What is a Patella?
The patella is a small bone that is located on the front of the stifle (or knee) within a large tendon. It slides along a groove in the femur (thigh bone) when we bend and extend our knee. Most of us call it a kneecap and we can easily feel it on our own knees but did you know that most of the animals you see have them as well? Most mammals including dogs, cats, rabbit, and rodents have a patella as well as many birds. It functions to stabilize the knee joint and to help it move in a normal fashion. When the patella is not doing its job, the knee can develop many other problems.
What is a luxating patella?
The term luxating simply means movement of the patella out of its normal position. It typically will slide off the medial or to the inside of the leg but it can also travel the other direction. Most of the time, it doesn’t seem to hurt much when this happens but it can lead to some serious disorders. As the patella slides the wrong direction over the femur, it will slowly erode the normal bone and create inflammation. This inflammation in the knee joint will lead to arthritis and long-term pain in the knee. In addition, since the patella is responsible for stabilizing the knee, more serious ligament injury such as a cruciate ligament rupture can occur if the patella is not in the correct position.
Who is at risk?
Any animal with a patella can develop a luxating patella after an injury. However, some animals are more likely to have this condition because of the traits they inherit from their parents. Dogs are the most likely species to have a luxating patella and the small or toy breed dogs are most affected.
What are the symptoms?
It may be difficult to identify a luxating patella in the early stages because affected dogs will not often show signs of pain. However, you may notice an intermittent limp or missed step in one or both of the rear legs. In addition, some dogs may have trouble jumping up or standing on their hind legs. If left untreated, more serious symptoms of arthritis in the knee will develop and a dog may limp and show signs of pain.
How is it diagnosed?
If you are concerned that your dog may have a luxating patella, it is best to make an appointment with a veterinarian. A physical examination and palpation of the knee is often sufficient to determine if the patella is slipping out of place but an x-ray is often used to determine if arthritis is present.
How is it treated?
The best way to keep a wandering patella in place is with surgery. A special procedure can be done to move the patella into a more normal position and prevent further damage to the knee. After surgery, dogs require confinement and physical therapy for 4-6 weeks to ensure a smooth recovery.
What if I can’t do surgery?
While surgery is the only way to ensure the patella will not luxate, there are precautions you can take to minimize damage to your dog’s knee. The most alarming consequence with a luxating patella is damage to the cruciate ligaments within the knee. Once torn, these ligaments will not heal without surgery and this condition is very painful. Prevention of this catastrophic injury can be done by carefully limiting the activity of your pet. Try to prevent any excessive jumping, running, rough play and weight gain. Any activity or condition that increases stress on a weak knee can lead to severe injury.