Congenital Patella Luxation

General information:
--most common stifle joint abnormalities
--May be traumatic or congenital
--may either be medial or lateral luxation

Breed Predisposition:
--Pomeranians are predisposed for medial luxation

Pathophysiology:
There is a malformation involving the extensor mechanism of the stifle joint (quadriceps, 
muscle group, patella, trochelar groove, straight patellar ligament, and tibial tuberosity)
A straight line through the extensor mechanism is necessary. There are musculoskeletal 
abnormal findings:
1. Coxa Vara
2. Lateral torsion of the distal femur
3. Medial displacement of the quadriceps
4. Lateral bowing of the distal 1/3 of the femur
5. Shallow trochlear groove
6. Dysplasia of the femoral epiphysis
7. Rotational instabilities of the stifle
8. Tibial deformities
9. Degenerative disease