The TTA relies on the patellar tendon to stabilize the knee.
This involves moving the patellar tendon forward to the point that it is perpendicular (at 90 degrees) to the tibial plateau with the limb in a standing angle. This movement relieves the load of the CCL, applying that load to the patellar tendon.
The amount of distance necessary to advance the patellar tendon to make it perpendicular to the tibial plateau is measured from preoperative radiographs.
The patellar tendon is attached to the tibial tuberosity (the front top portion of the tibia) and it is the tibial tuberosity that is actually advanced. The tibial tuberosity is cut in a wedge fashion and moved forward the predetermined amount.
It is held in place by a titanium cage, fork and tension band plate. Bone grows over and through the cage and fills in between the tibia and the advanced tibial tuberosity.
This technique is not appropriate for dogs with tibial slopes greater than 27° to 30°.