The patella is the medical term for the kneecap.  Luxation means the kneecap is dislocated, either temporarily or permanently.  This is an extremely common condition in small breed dogs such as Chihuahuas, Pomeranians, Toy Poodles, Yorkshire Terriers, Papillons, Pugs, Maltese, Pekingese, and Shih Tzus.   In most cases this is congenital, or present from birth, and is a genetic problem. 

There are four grades of luxation:

1. The patella can be luxated with manipulation but pops right back into place.  Lameness is usually not present except at the exact moment the kneecap is dislocated.
   
2. The patella luxates with flexion and extension of the knee but returns back into place when the pet is standing.  This grade may or may not be associated with lameness.
3. The patella easily luxates with flexion and extension of the knee and only returns back into place with manual manipulation.  These pets usually have considerable lameness.
4. The patella is permanently luxated and cannot be put back into place.  These pets are usually not weight bearing on the limb(s) affected.

Treatment for patellar luxation depends on the symptoms.  For those dogs that are showing no lameness or pain, usually no treatment is necessary.  Occasionally these dogs will have to go on joint diets or early arthritis medication, but some have no problems well into older age.  For dogs with lameness, there is medical and surgical treatment.  Medical treatment includes rest, anti-inflammatories, physical therapy and certain exercises, and weight reduction in overweight and obese dogs.  With surgery, we deepen the groove that the patella sits in as well as tighten the ligaments that hold the patella in place.  We only recommend this surgery if your pet is in pain.  These pets still likely need to be on some sort of joint protective medication, but surgery improves the majority of their symptoms and pain.