Anterior Cruciate Ligament

Dogs knees are similar to humans. Knees have five ligaments, two menisci, a knee cap, and joint cartilage. The ligament most commonly affected in the dog knees are the cranial cruciate ligament, the same ligament most commonly damaged in humans. Dogs usually tear this ligament when playing.

The cranial cruciate ligament is a large ligament located within the knee joint. It is not actually a single structure, but is in fact made up of a bundle of individual fibers tightly bound together to form the ligament. Most of the time when the ligament is injured, it is completely torn in half. Sometimes, though, only a portion of the ligament will tear. Even though only a portion of the ligament may be torn, the whole ligament is damaged.

When a cranial cruciate ligament is torn, it causes sudden extreme pain and results in the dog holding its leg up. It also causes an instability in the knee joint. The dog may put the leg down and start using it within a day or so, but will continue to limp for several weeks. Normally, at the end of several weeks, the initial pain subsides and the dog  is willing to use its leg more, but the joint remains unstable. Every time the dog puts weight on the leg, the tibia (shin bone) slides forward in relationship to the femur (thigh bone). This abnormal motion causes wear and tear on the joint cartilage, causing pain and leading to arthritis. This motion can also put excessive stress on the menisci (C shaped pieces of cartilage within the knee joint), causing tearing and or damage.

Surgery is the only corrective measure for cranial cruciate ligament injuries. Many surgical procedures have been tried on people and dogs but most orthopaedic surgeons agree that the procedures are not as successful as they would like. Knees that suffer this injury are never completely normal even after surgery is performed. Surgery does stabilize the knee, allowing it to regain normal motion and reducing the formation of arthritis. Surgery is the treatment of choice for this injury. If surgery is not performed, arthritis will occur and the lameness will worsen with time.

There are many different ways to stabilize a knee with a cruciate ligament injury. The procedure most often used  involves placing either heavy gauge suture material or orthopaedic wire from the back of the femur, across the joint, and to the front of the tibia. This will tighten up the joint and stabilize it. Over time, scar tissue will lay down around the suture or wire to form a structure which mimics the function of the normal cranial cruciate ligament. The majority of dogs will regain normal or near normal use of their leg after the surgery and rehabilitation. Limited activity is necessary after the surgery for a period of at least six weeks so that the dog does not over stress the repair before the scar tissue has formed. Total rehabilitation time, can be several months.

For more information and diagrams please visit these PetSurgery.com links: Anterior Cruciate Ligament Rupture and Tibial Plateau Leveling Osteotomy.

Here is Harley a beautiful Dane whose mom wants to tell his story.

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