Anterior Cruciate Ligament Injury In Dogs
Canine Cruciate Knee Injuries
Joints allow movement between bones. Movement is controlled by ligaments and tendons which are made of very tough tissue which are attached to the bones.
The knee joint is particularly susceptible to damage from strained or torn ligaments.
Rupture of the anterior cruciate ligament (which is sometimes also called the cranial cruciate ligament) is the most common injury seen in the canine knee joint (stifle).
The anterior cruciate ligament attaches the femur to the tibia (�shinbone�) preventing excessive motion between these two bones and keeping the joint stable.
Over-extension of the knee joint may tear this ligament allowing the two bones to slide back and forth causing pain, lameness, and instability.
This may occur in a young dog who is very active and takes a bad step while playing, injuring the knee.
This is especially common in large breed dogs.
This type of injury may also involve an older dog, especially a dog who is overweight. These dogs frequently have weakened ligaments which have been slowly stretched or partially torn. The partial tear (or rupture) may not be apparent until the ligament breaks completely, which may be the result of a simple action, such as jumping off a bed or couch.
(Note: Large overweight dogs who rupture one anterior cruciate ligament frequently rupture the same ligament in the opposite leg within a year’s time.)
Symptoms Of Anterior Cruciate Ligament Damage:
The history usually involves a rear leg suddenly so sore that the dog can hardly bear weight on it.
If left alone, it will appear to improve over the course of weeks but the knee will be notably swollen and arthritis will set in quickly, eventually causing chronic pain.
Diagnosis Of Anterior Cruciate Ligament Damage:
Diagnosis of anterior cruciate ligament rupture involves an examination by your dog’s veterinarian.
Your dog’s veterinarian will look for an abnormal motion within the knee joint called “drawer movement”. To look for this movement, the veterinarian stabilizes the position of the femur with one hand and manipulates the tibia with the other hand. If the tibia moves forward (like a drawer being opened), the cruciate ligament is ruptured.
Radiographs (x-rays) of the affected knee joint will probably also be necessary to check for evidence of arthritic changes and other abnormalities within the knee joint.
Treatment Of Anterior Cruciate Ligament Damage:
Conservative medical therapy initially using anti-inflammatory drugs (frequently non-steroidal anti-inflammatory medications) may allow healing if the ligaments are merely stretched instead of being torn.
Complete rest is essential for any chance of healing to occur.
If the ligament is actually torn, or even partially torn, surgical repair will most often be needed to form new ligaments and tighten the joint, giving the stability needed for normal movement and activity.
Without surgery, the development of arthritic changes within the affected knee joint are likely to cause chronic pain and discomfort for your dog.
There are a number of surgical alternatives available to repair a ruptured anterior cruciate ligament. These include:
- intracapsular (“inside the knee joint capsule”) methods,
- extracapsular (“outside the knee joint capsule”) methods
- and the tibial plateau leveling osteotomy (TPLO).
All of these surgical methods have advantages and disadvantages and your dog’s veterinarian will help in determining which technique is likely to be most successful for your dog.
During surgery, your dog’s veterinarian will also probably examine the menisci (pads of cartilage located between the bones which provide a smooth surface for the joint to move on). If the menisci are damaged, your dog’s veterinarian will probably remove them during the surgery.
For those dogs who have previously experienced ruptures of the anterior cruciate ligament and have developed arthritic changes as a result, surgery may or may not be a possibility.
If surgery is not a practical option, medical management to control pain may be the only option. Medications frequently used are the non-steroidal anti-inflammatory medications, such as Rimadyl, Etogesic, Deramaxx, and other similar products. Formulations containing glucosamine and/or chondroitin may also be useful in improving joint health and decreasing pain.
Collateral ligament rupture of the knee allows the femur and tibia to move from side to side. Surgical repair involves reconstructing these ligaments. This type of injury does occur but is much less common than cruciate injuries to the knee.