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).
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. Obesity appears to be one of the most important predisposing factors in CCL ruptures, however, as excess weight can cause further strain on ligaments. So watch those treats!
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. Plus, 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 up, walking and squatting to urinate or defecate become very difficult, and the dog’s quality of life may suffer.
For many years, different surgeons have advocated for different procedures to repair ruptured cranial cruciate ligaments. Historically, many procedures have been performed and have fallen out of favor as more research and technology has emerged to suggest these procedures were not as good as initially thought. 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.
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. Bone grafts are used to assist healing. 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, both of which are offered by Dr. Travis Wodiske at Family VetCare. Dr. Wodiske has been specially trained to perform this procedure, which means referral to an orthopedic specialist is not necessary. This also means it is significantly less expensive than the TPLO (mentioned below). The primary benefit of the TTA is a more predictable return to functional use of the limb. This procedure is currently the treatment of choice for many surgeons to treat CCL ruptures, especially for larger dogs.
The TPLO is another take on using the biomechanics of the knee to recreate stabilization. With this surgery, a different portion of the tibia bone is cut (the weight bearing surface), then rotated and stabilized to change the biodynamics of the joint to negate the need for a cruciate ligament. Because the weight-bearing surface of the tibia is cut, return to functional use of the limb is slow and generally takes much longer than the TTA procedure. For this reason, it is often viewed as a more invasive surgery and is often a less desirable procedure for many surgeons and pet owners. TPLO surgery is complex and requires years of specialized training in this technique. For this reason, referral to an orthopedic specialist is necessary, and therefore it is substantially more expensive. Cost aside, it is a very effective surgery, especially for larger breed dogs.
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 very 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. A slower return to limb use after surgery often means more muscle loss due to disuse. Consequently, more physical therapy is often required to regain the lost muscle mass in dogs that have the TPLO procedure. For this reason and others, Dr. Wodiske prefers the TTA procedure over the TPLO for most patients.
Both the Lateral Fabellar Suture and Tight Rope procedures are considered extracapsular repairs (outside the joint). These procedures are 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 suture or braided line 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. These surgeries can be very effective and are 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 or braided line breaks before the surgery site fully heals, a second surgery would be required.
Yes, statistics tell us that 40-60% of the 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.
As previously stated, obesity is one of the most important contributing factors in cranial cruciate injuries. If your dog is currently overweight, then focus your efforts on a prescribed weight loss program. If you’re not sure if your dog is obese, simply ask your veterinarian and they’ll assess your dog’s current body condition score and will explain what it means for you and your dog.
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 Family VetCare, 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 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, Family VetCare is committed to walking this journey with you and your dog so we can achieve the best possible outcomes following surgery!