Anterior Cruciate Ligament Rupture

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ANTERIOR CRUCIATE LIGAMENT RUPTURE

Joints allow movement between bones. Movement is controlled by ligaments and tendons that are made of very tough tissue that attaches to the bone. The knee joint is particularly susceptible to damage from strained or torn ligaments.

The Anterior Cruciate Ligament attaches the back of the femur (thigh bone) to the front of the tibia (shinbone) preventing excessive motion between these two bones and thus keeping the joint stable. Over-extension of the knee joint may tear this ligament, allowing the two bones to slide back and forth. This causes pain, lameness, and instability of the joint.

It is thought that the tendency to tear the ligament may be genetic. A torn cranial cruciate ligament is also common in dogs that have a very upright knee joint, where the leg is straighter and has less shock absorbing capability than a more flexed-appearing knee. Overweight, large breed dogs are most susceptible due to the excess pressure created on the joints, but this disease may occur in medium sized or small breeds. In cats it rarely occurs unless there has been a severe trauma to the knee.

Conservative medical therapy initially using anti-inflammatory drugs may allow healing if the ligaments are merely stretched instead of being torn, or if the tear is small. More commonly the ligament tears little by little and then suddenly gives way altogether and tears completely. Depending on the severity of the rupture, treatment may consist of rest and medication or surgical repair of the torn ligament. Your doctor will advise you concerning the treatment necessary for your pet. Small tears will heal with rest and time but each time a tear occurs the ligament is weakened, increasing the chances of a complete rupture later on. It is also common for dogs to eventually rupture both knees.

If the ligament is completely torn dogs will usually need surgery to repair the knee. Cats often heal without surgery if this is the only ligament that tears. If extensive damage has occurred to the other ligaments in the knee a cat may need surgery as well.

Without medical/surgical attention, abnormal wear and tear from excessive movement of the joint
will lead to arthritis and chronic discomfort.

If surgery is recommended, it may consist of the following:

1. Removal of the damaged cartilage.

2. Creation of an artificial ligament in replacement of the torn ligament.

3. Tightening of the joint to help prevent abnormal movement.

Even after surgery, recovery may take weeks depending upon the individual. Due to the injury, some arthritis is inevitable. Therefore, the joint will rarely be “good as new,” but should be noticeably better.

Remember, rupture of the anterior cruciate ligament most frequently occurs in overweight dogs.

Because of this, the problem could occur in the other leg at a later time. Weight reduction is highly recommended.

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