Cranial cruciate ligament (CCL) tear is the most common traumatic orthopedic injury seen in dogs of all ages and breeds. Since the late 1990’s Tibial Plateau Leveling Osteotomy – TPLO – has become a commonly performed technique to address the condition due to its significant success in large and active canine patients.
Anatomy of the stifle (knee)
The cruciate ligaments are important stabilizing elements within the canine stifle joint. There are two cruciate ligaments in the knee, called the cranial (anterior) and caudal (posterior) cruciate ligaments. The cranial cruciate ligament (CCL) is commonly injured in both canines and humans (referred to as the ACL in humans).
Effects of CCL rupture
Early signs of CCL stress or partial rupture include stiffness or mild lameness. As the CCL continues to tear further, symptoms increase. A full tear usually results in marked lameness in the affected leg. In some cases, the knee will make a clicking or popping sound as the dog walks. This often indicates damage to the cartilage cushion (meniscus) within the knee. When the CCL is ruptured, stifle instability ensues. This instability is often described as cranial tibial thrust or “drawer” movement. This shearing motion causes excessive wear of the cartilage on the ends of the bones within the joint, and stretches the surrounding tissues, causing pain. It can also injure the medial meniscus within the stifle. The TPLO procedure can eliminate excessive tibial thrust, thus creating a more functionally stable joint and sound gait.
Diagnosis of a CCL tear is made by palpation (feeling the knee) and radiographs (x-rays). The radiographic findings associated with a ruptured CCL include osteoarthritic changes and joint effusion (swelling). The actual ligament cannot be seen on the radiographs.
Description of TPLO procedure
A curved cut (osteotomy) through the tibia bone is made using a specially designed saw blade. The top portion of the tibia is then rotated a precise number of degrees in order to level the slope of the tibial plateau and prevent the instability and sliding that occurs with a CCL tear. A bone plate and screws are then placed on the tibia to stabilize it and allow healing to occur.
Prognosis with TPLO
The TPLO technique has gained acceptance throughout the country due to consistent reports indicating that dogs treated with TPLO have excellent functional outcome and decreased development of osteoarthritis. The exciting aspect of the TPLO technique is the possibility of returning your dog to nearly normal long-term function following CCL rupture (which has not been the typical expectation with any of the traditional techniques attempted before) and the prospect of a reduction in the future progression of arthritis.