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Cruciate Ligament Surgery

Cruciate ligament injury is the most common cause of hind limb problems in dogs and sadly around 50% of dogs develop this condition in both back legs.

What are cruciate ligaments?

There are two ligaments in the knee (the cruciate ligament) that help stabilise the joint when walking. One of these ligaments is prone to tearing, either from trauma or from slow degeneration (weakening and inflammation).

Once the ligament is torn, the knee becomes unstable and swollen. This can lead to structural damage to the joint when the bones accidentally bump against each other.

Walking becomes very painful and the muscles in the thighs rapidly weaken due to reduced use. If left untreated, severe arthritis can also form, causing joint discomfort for years.

Diagram displaying the Cranial Cruciate Ligament (Red) and Caudal Cruciate (Blue), as they should be.

Diagram displaying the Cranial Cruciate Ligament rupture. Once this occurs, the tibia crest can shift forwards.

What happens when the cruciate ligaments are damaged?

The cruciate ligaments help stabilise the knee and prevent it from moving in specific directions. Damage to these ligaments causes abnormal joint movement, overload, and damage to other structures, such as the meniscus, which are hard pieces of cartilage that sit in the knee joint and act as shock absorbers to help distribute weight. evenly distributed over the joint and helps add stability.

As a result, the cruciate ligament ruptures causing abnormal wear, instability, limping, and pain in the affected knee joint. In the short term and long term, it also causes degenerative joint disease, which should be noted.

What are the causes?

Degenerative disease (Common)

This is the most common cause of cruciate ligament rupture. Dogs affected by this disease will have diseased, inflamed, and weak ligaments that tear during normal activities, such as playing in the garden.

Several factors can predispose a dog to this condition, and breed is thought to be the most influential. Some breeds are known to be at higher risk than others due to suspected genetic factors, for example, Golden Retrievers, West Highland Terriers, Rottweilers, Bull Mastiffs, Labrador Retrievers, Boxers, and Newfoundland breeds.

Furthermore, some-body conformations (bone structure) also predispose the ligament to rupture; for example, those with bowed hind legs or an upright posture.

Also, dogs carrying excess weight are also more at risk of this disease, which is another reason for maintaining your dog’s healthy weight (speak to one of our vets or nurses for advice about the optimal weight for your pet).

Trauma (rare form)

Overloading the healthy cruciate ligament from a sudden knee injury can damage and even rupture the ligament. It is equivalent to a cruciate injury in people whose normal ligaments are injured during sports.

How is it diagnosed?

Anterior cruciate ligament failure can be diagnosed solely by history and physical examination. However, diagnostic tools such as MRI, arthroscopy (keyhole surgery), and radiography (X-rays) may also be needed to fully evaluate the joint.

What treatment can be provided?

The knee joint needs to be stabilised to help relieve pain and try to prevent further damage to internal structures. This is usually achieved with surgery, but sometimes for small dogs and cats, we can opt for conservative (non-surgical) treatment, i.e. strict rest. This decision will depend on individual circumstances and will be discussed with the vet.

Conservative treatment will involve restricting their exercise, ensuring they stay at a lean body weight, administration of pain relief, hydrotherapy, and physiotherapy.

The majority of dogs that are affected by this condition require surgery.

What does the surgery entail?

Surgery aims to stabilise the knee joint and prevent abnormal movements. There are many different techniques that can be used to treat cruciate ligament disease. The specific technique that may be recommended for your pet will depend on many factors and will be discussed with you one of our vets. The choice of technique can depend on many factors, from patient size to available budget.

What are the surgery options?

Lateral Suture Technique (LS)

This technique aims to solve the instability in the dog’s knee joint by placing a strong piece of suture outside the knee joint to act in a similar fashion to the cranial cruciate ligament.

The aim of LS surgery is to place a suture that prevents the two bones from moving too far apart so that the tibia does not shift forward during weight-bearing. After a period of healing, the soft tissues around the joint form scar tissue around the knee, which provides support in the same way as the suture. Over time, the suture itself will weaken but by this point, the scar tissue should have taken over its role.

Modified Maquet Procedure (MMP)

MMP for dogs is based on a surgical technique for human knees that an orthopedic surgeon named Dr. Maquet developed over 50 years ago.

One of the goals of the Modified Maquet Procedure is to change the angle of the tibia (one of the bones between the knees and ankles) and move it forward so that it is 90 degrees to the patellar tendon. An Orthofoam implant provides stability as well as promotes healing and accelerated bone growth.

Cranial Closing Wedge Osteotomy (CCWO)

This is a surgical procedure that involves adjusting the tibial plateau (the surface at the top of the shin bone) by cutting out a wedge of bone from the front of the shin.

Generally, surgery will start with opening the capsule surrounding the knee joint and assessing for any damage to the shock-absorbing cartilage pads which sit between the bones (menisci). If any damage is seen then these areas must be removed before the CCWO is performed. The shin bone is exposed and marked with measurements calculated from the pre-operative X-rays.

A wedge-shaped section of bone is then cut using a saw blade and the cut portion is removed. The remaining two sections are closed using a special plate and screws to hold the bone together while it heals.

Tibial Plateau Levelling Osteotomy (TPLO)

TPLO surgery works to make the top of the tibia almost flat, so when the dog is weight-bearing, the femur rests on the top of the tibial plateau rather than slipping backward and pushing the tibia forwards.

Generally, surgery will start with opening the capsule surrounding the knee joint and assessing for damage to the shock-absorbing cartilage pads that sit between the bones (menisci). If damage is seen, then the damaged portion is removed before the TPLO is performed. The bone is cut with a special curved saw blade, and then the cut portion is turned to a new

position. At this point, a special TPLO plate and screws

are used to hold the bone in place while it heals.

Thanks for reading!