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Cruciate Injury

The cranial cruciate ligament (CCL) is the main ligament that stabilizes the stifle joint (knee). Its function is to minimize internal rotation and hyperextension of the knee, in addition to preventing forward displacement of the tibia (shinbone) in relation to the femur (thigh bone) Although CCL disease in humans is often the result of a traumatic injury such as a skiing or football injury, CCL disease in animals is normally a chronic process. This disease leads to a degeneration in the CCL which can lead to instability in the knee joint resulting in pain and osteoarthritis.

Eventually, the CCL ruptures which can lead to complete instability of the stifle joint and severe pain. This often manifests itself as a lameness of the affected leg. Initially, the disease may be apparent in one leg, but more often than not, rupture of the CCL in the other leg will occur within 6-12 months of the first ligament tear.

It is said that in 50% of cases with a CCL rupture, there are concurrent injuries to the menisci. Each stifle has 2 C-shaped cartilage pads called menisci that act as shock absorbers in the knee.

Like many diseases, CCL disease is multi-factorial and has a genetic component. It is more common in older animals where degeneration of the ligament has occurred for some time leading to eventual rupture. In younger animals, it tends to occur more frequently in large-breed dogs. Abnormal anatomy of the hindleg e.g. a sloping plateau of the tibia can predispose to CCL rupture.

Clinical signs

The main clinical sign is lameness (limping) of the affected leg. The degree of lameness can vary depending on a complete or partial rupture of the ligament, the mode of rupture (acute or chronic), the degree of arthritis and if there is any meniscal damage.

Diagnostic tests

The main method of diagnosis is a thorough examination of the leg. Often, this may be necessary after sedating your animal (allowing the muscles to relax) and minimizing any discomfort/pain to your pet. Examination of the joint may reveal swelling/inflammation and excessive instability  (especially movement of the tibia in relation to the femur).

Two commonly performed manoeuvres are called the cranial drawer motion and the tibial compression test.

In Acorn, we recommend x-raying the affected stifle to assess if any osteoarthritis (degeneration of the joint) is visible.


Commonly, surgery is performed to aid a faster recovery and improve the function of the leg. In small patients such as small breed dogs and cats, conservative treatment of restricted rest and pain relief may be sufficient. In larger animals, surgery is normally recommended.

There are many different surgical techniques for repairing a CCL rupture. The fact that there are so many techniques indicates that not one single surgery has be conclusively proven to be better than another! The main techniques include:

·      Intra-articular techniques that create a new ligament by using the animal’s own tissue e.g. patellar tendon or alternatively, synthetic materials.

·      Extracapsular techniques that stabilize the joint by surgery outside the stifle, e.g. lateral suture placement.

·      Biomechanical techniques that attempt to change the angles and forces within the stifle joint such as tibial plateau leveling osteotomy (TPLO), tibial tuberosity advancement (TTA) and triple tibial osteotomy (TTO).

If meniscal damage is found during inspection of the joint during surgeon, many veterinarians elect to remove the damaged portion to minimize pain in the joint.

Following surgery, animals may need a period of restricted activity combines with physical rehabilitation and/or exercises.

Many animals can return to normal function following treatment although osteoarthritis may still be present/develop. In severe cases of osteoarthritis, medical therapy (pain relief and supplements) may be needed.

Stem cell therapy is a new treatment option, which may become more frequently used in the future to aid recovery and healing of the damaged stifle joint associated with CCL disease.