Patellar luxation is basically the official terminology for a knee that pops out of place. The problem usually affects small breed dogs much more than medium or large breeds.
The most common breeds to have this knee problem are Yorkshire Terriers, Pomeranians, Poodles, Pekinese, Lhasa Apso, and other toy breeds.
Dogs that have a knee that pops out of place usually have a malformation of the knee. Sometimes the knee joint does not have grooves that are deep enough to keep the joint in place, so sometimes the knee pops out of place, often while the dog is just running across the room or yard.
In many cases the dog will be able to return its knee to the proper position, although this can only happen when the dog relaxes the muscles in the leg.
Usually luxation affects one or both of the hind legs, and dogs are often middle-aged before they experience this problem.
The good news is that the pain these dogs experience from luxation is often short-lived. They feel a very sharp pain in the moment when the knee pops out of place, but they do not feel any pain while the joint is out of place.
They simply adjust their movements to account for the patellar luxation, and the muscles do eventually relax, allowing the knee to pop back into place.
The most common symptom of luxation generally is episodes of intermittent lameness in one or both of the hind legs.
Dogs that have this problem usually experience it while they are running, and they may yelp suddenly mid-stride, right before they lose the use of their hind leg.
Of course there are elements of luxation that can make dog owners wonder if it is a serious problem. The fact that the joint goes back to normal on its own may make it seem like it is not serious at all, although the yelp of pain does certainly indicate that there is a problem.
The biggest issue with luxation is that it can lead to permanent lameness if it is not treated. The dog will also experience arthritis in the joint, which can really take away from the animals enjoyment of moving around.
The bad news about luxation is that surgery is really the only option for treatment. However, this bad news is tempered by the fact that not every dog that has a patellar luxation will have to have surgery to correct it.
Also most of the dogs that do have surgery for luxation will go on to lead completely normal lives.
The surgical procedure to correct luxation basically involves deepening the grooves in the knee so that it is not as likely to pop out of joint with regular movement.
The veterinarian may also make adjustments to the knee cap to tie it down. Usually recovery from the surgery for luxation does take about one or two months, but the dogs usually experience a complete recovery with very few problems afterward.