What is it?
A Luxating patella (aka patellar luxation) is when the kneecap (aka patella) pops out of place either medially (towards the inside of the leg) or laterally (towards the outside of the leg) The most common luxation is a bilateral luxation, which means that both knees are affected, but there are cases where there is a unilateral luxation (where only one knee is affected). Dogs as young as 8 weeks can be affected by this.
What causes Luxating Patella?
There can be several causes for the patella to luxate…
- shallow trochlea (the groove where the knee cap sits)…the kneecap does not have a deep enough grove to sit in and therefore luxates back and forth
- sometimes the ligaments and muscle holding the kneecap in place are either too tight or too loose and therefore pull the kneecap out of alignment
- trauma: trauma can sometimes cause a luxation in the patella. Anything that causes the patella to be forced out of alignment will contribute to the condition.
Luxating patella’s are grades based on severity. There are 4 grades…
Grade 1 Luxation: The patella can easily be popped out manually, but will return to the correct position by itself. Occasional carrying of the leg is seen, often described as skipping or hopping, which may be transient, often returning to normal by itself. Pain may be evident only when the kneecap is luxated. This can be treated with anti-inflammatory meds and rest. Usually therapy and certain exercises will be assigned to stop the luxation from getting worse. Dogs with grade 1 luxation can live a fairly normal and pain free life without the need for surgery.
Grade 2 Luxation: At this point the luxation occurs more frequently. Sometimes the patella wont be able to return to the correct position and this causes more pain and discomfort in the dog. At this point the patella needs to be manually returned into the correct position. Symptoms are generally the same as grade one; only more frequent and at times more sever. Same type of treatment can be used for grade 2 luxation, but the long-term effects of the patella grinding over the grove it sits in can cause more long-term issues such as arthritis. Because of this surgery is often recommended.
Grade 3 Luxation: The kneecap will stay luxated (dislocated) and will not return to its correct position on its own (a vet might be able to return it to normal position but it will easily luxate back). This can be very painful for the dog. The dog might still be able to bear weight through this leg, but the stance will not look normal and they might appear to be leaning or bow-legged. Most of the time the dog will shift its weight over to the less painful leg. You might see your dog stretch the effected leg back in order to try to pop the kneecap back in. Surgery is highly recommended, especially in younger dogs. If a dog has a grade 3 luxation and is allowed to grow with the problem other deformities can result.
Grade 4 Luxation: The patella is permanently dislocated and the dog is not able to bear any weight on the leg at all. Surgery is a must in this case because bone deformity in the femur and tibia/fibula can develop. (also very painful for the dog)
For grade 1 treatments are simple and usually just require rest, anti-inflammatories and simple exercises. A dog might need to go on supplements with glucosamine in it to aide in the healing of the joint. Often dogs are on the supplements for life.
For grade 2-4 surgery is often recommended, depending on the severity (with grade 3 and 4 needing surgery to fix). Often the surgery requires either the deepening of the groove that the patella sits in to keep it from sliding out or some of the ligaments and muscles must be cut to loosen the tension that is pulling the patella out of alignment. Rehab is highly recommended after such surgery and it will be suggested that the dog be on supplements for life. Dogs who get the surgery and do the rehab usually recover nicely although some dogs (mostly smaller breeds) will not want to use the leg again and the owner will have to be patient and work on weight bearing exercises and slow leash walks in order to encourage the dog to walk on it.