A luxating patella is when the kneecap pops out of the groove that it is supposed to sit in.
It is very common in small breed dogs, including Toy Poodles, Yorkshire Terriers, Pomeranians, Pekingese, and Chihuahuas.
Luxating patellas can be due to conformation or they can develop as a result of trauma. In small dogs, it is typical that the kneecap will slide out to the inside (medially) while in larger dogs, it typically slides to the outside (laterally).
A luxating patella can be diagnosed during a routine physical exam by feeling the knee while the leg is moved. Many dogs with luxating patellas do not have any symptoms. Some dogs will hold up the leg for a step or two, appearing to almost skip, then will go back to normal, just like nothing ever happened.
Luxating patellas are graded on a scale of 1 (mildest) to 4 (most severe). For dogs that do not show any lameness from the luxating patellas, no treatment is needed. For dogs that are more severely affected, surgery is sometimes recommended.
Surgery can involve one or multiple strategies for correction including deepening the groove the kneecap sits in and reconstructing the soft tissues around the kneecap. Dogs are typically placed on exercise restriction for several weeks after surgery while the knee heals.
Michelle Sonnema, DVM, earned her DVM degree from Rutgers University. Learn more about her here.