Tibial Tuberosity Advancement (TTA)

This  is by far the most frequent orthopedic injury in dogs. The cranial  cruciate ligament is very similar anatomically to the anterior cruciate  ligament (ACL) in people. The ligament lives inside the knee joint, and  provides stability between the femur and tibia. When this ligament is  completely torn, the knee becomes unstable. Initially this injury causes  pain and inflammation, and over time it leads to significant  arthritis. 

What a Typical Canine CCL Injury Looks Like:

Diagnosing  a torn cruciate ligament is based mostly on a good physical exam.  Unlike people, who usually completely tear the ligament, many dogs  slowly degenerate this ligament over several weeks to months. Some dogs  have sudden symptoms, but others have intermittent or chronic lameness.  When evaluated by your veterinarian, there are several signs that can  lead us to suspect a CCL injury. Most dogs will have a pronounced limp,  that causes a toe touching lameness. Effusion (swelling) can usually be  palpated in the joint, and most dogs have pain upon extension of the  knee. When the ligament is fully torn, the knee is unstable, which leads  to a positive drawer sign. This means that your doctor can grasp the  femur and tibia, and abnormally move them back and forth. While  radiographs are usually performed to evaluate the knees and hips, the  CCL is not visible. However early arthritis and effusion are usually  appreciated. 

Surgery: 

Whenever  we diagnose a CCL, most veterinarians will recommend surgery to restore  stability to the joint and prevent the onset of arthritis. There are  many procedures available, all with their own pros and cons. With all of  our cruciate surgeries, the joint is explored and evaluated. This will  confirm the rupture of the CCL and evaluate the meniscus for injury. 

Here at TVVH , we perform two surgeries as detailed below. Both of them require a full 3 months of exercise restriction. 

Tibial Tuberosity Advancement (TTA)

Dr.  Smith performs the TTA at TVVH. While other procedures focus on  attempting to create a new attachment between the tibia and femur, the  TTA relies on adjusting the existing anatomy to allow for the knee joint  to function without a cruciate ligament. In the TTA, a osteotomy (cut  in the bone) is created through the tibial tuberosity (front aspect of  the shin bone). Several implants are placed, including a cage, plate,  and several screws. This moves the insertion of the patellar ligament  forward, which in turn creates a force against the tibia preventing the  forward motion that occurs with cruciate ligament rupture. The main  benefit of this procedure are a quicker return to function, especially  for our larger patients. The downside is the additional cost, and the  nature of the procedure requires more dramatic implants. Most patients  with a TTA will start to use their leg within a few days, and have good  function within the first two weeks. However, it will take at least 6-8  weeks for their bone to heal around the implants. Above is an image of  the knee after a TTA has been performed. Below is a video of a patient  walking 2 weeks after their TTA surgery. 

Extracapsular Repair:

During  this procedure we place an implant on the outside of the joint, which  acts as an external cruciate ligament. A large nylon suture is either  passed behind the fabella (a small bone behind the femur) or placed in a  bone anchor (a stainless steel screw placed in the femur). The line is  then passed through a tunnel in the tibia, and returned to the outside  of the joint. The line is secured in place, which stabilizes the joint.  The benefit is a less invasive and more economical procedure, the  downside is a slower return to function especially for our larger  patients. It is not uncommon for a dog to hold his leg up for 1-2 weeks  following surgery. It may take 3 months before a dog has good use of  it’s leg.

What To Expect: 

When  your dog presents the morning of surgery, basic bloodwork is always  performed to ensure that their liver and kidneys are healthy enough to  undergo anesthesia. Unless already performed, radiographs (x-rays) are  taken of both knees and the hips to allow us to complete an entire  orthopedic picture of your dog. The surgery itself usually only lasts a  couple of hours, but we usually keep our orthopedic patients overnight  to control their pain and allow them to rest. 

After  surgery, it is vital to restrict the activity of your dog. While the  implant is in place, the body is actively healing around it. If your dog  suddenly puts excessive stress on the implant, it can rupture, leading  to failure. Therefore for the 3 months after surgery, no running,  jumping, playing, or any off leash activities should be permitted.  However, we do recommend introducing well controlled leash walks as  tolerated by your dog.

After  3 months, modest exercise can be permitted. However occasional limping  or pain may be noticed after excessive activity. For many dogs, it takes  a full 9-12 months before no symptoms are noted. 

If  you have any questions or concerns about cruciate disease and either  one of these surgeries, please feel free to contact Dr. Smith at TVVH by  e-mail or phone.