Pet Health Library
Cranial Cruciate Ligament Disease (ACL Injury)
The cranial cruciate ligament (CCL) in dogs is the equivalent of the anterior cruciate ligament (ACL) in humans. It is one of the ligaments that connects the thighbone (femur) to the shinbone (tibia) where they meet at the knee (known as the stifle joint in dogs) and help keep the joint stable. When the cranial cruciate ligament ruptures, the knee joint destabilizes, twists, and slips. If the ligament is partially torn, your dog may just limp, but once the ligament completely ruptures, your dog may refuse to put weight on the limb and walk on three legs. Movement of the misaligned joint causes further damage, inflammation, pain, and eventually arthritis.
In humans, injury to the ACL usually occurs during sports that involve sudden stops or changes in direction, such as football or skiing. In dogs, the cranial cruciate ligament tends to degenerate over time until the ligament weakens and ruptures. Since the disease process is degenerative, both the right and left cranial cruciate ligaments are often affected. About half of dogs who rupture one CCL eventually will rupture the second.
Overweight and out of shape dogs are also more likely to rupture a CCL than dogs in good condition. While cruciate disease can affect dogs of all sizes and ages, it is more prevalent in large and giant breed dogs and the following breeds:
- Chesapeake Bay retrievers
- Labrador retrievers
- Saint Bernards
- Staffordshire terriers
- West highland white terriers
Signs that your dog may have suffered a CCL injury include:
- Hind leg lameness
- Reluctance to put weight on a limb
- Lifting the limb or holding it to the side
- Swollen knee
- Clicking sound when walking
- Decreased range of motion
- Reluctance to exercise
- Stiffness after exercise
To rule out other causes of lameness, your veterinarian may move the leg to check the joint looseness, which is known as the cranial drawer test. X-rays may suggest, but cannot confirm, a partial tear or a complete rupture.
Dogs with an unrepaired ligament frequently develop severe arthritis in the affected knee, but surgical repair offers the chance of a good recovery, with 80-90% of dogs returning to full function. The two most common surgical techniques are tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA). Both techniques cut and replace a section of the tibia using special bone plates. TPLO is performed most often due to its high success rate and relatively short recovery time. TPLO surgery works by altering the mechanics of the knee so the dog can still use the limb without relying on the CCL. This is done by changing the angle of the top of the tibia (shin bone) by cutting the bone and rotating it so that the other muscles supporting the knee can take over the functions of the CCL.
After surgery, physical rehabilitation has been shown to improve function and speed of recovery. Some dogs also do well with rehabilitation therapy alone. This is especially helpful for dogs who cannot have surgery due to other medical conditions.
Static stabilization of the stifle can be achieved using the Lateral Suture Technique.
Maintaining a healthy weight and body condition can help reduce a dog’s risk for developing CCL disease. Both of these factors can be kept in check by making sure your dog gets regular exercise and eats a healthy diet.
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