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ACL Injury in Dogs

Anterior cruciate ligament injury

The knee, or stifle, of a dog is built much as our own knee. Like people, dogs can injure any of the ligaments in their knee. The most common injury is a tear of the anterior cruciate ligament (ACL), one of two ligaments which form an “X” pattern within the joint. An ACL tear causes the joint to become unstable, resulting in pain and the formation of arthritis. This may be seen by the owner as a chronic lameness, limp in one of the rear legs, or reluctance to use that leg. With time, the dog may have problems getting up in the back legs. The original injury can occur as a result of an unusual twisting motion. However, scientists now recognize that in some breeds, the injury is a spontaneous occurrence which follows the development of arthritis in the knee. The reason for the development of the arthritis is unclear at this time.

While the injury can occur in any breed, large breed dogs are the most likely to be affected. In these large dogs, nearly 50 percent have a torn piece of cartilage (meniscus) in addition to the torn ligament. The Rottweiler breed seems to be prone to the development of arthritis in the knee, which is then followed by the torn ACL. For smaller animals (less than 10 to 16 pounds) surgery may not be necessary to reduce pain, allow proper use of the leg and decrease potential for developing arthritis. Surgery for an ACL tear involves opening the joint and removing the damaged ligament and cartilage, if present. After removing the damaged tissue, the joint must be stabilized. There are a number of methods which can be used to perform this task. One common procedure uses heavy suture material to artificially duplicate the function of the ligament and stabilize the knee joint. Other procedures, such as TPLO and TTA, involve cutting the tibia and realigning it with a bone plate. TPLO or TTA are recommended most for large or very active dogs. After surgery, the patient needs to rest the knee for the next 6-12 weeks to give it a chance to finish healing. The success of these procedures is very good. Around 90-95 percent of the patients will return to normal activity. Even with surgery, some arthritis may be present in the knee. This may cause the patient to have an occasional bad day much as when people over exercise on a bad knee. This is usually controllable with anti-inflammatory medication. Surgical correction of a torn ACL usually allows pets to return to their normal routine. Unfortunately, having an ACL tear does result in one other major problem. If a dog has torn the ligament in one knee, the odds of the same injury occurring in the other knee are greatly increased. If the ligament in the other knee tears, it will most likely occur within two years following the original injury. Surgery can then be performed on the other knee to resolve that problem.