Cranial Cruciate Ligament – What’s it all about?

23rd Nov, 2021

Written by Dr Tanya Grantham BSc (Hons) BVSc 

The cranial cruciate ligament (CCL) in dogs is the equivalent of the anterior cruciate ligament (ACL) in humans.

In people, ACL injury is almost always traumatic and is especially prevalent among athletes. Rugby players, skiers, those who participate in squash – any sport that requires a lot of knee engagement with the potential to twist – will predispose an individual to ACL injury.

The situation in dogs is different. It’s rare to find that trauma is responsible for a CCL tear, although it does occur. More common is the degeneration of the CCL which weakens the ligament and predisposes it to injury. Repeated high-energy movements result in microtears of the CCL. These are repaired with scar tissue that’s not as strong or resilient as normal ligamentous tissue. Repeated tears weaken the ligament. With time, the degeneration is sufficient to result in instability of the knee. This is painful for your dog.

Why CCL damage causes problems

The role of the CCL is to stabilise the femur (thigh bone) in relation to the tibia (shin bone). The ligament lies between the two bones and prevents the femur from “slipping off the back of the tibia”.

By looking at this diagram, it’s clear that, without the stabilisation of the CCL, the tibia will move forward in relation to the femur, or the femur will move backwards in relation to the tibia.

The resultant instability creates pain and lameness. Other signs to look for include:

  • difficulty jumping or climbing
  • a weight shift onto the back leg that is unaffected when the dog is standing
  • loss of muscle mass in the injured leg
  • tendency to be unable to sit straight with the affected leg bending less at the knee.

Treating the CCL

The knee (called a stifle in dogs) is a complicated joint. Traditionally, CCL disease is treated surgically. There are at least 25 different ways to surgically stabilise the stifle following CCL injury. Not a single one of these procedures is better than the other; the fact that so many exist is proof of that.

The goal of surgery is to return your dog to function as soon as possible. Surgeries fall into three categories:

  1. Stabilisation outside the joint
  2. Stabilisation using techniques that enter the joint
  3. Surgeries that change the angles of the bones within the joint, in relation to each other. These are referred to as osteotomies, because this type of surgery involves the cutting of a bone and subsequent realignment.

Conservative therapy is gaining momentum. This means that no surgery is performed. Instead, the body is allowed to repair the injury. As humans, our role is to facilitate healing by reducing weight and managing movement to allow for the body to stabilise the joint.

In all instances, the end result is osteoarthritis of the joint. There’s a very large possibility (50%) that if one CCL tears, the other will follow within a year. Aside from seeking veterinary attention when your companion is injured, veterinary physiotherapy (physical rehabilitation) is readily available to help your dog regain mobility and strength. A rehabilitation practitioner can assist whether or not your dog undergoes surgery.

Helping to prevent CCL

To prevent or reduce the risk of cruciate ligament disease in dogs, reduce ball chasing, jumping, and racing with quick turns. All of these actions will over time predispose a dog to injury.

Should you wish to pursue any of these activities, it makes good sense to start with a canine fitness and conditioning programme (your veterinarian will be able to point you in the right direction). Sportsmen and women spend hours training and honing their skills – the same principles can be applied to canine athletes.

Important

If you notice that your pet has any of the signs mentioned, it’s important to take them to their veterinarian promptly. They’ll be able to provide pain relief and recommend the best treatment options to get your canine companion back on all paws.