Owner Fact Files: Cruciate Ligament Injury
The second in the series of my Owner Fact Files, this time talking about a condition which is one of the most common causes of lameness in dogs - Cruciate Ligament Injury.
What is the Cruciate Ligament?
Ligaments are bands of tough connective tissue which connect bones and hold joints together. In the canine knee (stifle) joint there are two cruciate ligaments which form a cross, the cranial cruciate ligament and the caudal cruciate ligament. In cases of injury, it is the cranial cruciate ligament (CCL) that most commonly ruptures.
Humans have very similar anatomy, and the CCL is the equivalent of the anterior cruciate ligament (ACL) in humans. The CCL is an important ligament that sits within the knee joint, forming an attachment between the thigh bone (femur) and the shin bone (tibia). This connection allows the knee to move back and forward like a hinge, but limits side to side movement.
What is the function of the CCL?
The CCL has 3 main functions which are to;
Prevent the shin bone (tibia) from moving forward relative to the thigh bone (femur)
Prevent over extension of the knee (stifle) joint
Prevent internal rotation of the shin bone (tibia)
Overall the CCL works effectively to stabilise the stifle joint, holding it together. The knee joint itself has no interlocking bones, so without the ligaments it would be very unstable. This explains why the function of the CCL is so important.
What causes the CCL to rupture?
In most cases the ligament ruptures because it has degenerated over time and become weak. Initially the ligament will become stretched or partially torn, but with continued use of the joint the condition will worsen and eventually rupture completely. This complete rupture can occur during normal activity, with the joint under normal forces - for example on a walk.
There are various factors which are thought to increase the chance of the degeneration of the CCL. It seems to be more likely to happen in certain breeds; Newfoundland, Bull Mastiff, Rottweiler, Golden retriever, Labrador retriever, Boxer and West Highland White Terrier, possibly linked to their genetics. The conformation of a dog can also increase the risk, which is the shape and structure of the animal - for example if a dog has very upright limbs. As with all joint problems, body weight also plays a role, with over weight dogs more frequently rupturing their CCL.
Unfortunately, once one CCL has ruptured, it is likely to occur in the other hind limb as well. Around 30-50% of dogs will injure both CCLs within 1-2 years of each other, this is why careful rehabilitation and a safe and gradual return to exercise is key.
In some cases the CCL can rupture suddenly due to a trauma or accident, normally when the knee joint is twisted. This happens most often when the dog is running and makes a sudden change of direction.
What is happening in the joint when the CCL is injured? (the science bit)
Once the CCL has ruptured, it can no longer function as it should. This means that when then dog puts weight on the leg, the thigh bone (femur) is free to slide backwards and down the slope of the shin bone (tibia). In other words, the shin bone moves forward in relation to the thigh bone, which was one of the key movements the CCL works to prevent. This movement creates abnormal forces in the joint causing pain.
Vets will use a test called the cranial drawer test to identify whether the CCL has ruptured, as it will show abnormal forward movement of the shin bone meaning there is instability in the knee.
- Hind limb lameness (limp)
- Joint pain
- Joint swelling
- Difficulty rising and jumping
- Clicking noises in the joint
- 'Pottery' movement
- Cannot get up at all in severe cases
As ruptures can be partial, or complete, signs can be varied case to case. With partial ruptures you may see an improvement after rest, and worsening during/straight after exercise. Most partial ruptures are likely to completely rupture over time, as the ligament wears down with repeated use.
A very small number of cases can be managed conservatively, without the use of surgery. This may be an option with smaller breeds, under 15kg, or if the dog is high risk and cannot be put under anaesthetic. Conservative management of CCL injury would include; restricted exercise, weight management to maintain an ideal, pain relief, and physiotherapy and hydrotherapy to strengthen the structures around the joint for support.
In most cases surgery will be needed to stabilise the knee joint and prevent pain. The surgical options either work by replacing the ligament, or by altering the structure of the knee so the CCL is no longer needed. The most common of these surgeries performed are a TPLO - tibial plateau levelling osteotomy, or a TTA - tibial tuberosity advancement. Following surgery it is important that your dog is rested, with exercise being gradually re-introduced over time.
How can physiotherapy help?
Physiotherapy is an essential part of both conservative management, and post-operative management. The techniques that I use focus on initially relieving the pain and swelling which is seen in the early stages, this can be done using massage and cold therapy. I then work with my clients to begin a gradual and safe return to exercise, slowly increasing walks and introducing new therapeutic exercises. The goal is to strengthen the muscles around both knee joints, for support, and hopefully to prevent the second CCL from rupturing. I also work on improving motion in the joint, as this is often restricted, especially if the dog has been on crate rest following surgery.
For more information on how physiotherapy could benefit a case of CCL injury, please do get in touch - email@example.com // 07795163445.
Unfortunately, in cases of CCL injury, dogs will inevitably develop osteoarthritis in the joint, but this can be managed. Post-operative recovery will take at least 3 months, with exercise restricted, and research shows that 90% of dogs will return to normal activity.
So that's your Cruciate Ligament Injury Owner Fact File - if you have any other questions about this condition I am happy to help with answering what I can.
Keep an eye out for next month's post on another common condition - any feedback on my blogs would be greatly appreciated and I really hope you are finding them informative!
As always drop me a message if you think there is anything I could do to help your animals - Nancy
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