Luxating patellas also called floating knee caps or trick knees are very common in small breed dogs such as toy poodles, yorkies, pomeranians, pekingnese, chihuahuas and boston terriers. About half the dogs are affected in only one knee. Normally the patella (knee cap) sits in a groove on the front of the femur, and it slides up and down as the knee bends and straightens. Patellur luxation occurs when the patella shifts or luxates out of it's groove. In small dogs, the shifting generally occurs to the inside of the leg, called medial patellar luxation (MPL). Over time that shifting causes wear and tear to the cartilage that covers the bone of the knee. This causes pain and decreased mobility along with degenerative joint disease (arthritis). Some signs of patellar luxation can be stiff legs, whimpering, hiding, and lameness. Most cases can be diagnosed with a good physical exam. Your veterinarian can palpate the luxation in the knee. There are four grades of patellar luxation:
Grade 1: Spontaneous luxation rarely occurs.
Grade 2: Patella luxates when the knee is bent. Pet occasionally skips when walking/running
Grade 3: Patella remains luxated most of the time. Pet skips or is weight bearing lame
Grade 4: Patella is permanently luxated and cannot be repositioned. Pet cannot fully extend hind legs.
Minor luxating problems (Grade 1 and 2) can be managed with anti-inflammatory medication and rest. For the more severe grades (3 and 4) surgical correction is typically advised. This involves a 6-8 week recovery time with restricted activity levels. This problem can worsen over time if not treated properly. Cats can ocassionally have grade I patellar luxations because their femoral grooves are shallower than dogs, but the majority of this problem in cats is secondary to trauma.
If you feel that your pet may be experiencing this kind of issue please contact the Doctors or Staff at Eagle Animal Hospital. We serve Chester Springs, Downingtown, Exton, Glenmoore, and surrounding areas.
written by Amy Poole, Veterinary Technician