Knee Anatomy

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The knee joint is the largest joint in the body and is a weight bearing joint. Each bone end is covered with a layer of smooth shiny cartilage that cushions and protects while allowing near frictionless movement. In addition there is a special washer like cartilage between the joint surface of thigh and leg bones called meniscus. The cartilage which contains no nerve endings or blood supply, recievs nutrients from the fluid contained within the joint. Surrounding the knee structures is the synovial lining which produces this moisturising lubricant. If damaged, the cartilage is not capable of repairing itself.

Srong fibres called ligaments link the bones of the knee joint and provide stability and elasticity to the joint.

Three bones meet to form your knee joint: your thighbone (femur), shinbone (tibia), and kneecap (patella). Your kneecap sits in front of the joint to provide some protection.

Bones are connected to other bones by ligaments. There are four primary ligaments in your knee. They act like strong ropes to hold the bones together and keep your knee stable.

Cruciate Ligaments

These are found inside your knee joint. They cross each other to form an "X" with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the back and forth motion of your knee.

The anterior cruciate ligament runs diagonally in the middle of the knee. It prevents the tibia from sliding out in front of the femur, as well as provides rotational stability to the knee.

The anterior cruciate ligament can be injured in several ways

• Changing direction rapidly
• Stopping suddenly
• Slowing down while running
• Landing from a jump incorrectly
• Direct contact or collision, such as a football tackle

Several studies have shown that female athletes have a higher incidence of ACL injury than male athletes in certain sports. It has been proposed that this is due to differences in physical conditioning, muscular strength, and neuromuscular control. Other suggested causes include differences in pelvis and lower extremity (leg) alignment, increased looseness in ligaments, and the effects of estrogen on ligament properties.

Symptoms

When you injure your anterior cruciate ligament, you might hear a "popping" noise and you may feel your knee give out from under you. Other typical symptoms include:

• Pain with swelling. Within 24 hours, your knee will swell. If ignored, the swelling and pain may resolve on its own. However, if you attempt to return to sports, your knee will probably be unstable and you risk causing further damage to the cushioning cartilage (meniscus) of your knee.
• Loss of full range of motion
• Tenderness along the joint line
• Discomfort while walking