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.
Grades
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)
Treatments:
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.