Cranial Cruciate Ligament Repair
One of the most common injuries to the knee of dogs is tearing of the cranial cruciate ligament (CCL). This ligament is similar to the anterior cruciate ligament (ACL) in humans. There are actually two cruciate ligaments inside the knee: the cranial cruciate ligament and caudal cruciate ligament. They are called “cruciate” because they “cross” over each other inside the middle of the knee. For more information on these ligaments and how they can become damaged, see the handout “Cranial Ligament Rupture in Dogs.”
When the CCL is torn or injured, the shin bone (tibia) slides forward with respect to the thigh bone (femur), which is known as a positive drawer sign. Most dogs with this injury cannot walk normally and experience pain. The resulting instability damages the cartilage and surrounding bones and leads to osteoarthritis (OA).
What options are there for repairing my dog’s torn CCL?
When the cranial cruciate ligament is torn, surgical stabilization of the knee joint is often required, especially in larger or more active dogs. Surgery is generally recommended as quickly as possible to reduce permanent, irreversible joint damage and relieve pain. “Surgery is generally recommended as quickly as possible to reduce permanent, irreversible joint damage and relieve pain.”
The goals for treatment of CCL injury are to provide stability in the knee. This stability is designed to relieve pain, restore function and slow down the formation of osteoarthritis. Numerous surgical procedures have been described and studied, but no one treatment has been shown to be superior. Non surgical options have been described, but are often difficult to control and can have a disappointing result in active dogs. Though no one procedure is found to be superior, the prognosis for return to function and prevention of further damage is best attained with surgical stabilization of the knee. The decision on which procedure should be performed is based upon surgeon experience with the technique, scientific data to support each technique and patient suitability for the procedure. Present techniques can be divided into broad categories. These categories are best described as those techniques that work to replace the function of the CCL or techniques that use manipulation of the bones of the knee to provide stabilization (tibial plateau leveling osteotomy or tibial tuberosity advancement). Either procedure begins with a thorough exploration of the joint to address any other damage to internal structures of the knee (such as the meniscus).
TPLO - Referral Surgery - Mississauga-Oakville Veterinary Referral Hospital
A major advancement in the treatment of CCL rupture has been the development of tibial plateau leveling osteotomy or TPLO. This surgery changes the angle and relationship of the femur and the tibia. The overall intent of the surgery is to reduce the amount that shifts forward during a stride. This is accomplished by making a semicircular cut through the top of the tibia, rotating the top of the tibia, and using a bone plate to allow the tibia to heal. This realignment of the surfaces within the stifle helps to provide stability during a stride, and helps to reduce future joint inflammation and OA. By carefully adjusting the angle or slope of the top of the tibia, surgeons are able to replicate a more normal configuration of the knee joint and reduce mechanical stress.
“A major advancement in the treatment of CCL injuries has been the development of TPLO.
To better understand the purpose of leveling the tibia, we often use the analogy of a wagon on a hill.
Imagine a wagon tied to a post on the slope of a hill. As long as the rope holds, the wagon doesn’t roll downhill. If we add excess weight (or downward force) to the wagon, the rope could break and the wagon will roll down the hill. However, if the wagon is on level ground, it will not roll forward with added weight, even if the rope is broken.
In this example, the wagon is the femur, and it slides down slope of the top of the tibia when the CCL is ruptured. This instability leads to damage and destruction of the cartilage and bones of the knee joint. TPLO surgery “levels” the tibia to prevent the femur from sliding forward, thereby stabilizing the joint.
TPLO surgery involves making a curved cut in the tibia from the front to the back, much like half a smiley face. The top section of the tibia is then rotated backward until the angle between the tibia and femur is deemed “appropriately level,” typically between 2 and 14 degrees, with 5 degrees being the ideal angle. A metal bone plate is then used to affix the two sections of tibia in the desired positions, allowing the tibia to heal in its new configuration.
TTA is similar in concept to TPLO. Because it is considered slightly less invasive than TPLO, many dogs appear to recover slightly quicker. Most dogs, regardless of which of these two procedures are performed, are nearly normal 4 months after surgery.
The TTA procedure is more commonly performed in dogs with a steep tibial plateau, or angle of the top part of the tibia. Your dog’s surgeon will evaluate the joint geometry to determine which procedure is ideal.
In simplest terms, the front part of the tibia is cut and separated from the rest of the tibia. A special orthopedic spacer is screwed into the space between the two sections of bone to slide the front part of the lower knee forward and up. This moves the patellar ligament (the thick fibrous band that runs on the front of the knee from the top to the bottom of the joint) into better alignment, thereby removing some of the abnormal sliding movement. A bone plate is then attached to hold the front section of the tibia in the proper position. By changing the alignment of the patellar ligament, the forces that cause the femur to slip backward when the CCL is torn instead move straight down the tibia, resulting in less shearing force or instability.
SwivelLock Extracapsular Repair. (We perform this technique)
The SwiveLock Knotless technique is a minimally invasive technique that uses prosthetic materials designed to mimic the function of the CCL. The materials that sit on the outside of the knee (extra articular) are secured using a vented PEEK SwiveLock Suture Anchor at points biomechanically similar to the CCL. This incredibly strong prosthetic material has been used with great success in human joint stabilizing procedures and provides the temporary stabilization necessary for scar tissue formation and long-term joint stability and function. Other techniques that provide stability through bone manipulation include the tibial plateau leveling osteotomy (TPLO) and the tibial tuberosity advancement (TTA). These procedures require cutting and alteration of the bone to provide weight bearing stability. These procedures are options for those pets who have conformational issues that contribute to CCL injury and long term stability. It is important to recognize that there is not one procedure designed to fit every case. It is crucial that you work closely with your veterinarian to form a plan that best suits your pet. The process requires a complete examination, realistic goals and a post operative plan that allows for physical rehabilitation and rest. The commitment, regardless of surgical or non surgical choice, requires 10-12 weeks for healing and is enhanced by seeking support from multiple sources.
It is important to establish and follow a post-op plan with your veterinarian. It will most likely include restricted kennel rest when unobserved and controlled muscle building activities (i.e., leash walking) for eight weeks post-op. Professional rehabilitation is encouraged.