Dr. April Guille
Damage to the cranial cruciate ligament (CCL) is one of the most common orthopedic injuries in dogs. The majority of dogs have secondary degenerative changes in the ligament that lead to rupture. The causes for cranial cruciate ligament degeneration are multifactorial (a combination of genetic and environmental factors). Trauma leading to rupture is seen in a smaller percentage of patients.
The cranial cruciate ligament is a major stabilizer in the stifle (knee) joint, both limiting forward motion of the tibia in relation to the femur (termed cranial thrust) and internal rotation in the joint. Unfortunately, the torn ligament will not heal itself and partial tears almost always progress to complete rupture of the ligament. After rupture, the stifle joint becomes unstable, leading to inflammation, pain, meniscal injury, fibrosis, and osteoarthritis in the joint.
Clinical signs: CCL rupture causes pain and lameness in the affected leg. Dogs with partial tears may initially improve after restriction of activity, but the lameness will typically return as they continue to tear their ligament, leading to a cyclical course of lameness and improvement with rest. The lameness often becomes progressively worse to the point of a permanent lameness of varying degrees. Dogs can also become very lame after tearing their medial meniscus. Other clinical signs include stiffness, sitting with the leg out to the side, muscle atrophy, decreased activity, and occasionally, owners may hear an audible “click” if the medial meniscus is torn.
Diagnosis: The diagnosis is based on history, physical exam, and radiographic findings. On physical exam, we will check the stifle for drawer motion, or an abnormal forward motion of the tibia in relation to the femur, and cranial thrust. Joint effusion (swelling) is present in the joint and long-standing ruptures will have secondary fibrosis around the joint, especially on the inner aspect, termed medial buttress. The cruciate ligament is not visible on plain radiographs, but radiographs are taken to rule out other causes of the lameness, evaluate the joint for evidence of effusion and osteoarthritis, and pre-operative planning. Occasionally, some dogs can be very tense, and sedation will allow better evaluation of the stifle for abnormal motion.
Medical Management: Cruciate ruptures are best handled with surgery (see below). But in addition to surgery, medical management is used to assist with the joint health, manage osteoarthritis, and assist with the recovery from surgery. This may include but is not limited to: glucosamine and chondroitin supplementation, non-steroidal ant-inflammatories, physical therapy, and alternative therapies such as laser or acupuncture treatments. Please see the page on managing osteoarthritis.
Surgical Treatment: Although the arthritis in the joint cannot be reversed, early surgical intervention may mitigate the progression of osteoarthritis and therefore improve overall long-term function of the joint. Surgical techniques can broadly be divided into intracapsular (within the joint) and extracapsular (outside of the joint) repair. Regardless of the technique used, the joint is entered and the medial meniscus is evaluated at the time of surgery. The two menisci in the joint act as a cushion and shock absorber. A portion of the medial (inner) meniscus can become pinched and torn due to the abnormal motion present in a CCL deficient stifle joint. This torn piece, if present, is removed.
Below is a summary of the three surgical treatments we use here at PVS for treatment of CCL rupture. We will discuss these options with you at the time of your appointment and what might be best suited to you and your pet’s needs.
Lateral Fabellar Suture Technique
After closure of the joint capsule, two sutures are passed around a small bone (lateral fabella) on the back side of the femur and through a bone tunnel created in the top of tibia. They are then tied to an appropriate tension. This orientation mimics the cranial cruciate ligament, providing temporary stability. The ultimate stability is provided by scar tissue that surrounds the joint.
Patients that receive this surgery typically take a little longer (up to 6 months) to be at their best function post-operatively. There is a subset of larger dogs, especially active dogs, who may not do as well with this surgery compared with the biomechanical stabilizations (discussed below).
Tibial Plateau Leveling Osteotomy (TPLO)
The TPLO is a form of biomechanical stabilization that eliminates the need for the cranial cruciate ligament by altering the forces acting on the stifle joint and preventing cranial thrust of the tibia. After evaluation of the menisci, the joint is closed and the tibial bone is cut. The bone is rotated several millimeters and plated in a new position. These measurements are determined based on preoperative evaluation of specific radiographic positions. The tibia heals in its new orientation, “leveling” the tibial slope and stabilizing the stifle joint.
Tibial Tuberosity Advancement (TTA)
The TTA is another form of biomechanical stabilization of the stifle joint. Like the TPLO, the TTA eliminates cranial thrust by cutting the tibial tuberosity and repositioning it with a spacer and a titanium plate. The measurements for the implants are determined on specific pre-operative radiographic views.
Which surgery is right for your pet?
While all three surgeries help improve the lives of our pets, many factors determine which specific surgery is best for you and your pet. We generally find that dogs undergoing a biomechanical stabilization (TTA or TPLO) will have a better short-term and likely long-term recovery. However both of these surgeries, while approximately the same price, will cost more than the lateral fabellar suture technique due to the required equipment and expertise. Of the two biomechanical surgeries, the TTA is generally preferred by Dr. Guille. In comparison with the TPLO, the TTA is less invasive, requires a shorter anesthesia time, patients typically make a quicker recovery, and the complications are usually less serious in nature if they occur. Studies have also shown that of the three procedures, the TTA is the only one to restore the contact mechanics in the joint back to “normal”, or what existed prior to rupture of the cruciate. The TPLO, however, is able to be used in a broader category of bone conformations, so some dogs are not suited to the TTA procedure. The discussion of the pros and cons of each surgery, along with the recommendation for your pet, will be determined at the time of your consultation. Specific radiographic views may be required prior to surgery to make the final determination.