What is the cranial cruciate ligament?
The cranial cruciate ligament CCL (also called the ACL or anterior cruciate ligament in people) is one of the primary stabilizers of the knee joint. It is made up of multiple fibers of collagen that are woven together to form a strong band of tissue that connect the femur (thigh) and tibia (shin) bones. Its primary functions are to prevent sliding, hyperextension and rotation of the knee. Damage to this ligament is the most common cause of lameness in dogs. Call (406) 587-3996 to schedule an appointment today.
How is the cruciate ligament damaged?
Occasionally, there may be an acute injury to the joint from trauma, but more often, there appears to be a chronic degeneration of the ligament. There are some breeds that appear to be predisposed to ligament damage including Labradors, Pit bulls, Rottweilers, West highland white terriers and Newfoundlands. Excessive body weight appears to put animals at an even higher risk. Unfortunately, over 50% of the time, both legs will suffer cruciate ligament injury. Once the ligament tears, shearing or instability between the femur and tibia will often damage the meniscus. This cartilage pad sits between the two bones and acts as a cushion or stabilizer. Once damaged, it acts like a stone in the shoe and further contributes to pain.
What are the signs of cruciate ligament injury?
Lameness is the most common clinical sign. Sometimes this will be a non-weight bearing lameness, but in early cases, it may show up only after exercise. Dogs may be reluctant to exercise, not want to jump or go up stairs and often kick the leg to the side as it hurts to flex the knee. Many owners start to hear a “pop” or “click” when there are tears in the meniscus.
How is cruciate injury diagnosed?
Palpation of the affected knee by an experienced clinician is often enough to diagnose the condition in dogs. Especially when there is a complete tear of the ligament, a classic drawer or thrust motion will be present which is a definitive diagnosis. Early partial ligament injuries can be more challenging and may only have pain with hyperextension of the joint or rotation and mild joint swelling. Thickening of the inside of the joint (buttress) is often present in chronic cases as the body starts to form scar tissue to try to stabilize the joint. Radiographs (x-rays) can help identify joint swelling but will not show the ligament. MRI is commonly performed in people, but rarely used for a diagnosis in dogs. Confirmation of the injury occurs at surgery with direct visualization of the ligament. This can be done with arthroscopic or “keyhole” approaches to the joint. The meniscus is always inspected at the time of surgery to determine if damage is present. Meniscal injury to some extent is present in ~60% of patients with cruciate ligament injury.
How is cranial cruciate ligament injury treated?
Medical management—Unfortunately, without surgical intervention, most animals will progress to chronic lameness and arthritis. Medical management is geared toward treating the pain and joint deterioration that occurs. Weight loss in overweight dogs may be one of the most effective treatments. Non-steroid anti-inflammatory drugs, pain relievers, and nutraceuticals like glucosamine and omega 3 fatty acids are used to treat signs and try to limit the progression of arthritis. Some people advocate the use of braces or custom orthotics but due to poor patient compliance and failure to treat the underlying problem, the outcome is highly unpredictable. Call (406) 587-3996 to schedule an appointment today.
Surgical treatment—Over 100 techniques have been described to treat cranial cruciate injury. To simplify these, they can be separated into two main treatment types. Those that aim to replace the damaged ligaments function with something else and those that alter the geometry and physics of the joint.
- Replacement options: These techniques have been around since the mid 1900s and mimic procedures performed in people. A variety of tissues and substances can be used to mimic the function of the cruciate ligament. In people, these tissues may come from the patient (muscle, tendon or ligament) that are transposed into the joint or may come from cadavers. In dogs, Nylon and strong braided suture material are used most commonly. The problem with these procedures is that they don’t address the underlying cause of joint instability and anything that is used is typically biologically and mechanically inferior to the original ligament. The techniques are used most commonly in very small patients or animals with less active lifestyles. These procedures rely heavily on the body's own ability to create scar tissue to help stabilize the joint.
- TPLO (Tibial Plateau Leveling Osteotomy): The TPLO is the most common treatment for cruciate ligament injury in the dog. Instead of replacing the ligament, the TPLO aims to alter the forces that act on the joint and make the ligament less important for stability. This is done by altering the angle of the surface of the tibia (the tibial plateau). A controlled cut or osteotomy is performed on the top of the tibia bone and the surface of the tibia bone is isolated. The surface is then rotated to level the tibial plateau. A strong plate and screws are used to hold the bone in its new position. The analogy we often use is that of a car parked on a hill. If a car is parked on a hill, the parking brake (cruciate ligament) must be applied to prevent the car (femur) from rolling down the hill (tibia). If the car is parked on a flat surface, the parking brake is not needed. This summarizes the effect of the TPLO. It results in joint stability in the absence of the ligament.
What happens after surgery?
Most of our patients are hospitalized for pain control for 1 night after surgery. A typed discharge instruction will be sent home to describe the post-operative care and medications. Most dogs will walk on the leg within 1 day of surgery. The first 2 weeks will have the most exercise restrictions and patients typically are confined to a crate or small room and just go outside for eliminations. After the 2 week recheck, most patients will start progressive leash walking and a physical therapy plan. By 8 weeks out, dogs are typically doing 40 minutes of leash walking 2 to 3 times daily. At 8 weeks we take another set of x-rays to confirm healing and will begin off leash activity.
What is the success of surgery?
The definition of success is highly variable. Returning animals to their preinjury level of function and activity should occur 95% of the time. Some level of arthritis will progress, but much less with surgery than without. The most common complications include incision issues, infection, and swelling.
Why should I choose Bridger Veterinary Specialists for my pet’s cruciate ligament injury?
Experience is key. With over 40 years of knee surgeries and thousands of clinical cases, there is very little our veterinary team hasn’t seen. We use the most advanced equipment and implants to help assure an excellent outcome. We have a dedicated orthopedic operating suite to minimize the chance of any complications and infection. We use advanced pain management techniques like femoral and sciatic nerve blocks, epidurals and long acting local blocks in addition to an aggressive oral pain medication protocol to assure your pet’s comfort. Call (406) 587-3996 to schedule an appointment today.