1. What is the Cranial Cruciate Ligament?
The cranial cruciate ligament (CCL), called the anterior cruciate ligament (ACL) in humans, is a tough band of tissue that connects the two main bones of the knee joint. The CCL attaches the upper bone (femur) to the lower bone (tibia) and helps prevent excessive motion between these bones. A ruptured CCL is the most common orthopedic injury in dogs, and results in a painful and unstable joint. If left untreated, a ruptured CCL will lead to progressive and irreversible degenerative joint disease (arthritis).
2. Why did my dog rupture this ligament?
There are generally two ways a dog’s cranial cruciate ligament can rupture. The first way is similar to a sports injury in people. Like a basketball player who plants his leg aggressively and then tears his ACL, a dog’s CCL may suddenly rupture from excessive force and leave the dog with an unstable and painful knee. Alternatively, a dog can experience years of normal “wear and tear,” which can leave the ligament weak and prone to full rupture. We don’t always know why or how a ligament ruptures. Some dogs begin limping after playing aggressively in the park, while others simply step off a curb and begin limping. We do know that obesity appears to be one of the most important predisposing factors in CCL ruptures, as excess weight can cause further strain on ligaments. So, watch those treats!
3. Why does my dog need surgery?
When a dog ruptures a cranial cruciate ligament, the joint becomes unstable. When he places weight on his limb, there is a shearing force on the joint. This shearing force is not just painful, but also potentially damaging to the cartilage (meniscus) in the joint. This abnormal shearing movement (called “tibial thrust”) predisposes the menisci (cartilage pads) to damage and promotes arthritic changes within the joint. These changes often become painful enough to render the limb mostly useless, especially in larger dogs. Surgically repairing a knee joint after a CCL tear provides stability to the joint, and thereby reduces the rate of future arthritic change. Additionally, when one CCL is ruptured, a dog will naturally transfer most of its weight to the other leg. In doing so, they inadvertently put the other CCL in danger of rupture due to overuse. If a dog has tears in both cranial cruciate ligaments, simple tasks such as rising, walking, and squatting to urinate or defecate become very difficult, and the dog’s quality of life may suffer.
4. Why do different surgeons recommend different procedures?
For many years, different surgeons have advocated for several different procedures to repair ruptured cranial cruciate ligaments. Over time, many procedures have fallen out of favor as more research and technological advancements have emerged. As the veterinary industry learns more and more about cranial cruciate ruptures and repair options, there remains three procedures that consistently show the best results: Tibial Tuberosity Advancement (TTA), Tibial-Plateau-Leveling Osteotomy (TPLO) and Lateral Extracapsular Suture. Each of these procedures have their pros and cons, and most recommendations are made from the surgeon’s personal preference in accordance with what is best for each individual patient.
5. What are the pros and cons of the TTA procedure?
During this surgery, the tibia is cut, repositioned, and stabilized in a new position that effectively changes the biodynamics of the joint, so a cruciate ligament is no longer needed. The theory behind this procedure is that when the cruciate ligament is torn, the tibial plateau (the top of the tibia) and the patellar ligament should be repositioned at 90 degrees to one another to combat the shearing force generated as the dog walks. To make this happen, the tibial tuberosity (front of the tibia where the patellar ligament attaches) is separated and anchored in its new position by a steel bone plate. Many surgeons prefer it to the TPLO (see below) since dogs seem to heal and return to functional use of the limb faster.
This procedure requires specialized equipment and training and is available at Shamrock Animal Hospital. The primary benefit of the TTA lies in the fact that it is a less invasive procedure than the TPLO , which translates to a more expedient and predictable return to functional use of the limb. It is especially good in medium to large breed dogs weighing more than 40-60 lbs. The TTA has excellent long-term outcomes and is significantly less expensive than the TPLO.
6. What are the pros and cons of the TPLO procedure?
The TPLO represents another take on how to use the biomechanics of the knee to create stabilization. With this surgery, a different portion of the tibia bone is cut, rotated, and finally stabilized to change the biomechanics of the joint to negate the need for a cruciate ligament. In this case, the natural weight-bearing of the dog stabilizes the knee joint. Like the TTA, the knee joint is opened to remove remnants of the cruciate ligament as well as portions of damaged meniscus if present. Benefits: Like the TTA, large breed dogs ( about 40-60lbs) are more likely to achieve full (or nearly full) return to function. Cons: The TPLO is considered a more invasive surgery than the TTA and as such, it is associated with a slower return to functional use of the limb. This surgery is the most expensive surgical option available, but remains a viable surgical option, especially for large breed dogs.
7. How do TTA and TPLO procedures affect outcome?
In the TPLO procedure, the bone cut is made in the weight-bearing region of the tibia. Because of this, the surgery results in a longer and slower recovery, as dogs have limited use of the limb for several weeks following surgery. In the TTA procedure, the bone cut is made in a non-weight bearing region of the tibia, which means dogs often begin using the limb the day after surgery. Many pet owners with dogs who have undergone a TPLO on one leg and a TTA on the other report a much faster and easier recovery with the TTA. With the TPLO, a slower return to limb use after surgery often means more muscle loss due to disuse atrophy. Consequently, more physical therapy is often required to regain the lost muscle mass in dogs that have the TPLO procedure.
8. What are the pros and cons of Lateral Fabellar Suture Surgery (extracapsular repair)?
The Lateral Fabellar Suture is considered an “extracapsular repair” (i.e., outside the joint). This procedure is very effective for most small-to-medium sized dogs and cats. In these surgeries, the knee joint is opened and inspected. The torn or partly torn cruciate ligament is removed. If the meniscus is torn, the damaged portion is removed. A strong monofilament suture is used to tighten the joint to prevent the shearing force in the knee (tibial thrust motion) and effectively takes over the job of the torn cranial cruciate ligament. This surgery can be very effective and is typically reserved for smaller dogs or cats (often weighing less than 40 pounds). Although it’s typically the least expensive option for repair, it’s also considered the most vulnerable to failure (especially in dogs over 60 pounds). If the suture line breaks before the surgery site fully heals, a second surgery would be required.
9. I have been told that my dog may eventually rupture the cranial cruciate ligament in the opposite leg. Is this true?
Statistics tell us that 40-60% of dogs that rupture one cranial cruciate ligament will eventually rupture the other one as well. This is likely multifactorial and caused in part by obesity, genetics, and continued wear and tear on the ligament over time.
10. What can I do to lower the chance my dog will need surgery in the opposite leg?
As previously stated, obesity is one of the most important contributing factors in cranial cruciate injuries. If your dog is currently overweight, focus your efforts on a prescribed weight loss program. If you’re not sure if your dog is obese, just ask one of our veterinarians—they’ll assess your dog’s current body condition score and will explain what it means for you and your dog.
11. What can I do to speed up my dog’s recovery?
Just like with humans who undergo knee surgery to repair torn ACLs, dogs will benefit greatly from a physical therapy plan following surgery for a ruptured CCL. At Shamrock Animal Hospital, we provide just that. After surgery, we’ll provide a customized 8 to 12 week physical therapy plan that outlines daily exercises to help your dog heal faster and return to normal function sooner. This plan is thoroughly explained to you before and after surgery, and we are happy to demonstrate the specific exercises with you and your dog, so you feel comfortable and confident during your dog’s healing period. From start to finish, we’re committed to walking this journey with you and your dog so we can achieve the best possible outcomes following surgery!