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.
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.
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.