Patella luxation in dogs is a condition where the patella or “knee-cap” can move from its normal central position at the front of the knee or “stifle joint” to one side or the other. This condition is more common in the smaller breeds, however it may occur in large breeds and also cats.
In most dog breeds the most frequent direction of abnormal movement or “subluxation” is towards the midline of the dog- “medial patellar luxation”. In some cases the subluxation can be away from the midline of the dog and is called “lateral patellar luxation”.
The Putnam grading system, grades dogs from Grade 0 – no luxation present and normal to increasing severity from grade 1-4.
Grade 0: Normal.
Grade 1: The patella can be manually luxated but will immediately return to the correct position when pressure is released.
Grade 2: The patella can be luxated manually but manipulation of the hind limb is required for the patella to gain its correct position.
Grade 3: The patella is spontaneously luxated with the Pug in a standing position or it is permanently luxated but can be repositioned manually.
Grade 4: The patella is permanently luxated and cannot be repositioned.
Excessive force should not be used when manipulating the patella.