Tibial Tuberosity Advancement Instead of altering the slope of the tibial plateau, however, the TTA alters the point of insertion of the patellar tendon. Only part of the bone (the tibial tuberosity) is cut, “advanced” by means of a titanium cage, and secured with a plate and screws. This advancement acts to “tighten-up” the joint, alleviating the instability. A theoretical advantage of this procedure is its less-invasive nature — there is less surgical dissection of the soft tissues and the tibia is not cut within the weight-bearing axis. TTA cages have been proven to work just as effectively with a forkless plate and using standard cortical screws.