CRUCIATE LIGAMENT RUPTURE
I know that knee injuries are common in people. Do they occur in dogs?
Just as football players frequently suffer knee injuries, the dog may also
be prone to knee injuries since the knee joint is one of the weakest in the
Why is the knee so likely to be injured?
The knee joint is relatively unstable because there are no interlocking bones
in the joint. Instead, the two main bones, the femur and tibia, are joined with
several ligaments. When severe twisting of the joint occurs, the most common
injury is a rupture of the anterior cruciate ligament which is one of two ligaments
which actually cross over within the joint and ensure that it is stable and
works in one plane. When it is torn, an instability occurs that allows the bones
to move in an abnormal fashion in relation to each other. It is not possible
to bear weight on the leg without it becoming unstable.
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, or is
uncooperative, it may be necessary to use a sedative or a light anesthetic in
order that the veterinary surgeon may examine the joint thoroughly.
How is it treated?
Correction of this problem requires surgery. A skilled surgeon can fashion
a replacement ligament and stabilize the joint so it functions normally or near
normally. Massive arthritic changes will begin that cannot be reversed, even
I have heard of torn cartilage. Does this also occur?
Occasionally the injury that causes a ruptured anterior cruciate ligament
will also result in tearing of one or both of the menisci or "cartilages". At
the time of surgery, these are examined and treated, if necessary.
What happens if surgery is not performed?
Occasionally, the dog that has a ruptured cruciate ligament will become sound
(will no longer limp) even if surgery is not performed. However, arthritis will
usually begin and result in lameness a few months later. That lameness is usually
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. The ligament
may become weakened due to carrying too much weight; this causes it to tear
easily. 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. Prescription
diets are available and will assist weight reduction.
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