Patellar luxation is a dislocation of the knee cap, most often seen in small dogs. The patella (knee cap) is a movable bone located over the knee that connects the muscles of the upper leg (thigh) to the lower leg (shin). When the patella functions correctly normal movement of the leg occurs. Many small breed dogs are often born with a hereditary defect causing weakness of the kneecap structure. A fall or twisting injury can also cause patellar dislocation or aggravate the condition in susceptible individuals.
A common symptom of this "trick knee" condition is when the pet occasionally holds up the leg while running, then spontaneously starts using it again. This happens as the knee cap pops in and out of place. Often the dog will give out a short cry or yelp when this happens, although not always. Some pets tolerate the discomfort better than others and never demonstrate lameness. The doctor may recommend and x-ray of the knees to help assess how badly your pet is affected by the condition.
Medically little can be done, other than to administer anti-inflammatory medication when the condition flares up. If the pet is severely affected with chronic pain or disuse of the affected leg surgery may be recommended. With severe patellar luxation surgery is the best means to try to prevent crippling arthritis and deformity. Several different types of surgery have been developed and the doctor will advise you. Often the exact method of repair can only be determined during surgery, when visual inspection is possible.