Cranial Cruciate Ligament Rupture

Dog and cat knees are similar to humans. For example, knees have five ligaments, two menisci, a knee cap, and joint cartilage. The ligament most commonly affected in dog and cat knees - the cranial cruciate ligament - is the same ligament most commonly damaged in professional athletes. Dogs and cats usually tear this ligament when out running around, or sometimes when landing wrong after a jump.

Most of the time when the ligament is injured, it is completely torn in half. Sometimes, though, only a portion of the ligament will tear. Though only a portion of the ligament may be torn, the whole ligament is damaged.

When a cranial cruciate ligament is torn, it causes sudden pain and often results in the pet holding its leg up. It also causes an instability in the knee joint. The pet may put the leg down and start using it within a day or so, but will continue to limp for several weeks. Normally, at the end of several weeks, the initial pain subsides and the pet is willing to use its leg more; however, the joint remains unstable. Every time the animal puts weight on the leg, the tibia (shin bone) slides forward in relationship to the femur (thigh bone). This abnormal motion causes wear and tear on the joint cartilage, causing pain and leading to arthritis. This motion can also put excessive stress on the menisci (C shaped pieces of cartilage within the knee joint), causing damage or tearing.

Surgery is the only corrective measure for cranial cruciate ligament injuries. Many surgical procedures have been tried on people and animals during the last 60 years; however, most orthopaedic surgeons agree that the procedures are not as successful as they would like. Knees that suffer this injury are never completely normal even after surgery is performed. Surgery does, though, stabilize the knee, allowing it to regain normal motion and thereby reducing the formation of arthritis. Surgery has been and remains the treatment of choice for this injury. If surgery is not performed, progressive arthritis will occur and the lameness will worsen with time.

There are many different ways to stabilize a knee with a cruciate ligament injury.  With larger or more athletic dogs we are now doing an advanced surgical repair technique called a Tibial Plateau Levelling Osteotomy (TPLO). This technique basically alters the biomechanics of the joint so that the dog can walk without the cranial cruciate ligament (CrCL). We are able to alter the angle of the joint by making a special curved cut in the tibia and rotating the bone. The bone fragment is then secured in place with a plate as pictured

Dogs treated with this technique have a faster return to weight-bearing and develop fewer degenerative joint changes.

We perform a nerve block on the leg to be operated on. This is to provide better pain relief during your dog's recovery period.


Potential Risks of Operation

As with all operations, there are risks.  Potential complications include infection of the wound, screw loosening or breakage, haemorrhage and loss of function of the limb. While we can keep these risks to a minimum with our level of care,  we need you to follow the instructions below to minimise these risks. 



Your dog will need to be confined in a crate, pen or small room for at least 6 weeks. This means no free run in the house unsupervised exercise, jumping up and down on furniture or walking up and down stairs. Take care to avoid slipping when walking on wet or smooth surfaces. An old towel can be used as a hind-quarter sling if it is placed underneath the abdomen.  The only exercise allowed is short-duration (10 minutes maximum), slow walks on a leash for toileting purposes. 

Our vets will advise you when you are able to gradually increase you dog's exercise and show you how to do the physiotherapy exercises.


Longer-term follow-up and care:

At 8 weeks post-operatively a radiograph of the stifle will be done under sedation. This is to assess the progress of healing at the osteotomy sites and assess if there has been any movement of the screws. If the bone has healed, the vet will give you the ok to gradually return your dog back to normal exercise