The TTa procedure is based on the research that the Patellar Ligament can stabilize the joint if it is at a 90 degree angle to the Tibial Plateau. The Patellar Ligament is one of the toughest ligaments in the body, and it is completely controlled by one of the biggest muscles in the body, the quadriceps muscle on the front of the leg. By advancing the Tibial Tuberosity, we can ivercome the abnormal front to back motion called the Tibial Thrust, and can also tend to overcome the tendance for Pivot Shift. Current thought is that this procedure leads to less arthritic change in the joint. This procedure can be sucessfully done on any size dog, and is currently the treatment of choice by many surgeons.