What is Canine Cruciate Disease?
Injury or failure of the cranial cruciate ligament (commonly referred to as Cruciate Disease) is a very common problem that can be encountered by dogs of all shapes and sizes. Some breeds such as the Labrador Retriever, Rottweiler, Mastiff breeds and West Highland white terrier appear predisposed whereas some breeds such as greyhounds are seldom affected. Cruciate disease is the most common reason for orthopaedic surgery being performed and the most common reason for referral to a specialist orthopaedic surgeon being considered. Cruciate ligament rupture also occurs in cats but is far less common.
What are the cruciate ligaments?
Ligaments are tough bands of tissue situated in and around joints to provide stability whilst still permitting normal movement of the joint. There are two cruciate ligaments found within the stifle (knee) joint – the cranial cruciate ligament and the caudal cruciate ligament. The cranial cruciate ligament originates between the condyles (knuckles) of the femur and passes diagonally forwards and medially (towards the inside of the joint) to attach on the upper surface of the tibia. The caudal cruciate ligament sits behind the cranial cruciate ligament and passes in the opposite diagonal (from medial to lateral). When both cruciate ligaments are viewed from the front of the joint they form a cross or X shape, hence the name cruciate.
The cranial cruciate ligament is more important than the caudal cruciate ligament and is responsible for preventing three movements that may become apparent where the ligament fails:
- Tibial thrust – The tibia slides forwards in relation to the femur, leading to the sensation that the joint will not lock out when standing/walking.
- Internal tibial rotation –the tibia and lower limb pivot around the long axis of the bone. This may result is the paw turning inwards when the foot touches the floor, a so called pivot shift.
- Hyperextension – Some dogs will cause rupture the cruciate ligament by hyperextending the stifle joint. This most commonly happens where the hindlimb gets caught in a fence whilst jumping.
Why do cruciate ligaments become injured?
The majority of dogs develop rupture of the cruciate ligament as a consequence of a degenerative process where the fibres within the ligament gradually break down. The cause of this degeneration is unproven at this time. Ligament degeneration occurs with normal activity and can take many months. Owners frequently report intermittent periods of mild lameness that then seem to resolve spontaneously. Unfortunately the ligament is typically getting progressively weaker and eventually will rupture. Some dogs can be persistently lame with a partial tear of the cruciate ligament, where others will only become lame at the point of complete rupture.
A relatively small proportion of dogs will injure their cruciate ligament during a traumatic incident, such as where the limb is caught in a fence. If cruciate rupture has resulted from such an accident, there will often be other damaged ligaments that must be recognised and appropriately treated if limb function is to be restored.
Read more about cruciate disease in dogs at TheVeterinaryExpert.com