Monday, March 21, 2011

Understand the basic anatomy of your dog's knee.

When a dog has been diagnosed with a torn anterior cruciate ligament (ACL) the treating veterinarian may suggest surgery to correct the problem.
Unfortunately, veterinarians sometimes use language that is difficult for the average dog owner to understand. This, coupled with stress, the dog owner is at the bottom, making it difficult to make appropriate decisions for the dog.
Here's what's involved in an ACL (anterior cruciate ligament) injury and its repair, explained in plain English:
In canine patients, the ACL correctly called a CCL, or cranial cruciate ligament. The term refers to both the ACL structure, but with people. I'll be using the correct term, cranial cruciate ligament, or CCL, from now on.
The knee joint of the dog's (the joint where the cranial cruciate ligament resides) is called the knee joint. The knee joint is composed of three large bones, the femur (thigh bone to the people), the tibia (shin bone in humans) and patella (kneecap people). The end of the bone is surrounded by cartilage, the slippery stuff that allows for movement. They sit together in a liquid called synovial fluid, and there is a brand around the joint is called a joint capsule.
CCL is located within the joint, with a second ligament called the caudal cruciate ligament. These ligaments cross each other, which is where the name cruciate (ie cross) came from. It is important later when explaining the joint function.
Also common are two shock absorbers called menisci (plural of meniscus). When the knee is seen in an X-Ray, femur and tibia appear to be separated by a space - but the femur actually sits on top of the meniscus - it's just that the ligaments are not visible in X-Ray - so the CCL does not show up on an X-Ray.
The function of the knee joint;
The knee joint is a complex joint, but here's an analogy that might help: Think of the knees like a hinge that can only swing in two ways, forward and back, not sideways. In the middle of the hinge within the knee joint. When it swings forward, it carries weight. When it swings back (in the swing phase of gait motion), it is not weight bearing.
As you know, when you walk, just one foot on the ground at any time. Cranial and caudal cruciate ligament is to hold the femur in alignment with the tibia during movement. The two ligaments in the form of an X to maintain adequate contact between the two bones.
CCL put on the back of the femur and appears to attach to the front of the tibia. The ultimate cruciate ligament attaches to the front of the femur, and goes back to attach to the back of the tibia. Where they intersect is the "hinge" point.
Once you understand this, you will have a basis for understanding what happens when the cranial cruciate ligament ruptures.

1 comment:

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