What causes the patella to luxate?
The patella slides in a groove on the lower end of the femur (the bone that runs between the hip and the knee). There is a ligament called the “patella ligament” which runs from the bottom of the patella to the tibia, (the bone just below the knee joint). This ligament keeps the patella in place. The thigh muscles are attached to the top of the patella. When the thigh muscles contract, the force is passed through the patella and through the patella ligament, which results in straightening of the knee joint. The patella can luxate because the point where the patella ligament attaches to the tibia can sometimes be attached too far inward. As the thigh muscles contract, the force pulls the patella against the inner groove that it is sitting in. After several months, the inner side of the groove wears down and the patella is free to move out of the groove or luxate. This can be quite painful when this happens and the dog may have difficulty putting weight on the leg. After a while, some do
