Patella Luxation is when your dog’s kneecap no longer slides up and down smoothly in your dog’s thigh. When your dog has luxating patella, they can limp occasionally or consistently, depending on how severe their condition is. They will also show signs of stiffness, for example not being able to get out of their bed easily or only walking short distances. Dogs with a Luxating Patella need to have their kneecap supported, to help stabilise their patella as well as reduce the chances of sustaining a more severe injury to the luxating patella.

A Luxating Patella in dogs

A luxating patella, also known as a floating kneecap, is a common orthopaedic condition that affects dogs. It occurs when the patella (kneecap) becomes dislocated from its normal position within the groove of the femur (thigh bone). This displacement can cause varying degrees of lameness and discomfort for the dog.
It is a genetic condition that can affect any dog breed but more commonly toy and miniature breed dogs such as Poodles, Chihuahuas, Yorkshire Terriers and Pomeranians. The condition will sometimes only affect one leg but can be seen in both knees in around 50% of dogs.

Signs and symptoms of a luxating patella

Symptoms of luxating patella in dogs can vary, depending on the severity of the condition, however some common symptoms are:

• A ‘skipping’ or ‘hopping’ lameness where one or both legs are held up for several steps while running, then return to normal
• Where both legs are affected, you may see ‘bunny hopping’ or dragging of the legs for short periods as well as a stiff and awkward gait
  Difficulty extending the affected leg or reluctance to bear weight on it
• Pain or discomfort, especially when the patella is out of place
• Swelling or thickening around the knee joint
  

A luxating patella can be caused by various factors, sometimes in combination. Predominantly however it is a result of selective breeding and is therefore genetic. Where selective breeding has occurred to promote bow-legged confirmation, a luxating patella is more likely to occur.

Dog breeds such as Chihuahuas, Pomeranians, Yorkshire Terriers, and other small and toy breeds, are more prone to developing luxating patella due to their conformation. Due to genetics, these dogs have often developed a shallower trochlear grove. This is the groove on the femur in which the patella should sit and slide up and down smoothly, as the knee joint bends and straightens.

Dogs suffering from patella luxation often have a very shallow groove, so that the patella will slip in and out easily. Another genetic factor is having a Medially placed tibial crest. The patella sits within the patella tendon which attaches the quadriceps muscles to the tibia (lower leg bone) via a prominent piece of the bone known as the tibial crest. In dogs with patella luxation, the tibial crest is often situated on the medial (inside) part of the bone, meaning the patella is pulled slightly medially rather than straight up and down through the trochlear groove.

More unusually a luxating patella can occur due to a traumatic injury to the knee joint which causes the patella to become dislocated.

Grading system for patellar luxation

There is a grading system for patellar luxation, where it is graded 1-4 depending on severity.

Grade 1: The Knee cap can be manipulated out of position manually but doesn’t occur spontaneously and causes no clinical symptoms — usually an incidental finding.

Grade 2: The knee cap spontaneously luxates out of position, is typically associated with a skipping lameness when the knee cap moves

Grade 3: The knee cap is out of position most of the time, can be manipulated back into place but will luxate again quickly

Grade 4: The knee cap is permanently out of position and cannot be manipulated into the trochlear groove at all

What age does a dog get a luxating patella?

The onset of a luxating patella is variable and can occur at any age however most animals start to show signs as puppies or young adults, although onset of signs in mature dogs is also common.

Treatment for patella luxation is usually dependant on the severity of the patella’s condition. If you suspect that your dog has a luxating patella, it's important to have them seen by a vet who can assess the severity of the condition.

Grade 1 luxating patellas should be left and monitored as they rarely cause any problems. However measures such as weight loss, restricted exercise or physiotherapy will help. Equally applying a brace can also greatly help to support the joint.

With Grade 2 luxating patellas, surgery can be considered but is dependent on factors, such as pain and frequency of the signs. Over time Grade 2 medial luxating patellas can deteriorate into higher grades.

For Grades 3 and 4, surgery is nearly always the recommended treatment, as these will erode cartilage and cause the development of osteoarthritis over time. Similarly, dogs who have medial luxating patellas are more prone to developing cruciate ligament disease. As with most things, the earlier a problem is addressed, the better it is for the dog in both the short and the long term.
There are a variety of surgical techniques which can be used, the choice depends on the individual case and the individual vet’s expertise. Usually it is one or more of the following:

• Deepening the trochlear groove
• Transposition of the tibial crest to a more lateralised position (moving it sideways to straighten up the patella mechanism) — this is held in place with one or two small pins and a piece of wire to hold the tension
• Release of medial tissue — cutting/loosening tissues on the inside of the leg to reduce sideways tension on the patella and patella tendon
• In some extreme cases, surgery to correct the bowing of the femur may be required

The prognosis for dogs with a luxating patella can vary depending on the severity of the condition and the chosen treatment approach. In many cases, with appropriate management or surgical intervention, dogs can experience significant improvement in their quality of life.
It's worth noting that luxating patella can often be a progressive condition, and dogs with a history of luxating patella can be more prone to developing arthritis in the affected joint later in life. Regular monitoring and proactive management such as giving your dog a joint supplement or applying a brace to give support to the joint, can help minimise long-term complications.



Zoomadog questions

Q: "Hi I was looking on your site for Luxating patella dog brace as my dog had a double luxating patella operation to correct her knees. I was wondering if the walkabout cruciate dog knee brace would support it when she is on walks or maybe you could recommend something else that would help her?"

A: Thank you for your email and yes a knee support will really help your dog weight bear again and reduce the risk of re-injury. We have broadly three levels of knee brace: light, medium and firm. You might it useful to see the link here: https://zoomadog.co.uk/collections/patella-luxation-in-your-dog

I would suggest looking at the Walkabout or the Balto Jump to start with. Let me know if you have any other questions, we are here to help.