Cranial Cruciate Ligament Disease in Cats

What is cranial cruciate ligament disease?

Cranial cruciate ligament disease (CCLD) is a disease of the knee joint in which the cranial cruciate ligament tears or ruptures, causing an unstable knee joint that creates pain, osteoarthritis, and limping.

What are the cruciate ligaments?

The cruciate ligaments are two strong bands of fibrous tissue inside each knee joint that connect the femur (thigh bone) to the tibia (shin bone). They cross over each other in the center of the knee and help keep the stifle (knee) stable during movement, allowing it to move in only a hinge-like motion.

The cranial cruciate ligament (CCL) is attached to the front of the tibia and the back of the femur, while the caudal cruciate ligament is attached to the back of the tibia and the front of the femur. Since there are no interlocking bones in the knee joint, ligament strength is essential for preventing abnormal joint motion and damage.

The cranial cruciate ligament is similar to the anterior cruciate ligament (ACL) in humans and is the main stabilizing ligament in a cat’s knee. Its primary function is to prevent the tibia from sliding too far forward relative to the femur during movement. Cruciate ligament injuries are common in dogs and relatively uncommon in cats.

What causes cranial cruciate ligament disease?

The most common cause of CCLD in cats is believed to be trauma. This usually occurs when the knee twists suddenly, placing excessive force on the cranial cruciate ligament. Depending on the severity of the injury, the ligament may become stretched, partially torn, or completely ruptured. A few cats may experience chronic degeneration of the ligament, seen more commonly in dogs. This degeneration causes progressive weakness of the ligament until it breaks down or ruptures.

A complete rupture makes the knee unstable, allowing the bones to move abnormally in relation to each other, and making it difficult for the cat to bear weight on the leg. The injury is painful and, if untreated, can lead to permanent joint damage.

A cranial cruciate ligament rupture can also damage the menisci, pieces of cartilage between the femur and tibia that act as shock absorbers in the knee. The collateral ligaments (the fibrous bands running along the sides of the knee) or the patellar ligament (which runs along the front of the knee with the patella, or kneecap) may also be injured.

How is a cranial cruciate ligament disease diagnosed?

When a cat has an acute (sudden) cruciate injury, there is often a history of trauma, such as an automobile accident or a fall from a height. In some cats, the injury occurs secondary to another knee problem, such as a luxating patella (a kneecap that slips out of place).

Your veterinarian will examine your cat’s knee and check for abnormal movement using the drawer test or tibial compression (thrust) test. These tests check for abnormal forward movement of the tibia in relation to the femur, which indicates instability in the knee caused by damage to the cranial cruciate ligament. If your cat is in pain, has strong leg muscles, or is unable to relax, sedation may be needed to allow a thorough examination of the joint.

Other diagnostic tests, such as radiographs (X-rays), may also be necessary. Although ligaments are not generally visible on X-rays, your veterinarian may see evidence associated with ligament damage, such as inflammation within the stifle joint or abnormal positioning of the femur and tibia.

How is cranial cruciate ligament disease treated?

Treatment for CCLD may involve surgery or nonsurgical management. Surgery may be recommended to provide additional joint stability, slow the progression of arthritis, and reduce chronic pain. A surgeon can evaluate the joint, address complicating conditions like meniscal tears or patellar luxation, and stabilize the joint so it functions normally or nearly normally. After the operation, you must limit your cat's exercise for several weeks and rehabilitation may be recommended.

What does surgery involve?

There are various surgical techniques to stabilize the knee joint following cranial cruciate ligament rupture. These techniques fall into two broad categories:

• Extracapsular technique: These techniques involve placing a specially designed suture that acts like an artificial ligament (usually placed outside the joint capsule) to stabilize the joint and prevent abnormal motion.
• Bone cutting techniques: Procedures such as tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA) change the knee’s mechanics to improve joint stability.

During surgery, the surgeon will examine the joint, remove fragments of the ruptured ligament, and repair or remove damaged meniscal tissue. Cats with concurrent patellar luxation may have that condition repaired at the same time to further stabilize the knee. Your veterinarian or surgeon will discuss the most appropriate surgical option for your cat.

Can cranial cruciate ligament disease be treated without surgery?

In some cats, a cranial cruciate ligament rupture can be managed without surgery. If surgery is not an option, your cat's activity must be severely restricted for up to six weeks, with no running or jumping allowed. Nonsurgical treatment typically involves strict rest followed by a gradual return to activity, along with pain medication, weight management, and veterinary rehabilitation. Laser therapy and acupuncture may also help control inflammation and relieve pain. If improvement does not occur, surgery is usually recommended.

Cats with a cranial cruciate ligament rupture commonly develop arthritis in the affected knee. Your veterinarian can help determine the best treatment option for your cat.

What can I expect after surgery?

After surgery, your cat will need limited and controlled activity for at least six to eight weeks. The period of activity restriction may be shorter if a TPLO or TTA has been performed. Provided you can follow your veterinarian's instructions, good function should return to the limb within three months.

Cats may also receive physical therapy (rehabilitation) after surgery to improve recovery, help them return to function, and reduce complications. Your veterinarian will discuss the recommended rehabilitation plan for your cat.

Surgery cannot prevent arthritis, but it can slow its progression and improve long-term comfort and function. Weight control and nutritional supplements may help delay the onset of arthritis.

Does obesity play a role in this condition?

Yes, obesity or excess weight can significantly increase the risk of CCLD. Carrying excess weight places additional strain on the ligament and may also cause changes that make it more likely to tear.

If your cat is overweight, recovery after surgery will often take longer, and the other knee is at greater risk of developing a cruciate ligament injury or rupture, particularly during the recovery period. Weight loss is an important part of promoting a return to normal function and reducing stress on your cat’s joints. Your veterinarian can help develop an appropriate weight-loss plan for your cat.