condition occurs in dogs. A luxating patella happens when the kneecap, or patella, which usually sits snugly in its groove on the femur (the thighbone), decides to shift out of alignment. This misalignment can occur in one or both of their hind legs. Typically, in small breed dogs, this unsettling movement tends to occur towards the inside of the limb, which we call medially. However, in larger breeds, it's less common for the kneecap to shift laterally.

When the patella luxates or dislocates, your pet might experience moments of hind limb "skipping," lameness, or even their leg locking up at an awkward angle. But here's the silver lining: once the patella returns to its rightful position, the discomfort decreases.

The roots of a luxating patella in dogs can vary. While a traumatic injury can be a cause, it's more often linked to abnormalities in joint or limb structure. These issues could range from the groove where the kneecap sits on the femur being too shallow to the area where the kneecap attaches to the shinbone (tibia) being displaced. These structural changes alter the forces acting on the knee and eventually lead to the patella's luxation.

Diagnosis and grading of a luxating patella

Your veterinarian is your trusted partner in this journey. They'll conduct a thorough physical examination and grade the condition based on its severity, which falls into categories from I to IV. Their grading considers any signs of discomfort or pain you've noticed in your cherished companion.

  • Grade I: At this stage, the kneecap dislocates with manual pressure but swiftly returns to its normal position when the pressure is released. Typically, Grade I is discovered incidentally during a veterinary examination and doesn't usually cause visible symptoms.
  • Grade II: In this scenario, the kneecap easily shifts out of place with manual pressure and stays displaced until it's manually adjusted. Lameness is often intermittent when the patella luxates, and it can be painful if cartilage damage occurs due to frequent dislocation.
  • Grade III: Here, the kneecap spends most of its time out of place but can be coaxed back into position with manual pressure. However, once that pressure is removed, the patella tends to spontaneously luxate. Dogs at this grade may experience more pain and exhibit increased lameness due to structural changes or cartilage damage from repeated luxation.
  • Grade IV: This is the most severe stage, where the kneecap is permanently dislodged from its normal position and cannot be manually repositioned. Typically, there are significant limb structure changes present, leading to lameness, impaired mobility, and reduced limb function.


Dr. Jessica Seid Dr. Jessica Seid

Jessica Seid is an emergency veterinarian practicing in the New England area. She is a graduate of the North Carolina State College of Veterinary Medicine and has been in the field for more than a decade. When she's not helping patients, she enjoys spending time with her husband, daughter and French bulldog.