CRUCIATE LIGAMENT RUPTURE
What is this?
The cranial cruciate ligament is one of 2 ligaments in the knee or stifle joint which form a cross inside the joint. The 2 cruciate ligaments together stop the 2 major bones of the knee ,( the femur and the tibia) from moving back and forward relative to each. When the cranial cruciate ligament is damaged or ruptured the 2 bones move around causing severe pain and damaging other internal structures within the joint (commonly the menisci which are the soft cartilage pads between the bones). Rupture of the cranial cruciate ligament in dogs is thought to be almost always caused by a slow degenerative process ending in rupture of the severely weakened ligament. Rupture of a normal strong cruciate ligament is thought to occur only very rarely.
How is it diagnosed?
One of the most reliable means of diagnosing this injury is to move the femur and tibia in a certain way to demonstrate the instability. This movement is called a "drawer sign". It can usually be demonstrated with the dog conscious. However, if there is severe pain, the dog has very strong leg muscles, and /or the dog is very nervous, it may be necessary to use a sedative or an anaesthetic to be able to make the diagnosis. Occasionally it may be necessary to x-ray the joint to make the diagnosis or rule out other complications.
How is it treated?
Correction of this problem requires surgery. Surgery involves opening the joint and examining the menisci for damage. If they are damaged they must be removed as damaged menisci cause considerable pain and never heal. The joint is then closed and an artificial ligament is placed along side the joint and secured in the bones to produce the stabalisation that the normal ligament did before. The objective of the surgery after healing is to eliminate pain as much as possible and return function to as near normal as possible.
Possible complications include those that occur with other surgical procedures: wound infection , wound break down , sutures coming apart, swelling or pain at the surgery site. Occasionally a menisci may be damaged at some time after the surgery. In addition the repair can never be as strong as a normal ligament and patients must not over stress the repaired joint or the artificial ligament may rupture or tear out. Unfortunately most dogs that rupture their cruciate ligament have or end up with some degree of arthritis in the joint. Rupture of the cruciate ligament in the other leg unfortunately is not uncommon
What happens if surgery is not performed?
Some smaller dogs, (usually less than 12kg), that have a ruptured cruciate ligament will recover without surgery, given time and rest. However some go on to damage their menisci and these dogs then do not recover without surgery and are less well off than those that have the surgery before the menisci is damaged .
My dog is overweight. Does that relate to this injury?
A special note is appropriate concerning the dog's weight. Obesity or excessive weight can be a strong contributing factor in cruciate rupture. Obesity will make the recovery time much longer, and it will make the other knee very susceptible to cruciate rupture. If your dog is overweight it is worth consulting your veterinary surgeon regarding the problem. Various weight reduction programs are available and will assist weight reduction.