Patellar luxation is a fairly common condition in dogs. Patellar luxation is the scientific term for a knee cap that dislocates or moves out of its’ normal position. This can occur for a number of reasons and can affect one or both knees in your dog. But should you be concerned when this happens? What are the long term effects of this condition? Is your dog in pain? Continue reading to learn more about canine patellar luxation.
What Is Normal for a Dog Patella?
The patella is the scientific term for the knee cap. Like humans, dogs have two kneecaps – one on each back leg. The knee, or stifle, in a dog shares many similarities to the human knee joint. However, because humans stand upright, and dogs stand on 4 legs, there are some differences. Without going into a long boring discussion about anatomy with you, we’ll keep it simple. The patella normally “sits” within a small groove called the patellar groove along the front of the femur, or large upper leg bone. The end of the femur closest to the knee (where the knee and back leg bends) is where the patella normally sits, usually in the center. The quadriceps muscles, patellar groove and a tendon all work together to hold the patella in place. When a dog flexes and then extends their leg, these three systems work to keep the kneecap from moving out of place.
What Is Patellar Luxation?
Patellar luxation is classified as medial (towards the inside) or lateral (towards the outside) depending on where the kneecap abnormally tracks. Whether it is to the outside or inside can be determined on exam by your veterinarian and often times with radiographs of the affected knee.
Patellar luxation can be congenital or traumatic. Congenital patellar luxation is when a dog is born with an abnormally moving patella, and is most common in small breed dogs. ~7% of puppies are affected by patella luxation. Dogs can have one or both patellas affected, and each occurs about 50% of the time.
The cause to congenital luxation can include several factors, but often times a shallow patellar groove is found. If the groove is too shallow, the kneecap can easily float to either side, coming out of place. There is no way an owner or veterinarian would know this by exam or radiographs only. This is often found at the time of surgery.
Traumatic patellar luxation means that your dog was not born with the condition. Rather the patella moved out of place, often times staying in the abnormal position, after some sort of trauma. This could mean falling, running and chasing a ball, landing wrong after jumping off the couch, etc. Any type of “activity” that could harm the knee can be considered a trauma.
How Do I Know if My Dog Has a Patella Luxation?
Your veterinarian should complete a thorough physical exam at your dogs’ annual appointment. The congenital condition may be diagnosed at that time. Patellar luxation occurs much more commonly in small breed dogs, with medial luxation being the most common, though large breed dogs can be affected.
As an owner, you may or may not notice any abnormalities at home. Some dogs, especially those who are born with patellar luxation, may run, play and jump like normal at home. Others will have periods of time where they “bunny hop” or “skip” and/or limp on one of their back legs (sometimes both). The dog will then start to acutely run normal again. The hopping and skipping are often seen when the patella is in the wrong place. As the patella “pops back in”, the dog is then able to run normal again.
Other times a patellar luxation can be seen on radiographs. If the patella is currently out of place, it will show up abnormal on a radiograph. However, not seeing it on a radiograph doesn’t mean your dog isn’t experiencing the knee cap pop in and out on occasion. Your veterinarian should be able to determine this by exam. Sometimes sedation is needed for an adequate orthopedic exam or radiographs depending on how nervous and tense your dog gets at the vet.
Over time, your dog may develop more episodes of hopping, skipping, or limping on either or both back legs. This is because arthritis will develop over time. Also, as the patella continues to pop in and out, it may cause extra wear and tear on the ligaments. These may become damaged and abnormal over time as well, adding to your dogs’ limping.
How Can I Treat a Patellar Luxation?
Your veterinarian will determine what grade of luxation your dog has. There are four different grades, increasing in severity and often discomfort the higher the grade. If your dog has a low grade luxation and has little to no abnormal signs – in other words they are not limping, skipping, hopping or showing any pain – or they only do these things on the rare occasion – then they are often monitored and treated occasionally with pain medications. If your dog has constant pain, is skipping and/or hopping all of the time, and/or does not want to put weight on one or both legs, then surgery is often needed.
Surgical correction varies by the breed of the dog, body size and if there are also concurrent issues such as ligament damage. The type of surgery recommended and needed will be determined by all of those factors and after your dog has been thoroughly evaluated by a veterinarian.
Not all veterinarians do orthopedic surgeries. If your dog has been diagnosed with a patellar luxation and surgery is recommended, please make sure you speak with your veterinarian about surgical options. In some cases it may be recommended that a dog have surgery completed by a board certified surgeon. Again, your veterinarian will give you all the options at the time of exam.
Patellar luxation is a very common orthopedic condition in dogs. It mostly affects smaller breed dogs but larger breed dogs can also have the condition. One or both knees can have a patellar luxation.
Please make sure your dog is evaluated by a veterinarian to determine the best course of action for your pet.