What is TTA surgery?
TTA is the abbreviation for tibial tuberosity advancement. This a surgical procedure used to treat cranial (or anterior) cruciate ligament rupture in the knee joints of dogs. It involves cutting the top of the shin bone (the tibia), moving it forward and stabilising it in its new position in one of a number of ways.
Cranial cruciate ligament rupture is the most common cause of hind limb lameness in dogs. As a result, TTA and other operations that involve altering the shape of the tibia are common orthopaedic surgical procedures performed in dogs in specialist orthopaedic practices. (See also Cranial Cruciate Ligament Rupture Information Sheet)
How does TTA surgery work?
Following rupture of the cranial cruciate ligament, the knee (stifle) becomes unstable. When the dog takes weight on the limb this instability allows the shin bone (tibia) to move forward relative to the thigh bone (femur). The stifle feels as though it is ‘giving-way’ and this can cause the dog to appear severely lame.
One reason the tibia moves forward with weight-bearing is that the top of the bone (called the tibial plateau) is not perpendicular (90 degrees) to the tendon (the patellar tendon) that joins the knee cap (the patella) to the tibial plateau.
TTA surgery aims to make the tibial plateau perpendicular to the patellar tendon and, in doing so, prevent the shin bone moving forwards. The knee then feels stable for the dog when weight-bearing, despite the fact that the ligament has been ruptured and not directly repaired.