a.k.a. Torn knee ligament in dogs
It’s the most common cause of hind limb lameness, pain and subsequent arthritis in dogs, but it’s probably something most people have never heard of.
Cranial Cruciate Ligament Disease (CCLD) is the partial or complete tearing of a ligament in the knee, or stifle, on the back leg. (In humans, this ligament is called the anterior cruciate ligament, or ACL).
What causes it?
While trauma can cause injury to the CCL, more often it is related to age, obesity, poor physical condition, conformation and breed.
“Ligament injury is a result of subtle, slow degeneration that has been taking place over a few months or even years rather than the result of acute, sudden trauma to an otherwise healthy ligament,” explained Dr. Brett C. Wood of Asheville Veterinary Specialists/REACH of Asheville.
Wood is well acquainted with CCLD, and it is one of the most common surgeries he performs as a veterinary surgery specialist.
Although some of the large and giant breeds have a higher occurrence of CCLD, such as Rottweilers, Golden Retrievers, Staffordshire Terriers, Mastiffs, Akitas, Saint Bernards, German Shepherds and Labrador Retrievers, any dog of any size or breed can suffer from this injury.
Body condition and weight are usually the bigger risk factors for developing CCLD because poor muscling and extra weight put a lot more strain on the ligament.
“The only way to probably reduce the risk of CCL injury is to keep the pet at a good body condition and an active lifestyle,” Wood said. “Both of these factors can be influenced by pet owners. A good fitness level of regular activity is advised and will also help avoid obesity.”
Because ligaments do not have the ability to heal on their own, CCL injuries usually require some form of treatment, ranging from therapy to surgery.
“Usually CCL injury is the result of chronic over stressing of the ligament causing initially a partial injury that in most patients progresses with time to a complete injury,” Wood said. “Instability of the stifle joint results from CCL injury and secondary meniscal tears and produces knee pain that manifests as lameness.”
If the injury is mild and caught early on, restricted activity and medications can be effective treatment, particularly in smaller patients, but in larger patients, the injury tends to be progressive and tears often require further measures.
If surgery is needed, there are several options available depending on the patient’s weight, body size, age, health status, normal activity level and the owner’s expectations.
The lateral suture technique involves surgically implanting a prosthetic ligament to mimic the function of an intact cranial cruciate ligament. When the dog places weight on the knee joint, the sutures keep the lower tibia bone from moving too far forward in relation to the upper femur bone.
“With restricted activity, physical therapy and over time, the formation of scar tissue provides long-term stabilization of the joint,” Wood explained.
However, the sutures can be strained or overstretched resulting in poor function of the joint. A newer technique called Tightrope (TR) addresses these issues by fixing the bone at both the tibial and femoral attachments, using more accurate isometric placement and improving strength and stiffness characteristics of the implant with less invasive capabilities.
Other options are the osteotomy techniques available: the Tibial Plateau Leveling Osteotomy (TPLO) for medium to large breeds or the Tibial Tuberosity Advancement (TTA).
Both of these techniques modify the function of the knee joint itself rather than attempting to repair the function of the torn ligament. Basically, these procedures replace the function of the torn CCL without replacing the structure itself.
What is the prognosis?
Prognosis for surgical repair of CCL injuries are generally good, Wood said.
A good long term outcome for large-breed dogs without surgery is 10 to 20 percent. In dogs with the lateral suture repair, it increases to 75 percent, and dogs who have either a Tightrope or TPLO/TTA procedure have a 90 percent positive long-term outcome.
“In general, there is no universal ‘silver bullet’ to fix all CCL injuries and even with the newer techniques, all dogs will likely suffer from some degree of ongoing osteoarthritis,” Wood said, but “historically, a good functional long-term outcome is seen.”
Regional Emergency Animal Care Hospital and Asheville Veterinary Specialists is a 24-hour veterinary emergency and specialty hospital at 677 Brevard Rd. in Asheville, NC. For information or pet emergencies, call 828-665-4399 or visit www.reachvet.com.