What Is The Cranial Cruciate Ligament?

In a cat’s stifle (knee joint), there are four primary ligaments: two on the outside known as the collateral ligaments and two inside the joint referred to as the cruciate ligaments, which form a cross pattern. The cruciate ligament located towards the front of the joint is the cranial cruciate ligament, similar to the anterior cruciate ligament (ACL) in humans. This ligament connects the femur (thigh bone) to the tibia (shin bone), helping to prevent the tibia from sliding forward relative to the femur, as well as limiting over-extension and rotation.

What Causes Cruciate Ligament Disease In Cats?

In cats, cranial cruciate ligament rupture is most commonly caused by trauma, unlike in dogs. Although degenerative disease can occasionally occur, it is typically seen in overweight cats.

How Can I Tell If My Pet Has Cruciate Ligament Disease?

The most frequent indication of cranial cruciate ligament disease is limping on the hind leg.

In cats, limping usually appears suddenly following a traumatic incident. Occasionally, with degenerative changes in the ligament, more subtle symptoms may develop, such as stiffness and difficulty jumping properly.

How Is Cranial Cruciate Ligament Disease Diagnosed?

A clear diagnosis of cranial cruciate ligament injury can be straightforward if the ligament is fully ruptured, and is typically confirmed by an experienced orthopedic surgeon during an examination. Partial tears are less common in cats, and diagnosing them can be more challenging due to the reduced joint instability. Additional tests, such as radiography (x-rays) or evaluation under anesthesia/sedation, may be needed. X-rays may reveal signs of osteoarthritis and increased bone deposits in the joint, which are common in cats with cranial cruciate ligament issues. To confirm ligament damage, exploratory surgery or arthroscopy (keyhole surgery) may be performed. The cartilage in the joint is also examined since meniscal (cartilage) damage often accompanies cranial cruciate ligament disease.

Management Options Of Cranial Cruciate Ligament Disease:

Non-Surgical / Conservative Management:

This management approach involves controlling weight, regulating exercise, providing rehabilitation, using non-steroidal anti-inflammatory drugs, and offering dietary supplements. The effectiveness of this method in cats is less clearly defined compared to dogs, but it may still lead to positive outcomes. If the stifle joint is highly unstable, surgery is often recommended. For cases with minimal instability, conservative treatment may be started, with surgery being considered if the initial treatment does not yield satisfactory results.

Surgical Management:

• Ligament substitute:

Using a prosthetic ligament, like a lateral extracapsular or fabellotibial suture, is a common approach for cats. Nylon is used for the replacement, but it can stretch or break over time. Despite this, the method generally shows better results in traumatic injuries, as the knee was normal before the rupture.

In cases of traumatic cranial cruciate ligament ruptures, other ligaments may be affected and can be managed with the same prosthetic material, known as a multi-ligamentous or global knee injury.

• Tibial Plateau Levelling Osteotomy (TPLO):

This technique, commonly used in dogs but rarely documented in cats, aims to restore limb function by creating a more stable joint. It involves making a semi-circular cut in the top of the tibia and leveling the bone to improve stability, then securing it with a plate and screws. Although there’s limited data for cats, the procedure is generally well tolerated, with most cats bearing weight on the leg within 48 hours post-surgery.

• Cranial closing wedge ostectomy (CWO):

This technique also levels the top section of the tibia, similar to the TPLO method, but involves removing a wedge of bone instead of making a curved cut. It is the predecessor to the TPLO procedure and is sometimes used, particularly for small breeds. The bone is stabilized with a bone plate and screws. However, this method is also rarely performed in cats.

• Tibial Tuberosity Advancement (TTA):

This technique involves making a cut in the top of the tibia (shin bone), but instead of leveling the bone, it shifts the front of the knee forward to alter the forces within the joint. While this method is described for cats, there is limited information available. In our clinic, very few patients are deemed suitable candidates for this procedure.