Cranial cruciate ligament disease

WestVETS offers a complete range of treatment options for CCL disease, from diagnosis, advice on pain management and chondroprotective agents to surgical options for all breeds and sizes. We are proud to offer Tibial Plateau Levelling Osteotomy (TPLO), Tibial Tuberosity Advancement (TTA) and Extracapsular lateral suture (DeAngelis) at competitive prices. Our goal is to make advanced Cranial Cruciate Ligament surgery more accessible to more dogs with CCL disease.

With regards to which procedure is best, this will generally be decided based on patient size, activity levels and financial considerations. There is growing evidence to support TPLO as the gold standard procedure for cranial cruciate ligament tears with better return to function, lower rate of post-surgical/late meniscal tears and less progression of osteoarthritis over time. This is the most widely performed technique used in Referral Specialist centres in Australia.

Recovery is generally very good with patients able to weight bear within days, and as part of our inclusive weekly post operative checks and rehabilitation guidelines, we encourage gradually increasing leash walks with many patients having excellent mobility by 6 weeks post-surgery.

We aim to be as transparent on costs as possible, with estimates tailored to each patient based on size, what diagnostics have already been performed and what medications patients are already on. We aim to provide estimates that cover all expected requirements from admission to discharge, including take home medications, weekly follow up checks and 6 week post-operative X-rays.

What is the Cranial Cruciate Ligament (CCL) and why is it so important?

The knee joint is unique. For a joint with a high range of motion, responsible for transferring large forces, the mechanical interface between the thigh and shin offers almost no structural integrity to the joint. The two round condyles on the end of the thigh sit on top of two very shallow depressions on the top of the shin. They are so shallow, it appears as a flat surface on X-ray and this region is referred to as the tibial plateau. As such, almost all stability of the knee is provided by its ligaments and the meniscal cartilages. The Cranial Cruciate Ligament (CCL) is the most clinically significant of these.

The cranial cruciate ligament is equivalent to the human anterior cruciate ligament. It is a substantial ligament which originates on the thigh bone at the back of the knee and courses toward the front of the knee inserting on the shin bone. It functions to counteract cranial drawer or the forward sliding of the shin bone in relation to the thigh bone. It also controls internal rotation in the knee.

What happens when it ruptures?

In a knee with a completely ruptured CCL, it can be quite easy to demonstrate significant instability in the knee. This abnormal movement is commonly referred to as cranial drawer which simply means the shin is sliding forward in relation to the thigh bone. An alternative way to demonstrate cranial drawer is to perform a tibial compression test to induce cranial tibial thrust. This is intended to replicate the forces on the knee when the patient is weight bearing.

This is not an artificial strain placed on the knee to demonstrate laxity. This movement occurs under mechanical load of the knee with every single step. The consequences are;

Shear forces (sliding and grinding) between the cartilage of the thigh and shin causing abnormal wear and tear.
Shear forces are also applied to the meniscal cartilages on top of the shin which are often crushed and folded by this abnormal movement.
Meniscal injury is one of the most debilitating and common complications associated with CCL disease.
Other ligaments, particularly the medial and lateral collateral ligaments are placed under abnormal strain whilst they are forced to control movement they are not designed for.
Inflammatory mediators are released in the joint causing swelling, pain and progression of osteoarthritis
As osteoarthritis progresses bony osteophytes build up around the edges of the joint and the joint capsule thickens. Most pronounce on the inner side of the knee, this is often referred to as a medial buttress and is quite easy to feel this abnormality. There is often significant muscle wasting in the thigh and if one leg is worse than the other this can be obvious to see.

What causes CCL disease?

Only about 20% of dogs with a torn CCL suffer a true traumatic tear. This is a substantial ligament, responsible for controlling large forces of cranial drawer and internal rotation. Over extension of the knee or excessive internal rotation are thought to result in these sorts of tears.

The vast majority of dogs (approximately 80%) suffer a degenerative form of CCL disease, hence the classification of “disease”. There is no widely accepted consensus on what causes this. It is thought to be a degenerative condition where the CCL is weakened possibly through immune mediated processes, degenerative joint disease, abnormal biomechanics and there may be a genetic component. These are the patients more likely to have a gradual onset of CCL disease, typically a waxing and waning lameness, often with little or no trauma. They are also more likely to involve both knees!

How is it diagnosed and do I need x-rays?

To diagnose CCL disease we generally want to demonstrate;

A positive cranial drawer sign and/or
A positive Tibial compression test
X-ray findings may be required for diagnosis if the above are not convincing

Some dogs will have easily palpable laxity as demonstrated by a cranial drawer sign or positive tibial compression test, but many with partial tears will not. If laxity is not present we may have suspicion of CCL disease from other signs like knee pain, knee effusion, muscle atrophy, thickened medial buttress or a meniscal click, or we may have no convincing localising signs whatsoever. Even though we cannot see the cruciate ligament itself on X-rays we can usually see other changes which support the diagnosis of CCL disease.

Even if the cranial cruciate ligament rupture can be diagnosed on physical examination alone, there may be reason to still perform x-rays.

X-rays are particularly useful in assessing the opposite leg which may seem OK at the time, but as so many dogs have this condition in both knees, it is only reasonable to assess the opposite knee so you can get an idea of your dog’s likelihood of having the same problem in the other knee.
Depending on the patient, it may also be useful to assess other joints in the back legs to make sure there is not more than one problem which may alter our expected outcomes of treatments.
X-rays are needed for pre-operative planning of certain types of cranial cruciate ligament surgery in order to take precise measurements and select appropriately sized implants.
Measurements taken for pre-operative planning may provide information that will determine if one type of surgery is more suitable than another for that patient’s size and conformation.

How is CCL disease treated

Treatment is broadly separated into conservative management, medical treatments and surgical treatment. Veterinarians will typically recommend a combination of these.

Conservative treatments include weight loss where appropriate and activity restriction, particularly in the acute phases, to moderating the intensity and duration of exercise over the long term. Comfortable and warm bedding can be useful in overall patient comfort and reducing muscle soreness in patients who may be laying down more due to their injury. Physiotherapy and biomechanical medicine are also becoming more accessible.

Medical management includes;

Nonsteroidal Anti-inflammatories (NSAIDs) – provide pain relief and can be used long term provided we monitor them for side effects.
Chondroprotective agents – these compounds act in various ways to maintain healthy cartilage. This can be in the form of pentosan polysulfate injections and nutraceutical supplements such as glucosamine, chondroitin and fish oil supplements.
Monoclonal Antibody injections (MABs) – These are a new class of drugs used in human and veterinary medicine for a range of conditions. One particular formulation has been developed for arthritis in dogs and works by targeting nerve growth factor.
Surgical treatment – Ultimately CCL disease is a physical problem and the best ways to address this is to stabilise the knee with some form of surgery. There are many types of surgeries available;
Extracapsular suture (DeAngelis) – This is the traditional repair technique for CCL disease. A heavy gauge non-absorbable suture is anchored to the femur and tibia such that it replicates the direction of the cruciate ligament. The suture will provide static stabilisation and improved function. It is best suited for small dogs.

The remaining procedures all aim to alter the biomechanics of the knee joint by way of osteotomy. An osteotomy means to surgically cut bone and, in this instance, to change its alignment. The alignment is altered in biomechanically favourable ways to neutralise shear force in the knee during weight bearing providing “dynamic stabilisation”. These techniques are very effective for larger and more active dogs which otherwise are more likely to have less favourable results with an extracapsular suture. The most common types of dynamic stabilising osteotomies performed are TPLO, TTA and TTO.

TPLO – Tibial plateau levelling osteotomy. A radial (semicircular) cut is made at the top of the shin bone and the fragment is rotated and plated into a position in which the tibial plateau (joint surface) is almost level with the weight bearing axis of the bone. This stops the femur sliding backward off what is normally a steep joint surface when the cruciate ligament is ruptured.
TTA – Tibial tuberosity advancement. The bony prominence on which the patella tendon inserts is cut and braced in a more forward position. A slightly harder concept to visualise but the net result is to achieve a 90 degree relationship between the tibial plateau and the patella tendon. In doing so, the quadriceps muscle effectively exerts a neutral force on the tibial plateau eliminating shear force. This technique is not always effective for particularly steep tibial plateaus.

TTO – Triple Tibial osteotomy. This essentially is a combination of the above 2 procedures. Three cuts are made in the bone. One to separate the tibial tuberosity and behind this, two cuts to remove a small wedge of bone that when closed both acts to flatten the tibial plateau and push forward the tibial tuberosity.

CWO/TWO – Closing wedge osteotomy and Tibial wedge osteotomy. These are older versions of the TPLO.

Is surgery essential for cruciate ligament disease?

For most dogs with Cranial cruciate ligament disease, there will usually be some, if not significant benefit with appropriate surgical management and earlier intervention will likely mean more favourable results. So I will generally always recommend surgery as part of a complete and holistic treatment regime for my patients. Every case needs to be considered on its own merits, and the type of surgery I recommend and how urgently I think it should be considered requires consideration of how lame they are, their age, body weight, activity level and whether they have other health or mobility problems. There are also pet owner factors which need to be considered, particularly what activity levels they expect from their dog and what they can afford to do.

Surgery is also known to greatly reduce the incidence of a meniscal tear in the knee. For many dogs, the meniscus is often already torn at the time of diagnosis, however if not, early surgical intervention may reduce the risk of the meniscus tearing.

What does it cost?

We are more than happy to discuss individual cases over the phone. Our goal is to make advanced surgical treatments for cranial cruciate ligament disease more accessible to more dogs. We can discuss your dog’s condition and where possible review X-rays you may already have.

Our estimates are intended to give you a realistic expectation of the whole surgical procedure, take home medications, routine follow-up checks and x-rays typically required for that procedure.

If you want to spread out the costs associated with this surgery, one option you may wish to consider is applying for Vetpay, an independent credit provider for veterinary services. Once we’ve discussed your dog’s case and given you an estimation of costs, you can go through an online, commitment free pre-approval process to see if you qualify.

Should this surgery only be done by a specialist surgeon?

Your regular vet may have recommended a specific type of surgery such as a TPLO, TTO or TTA and furthermore may have recommended a specialist to do this. This is certainly reasonable advice. Many general practicing veterinarians are comfortable performing the more traditional Extracapsular lateral suture or DeAngelis surgery for cranial cruciate ligament disease. This is not suitable for all dogs however where osteotomy procedures such as the TPLO, TTO or TTA are more appropriate. It is true that the majority of veterinarians in general practice do not perform these more advanced cranial cruciate ligament surgeries which previously have been the domain of veterinary specialists.

Due to the high incidence of this condition in dogs, many training programs have been developed to allow general practicing veterinarians, such as myself, who have a passion for orthopaedic surgery to advance their skills in these areas. Consequently there are a growing number of general practicing veterinarians who can perform more advanced types of cruciate ligament surgery.

Veterinary specialists have undergone years of intensive training and examination to achieve their qualification. They are capable and prepared for a wide range of complicated surgical conditions of all organ systems from spinal surgery, to complicated reconstructive soft tissue surgery. They have fully equipped surgical suites to cater for this and justifiably charge more than general practicing veterinarians. They are more than capable of performing surgery for cranial cruciate ligament disease. We owe a great deal to specialists for leading the way in many of the advancements in the veterinary field.

So the answer to this is not a simple yes or no answer. My advice would be that if you want a specialist surgeon to do your pet’s surgery and your finances permit it, then you should not be discouraged to do this. If the cost of a specialist is beyond what you are comfortable with, then we have the training, skill and experience to provide you with a great alternative.

Are there any complications I need to know about?

Any surgical procedure can have complications and it is essential to have a healthy respect and understanding of these. Every treatment whether it is medical or surgical needs to have its benefit weighed against its risk. These risks are not only determined by the condition itself but by other patient factors such as age, activity levels, weight, breed, concurrent medical conditions and what supervision patients will have at home after surgery. Veterinarians are assessing the degree of risk for every patient. Ultimately, we want to get an idea as to whether a patient is going to have a better outcome with surgery than without. At the same time, we are trying to give you an expectation of what degree of benefit your dog will get from surgery so you can make your own judgment as to whether the value of surgery is right for you.

The benefit of cranial cruciate ligament surgery

Ultimately most dogs can expect good to excellent results with surgery. Even though some component of arthritis is always going to be present in these patients, many can still remain active and athletic after recovery from surgery.
Even in circumstances where a patient has other mobility problems such as hip dysplasia or spinal disease, if cranial cruciate ligament disease is contributing or adding to their morbidity, cruciate surgery can still be very beneficial. It does need to be considered in context of the patient as a whole.

The risk of cranial cruciate ligament surgery

Most complications are minor and treatable, these include infections at the surgery site, wound breakdown from stitches loosening or being chewed out.

More serious complications can develop such as infection within the joint or in the bone around the surgical implants. These also are generally treatable however they can require long courses of antibiotics and on occasion, removal of implants.

Implant failure can also occur. Extracapsular sutures can break or pull through the Fabella’s ligamentous attachments. This is the main reason why I avoid using them with larger or more active dogs. Over the years, various types of extracapsular suture and anchoring devices have been developed to reduce the frequency of this complication. No one implant type is completely failure proof.

Osteotomy procedures use specially engineered bone plates to secure bone fragments created by surgically cutting bone and reconfiguring the fragments into biomechanically favourable positions. Plates and screws are very strong but failure to restrict activity can result in implants or bones breaking. There are certainly circumstances where a patient’s temperament or inability to confine a patient for 6 weeks post operatively may mean an increased risk of this complication.

Patella tendon thickening is common but generally resolves with time and Nonsteroidal anti-inflammatories.

Late Meniscal tears are an important topic to cover prior to committing to a cruciate surgery. Meniscal injury is in my opinion one of the most important reasons for performing surgery for cranial cruciate ligament disease, either because it has happened already, or it will likely happen without surgery. It is a significant source of pain and contributor to the progression of osteoarthritis. It is the main reason to consider performing surgery early if there is hope to preserve a meniscus not yet torn. I spend a significant amount of time in each procedure carefully evaluating the meniscus to determine if it is damaged or not. Unfortunately, if it is already damaged, the meniscus is not amenable to healing well. Primary repairs that can be performed in a small proportion of human cases are not typically feasible in veterinary surgery as the poor blood supply to the meniscus means healing time is prolonged and requires a level of immobilisation that is not often possible. Depending on the level of damage the meniscus may have damaged portions trimmed or sections of the meniscus removed entirely. If the meniscus is intact, I elect to leave the meniscus alone.

What about a meniscal release? A meniscal release is a procedure that has been proposed as a means to reduce the incidence of late meniscal tears. An incision is intentionally made in the medial meniscus to provide flexibility in an unstable stifle. Performing one however removes the meniscus’ ability to withstand “hoop stress”, a fundamental function of the meniscus’ cushioning properties in the joint. I do not routinely perform a meniscal release when doing a TPLO as this has been shown to have deleterious effects on the joint. A healthy meniscus is far more beneficial than one that has had a meniscal release performed.

When the knee is stabilised appropriately with a cruciate surgery, the risk of meniscal tears occurring is reduced. The incidence however of a tear occurring is not completely removed with reports of late meniscal tears following TPLO being 3-6% and with a TTA it can be as high as 27%. A meniscal release can reduce the incidence of late meniscal tears for TTA down to 5-17% however as discussed above, meniscal release is controversial and one reason why TPLO is becoming the favoured procedure for cranial cruciate ligament disease.

About the author

Asher has been with the WestVETS team since 2008. Graduating from the University of Queensland in 2001 he has further completed a Masters in Veterinary Studies in 2010 which had a heavy focus in Medicine and Surgery. More specific to cranial cruciate ligament disease, Asher has undertaken formal training in Extracapsular suture repair, Tibial Tuberosity Advancement (TTA), Triple Tibial Osteotomy (TTO) and Tibial Plateau Levelling Osteotomy (TPLO) and meniscal surgery.

His is ongoing interest in this field is largely due to the fact that so many dogs suffer from this condition, and it is an injury that really can benefit significantly with the right treatment. Asher has been performing Cruciate ligament surgeries in various forms for over 20 years and continues to look for ways he can expand his knowledge on this condition.