Tibial Tuberosity Advancement (TTA) system

Tibial Tuberosity Advancement (TTA) System: A Modern Surgical Technique for Canine Cruciate Ligament Repair

Introduction

The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments in the canine hind limb, leading to joint instability, pain, and eventually degenerative joint disease (DJD). Surgical intervention is often required to restore stability and prevent further damage to the joint. One of the latest surgical techniques for canine ACL repair is Tibial Tuberosity Advancement (TTA) system, which has gained popularity due to its effectiveness in improving joint function, reducing pain, and minimizing postoperative complications. In this article, we will delve deeper into the TTA system, its principles, applications, benefits, and limitations.

Anatomy and Physiology of the Canine Stifle Joint

Before we delve into the TTA system, it is crucial to understand the anatomy and physiology of the canine stifle joint. The stifle joint is the equivalent of the human knee joint and is made up of the femur, tibia, and patella bones. The ACL is responsible for stabilizing the joint by preventing the tibia from sliding forward relative to the femur. In dogs, the ACL is located within the joint capsule and is composed of collagen fibers that attach to the femur and tibia bones.

Pathogenesis of ACL Rupture in Dogs

ACL rupture in dogs can occur due to various reasons, including genetics, age, obesity, physical activity, and trauma. When the ACL ruptures, the tibia bone slides forward, causing the joint to become unstable, and resulting in pain, inflammation, and eventually DJD. Conservative management, such as rest, medication, and physical therapy, can help alleviate pain, but it does not address the underlying problem of joint instability. Surgical intervention is often required to restore stability and prevent further damage to the joint.

Principles of the TTA System

The TTA system is a modern surgical technique for canine ACL repair that aims to restore joint stability by changing the angle of the tibial plateau. The tibial plateau is the top surface of the tibia bone that articulates with the femur bone to form the stifle joint. In dogs with ACL rupture, the tibial plateau slopes downwards, causing the tibia bone to slide forward relative to the femur bone. The TTA system involves cutting the tibial tuberosity, the bony prominence located below the knee joint, and advancing it forward to increase the angle of the tibial plateau. The advancement is stabilized using a titanium cage and screws, which promote bone healing and fusion.

Advantages of the TTA System

The TTA system offers several advantages over traditional ACL repair techniques, such as the tibial plateau leveling osteotomy (TPLO) and extracapsular repair. First, the TTA system is more biomechanically sound, as it changes the angle of the tibial plateau to prevent forward tibial thrust, which is the main cause of ACL rupture. Second, the TTA system preserves the native ACL, reducing the risk of complications such as infection, graft failure, and implant failure. Third, the TTA system allows for early postoperative weight-bearing and rehabilitation, which improves joint function and reduces recovery time. Fourth, the TTA system is suitable for dogs of all sizes and breeds, as it can be customized to individual needs.

Limitations of the TTA System

Like any surgical technique, the TTA system has its limitations and potential complications. The most common complication is implant failure, which can occur due to mechanical stress, infection, or poor bone healing. Implant failure can lead to joint instability, pain, and the need for revision surgery.

Other potential complications of the TTA system include tibial crest fracture, patellar tendonitis, and joint effusion. Additionally, the TTA system is a complex surgical technique that requires specialized training and expertise, which may limit its availability in some veterinary clinics. Moreover, the TTA system is more expensive than other ACL repair techniques, which may not be feasible for some pet owners.

Candidates for the TTA System

The TTA system is suitable for dogs with ACL rupture and joint instability, as well as those with concurrent meniscal tears or DJD. The ideal candidate for the TTA system is a dog with a body weight greater than 15 kg, as smaller dogs may not have enough bone mass to support the titanium cage. Moreover, the TTA system is not recommended for dogs with severe patellar luxation, severe cranial cruciate ligament (CCL) degeneration, or medial patellar luxation.

Preoperative Evaluation and Planning

Before undergoing the TTA system, the dog must undergo a thorough preoperative evaluation, including a complete physical examination, radiographic imaging, and laboratory testing. The radiographic imaging should include both stifle joint views and hip views to rule out concurrent hip dysplasia or arthritis. Moreover, the surgeon should carefully plan the surgery, including the size and position of the titanium cage, the amount of tibial tuberosity advancement, and the type of anesthesia and pain management.

Surgical Technique

The TTA system is a technically demanding surgical technique that requires specialized training and expertise. The surgery is performed under general anesthesia, and the dog is positioned in dorsal recumbency. The surgeon makes an incision over the tibial tuberosity and detaches the patellar tendon from the tuberosity. The tuberosity is then cut using a specialized saw, and a titanium cage is placed over the cut. The cage is secured using screws, and the patellar tendon is reattached to the tuberosity. The joint is then checked for stability, and the incision is closed using sutures or staples.

Postoperative Care and Rehabilitation

After surgery, the dog is placed on pain medication and antibiotics, and the joint is monitored for swelling, pain, or infection. The dog is allowed to bear weight on the affected limb immediately after surgery, but restricted activity is recommended for the first few weeks. The dog should be kept on a leash and prevented from jumping, running, or climbing stairs. Physical therapy, including passive range of motion exercises and controlled exercise, should begin within a few days after surgery to improve joint function and prevent muscle atrophy. Regular follow-up visits with the surgeon are necessary to monitor the healing process and detect potential complications.

Conclusion

The Tibial Tuberosity Advancement (TTA) system is a modern surgical technique for canine ACL repair that aims to restore joint stability by changing the angle of the tibial plateau. The TTA system offers several advantages over traditional ACL repair techniques, including biomechanical soundness, preservation of the native ACL, and early postoperative rehabilitation. However, the TTA system has its limitations and potential complications, and it requires specialized training and expertise. Therefore, the decision to undergo the TTA system should be made after a thorough preoperative evaluation and consultation with a qualified veterinary surgeon.