A luxating patella, sometimes called a trick knee, is a condition in which the patella, or kneecap, dislocates or moves out of its normal location. It can be associated with damage to the anterior cruciate ligament.[1]
Patellar luxation is a common condition in dogs, particularly small and miniature breeds.[2] The condition usually becomes evident between the ages of 4 and 6 months. It can occur in cats, as well, especially domestic short-haired cats.[3]
There have been several reports of patella luxation in other species such as miniature pigs, alpacas, llamas, cattle and goats.[4]