Patella luxation is a relatively common orthopedic condition in dogs, and is the medical term for dislocation of the kneecap.
The patella, or kneecap bone, is normally located in a groove at the end of the femur, and slides up and down in that groove when the knee bends. In some dogs, various abnormalities of the leg will cause the kneecap to be dislocated from its groove, preventing the knee joint from bending appropriately. If the knee cannot bend correctly, it can cause pain, difficulty walking and even leg deformities.
What Is a Luxating Patella?
While trauma or injury can cause a dislocation, a luxating patella is most often due to the shape of structures in the leg that allow the patella to move easily out of place—or prevent it from ever being in the right place.
Luxating patella can occur where the patella dislocates medially (toward the other leg) or laterally (toward the outside of the leg). Medial luxating patella is especially common in small breed dogs. Laterally luxating patellas are less common; when they occur, they are typically in larger breed dogs.
A dog can have patella luxation in one or both hind legs. Luxating patellas vary in severity, and treatment depends on the severity. Your veterinarian will grade the severity as follows:
Grade 1: This is the mildest case, where the kneecap can be dislocated from its groove when pressed by a veterinarian, but generally stays in place otherwise. This grade often does not cause any symptoms for the pup.
Grade 2: With Grade 2 severity, the kneecap is in its groove most of the time, but pops out during movement. It may dislocate occasionally or frequently. You may observe your dog skipping or kicking his leg back for several steps because his knee cannot bend properly until it pops back in. You may also see temporary periods of limping.
Grade 3: When a dog has a Grade 3 luxation, the kneecap is out of its grove all of the time and when moved back into place, it immediately pops out again. This will often cause consistent limping and may also cause the dog to crouch down when walking.
Grade 4: In Grade 4 cases, the kneecap is so far out of place it cannot even be moved into its groove temporarily. A dog with this grade of severity always limps and is generally unable to walk or move his hind legs normally. This grade often causes changes in the structure of the leg that causes deformities of the bones and muscles.
Treatment for Luxating Patella in Dogs
The broad spectrum of grades and direction of the luxation (medial or lateral) result in a wide range of treatment needs. Your veterinarian will determine the best course of action for your individual pup. In a general sense, treatment ranges from simply monitoring to surgical repair.
In mild cases where the dog is not limping at all or limps occasionally for brief periods of time, monitoring is appropriate. Pay attention to whether your dog is limping more frequently, which may indicate medication or further treatment is needed. It is important to note that dislocation can actually wear down the patella’s groove over time, causing the luxation to become a more severe grade.
With Grade 1 or mild Grade 2 luxation where surgery is not needed, joint supplements can be helpful. The inappropriate movement of the joint can cause arthritis and joint pain as the dog gets older. Joint supplements including glucosamine, chondroitin and salmon oil have been shown to help reduce arthritis in dogs. Using supplements before arthritis develops can reduce joint pain associated with luxating patellas.
Your veterinarian may prescribe anti-inflammatory medications or other pain medications. Physical therapy may also help in some cases. Unfortunately, a dog leg brace generally is not beneficial in cases of patella luxation.
When Should Surgery Be Considered?
Surgery is recommended when clinical signs are present frequently or always. This usually occurs with Grade 3 and 4 luxations, as well as some lower grade luxations in larger breeds, which are often lateral and debilitating.
When a pet’s gait or stance is affected, surgery is almost always necessary. Changes in gait and stance may include frequent limping, hind legs bending inward near the knees, or the bottom of the hind legs turning outward. You may also notice your pup being unwilling or unable to jump or crouching his back legs when walking.
Surgery is also needed if the dog becomes suddenly very lame. This may be a sign of a torn knee ligament, which happens more frequently in dogs with luxating patellas. If any of these signs are observed, see your veterinarian right away, as continued abnormal gait can cause further problems in the leg.
The type and complexity of surgery varies substantially depending on the cause of the luxation and the individual dog’s anatomy in the hind legs. High grades of luxation can be due to alignment issues with the bones and muscles in the leg, and the luxation itself can cause further changes and deformities to the legs. In such cases, these abnormalities also must be surgically corrected to resolve the issue.
Surgery may include deepening the groove where the patella should be, loosening or tightening tissues around the knee joint capsule, changing the angle of leg bones, or moving muscle attachments in the leg. Surgery is often effective at resolving luxating patellas, but in severe cases or large dog lateral luxations, changes in the leg that occur over time due to the abnormal patella may not be able to be fully resolved. In such cases, consulting with a veterinary orthopedic specialist can be helpful, especially where complex corrections are needed.
Luxating patellas have a wide range of severity, and therefore have a wide range of treatment needs. Work with your veterinarian to find the right treatment for your individual pup.