FAQ  ›  CCL (Cranial Cruciate Ligament)

CCL stands for Cranial Cruciate Ligament, which is called the ACL (Anterior Cruciate Ligament) in humans.

Both refer to a tough band of tissue that connects the two main bones of the knee joint. The CCL attaches the upper bone (femur) to the lower bone (tibia) and helps prevent excessive motion between these bones. A ruptured CCL is the most common orthopedic injury in dogs and results in a painful and unstable joint. If left untreated, a ruptured CCL will lead to progressive and irreversible degenerative joint disease (arthritis).

There are generally two ways a dog’s cranial cruciate ligament can rupture. The first way is similar to a sports injury in people. Like a basketball player who plants his leg aggressively and then tears his ACL, a dog’s CCL may suddenly rupture from excessive force and leave the dog with an unstable and painful knee. Alternatively, a dog can experience years of normal “wear and tear,” which can leave the ligament weak and prone to full rupture. We don’t always know why or how a ligament ruptures. Some dogs begin limping after playing aggressively in the park, while others simply step off a curb and begin limping. Obesity appears to be one of the most important predisposing factors in CCL ruptures, however, as excess weight can cause further strain on ligaments. So watch those treats!

Why does my dog need surgery? When a dog ruptures a cranial cruciate ligament, the joint becomes unstable. When he places weight on his limb, there is a shearing force on the joint. This shearing force is not just painful, but also potentially damaging to the cartilage (meniscus) in the joint. This abnormal shearing movement (called “tibial thrust”) predisposes the menisci (cartilage pads) to damage and promotes arthritic changes within the joint. These changes often become painful enough to render the limb mostly useless, especially in larger dogs. Surgically repairing a knee joint after a CCL tear provides stability to the joint and thereby reduces the rate of future arthritic change. Plus, when one CCL is ruptured, a dog will naturally transfer most of its weight to the other leg. In doing so, they inadvertently put the other CCL in danger of rupture due to overuse. If a dog has tears in both cranial cruciate ligaments, simple tasks such as rising up, walking and squatting to urinate or defecate become very difficult, and the dog’s quality of life may suffer.