What in the World is Medial Patellar Luxation?

Medial Patellar Luxation is a dislocation of the knee joint

Thanks to the internet and the social groups out there now, I have been able to get in touch with many of my high school friends. Sometimes this is a wonderful thing but at other times all this does is serve as a reminder of why we stopped being close friends to begin with. There is usually a reason why certain people become lifelong friends and why some do not. That reason is usually obvious at the time but is usually forgotten over time. Well social media serves at times as a gentle, or not so gentle, reminder.

My friend Joe, who I recently met up with after twenty years of absence, was one of those friends that I lost touch with because of the hectic school load we both had combined with several moves around the country. On Sunday morning my recently-found friend called me to say good morning and to ask me a question about his dog “Lucky”. He proceeded to tell me that the vet told him that Lucky had a condition called “Medial Patellar Luxation” and prescribed a medication called Rimadyl. Rather than ask the vet at the time of the examination to explain the condition, Joe waited until 8 am Sunday morning to decide to call me and ask me. It’s always a pleasure to help out an old friend plus it gave me a good topic for this blog.

What is “Medial Patellar Luxation”? Let’s take it one word at a time. Medial is a term that relates to “middle”. The Patellar is known as the kneecap and it’s one of the three bones that come together at the knee joint. The Patella fits in the center of a groove at the end of the femur. Luxation is related to a Latin word “Luxare,” meaning to dislocate. So simply put, Medial Patellar Luxation means a dislocation of the knee joint. In some dogs, the ridges forming the patellar groove are very shallow so the patella will slip out if its normal groove and become trapped on the inside of the knee. This process causes the leg to lock up and dogs will usually lift their leg off the ground until the muscle relaxes. As time passes, osteoarthritis can develop.

Most dogs that have patellar luxation are born with the disease and about half the time both knees are affected. Females are more likely to be affected than males. Toy Poodles, Lhasa Apso, Pekingese, Pomeranians, as well as other toy breeds are susceptible to this condition. There is a major genetic factor to its development but even if the mother or father has this condition, the offspring may or may not be born with it.

Symptoms associated with patellar luxation vary greatly with the severity of the disease. This condition may be detected by your veterinarian upon routine physical examination or you may detect this when you notice your pet carrying the affected limb off the ground all the time. Some dogs will have patellar luxation their entire lives with no symptoms at all, while others will suddenly become more symptomatic over a period of time. The most common sign is when you see the dog suddenly carrying the limb up for a few steps. As the disease progresses in duration and severity, this lameness can become more frequent and can eventually become continuous. In young puppies with severe patella luxation, the rear legs often present a “bow-legged” appearance that can worsen with growth. In order to better understand the severity, medial patellar luxation is classified into 4 stages.

Grade 0 means the patella is normally situated. Grade 1 means the patella can be pushed out of the groove but spends most of the time in the groove. Grade 2 means the patella is approximately half the time in the groove and half the time out the groove. It can be manipulated in or out. Grade 3 is when the patella spends almost all the time outside the groove and it requires pressure to push it back into the groove. Grade 4 is when the patella spends all of the time outside the groove and even with pressure the patella cannot be pushed back into the groove.

Treatment many times depends on the symptoms and what classification the condition fits under. Once your veterinarian classifies your dog into the correct state, he or she will usually suggest the next step. Grade 1 and Grade 2 may only require medical treatment for pain and minor swelling within the knee joint. Grade 3 and 4 are best corrected with surgery. If surgery is necessary your veterinarian will refer you to a veterinarian who specializes in orthopedic surgery. Additional tests are often required to diagnose conditions often associated with patellar luxation and to help the surgeon recommend the most appropriate treatment for your pet.

The most common surgery is called Tibial Crest Transposition. The patella attaches to the top of the tibia. This area of the bone is separated from the shaft of the tibia and repositioned on the outside of the tibia. The bone is secured by pins and wires or with a surgical screw. Recovery from the surgery usually takes 6 to 8 weeks and most dogs can put weight on the foot within 1 to 2 days. During this period, the dog should have a lot of rest and be given antibiotics as well as pain medication. As soon as the surgeon gives the go ahead, physical therapy should be started. The owner is usually the one to do this with the dog and consists of walks for about five minutes for about a week. When you see the dog improving the walks may be increased to ten minutes if okay with your veterinarian.

Amoxicillin is used to treat bacterial infections

Medication may be used during various stages for a variety of different reason. Antibiotics such as Amoxicillin may be given after surgery. This antibiotic is classified as penicillin and is used to treat bacterial infections caused by susceptible organisms. In this case it can be used to prevent an infection from occurring in the bones and joints. The common dose for dogs and cats is 5-10mg/pound every 12-24 hours. Amoxicillin can be given with or without food. Some side effects of this medication include loss of appetite, nausea, vomiting or diarrhea. If an allergic reaction occurs, symptoms include rash, fever, swelling of the face or limbs, difficulty breathing, rapid heart beat and lack of coordination. This medication should not be used if an animal is allergic to penicillin. If an allergy is suspected it is very important to get immediate veterinary assistance.


One of the most common pain medication prescribed is called Metacam which is a non-steroidal anti-inflammatory oral suspension used for the treatment of pain and inflammation in dogs. It is available as 10ml, 32ml, or 100ml dropper bottles. It should generally not be used in animals with heart, kidney, or liver disease. As with any prescription medication, the dose should be suggested by your veterinarian. Some side effects include loss of appetite, vomiting, diarrhea, dark or tarry stools, and drowsiness. Symptoms of an allergic reaction to this medication can include facial swelling, hives, and rash.

Rimadyl is used for the treatment of postoperative orthopedic pain and inflammation in dogs.

Other medication prescribed include the cox-2 inhibitor Deramaxx and it is used for the treatment of postoperative orthopedic pain and inflammation in dogs. Rimadyl is a non-steroidal anti-inflammatory drug that may also be used to reduce the pain and inflammation associated with this condition or with the surgery.

The best thing you can do for your pet when dealing with this condition as well as other conditions is to develop a good relationship with your veterinarian and as always, a 1800petmeds pharmacist is available to answer any medication related questions that you may have.

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