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All about cruciate ligament ruptures

What is the cranial cruciate ligament?

The cranial cruciate ligament (CCL) is in the same location as the human anterior cruciate ligament (ACL). It is a ligament that runs between the shin bone (tibia) and thigh bone (femur) to help prevent cranial thrust of the tibia in relation to the femur. This means that, without this ligament, the shin would slide forwards in relation to the thigh when weight is put on it e.g. during walking. Therefore, this is what occurs when the ligament is ruptured, and is an issue because instability of a joint leads to the development of joint disease like osteoarthritis (OA). In fact, the reason we know that OA occurs in unstable joints is because of old research done on dogs where this ligament was cut and the development of OA in the joint was measured over time. There is also a caudal cruciate ligament that runs in the opposite direction within the knee but this is a much rarer injury in dogs.


How does it get injured?

A rupture of the CCL is the most common cause of hind limb lameness in dogs. It can occur by acute trauma as it does in people, but this is rare. More often than not, it happens through long-term or chronic degeneration. This is thought to be mainly due to the anatomy of a dogs knee (stifle), which appears to cause shearing stress on the joint during motion. The CCL is at it’s strongest at around 3-4 years of age but it does get weaker with age.


The chance of this ligament rupturing can be impacted by several factors including gender and neuter status (female spayed dogs are at a highest risk of rupture), weight (dogs over 22kg are at a higher risk), and the type of breed (some breeds like the West Highland White Terrier have anatomical/conformational abnormalities that put the ligament under extra stress).

Photo credit: PDSA


What should I do if I think my dog has ruptured it’s CCL?

Without specific diagnostics, it can be difficult to detect the exact cause of a lameness, therefore, if you dog starts to limp or stop using a leg, it is important that you take them to see your vet as soon as you can.


Until you’re able to get an appointment to see your vet, you should make sure that your dog is cage rested. This means no play with other dogs, only short toilet breaks out in the garden, no jumping on the furniture or doing stairs. Non-slip matting should also be provided if the floors are slippery. Whilst these may seem like harsh measures, it is a really important step in preventing further damage, which could limit the final outcome for your dog, require a more invasive surgery, or cause more OA to develop. It is also because moving on the leg will likely be quite painful so the less the dog does until it is treated, the more comfortable they will be.


How is it diagnosed?

A physical exam is often the starting point for diagnosis if you notice you dog is limping. This will include looking at the dog standing to see if they are putting weight on the leg and watching them walking to see if they are using the leg, and if so, to what degree. Some cases can rupture both sides at the same time or within a short time frame of one another and these patients can sometimes look as though they have a neurological condition affecting their back legs when they move. Your dog may also be asked to perform some functional tasks like sitting and going up/down stairs. A hands on assessment will follow and be required in order to feel for muscle loss (commonly around the gluteals, hamstrings, and quadriceps) on the leg and to check the range of motion (ROM) of the knee/stifle joint whilst also feeling for any swelling or clicking/crunching in the joint during motion.


There are also some special tests that can be done to check for instability, these include the cranial drawer and cranial tibial thrust tests and they simply check to see if the shin bone is able to move forwards in relation to the thigh. Ideally, there should not be any movement of the bones during these tests but if the dog is very young there might be a little bit, in which case the rest of the examination/diagnostics would be required to confirm a CCL injury.


Your dog will also likely require anesthetising for an x-ray or CT scan to check the joint for more swelling and to look for signs of arthritic changes. A meniscal tear might be suspected alongside the CCL rupture during the physical exam but it is only properly diagnosed by keyhole surgery and requires a surgical repair.


Can you manage it conservatively?

In most cases, conservative management does not give as good of an outcome as surgery does for this condition. This is due to the factors mentioned above in terms of the anatomy of a dogs knee compared with a humans knee (it is becoming more common for humans to receive conservative treatment before considering surgery). Additionally, because the ligament slowly wears away in dogs, the increased progression of OA whilst the joint is unstable will become painful and means they may always have a mild limp.


Having said that, there are certain instances where conservative management can be trialled. These situations include where a patient is very old or has an underlying condition that puts them at risk should they be anaesthetised for surgery. However, conservative management is only possible if there has been a partial rupture. If a full rupture has occurred, the body is not able to stabilise itself sufficiently enough and surgery is the only option. Additionally, if there is a suspected meniscal tear (shock absorbing pads within the knee), conservative management will also not work as the joint will be too painful for the dog to weight bear on. These are further reasons to keep your dog rested if you suspect a cruciate rupture.


If you are considering conservative management for your dog, rehabilitation in the form of both physiotherapy and hydrotherapy is crucial.


What about braces?

Orthotics and bracing is a relatively new and emerging part of veterinary rehabilitation and so we don’t have a lot of hard evidence on how bracing a dogs stifle compares to surgery in the long term and so surgery is generally still considered the best option for the majority of patients.


If you are looking at bracing it is important to have a discussion with everyone in the vet-led team (GP vet, physio, surgeon, etc.) and even look to visiting a qualified prosthetist as a custom-made brace is going to be the only way to get a secure enough fit that would stabilise the stifle sufficiently enough for this to work. Custom made braces might be cheaper than surgery but they will certainly not be cheap and after being fitted, will require at least bi-annual evaluations to make sure that the brace is still fitting properly and not starting to break or cause pressure sores. So it is by no means a quick fix and can be just as big of a commitment as surgery, with rehabilitation also being very important once fitted.

Photo credit: Bionic Pets

What does surgery involve?

The surgery for this condition is usually performed by a vet who has undergone further training in orthopaedics. Your local vets may have someone within the practice who can do this or they may have to refer you to a local hospital to have it done. There are several surgery options, the most common techniques involve biomechanical alteration to prevent the shin moving so much under load, these are called extracapsular techniques. However, there is a technique that is intracapsular called the graft technique (this is similar to the surgery that is done in people) but this is falling out of fashion because, as mentioned above, the disease in dogs is usually chronic (due to the biomechanics/anatomy), with lots of inflammation and dead tissue within the joint which makes this technique challenging. Additionally, if a full rupture has occurred and not treated in a timely manner, the ends of the ligament will start to shrivel up which makes reconnecting them difficult to impossible. The common extracapsular techniques are detailed below:


· Lateral suture - use of a piece of monofilament suture between the small bones at the back of the stifle and the crest of the shin bone (tibia). This is placed on the outside of the knee and acts in a similar way to the CCL.

Photo credit: jorvet.com


· TPLO - a circular cut is made through the tibia to change the angle of the "tibial plateau" and reduce the instability when the joint is loaded.


Photo credit: Giant Creek Veterinary Services


· TTA or MMP - two surgeries that differ slightly but both involve a vertical cut down the tibia to move the attachment of the quadriceps further forward to make the muscle produce force across the joint and make the CCL redundant. The exact metal work used does differ between the two surgeries but the end result is intended to be similar.

Photo credit: ValpoLife


Can you do “prehab” before surgery?

The main purpose of prehab prior to surgery is to improve outcomes after the operation and for the patient to be able to have a higher level of function and ability, and potentially even heal quicker.


For CCL rupture’s, it is likely not ideal for the majority cases as weight bearing on the unstable joint will hasten the progression of OA. However, it could benefit patients that are obese and/or have other conditions like endocrine disorders, cardiac conditions, or have suffered cruciate ruptures in both legs at the same time. These conditions generally delay surgery anyway and so a period of prehab would likely benefit these cases. Therefore, if you do have a long wait before surgery, some prehab would be beneficial, with underwater treadmill hydrotherapy being a good option as well as learning some techniques like massage and passive range of motion (PROM) from a physiotherapist to maintain the extensibility of the joint and surrounding soft tissue.


What happens after the surgery?

In most cases, your dog is unlikely to be hospitalised more than a couple of days but when they come home, they will be required to be cage rested for several weeks and possibly require a sling to take them out to toilet initially.


Rehabilitation is very important following this type of surgery. Dogs will start to lose muscle mass during the first 2 weeks which, without rehab, will carry on for the next 5-10 weeks following the surgery and if rehab is not done at all, there will be permanent muscle loss. Therefore, physiotherapy should be started immediately after the surgery and continue for a minimum of 6 weeks (although to get the best results, >12 weeks would be needed), underwater treadmill hydrotherapy can generally be started at around 2-4 weeks (swimming is not the best option in the early stages as it is much less controlled and the dog’s movement in the water can be too rapid).


No dog will be 100% how they were before the injury, we unfortunately don’t have a surgery that allows for this yet but we can get them back to being able to live like a dog again through effective, graduated rehabilitation and steady return to activity.


Can my dog go back to doing sports after this injury?

Depending on the dog and the sport you’re trying to return to, it can be possible however, do bear in mind that your dog may not be able to perform to the same level after this sort of injury. If you are planning a return to sports for your dog, surgery is really the only way to achieve this and will take a lot longer commitment to the rehab period. This is because once most dogs reach the point of discharge, athletic dogs are only just beginning their return to sport programme and this must also be gradual to prevent reinjury and make sure they are reconditioned to their sport effectively. Therefore, using a qualified veterinary physiotherapist is really important for all patients but especially those looking to return to sport.


Will it ever happen again?

As most surgeries involve changing the joint biomechanics and do not involve repairing the ligament as such, it will not occur again on the same leg in these cases (although, a partial tear could become a full tear). However, once a dog has ruptured the CCL on one side, there is a significantly higher risk that the other side will go at some point in the future (commonly within around 2 years of the first). This is thought to be due to the same reasons as mentioned above, plus the extra load this side has taken whilst the other side was injured. This can be managed with continued rehabilitation to monitor the other side but there is no guarantee it will completely prevent it happening.


The best way to avoid the other side going again (more important if it has happened due to chronic degeneration rather than acute trauma), is to try and minimise the amount of high impact activities like jumping and chasing balls that your dog does. Whilst we want to get your dog back to living a normal life again, it’s important to understand that these sorts of activities carry an extra risk and if we can minimise the frequency your dog does them, we have a better chance of avoiding another CCL rupture.


Do get in touch if you would like advice on managing your dog’s CCL rupture!


All the best,

Matt


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