Patellar luxation, also known as luxating patella and sub-luxated patella, occurs when the kneecap slips out of the groove that holds it into the femur. Dogs are usually born with the physical conditions that cause patellar luxation; however, it can also be caused by traumatic or accidental injury. Patellar luxation is usually treated with surgery, but less severe cases can be treated using other methods. Surgical intervention usually returns normal function to dogs’ limbs.
Most dogs are born with the traits that will lead to their kneecaps slipping later in life. In general, dogs that have congenital patellar luxation start showing at 4 to 6 months of age, although some dogs can be diagnosed as early as 1 to 2 months. Patellar luxation may lead to rupturing of the cruciate ligament or degenerative arthritis later in life.
Three categories of patellar luxation exist: medial luxation in all types of dogs, lateral luxation in toy and miniature dog breeds, and lateral luxation in large and giant breeds. Medial luxation is primarily congenital, while lateral luxation develops later in life and may or may not be inherited. Patellar luxation also has four different grades, numbered one through four, in addition to the different categories. These grades describe the amount of pain, luxation, and restricted range of motion associated with the problem.
It is impossible to prevent most patellar luxation, because the disorder is generally present at birth. However, once it has been diagnosed, it is possible to reduce its effects through a healthy maintenance program. Vitamins such as ascorbic acid, vitamins B1 and B6, and vitamin E, are needed to build tissues that mitigate luxating patella and reduce arthritis-associated inflammation. Dietary supplements such as glucosamine, chondroitin, and omega-3 fatty acids also provide tissue-building and degradation-prevention benefits. Maintaining an healthy body weight for the breed, and various exercises that support the structures that support the knee, are also beneficial.
Non-steroidal anti-inflammatory drugs (NSAIDs) can be used to treat patellar luxation. These drugs can be used to improve and treat the condition, but not cure it. In addition, various forms of exercise and physical therapy, such as swimming therapy, can be used to support your dog’s joints. Medical treatments are most successful on Grade 1 patellar luxation.
Grade 1 patellar luxation typically does not require surgical intervention. Surgery is most often used for Grades 2, 3 and 4. One of three surgeries is performed. Trochlear modification deepens the groove in the femur to keep the patella from dislocating. Lateral imbrication “tightens” the kneecap to the outside of the knee, also keeping the patella from slipping. Tibial crest surgery is the most involved, in which the bony protrusion of the tibia is removed and reattached in another location on the bone. This change stretches the quadriceps muscle, improving the placement of the patella. Most dogs recover completely from their surgery and go on to live normal lives.