What is it?
Cranial cruciate ligament rupture (CCLR) is one of the most common orthopaedic injuries encountered in dogs. The cruciate ligament is an important ligament inside the stifle (knee) joint and plays an important role in stabilising the stifle during weight bearing. In humans it is called the anterior cruciate ligament. It prevents the tibia (shin bone) from sliding forward in relation to the femur (thigh bone) during weight bearing.
4) Cranial Cruciate Ligament
5) Caudal Cruciate Ligament
6) Lateral Meniscus
7) Medial Meniscus
What happens when cranial cruciate ligament ruptures?
When the cranial cruciate ligament fails the stifle is unstable which leads to pain and inflammation within the joint and development of osteoarthritis. Osteoarthritis develops rapidly in every case and is almost always present at the time of diagnosis. The osteoarthritis is progressive regardless of treatment.
Another consequence of CCLR is damage to the meniscus, a shock absorbing structure in the stifle. Meniscal damage is very painful. If your dog is undergoing surgery for CCLR then the meniscus will be inspected and any damaged sections removed.
What causes CCLR?
In people, rupture of the cranial cruciate ligament tends to be traumatic (e.g. while skiing or playing rugby or football). However in dogs CCLR generally occurs due to degenerative changes of the ligament that weakens it, predisposing it to rupture with minimal associated trauma. The reason for this degeneration is not well understood and research into this area is ongoing. There certainly appears to be breed predisposition with Labrador Retrievers, Golden Retrievers, Rottweilers, Mastiffs and Boxers being over-represented. A large number of patients are also overweight which suggests that this is a significant contributing factor.
How is it diagnosed?
CCLR can be complete and sudden or gradual and partial (usually leading to complete rupture if untreated). Common clinical signs include lameness, stiffness, sitting with the affected leg out to one side and a swollen and painful knee joint. It is diagnosed on history, clinical examination and radiography (under general anaesthesia). Dogs with CCLR usually sit with the affected leg extended.
How is it treated?
Some dogs, generally the smaller breeds, can be treated with non-surgical management. This consists of exercise restriction, weight control, physiotherapy and hydrotherapy, and painkilling drugs as necessary. However pre-rupture exercise levels are rarely achieved and most dogs with CCLR have ongoing stifle pain and instability and need surgery to correct this. There are many different surgical treatment options for stabilising the cranial cruciate ligament deficient stifle. They can largely be grouped into procedures that passively restrain abnormal stifle movement and those that change the mechanics of the stifle thereby changing the forces that act on the joint. Decision-making is based on individual patient assessment, the owner’s preference and compliance, as well as financial considerations. We perform the following three procedures routinely based on the above criteria.
Lateral fabello-tibial suture
This procedure involves placing a suture between the femur and the tibia to mimic the action of the cranial cruciate ligament. At TVC we generally use nylon leader line as illustrated below. The aim of the procedure is to stabilise the stifle, minimise pain and prevent any damage to the meniscus.
Schematic Drawing of a Lateral Suture
(image courtesy of Securos)
Tibial tuberosity advancement (TTA)
Tibial Tuberosity Advancement involves changing the mechanics of the stifle joint during weight bearing by adjusting the angle between the top of the tibia and the patellar ligament. This changes the forces that act through the stifle during weight bearing and allows the stifle to be stable without a cranial cruciate ligament. A longitudinal cut is made in the tibial tuberosity at the front of the tibia. This piece of bone is gently moved forward, and the tibial tuberosity is then fixed in its new position using a titanium cage and screws. This is the most common technique performed in our practice.
TTA Rapid and CWO pictures courtesy of Veterinary Instrumentation
Closing tibial wedge osteotomy (CWO)
Smaller breed dogs, especially terriers, can have an excessively steep tibial plateau angle and a procedure that levels the tibial plateau can be more appropriate. This is done by removing a triangular piece of bone from the tibia and stabilising the tibia with a bone plate.
What happens after the surgery?
Patients are sent home with a detailed rehabilitation program to cover the first eight weeks after surgery, which are the most restrictive. It can take dogs up to 3-6 months to regain pre-rupture exercise levels. The cost of the surgery also includes up to four sessions with our physiotherapy nurse, and owners will also be given instruction on how to carry exercises out at home. The veterinary surgeon will re-assess the patient regularly. If the dog has had a TTA the leg will be re-radiographed eight weeks post-operatively to ensure healing is progressing as expected so that off-lead exercise can commence.
Can hydrotherapy be of benefit?
We strongly recommend hydrotherapy as part of the rehabilitation program as it allows the muscles around the knee to strengthen with minimal forces acting on the joint itself. It is also an excellent weight loss tool.
What is the prognosis for CCLR?
The prognosis for dogs with CCLR is generally good to excellent after surgery though it is important to remember that the stifle never returns to normal function. All dogs inevitably develop osteoarthritis but the majority of dogs go on to lead an active comfortable life with minimal lameness, although a few will need ongoing anti-inflammatory medication. Keeping the weight down is a very important part of post-operative management. A dog that has had a CCLR in one leg is at risk of developing it in the other leg.