Tibial Tuberosity Advancement
(TTA Surgery)

The Tibial Tuberosity Advancement (TTA) surgery is a new, revolutionary surgical procedure developed at the University of Zurich, Switzerland, for repairing ruptured cranial cruciate ligaments in the canine knee. This is the most common orthopedic injury in the dog.

The procedure is similar to the Tibial Plateau Leveling Osteotomy (TPLO) in that it changes the biomechanics of the knee to stop the damage of forward shearing forces caused by the ruptured cranial cruciate ligament.

Both the TTA and the TPLO offer a quicker return to normal function and less progression of osteoarthritis so that the dog can function more like before the injury occured.

The TTA offers some advantages over the TPLO in that it is less invasive, less technical, and has fewer potential adverse problems.

A side view of the knee joint [the joint between the femur (thigh bone) above and the tibia (shin bone) below] shows the top of the tibia (tibial plateau), and the patellar tendon which attaches the patella to the tibia at the tibial tuberosity. The angle between the patellar tendon and the tibial plateau in most dogs is greater than 90 degrees, usually in the 115-120 degree range.












During weight bearing in the normal canine knee, the femur tends to slide down the backward slope of the tibial plateau, allowing the tibia to thrust forward. The function of the cranial cruciate ligament (CCL) is to prevent this movement and is therefore under constant stress, predisposing it to partial tears of ruptures. When the CCL is partially torn or ruptured, the abnormal movement in the knee results in an unstable, painful knee and ultimately, in debilitating, degenerative arthritic changes in the knee joint.











When the patellar tendon is placed at 90 degrees to the tibial plateau, this abnormal, forward thrusting motion of the tibia and the backward sliding motion of the femur is eliminated, even in the absence of the cranial cruciate ligament. Therefore, the purpose of the TTA is to change the geometry or bio mechanics of the knee joint, allowin git to function normally without a cranial cruciate ligament.

This is accomplished by making a cut (osteotomy) in the non-weight bearing portion of the tibia where the patellar tendon attaches (the tibial tuberosity), and advancing the tibial tuberosity forward a pre-determined distance, until the patellar tendon is 90 degrees to the tibial plateau.








The tibial tuberosity is securely anchored in its new position using specially designed titanium implants (a cage, fork and plate), and a bone graft installed into the open space created which stimulates very rapid healing. Thus the shape of the tibia is changed, placing the patellar tendon 90 degrees to the tibial plateau, which eliminates all abnormal movement in the knee when weight bearing takes place, allowing even the most athletic dogs full, pain free mobility with very minimal arthritic changes resulting.

Most patients are completely sound on the operated leg 6-10 weeks following surgery.

To view the titanium equipment used in TTA surgery, click here.