Patellar luxation is a problem commonly seen in dogs and occasionally seen in cats. The patella (a.k.a. knee cap) is a “floating” bone associated with the knee or stifle joint. Patellar luxation most commonly occurs in small breed dogs but can also occur in larger breeds. Most patellar luxations involve displacement of the patella to the inside of the knee, which is referred to as a medial patellar luxation (MPL). Patellar luxations can also be to the outside or lateral (LPL) – although this is much less common. Medial patellar luxations are associated with a “bow-legged” confirmation while lateral patellar luxations are associated with a “knock-kneed” posture.
A patellar luxation is diagnosed based on a physical examination by your veterinarian. Radiographs (x-rays) of the rear limbs are most often taken to document the severity of the bone deformity.
Surgery is recommended for animals with grades 2, 3 and 4 luxations that have significant lameness. Dogs with grade 3 or 4 patellar luxation generally will have significant lameness and therefore surgical correction is recommended. The goal of surgery is to keep the patella in its appropriate location at all times. This is most often accomplished with three surgical maneuvers.