Loose patella in dogs: symptoms, causes and how to help

Patella luxation in dogs is a fairly common orthopedic disease. But what do we mean by patellar luxation? So what does this mean for your dog if he has it?

I have been a veterinarian for eight years and have worked with specialists in two orthopedic clinics, so I have experienced luxating patellas more than once. I also have a terrier, Pixie, who has kneecap problems, but luckily hasn’t needed surgery yet. I simply took precautions to make her as comfortable as possible (e.g the best joint supplement for dogs) and I will continue to monitor her for signs that the patella needs surgery.

I know a little about patellar luxation in dogs, but if your dog has just been diagnosed, you’re probably feeling a little confused. So let me explain patellar luxation in dogs and make it easier for you to understand – here we go!

What is patellar luxation in dogs?

“Dislocation” means a dislocation, and “patella” means a kneecap, so “patella luxation” means a dislocation of the kneecap. Just like in humans, your dog’s patella is a bone located at the front of the knee. It is actually located inside the tendon that runs from the femur through the top of the knee joint to the shin bone. When a dog’s knee bends, the kneecap moves up and down in a smooth groove at the end of the femur. This is an important part of the knee extension function.

In a dog with a luxated patella, the kneecap sometimes pops out of its groove, “locking” the knee and causing pain or instability. This happens because the groove is too shallow, the tendon is too loose, or the leg angle is not correct, causing lateral tension on the patellar tendon.

The kneecap “pops” to one side when the dog uses the leg, causing the symptoms of patellar luxation. in approx 90% of casesthe patella pops out to the middle of the leg (“medial” patella luxation or “MPL”), but sometimes (especially in larger breeds) it pops out to the outside of the leg – “lateral” patella luxation or LPL.

(Photo: Getty Images/martinedoucet)

What are the symptoms of patella luxation in dogs?

A loose patella in dogs causes the very classic limp that all veterinarians recognize. Dogs with a luxated patella will use the limb normally and then begin to jump while holding the problematic knee up. After a few hops, the kneecap reappears and often the child walks completely normally again. The more serious the problem, the more often the kneecap will pop out.

If left untreated, patellar luxation can cause arthritis, so you may also experience other symptoms such as stiffness, reluctance to climb stairs, or licking at the knee joints. That’s all signs of dog pain.

What causes patella luxation in dogs?

It is commonly believed that patellar degeneration is a genetic disease. It is more common in certain dog breeds, such as the Pomeranian, Chihuahua, and Yorkshire Terrier, which have five to six times higher risk of patella problems. Women are also more likely to suffer from patellar luxation than men.

However, in addition to genetics, it is likely that early life experiences are related. Neutering may play a role because neutered dogs are more likely to develop patellar luxation, possibly due to delayed growth plate closure in dogs neutered before puberty. Exercising as you grow may also have an effect, and obesity will likely play a role as well. Nutritional imbalance caused by a poor diet can also contribute to abnormal bone growth and weakening of the kneecap.

In other words, patellar luxation in dogs cannot be completely prevented. However, if you are purchasing a small breed dog, ask the parents about the history of the patella. Make sure your puppy gets the right diet and exercise to help him grow strong legs, and ask your vet about the benefits and risks of neutering at different ages for your dog’s breed and lifestyle to make an informed decision.

(Photo: Getty Images/skiden)

How to treat a dog with a luxated patella?

If you suspect patellar luxation, it is a good idea to have your dog examined by a vet. They will feel the dog’s knee and give the patella luxation a “grade,” which tells you how badly it is dislocated.

Grade 1: The kneecap is mostly in place, but the vet can push it out
Grade 2: The kneecap sometimes dislocates on its own, but usually comes back on its own
Grade 3: The kneecap is permanently dislocated. You can push it back into place, but it goes back on its own
Grade 4: The kneecap is permanently dislocated and cannot be replaced

Depending on the severity, your dog’s symptoms, and the results of the x-rays, your veterinarian will advise whether patellar luxation requires treatment. Luxurious patella treatment involves surgery, which is often performed by specialized orthopedic veterinarians in referral offices. There are several techniques to help with patella luxation in dogs, and your orthopedist may recommend:

Deepening of the groove in the femur
Cutting and repositioning the tibia to tighten the patellar tendon
Cutting and repositioning other bones if they are severely deformed
Tighter stitching of the joint capsule to reduce space for lateral movement

Pixie has a grade 2 patella, but it’s very mild and doesn’t have the classic x-ray findings, so it’s hard to say whether surgery will help. The vet has advised me not to have surgery yet, but I may need it in the future. He thinks there’s a high chance he’ll break his ACL at some point, so it makes sense to do both surgeries at once if/when that happens.

(Photo: Getty Images/studio aquaArts)

How long can a dog live with a luxated patella?

Patella luxation itself is not fatal, and dogs can live full lives with mild patellar luxation. Arthritis is a natural consequence of patella luxation and can cause dogs to become very painful and may require euthanasia. When patellar luxation is more severe, dogs require surgery, and if surgery cannot be performed, euthanasia may be necessary. Even after surgery, dogs are likely to develop early-onset arthritis, and keeping them comfortable can be difficult. Generally speaking, patellar luxation is not a life-limiting condition, and if provided with comfort, dogs can live into old age with a luxated patella.

Patellar luxation in dogs sounds complicated, but it is just a patella luxation. Instead of moving up and down smoothly, the kneecap pops out of the groove where it should sit, causing pain and the classic limp. In some cases, it pops up so often that surgery is necessary. Over time, even after surgery, the knee will likely become arthritic, which may compromise your dog’s well-being. If you think your dog has a luxated patella, talk to your veterinarian who can help you understand your dog’s knee problems and whether it requires surgery.