The term patellar luxation describes a shift of the kneecap inwards or outwards from the trochlear groove. The condition is divided into 4 degrees of severity; it can occur on one or both sides and be a congenital or acquired disorder.
By far the most frequent form is congenital patellar luxation inwards, which occurs especially in many small dog breeds such as Yorkshire terriers, toy and miniature poodles, Chihuahuas, miniature pinschers, Pekineses and pugs. A typical symptom is often switching between walking on 4 legs and on 3 legs, when the affected hind leg is drawn upwards.
The aim of patellar luxation surgery is to stabilise the natural kneecap position. This is most commonly achieved by a combination of deepening the femoral groove, moving the patellar tendon insertion and tightening the joint capsule.