The cranial cruciate ligament (CCL) provides stability for the knee joint. Rupture of this ligament is one of the most common orthopaedic conditions seen in the dog.
In people, cruciate ligament rupture is usually a result of trauma, commonly a twisting motion while weight bearing such as happens during football. In dogs, there are many factors that may contribute to cruciate rupture.
Acute CCL rupture is often traumatic in origin and most commonly occurs when the leg is extended and rotated while weight bearing, such as can happen when the dog steps in a hole.
CCL rupture can also occur secondary to chronic changes in the joint, due to age related degenerative change, osteoarthritis, obesity, or conformational abnormalities.
Risk factors include large dogs being very active, obesity (putting extra strain on the joints) and animals that participate in the weekend warrior syndrome - ie unfit dogs overexercising and injuring themselves.
Regardless of the cause, CCL rupture sets off a cascade of events including articular cartilage degeneration, joint capsule inflammation, arthritis development and fibrosis of the joint capsule.
Rupture of the CCL also predisposes the joint to further injury (especially damage to the menisci which are the shock absorbers inside the joint), as the stability of the joint has been compromised.
Damage to the CCL can vary in presentation from a subtle lameness (especially if only partially ruptured) to a sudden non weight bearing injury.
CCL rupture can be diagnosed by physical examination. Signs include fluid accumulation around the joint, decreased range of motion and clicking of the joint. Instability (detected by a cranial draw movement) is diagnostic of the disease, however it may be difficult to detect with partial tears or in very tense dogs.
Xrays may be taken to confirm fluid acculuation, grade the amount of arthritis present and to rule out concurrent disease conditons such as cancer.
Lameness will improve within 3-6 weeks after injury without treatment. Some dogs less than 10 kg will continue to improve and regain good function without surgery. In larger dogs the lameness improves but they never regain good function of the leg without surgery.
Conservative treatment involves rest and non steroidal anti inflammatory medication for 6-8 weeks. A graded regime of exercise can be introduced once the pain and inflammation is reduced, and a weight loss program (if necessary) should be intiated. This treatment has the most success in dogs weighing less than 10 kg. Results are more unpredictable in larger animals.
There are various surgical options to treat CCL injury, but broadly they can be divided into 2 categories :- extracapsular (outside the joint), or intracapsular (inside the joint).
Most surgeons favour an extracapsular technique as it delivers equal or better results to intracapsular techniques, without added trauma to the joint.
Extracapsular techniques either aim to stabilise the joint by sutures around the joint (eg DeAngelis technique), or by changing the biomechanics of the joint so the animal can weight bear and walk without a cruciate ligament (eg Tibial Plateau Levelling Osteotomy or TPLO).
TPLO surgery requires cutting the tibia and applying a plate so that the top of the tibia sits at a different angle. It should only be performed by a veterinary surgeon with advanced training.
The decision of which surgery to perform should take into account the dogs age, activity level, size and temperament. Our vets will be able to go through your options with you so you can make the right decision for your pet.
Surgical complications include wound problems, bandaging problems, infection, implant (bone plate) failure and failure to return to normal function.
Ten percent of patients may have damage to their meniscus (cushioning cartilage within the joint) at a later date.
Up to 60% of patients will rupture the other cruciate ligament within 2 years.
All joints that have had a CCL rupture will develop arthritis later in life. Surgical repair technique does not appear to affect long term outcome for the joint providing the surgery has been successful, although there are a limited number of long term studies.
Activity is restricted to leash walking for a minimum of 6-8 weeks.
Supervised rehabiliation - including swimming and passive range of motion exercises - can decrease recovery time and facilitate a return to more normal function.
Our vets will advise you on exercises you can do at home, or we can refer you to a dedicated animal physiotherapist to help your dogs recovery.