Cruciate Ligament (TTA) Surgery
The most common knee injury in the dog is rupture of the Cranial Cruciate Ligament (CCL), also frequently called the Anterior Cruciate Ligament (ACL). This injury can occur at any age and in any breed, but most frequently occurs in middle aged, overweight, medium to large breed dogs. Rupture of this ligament leads to instability of the knee which leads to the development of painful arthritis.
An injured Cruciate Ligament is best corrected by surgery. There are several surgical options available. The most common techniques currently recommended are External Capsular Repair, Tibial Plateau Levelling Operation (TPLO), and Tibial Tuberosity Advancement (TTA). Dr Steve Ferguson of Macarthur Veterinary Group has undertaken advanced training in the TTA technique and has undertaken quite a number of these procedures. He has found the TTA technique results in significantly improved recovery times and much less discomfort for the patient.
The forces within the knee are very complicated and change as the
knee is rotated through its range of motion. In a normal standing
position there is a tendency for the lower end of the Femur to slide
backwards on the tilted Tibial Plateau. This force, called Tibial
Thrust, can be eliminated by cutting the Tibial Plateau and rotating it
into a flatter position (TPLO), or by advancing the Tibial Tuberosity
(TTA) thereby changing the angle of pull of the Patellar Tendon.
The TPLO procedure makes its bone cut on the weight bearing surface of the Tibia, necessitating the use of a large stainless steel plate to maintain stability while healing. The TTA procedure is considered to be less invasive because its cut is on a non-weight bearing area of the Tibia. That cut is then stabilized by the use of the more biologically friendly Titanium implants. The TTA procedure may not be right for every dog, but it does seem to make the leg more stabile, particularly with respect to rotation of the joint, known as Pivot Shift.
If you notice that your dog is limping, a trip to your veterinarian and a full workup on the leg is warranted. It has been shown that even a partial tear of the Cruciate Ligament can lead to instability and then to a complete rupture. The choice of surgical procedures can then be discussed with your veterinarian, once a diagnosis is made.