What is this about Floating Kneecaps?
Typically found in smaller breeds, there is painful condition known as floating kneecaps, or luxating patellas. Learn what causes the condition and what you can do to prevent or treat the problem in your pet.
Floating kneecaps are typically a small dog problem.
Many times these dogs appear fine. There may be not history of a traumatic leg injury. The dogs are active, running and playing – generally healthy and normal.
Out of the blue, the dog stops in mid run and lifts his back leg – with our without a yelp. Lame and holding the leg off the ground.
Of course you don’t know what’s just happened because you’ve been watching and everything seemed fine.
Then, just as suddenly, your dog lowers his leg and starts walking or running around again as if nothing ever happened.
So what happened? His kneecap popped out of place. This stopped him in his tracks. causing him to hold his leg up. The kneecap pops back into its original position, he is able to put his foot back down, and off he goes.
This is a typical description of what happens with the condition known as luxating patella.
Description of a Luxating Patella or ‘Floating Kneecap’
The kneecap sits in the same place for both dogs and humans – at the distal end of the femur. It’s jog is to help the quadriceps (thigh muscles) flow across the joint between the thigh and lower leg so your dog has mobility and use of her shin.
The kneecap moves up and down in a groove – and the Patella ridges hold the kneecap in place. As long as the ridges are deep enough, the kneecap can only move up and down as nature intended.
Unfortunately, some dog breeds have a very flat patella ridge meaning the kneecap doesn’t fit snugly in the groove. This causes the kneecap to pop out to either side.
Size and Breed Matters
A genetic predisposition to luxating patellas occurs in a variety of small and tiny dogs, including:
- Miniature and toy Poodles
- Jack Russell Terriers
- Boston Terriers
Short-legged dogs, aren’t genetically prone to the condition, but because their femurs are so short, it can change the angle of the seating of the kneecap causing these dogs to end up with luxating patellas as well. Typical examples are Basset Hounds and Dachshunds.
Larger breeds have less genetic predisposition to problems with the kneecap. They typically have a nice, deep groove for the patella to seat in.
However, larger dogs are prone to hip problems. If a joint above the kneecap like the hip joint, or one below the kneecap like the ankle develops a problem, it can change the ergonomics of the animal’s body and movement. Problems with joints above or below the know can cause a kind of ripple effect that forces the patella out of its groove.
Large and giant breed dogs with hip dysplasia often have a secondary condition of luxating patella which is caused by the malformation of the hip joint.
Cats can also develop floating kneecaps, however, the situation is usually much less clinically severe.
Cats are smaller and lighter in body weight than most dogs. They are also more flexible and their bodies move differently. A 5kg cat with a significant kneecap issue often won’t show many or any clinical symptoms such as limping.
Severity of the Condition
There are four levels of severity of a luxating patella. Grade 1 is the mildest; Grade 4 is the most severe.
- Grade 1: The kneecap pops out (or can be manually popped out of place), but pops right back in on its own.
- Grade 2: The kneecap pops out of place and doesn’t always pop back in automatically, sometimes requiring manual manipulation to re-seat it.
- Grade 3: The kneecap sits outside its groove most of the time, but can be manually positioned back in the groove, where it stays temporarily.
- Grade 4: The worst-case scenario. The kneecap sits outside the groove all the time, and won’t stay seated in the groove when it is manually popped into place.
You can see by these levels of severity why a displaced kneecap can cause intense pain for your pup.
Many times a young dog with strong, resilient joint cartilage, the patella can pop out and back in without obvious signs of pain. There may be an intense jolt of pain as the kneecap moves across the patella ridge, but it’s gone in a flash and usually not obvious to the owner.
The dog won’t want to put weight on his leg until the kneecap has popped back in (which can cause another jolt of pain), but otherwise he appears fine.
Ultimately, unfortunately the cartilage wears down from the frequent travel of the kneecap in and out of its groove. There will be bone-to-bone contact and the condition can become acutely painful for your pup.
Diagnosis and Treatment
If your veterinarian diagnoses even a mild Grade 1 luxating patella in your pet, address it right away.
Taking a proactive approach to treating the condition — no matter how mild, and especially in a young dog — can often prevent future surgery, joint degeneration, and diminished quality of life.
- The first thing you should do is help him achieve and maintain a healthy body weight. The heavier the dog, the more burden there will be on his knees. This means loads of lean muscle and reduced fat will reduce the amount of stress placed on the joints.
- It’s very important to keep your pet moving. Maintaining excellent muscle tone will help your dog’s body form a kind of cage around the knee which will keep the patella in place so keep him strong. Years ago, veterinarians advised owners of dogs with floating kneecaps to prevent their pets from moving around. We now know that’s a really bad idea. The more toned the muscles of your dog’s legs are, the more stable the kneecap will be. Building muscle is an extremely important part of reducing the clinical symptoms of a luxating patella.
- Provide your pet with oral joint support supplementation in the form of glycosaminoglycans, or GAGs. Good oral joint support supplements to help maintain the integrity of knee cartilage while also improving joint fluid production. Discuss the subject with your integrative or holistic vet, who will be able to suggest or provide the right supplements to rebuild and maintain strong and resilient cartilage and joint fluid production in your dog.
- Chiropractic, acupuncture. physio- and hydrotherapy treatments are also great modalities for dogs with luxating patella. Especially if you have a puppy with the condition, there are some very effective chiropractic manipulations that can be performed to keep the hips and knees in good alignment. This will in turn help prevent progression of the condition.
In addition to daily exercise to maintain your dog’s physical conditioning, I recommend you feed a species-appropriate diet. All foods are categorized as either pro or anti-inflammatory.
By feeding your dog an anti-inflammatory diet (one very low in carbohydrate content), you can help reduce or moderate the effects of inflammation in your pet’s body, including the joints. Feeding a species-appropriate, carb-free diet can significantly reduce the inflammation associated with a luxating patella.
When to Seek Surgery for Your Pet
Some veterinarians recommend surgery upon diagnosis of a luxating patella, regardless of the severity and some good veterinarians and orthopedic surgeons only recommend surgery as a last resort.
Unless the condition is destroying your dog’s quality of life and your pup can’t walk or run without intense pain, should surgical corrections be a consideration.
There are two main goals of corrective surgery for a Grade 3 or 4 luxating patella.
One method is to deepen the trochlear wedge. If the joints are flat, the veterinary orthopedic surgeon will cut a deeper V to help hold the kneecap in the groove.
The other goal of surgery is to moderate the amount of tension in the patella capsule or ligament by tightening down the joint capsule.
Explore all possible non-surgical options to help stabilize your dog’s knee before considering a surgical correction. Surgery for this condition carries the usual risks associated with anesthesia and infection, plus a few more because the correction is to a moving part of your pet’s body that is also weight bearing. Always discuss possible risks and precautions with your vet.
Some of the risks may include:
- Problems with a pin. If a pin is inserted to hold the joint in place it can migrate, requiring surgery to remove it. Also an abscess, called a seroma, can form at the site of the pin and require either draining or surgical removal.
- Repair collapse. Post surgery, your dog should not run or jump for about two months to allow the repair to stabilize. This is a tough order for most healthy dogs, and it’s not uncommon for the repair in an active dog to break down during this period.
- Failed surgery. Around 10 percent of dogs do not show significant improvement after surgery. They continue to experience pain. In addition, sometimes repair of the kneecap can cause problems to develop in other bones and joints. Always try to look for an orthopedic specialist surgeon where every possible.
Video and information source: Dr. Karen Becker
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