Knee Ligaments

Your knee is stabilized by four ligaments. These are bands made up of collagen and elastin - proteins that are found in connective tissue.

The ligaments in your knee hold the ends of your knee bones together. These ligaments help to ensure that your knee is stable and that it moves the way that it is supposed to move.

If the ligaments in your knee are loose - whether this is because you naturally have loose joints or because your ligaments have been injured- your knee will be unstable.

You can sprain or tear the ligaments in your knees if the bones in your knees are pulled too far apart.

If you tear or sprain a ligament in your knee, your knee will swell and you will feel knee pain that will increase over the next 24 hours. The pain will get worse if you try to walk or if you try to bend your knee.

The four knee ligaments are:

• The anterior cruciate ligament (ACL) - runs diagonally from the back of the femur (thighbone) to the front of the tibia (shinbone).
• The posterior cruciate ligament (PCL) - runs diagonally from the front of the femur to the back of the tibia.
• The medial collateral ligament (MCL) - runs along the inside of the knee
• The lateral collateral ligament (LCL) - runs along the outside of the knee

You can hurt your ACL when taking part in a contact sport, for example, if you are playing football and you collide with another player.  You can also hurt your ACL if you plant your foot on the ground or the floor and quickly change direction.

An ACL tear is extremely painful. If you tear your ACL, your knee may give way completely, and you may hear or feel something pop in your knee.

Your knee may swell up within a few hours, even after you have applied ice to it.

Your PCL may be injured if something forces your tibia backwards - for example, if you collide with another player during a basketball game, if you are in a car accident and your knee hits the dashboard, or if you fall on your knee.

You can injure your MCL if something hits you on the outside of the knee while your foot is planted on the floor or on the ground.  The force will put pressure on the inside of your knee, pushing your knees together so that you appear knock-kneed. You may feel like your knee is buckling and you may have the sensation of something ripping.

It is unusual for someone to damage their LCL without damaging another part of their knee. If your LCL is injured, you will probably be suffering from another injury to the outside of your knee.