The most common injury we see in our canine patients is a rupture of the cranial cruciate ligament (CrCL). Damage to this ligament can occur during normal activity and may not be associated with a specific traumatic event. These ligament injuries are most often a complete tear and the dog becomes dramatically lame in the injured leg. A smaller percentage of dogs will be experience an incomplete ligament injury. The lameness is typically not as significant and many dogs appear to recover with rest. Unfortunately, most of these dogs will have subsequent episodes of lameness as more of the ligament is injured. This is often referred to as the partial tear syndrome. The majority of dogs with a partial tear will eventually progress to a complete ligament injury.


When the hind leg lameness persists without significant improvement, an orthopedic evaluation is performed to determine the cause. Examination of the knee reveals several typical findings, with the most important one being the presence of a cranial drawer sign. This occurs when the lower bone of the knee (tibia) moves forward relative to the upper bone (femur). Radiographs (x-rays) may also be helpful in the diagnosis of cranial cruciate ligament injuries, although the torn ligament does not show up on an x-ray. Other changes in the knee joint, such as swelling or presence of small bone spurs, provide important evidence that the ligament has been injured. Advanced imaging studies, such as an MRI, do reveal the presence of a torn ligament. These diagnostic tests are not used routinely in dogs because of limited availability, significant expense, and the fact that general anesthesia is required for a dog to go through an MRI.

Surgical Repair:

There are two surgical procedures that Dr. Clark performs in order to treat injuries to the cranial cruciate ligament. The tibial plateau leveling osteotomy (TPLO) is performed most commonly in larger dogs, particularly those that are younger and have a more active lifestyle. The TPLO was developed by Dr. Slocum in the 1990’s and has been a well-accepted technique to treat cranial cruciate ligament injuries in dogs for over 20 years. Dr. Clark was fortunate to have learned this surgical technique directly from Dr. Slocum at his hospital in 1999. He has since performed over 3000 successful TPLO surgeries on dogs ranging in size from 25 pounds to over 200 pounds. The other technique that Dr. Clark performs for CrCL injuries is most commonly referred to as an extracapsular repair (ECR) or extracapsular stabilization (ECS). It is also known as a lateral suture repair or a standard repair. There are several variations of this surgical technique, but all of them utilize a synthetic ligament (typically monofilament nylon) to replace the damaged ligament and eliminate the instability in the knee joint. Dr. Clark has been performing this technique in dogs for over 30 years. The extracapsular procedure has the most consistent results in smaller and less active dogs. Regardless of the age or size of the patient, the best post-operative results are seen when the dog is properly restricted during the recovery period. The decision of whether to choose surgery for a CrCL injury in your dog, and which technique is the best option, is not always easy. A comparison of the two techniques and the factors influencing the choice of surgical procedure can be viewed by clicking on the link listed below. When a clear decision cannot be made before the day of surgery, Dr. Clark will wait to make the final choice after examining your dog on the day of surgery.

To learn more, please view the following articles

*Comparison of Surgical Techniques for Repair of Cranial Cruciate Ligament (CrCL) Injuries in Dogs

*A Prospective Study of the Clinical Characteristics of Cranial Cruciate Ligament Injury in Dogs: Results of 150 Consecutive Cases