What to Know About Luxating Patella in Dogs

yellow lab puppy at the vet

The breeding programs that various dogs have been put through over the centuries have led to a wide variety of purpose-bred dogs that have various specialties, talents, strengths, and quirks. Unfortunately, irresponsible breeding practices, inbreeding, and overbreeding over the years have led to a number of different disorders and challenges that can pop up in purebred dogs and mixed breed dogs alike. One health issue affecting many dogs is the luxating patella, which is also referred to as patellar luxation, a floating kneecap, slip knee, or a trick knee. Here’s what to know about luxating patella in dogs:

What is Luxating Patella in Dogs?

Luxating patella is a condition where the patella, or kneecap, is not contained to its normal location and can dislocate or move out of it. Although it most commonly shows up bilaterally, it can occur in only one leg instead of both.

For a dog, the kneecap is roughly in the same location on the leg as it is in a human. If you feel where the kneecap is on your leg, then you have a pretty good idea of the anatomy of a dog’s kneecap as well. This kneecap helps what are called the quadriceps muscles move across the joint that lies between the lower leg and the thigh.

This allows your dog to move about and use the part of their leg called the “shin”. Normally, the kneecap moves up and down in a space made for that movement. The large upper leg bone (femur) has a groove called the trochlear sulcus where the patella and other ligaments sit. When this groove is formed correctly, the kneecap stays in place and functions normally.

However, there are dogs that have a shallower or non-existent groove in their femur. This means that the kneecap does not reside firmly inside the groove. Instead of moving up and down normally, it dislocates and can slide out medially to the inside of the kneecap or laterally to the outside.

The 4 Grades of Patellar Luxation

When a dog is diagnosed with patellar luxation, they are usually assigned a grade from 1-4 depending on the severity. This is a grading system created by the Orthopedic Foundation for Animals (OFA).

Grade 1

Grade 1 is the lowest level of luxating patella. In patellar luxation assigned Grade 1, the patella can move out of the groove and dislocate, but it easily pops back in. Most of the time, the patella pops back into place on its own and the dog continues to walk on the leg unaffected.

Grade 2

With Grade 2 patellar luxation, the patella dislocates more frequently. It can be moved back into place easily and the dog can often still walk on the leg fine once it is back in place.

However, they may hold the affected leg up to avoid putting pressure on it while the kneecap is dislocated. Grade 2 patellar luxation can cause trauma to the knee over time due to how frequently the patella dislocates.

Grade 3

When luxating patella reaches or is assigned Grade 3, the femur groove is very shallow. As a result, the kneecap is dislocated most of the time.

At the same time, one of the lower leg bones, the tibia, is often twisted slightly. Dogs with Grade 3 patellar luxation may continue to use the affected leg, but they may do so with it in an abnormal position.

Grade 4

Grade 4 is the highest and most severe level of patellar luxation in dogs. In a dog with a Grade 4 luxating patella, the knee groove is non-existent or it is convex like a bulge instead of concave like a groove.

As a result, the patella is permanently dislocated. On top of that, the tibia is often severely twisted. The dog will often hold up the affected leg to avoid using it or putting any pressure on it.

Is Patellar Luxation Painful for Dogs?

Patellar luxation can be painful for dogs. In early or low-level stages where the patella easily slips back into place on its own, there may not be a lot of pain. However, over time, a luxating patella can cause inflammation, joint pain, cartilage damage, ligament tears, and more. Oftentimes, the more severe the patellar luxation is and the longer damage has been allowed to occur, the more painful it can be for the dogs who have it.

What Causes a Luxating Patella in Dogs?

Although trauma can cause a luxating patella in dogs, almost all of the dogs diagnosed with it were born with it. Patellar luxation is most commonly a developmental and congenital defect. It is often caused by either a birth defect or inherited through genetics. When it is congenital, luxating patella is often bilateral, occurring on both sides.

At the same time, any trauma to the knee can cause a luxating patella. For example, a dog that got hit by a car and injured their knee could develop patellar luxation in the injured leg. Other knee injuries can also cause this condition. Over time, obesity can also result in a luxating patella.

Which Dog Breeds are Prone to Luxating Patella?

Small dog breeds are particularly prone to luxating patella. Yorkshire Terriers, Pomeranians, Chinese-Crested, Toy and Miniature Poodles, Boston Terriers, Jack Russell Terriers, and more are all prone to having this condition. If you are interested in a toy, miniature, or other small dog breed, they will likely have a predisposition for patellar luxation.

Although patellar luxation is most common in small dog breeds, it can appear and cause issues in dogs of any size and there are some large dog breeds that can be prone to it. Labrador Retrievers seem to be a large breed particularly predisposed to patellar luxation. Akitas, Golden Retrievers, Boxers, Saint Bernards, Malamutes, Huskies, and more can also be prone to luxating patella.

How do I Know if My Dog Has a Luxating Patella?

Luxating patella can show up later in life, but it usually starts showing signs when your dog is between 4 and 6 months old. You may see signs that could indicate a luxating patella like your dog holding up a leg, favoring legs, consistent or intermittent limping, and more. You may see your dog bearing weight on a leg only when it is at an odd angle. You could even see the kneecap moving back and forth yourself!

These signs of a luxating patella could be absent completely or may be mild. If you suspect your dog may have patellar luxation, you’ll need to go to the vet to find out for sure. Diagnosing patellar luxation requires manual palpation of the knee to test whether it slips more than expected inside the joint. But, just because your dog may have a little bit of a “loose knee”, they still may not have patellar luxation.

After a physical exam and manual manipulation of the joint, your vet will be able to determine whether your dog has a luxating patella as well as the severity of it. From there, they can help you develop a treatment plan for your dog.

How do You Fix a Dog’s Luxating Patella?

The methods for fixing a dog’s luxating patella vary depending on the severity of it. If they have Grade 1 patellar luxation, it can often be treated with a therapeutic dose of glucosamine, which can help strengthen ligaments as well as surrounding tissues of the knee. In dogs with Grade 1, this can help prevent or delay surgery.

Dogs with Grade 2, 3, or 4 patellar luxation will need surgery in order to fix it if the dog has trouble walking. Glucosamine can delay surgery in less severe cases, but will probably not do so forever.

For dogs with any type of patellar luxation, you will want to make it easier for your dog to get up and down around your house. Pet ramps and dog stairs or steps and low-impact exercise can help your dog get around and help prevent additional pain or damage to the patella.

Should My Dog Have Surgery for Luxating Patella?

Dogs who have difficulty walking usually have a higher grade of luxating patella. Usually, surgery is required eventually for Grade 2, 3, and 4 patellar luxation. Your vet can help you determine the best route for you and your dog. Generally, if your dog’s patellar luxation has progressed severely enough to require surgery, then you should do it.

Without surgery, your dog’s kneecap will continue to dislocate or will remain dislocated. This will cause them pain and will cause more damage and issues over time. In severe cases, they can become lame and unable to use the affected leg, or legs, completely. They may also develop Osteoarthritis as a secondary condition.

The type of surgery depends completely on the type of abnormality in your dog’s bones. It often involves what is called a sulcoplasty. The trochlear sulcus is the groove where the patella sits. A sulcoplasty is a surgical deepening of this groove and realigning the attachment of the patella tendon on the tibia. It can also involve an implant inside the knee that prevents the patella from slipping over it and prevents it from dislocating.

Depending on how the patella slips and dislocates, surgery may also include tightening or loosening the capsule on each side of the patella to keep it from slipping from one side or both. Also, in some Grade 4 cases, surgery may need to be more involved in order to realign the upper and/or lower leg bones.

How Much is Patellar Luxation Surgery in Dogs?

Corrective surgery for a luxating patella almost always requires a board-certified veterinary surgeon. Because of this and because the severity of the condition varies from dog to dog, patellar luxation surgery may range from $1,000-$3,000 or more per affected knee depending on how involved the surgery needs to be to correct it. The more severe the patellar luxation, the more involved the surgery needs to be and the more expensive it tends to run.

You will also need to consider the cost of any long-term medications associated with post-surgery care. These could run $20-$50 or more per month. Speaking with the vet and the surgeon ahead of time should give you a better idea of what costs to expect for successful treatment and recovery.

Does Pet Insurance Cover Luxating Patella Surgery?

Some pet insurance plans may cover costs associated with patellar luxation surgery. However, some plans will only cover your dog if the policy was in place before they were diagnosed. You likely will not be able to get a pet insurance plan to cover the surgery once the condition is already diagnosed and surgery planned.

So, when you are planning to add a dog to your family, it may be a good idea to also invest in pet insurance. Just make sure you know what the policy you choose does and does not cover when it comes to your dog!

How do You Prevent Luxating Patella in Dogs?

1. If You’re Buying a Puppy, Only Buy From Reputable Breeders

Because most instances of luxating patella in dogs are inherited, the best way to prevent it is for breeders to focus on good, responsible breeding practices and for potential dog buyers to do their research.

Reputable breeders will screen their dogs to avoid passing on issues like this to puppies. As a potential buyer, it’s important to ask breeders about the genetic and health history of both of the parent dogs. You can also ask to see health clearances and test results that may be relevant.

2. If You’re Adopting a Puppy, Work With the Shelter

If you’re adopting a puppy from a shelter younger than 4-6 months old, you may not be able to avoid luxating patella if you don’t have any information about the parent dogs. However, the staff at the shelter should be able to do an examination of older dogs and give you an idea of what to expect.

3. Do What You Can to Prevent Trauma to the Knee

Aside from that, you can help prevent luxating patella in your dog by doing what you can to prevent trauma that may damage their legs and knees. Make sure you only let them off-leash in securely fenced areas and that you are practicing good safety tips for walking your dog in the dark. This can help reduce the chance of them getting hit by a car.

If you get your dog as a puppy, you want to make sure you keep exercise low-impact and non-strenuous until they have finished growing and their bones and joints are done developing. Doing too much, too soon on joints that are still developing can cause trauma that can lead to things like luxating patella and other joint issues. Puppies finish growing at different rates and some larger dog breeds can take up to two years to finish developing! Work with your vet to determine what’s best for your puppy.

Because obesity can, over time, lead to knee injury and cause patellar luxation. It’s important to make sure your dog gets enough exercise and is not overeating. If you are unsure, you can work with your vet to determine how often to feed a puppy and how much they should be getting in each portion.

Even if your dog is already grown up, it wouldn’t be a bad idea to check in with your vet to make sure they are getting the right amount of food to keep them healthy. They can also help you determine the right amount of exercise for your dog as well as some good, low-impact activities for puppies that are still growing, dogs at-risk for luxating patella, overweight dogs, or senior dogs.

Luxating patella in dogs can be no big deal or it can be serious depending on how severe it is. If you are set on buying a puppy, only purchasing from reputable breeders who screen their stock can help you avoid patellar luxation in your dog. When your dog is sick, not feeling well, or they are in pain, it’s a tough time for everyone. But, knowing what to look for and getting them the help they need can help both you and your dog get through it.