Cranial Cruciate Ligament Injury and TPLO Surgery for Dogs

Sentinel Veterinary Specialists & Emergency can diagnose and treat injuries involving your dog’s cranial cruciate ligament.

---

What is the cranial cruciate ligament?

A dog’s cranial cruciate ligament (CCL), known as the anterior cruciate ligament (ACL) in people, is made up of collagen fibers that are woven together to form a strong band of tissue connecting the femur (thigh) and tibia (shin). One of the primary stabilizers of the knee joint, the CCL prevents sliding, hyperextension, and rotation of the knee. Damage to the CCL is the most common cause of lameness in dogs.

How is the CCL damaged?

The CCL can become damaged by an acute injury, but more often the ligament suffers from chronic degeneration. Labradors, Pit Bulls, Rottweilers, West Highland White Terriers, and Newfoundlands seem to be predisposed to ligament damage, and dogs with excessive body weight are at an even higher risk. Unfortunately, CCL injuries affect both legs 50 percent of the time. Once the CCL tears, it creates shearing or instability between the femur and tibia, which can damage the meniscus—the cushion of cartilage between the two bones. Once the meniscus is damaged, it acts like a stone in a shoe and causes more pain.

What are the signs of a CCL injury?

Lameness is the most common clinical sign that an injury to the CCL has occurred, and in the early stages, it may be apparent only after exercise. Dogs with a CCL injury will typically be reluctant to exercise, jump, or go up and down stairs. They also often kick the affected leg to the side, as it hurts to flex the knee. Owners may even hear a "pop" or a "click" if the meniscus is torn.

How is a CCL injury diagnosed?

An experienced clinician can diagnose the condition simply by palpating the affected knee. When there is a complete tear of the ligament, a classic drawer or thrust motion will be present, which is a definitive diagnosis. Partial ligament injuries can be more challenging to identify, as they may cause only mild joint swelling and pain only with hyperextension or rotation of the joint. Chronic cases can sometimes be identified by a thickening of the inside of the joint (buttress) as the body starts to build scar tissue. X-rays can be used to examine joint swelling but will not show the ligament itself. Surgery with direct visualization is needed to evaluate the extent of the injury to the ligament. We can do this with an arthroscopic or keyhole approach, and we'll also inspect the meniscus to check for damage. Some degree of meniscal injury is present in about 60 percent of patients with a CCL injury.

How is a CCL injury treated?

Medical management—Surgical intervention is the best way to prevent chronic lameness and arthritis, but medical management can subdue the pain and control joint deterioration to some extent. For overweight dogs, weight loss can be effective. Non-steroidal anti-inflammatory drugs, pain relievers, and nutraceuticals such as glucosamine and omega 3 fatty acids can treat the symptoms of arthritis. Braces or custom orthotics are also options, but these don’t treat the underlying problem, and patient compliance is typically poor.

Surgery—More than 100 surgical techniques have been described to treat CCL injuries. These can be separated into two main types: Those that aim to replace the damaged ligament’s function with something else and those that actually alter the geometry and physics of the joint.

• Replacement options: Techniques using a variety of tissues and substances to replace the function of the CCL have been around since the mid-1900s. Used primarily on very small dogs or those with less active lifestyles, replacement procedures rely heavily on the body's ability to create scar tissue to help stabilize the joint. Nylon and strong braided suture material are the most common materials used. The main concern with replacement techniques is that they don't address the underlying cause of the dog’s joint instability, and any material used is inferior to an actual ligament.
• Tibial Plateau Leveling Osteotomy (TPLO): TPLO is the most common treatment for canine CCL injuries. Rather than replace the function of the ligament, the TPLO aims to create joint stability by changing the angle of the surface of the tibia (the tibial plateau). We do this by performing a controlled cut (or osteotomy) on the top of the tibia bone and rotating it. A plate and screws are used to hold the bone in this new position. The intent of TPLO is to level the angle between the tibia and femur to reduce the tibia's tendency to shift forward during a stride, much the same way that a car parked on a level surface won’t have a tendency to roll forward.

What happens after surgery?

We hospitalize most of our patients for one night following surgery so that we can administer appropriate pain control, and most dogs will walk on the leg within 24 hours of the procedure. We send our patients home with detailed instructions explaining post-operative care and medications. We typically recommend confining the dog to a crate or small room for the first two weeks to restrict movement as much as possible, other than going outside to eliminate. After a two-week checkup, most patients are cleared to begin progressive leash walking and physical therapy. By eight weeks post-op, dogs can usually do forty minutes of leash walking two to three times daily. At eight weeks, we take another set of x-rays to confirm healing and will typically give the green light for off-leash activity.

How successful is the surgery?

The definition of success can be different for different animals, but for the most part, 95 percent of surgery patients can return to their pre-injury level of function and activity. Some degree of arthritis may progress, but much less with the surgery than without. The most common surgery complications are incision issues, infection, and swelling.

If you are a primary care veterinarian, please call (406) 218‑2800 if you have questions about our CCL injury treatments.