What is a medial patellar luxation?

Medial patellar luxations, commonly referred to as "luxating patellas," are a common orthopedic issue in dogs, particularly among small to medium-sized breeds. This condition occurs when the patella, the kneecap, dislocates from its normal position within the groove of the femur. Several factors contribute to this condition, including genetic predisposition, conformational abnormalities, and trauma. Breeds such as Chihuahuas, Pomeranians, Pekingese, and Yorkshire Terriers are more commonly affected due to their unique limb structures, but it can also occur in larger breeds. The most common symptom is a skipping gait. Patella luxations in dogs are typically graded on a scale from 1 to 4, indicating the severity of the condition:

Grade 1: This is the mildest form of patella luxation, where the kneecap occasionally slips out of its normal position but readily returns to the groove in the femur when the leg is extended. Dogs with grade 1 luxations often show minimal lameness and discomfort.

Grade 2: In this grade, the patella slips out of its groove more frequently, but it can still be manually manipulated back into place with ease. Dogs may experience occasional discomfort and exhibit mild to moderate lameness.

Grade 3: Grade 3 luxations are more severe, as the patella frequently dislocates and doesn't readily return to its normal position. Dogs with this grade often exhibit lameness, pain, and may keep the leg partially flexed to avoid discomfort.

Grade 4: This is the most severe grade, where the patella remains persistently dislocated and cannot be manually repositioned. Dogs with grade 4 luxations experience significant pain, severe lameness, and may have difficulty using the affected limb.