TL;DR: Patellar luxation is a common condition where a cat's kneecap slips out of place, typically causing a temporary "skipping" motion that is rarely an emergency unless accompanied by severe pain. Capturing a video of your cat moving at home is the most effective way to help your veterinarian assess the severity.
What are the common causes and symptoms of patellar luxation in cats?
- Anatomical abnormalities present from birth, such as a groove in the thigh bone that is too shallow.
- Physical injuries to the leg or knee joint.
- Suddenly lifting a hind leg or "skipping" for several steps while walking.
- Stretching the leg out awkwardly to manually pop the kneecap back into its natural position.
Is my cat's slipping kneecap considered a medical emergency?
- In most cases, the urgency level is low, though the condition can lead to chronic mobility issues like arthritis over time.
- Contact a vet immediately if your cat is vocalizing in pain or completely refusing to put weight on the affected limb.
- Seek a professional exam if the leg appears visibly swollen or deformed to rule out more serious injuries like ligament tears.
Why should I provide photos or videos of my cat to help the vet with triage?
- Cats often hide symptoms of pain or lameness when they are stressed in a clinical setting.
- A video of the "skipping" motion captured at home helps the vet see exactly what is happening in a relaxed environment.
- Providing visual evidence allows for a much faster and more accurate diagnosis of the severity of the luxation.
Clinical Context (Merck Veterinary Manual)
Patellar luxation in felines presents with variable clinical signs dependent on the severity of luxation, and animals of any age may be affected. Palpation of the stifle joint reveals patellar displacement. In Grade I, clinical signs are mild and infrequent, and the patella can be manually luxated but easily returns to the trochlear groove. In Grade II, the patella luxates during flexion of the joint and is repositioned during extension, causing a resolvable skipping lameness. In Grade III, the patella is more frequently out of the trochlear groove than in, and lameness is consistent. Bone deformities are evident. In Grade IV, lameness and limb deformations are most severe. Radiography reveals various degrees of limb changes based on the grade of luxation. Medial patellar luxations can be associated with a reduced coxofemoral angle (coxa vara), lateral bowing of the femur, internal rotation of the tibia, shallow trochlear groove, and hypoplasia of the medial femoral condyle; lateral luxations cause the reverse changes. Surgical treatment is based on the severity of the luxation and can include orthopedic and soft-tissue procedures, such as fascial releasing incisions and joint capsule/retinaculum imbrications.
Chapter: Orthopedics
Source: The Merck Veterinary Manual, 11th Edition (Page 1195)