Tibial Tuberosity Advancement – TTA
a surgical procedure used to return normal function to knees (stifles) in dogs and cats that have suffered from a ruptured cranial cruciate ligament (same as the anterior cruciate ligament in people).
Cranial Cruciate ligament rupture is the most common orthopedic injury in dogs of all breeds and sizes. The TTA procedure is designed to return the cruciate deficient stifle to full function by surgically changing the biomechanics of the knee. This change is accomplished by moving the attachment of the straight patella tendon forward and involves an osteotomy of the tibia. The portion of the tibia that is moved is stabilized by a permanent titanium implant system. The major advantages of the TTA over other cruciate ligament augmentation procedures are:
- Rapid (1-2 weeks) return to full weight bearing.
- Protection of articular cartilage through rapid return of normal joint range of motion.
- Decreased progression of arthritis over time.
- Good prognosis for return to full athletic activity.
- Acute onset of a rear limb non-weight bearing or toe-touching lameness
- If left unattended the lameness cycles in severity over 6-8 weeks
- Decreased Range of Motion (stilted gait)
- Hind leg outstretched while sitting
- Weight shift while standing
The diagnosis of a cranial cruciate injury is made by manipulating the stifle into a position of anterior drawer (tibia slides forward). The only injury which allows this type of movement is cranial cruciate ligament injury. In addition soft tissue thickening on the inside of the stifle is often present, indicating the chronic nature of this disease (medial buttress.) If the meniscus is damaged an audible “click” or “pop” may be heard when the dog is walking or when the stifle is put through a normal range of motion.
The TTA procedure involves an osteotomy (cutting bone) of the tibial tuberosity (insertion of the straight patellar ligament). The top portion of the tuberosity is advanced forward and held in place with a titanium basket, plate, bone fork and screws. The stifle joint is inspected, if the medial meniscus is damaged the damaged portion is removed, remnants of the ruptured ligament are removed and the joint is flushed to remove inflammatory debris. A bone graft is collected from the femur and placed in the osteotomy gap.
The diagnosis of a ruptured cranial cruciate ligament can be suggested by your general practice veterinarian, and ultimately determined by consulting with a veterinary orthopedic surgery specialist, who will physically manipulate the joint and if needed evaluate radiographs to decide if your pet is a good candidate for the TTA procedure.
The TTA surgery is minimally invasive, with low complication rates, and can minimize the progression of degenerative joint disease (arthritis) by decreasing patellar-femoral pressure and femoral-tibial pressure. It is the only cranial cruciate ligament repair procedure that uses titanium, which is more biocompatible than stainless steel and reduces the risk of infection and rejection of the implants.