What is an ACL and PCL?

Knee ligaments, knee picture, knee diagram
Diagram of left knee joint
Diagram of ligaments and bones that make up the knee joint

The most common knee injury in sports is known as the anterior-cruciate-ligament, aka the “ACL.” If any ligaments in the knee is completely torn, reconstruction of the knee is inevitable as these ligaments cannot heal on their own.In 2013, the NFL had a record high of 269 ACL injuries- SportsIllustrated Additionally, the NBA had it’s highest number at 10 ACL injuries in 2013, according to Oklahoma News 6. With this in mind, let’s take a look and see what the ACL is as well as the PCL.

acl picture, knee picture, knee ligaments

Anatomy of the knee bones and ligaments

What is an ACL?

  •  An ACL is one of two cruciate ligaments inside the knee that cross the other ligament to form an “X.” An ACL is attached to the the tibia(shin bone) and crosses over the front attaching to the femur(thigh bone). –OrthoInfo

What is a PCL?

  • A PCL does the same as the ACL,  attaches from the tibia crossing to the femur, but crosses  towards the back of the knee, hence, “posterior.”  It is known to be the strongest ligament of the four knee ligaments. –Healthline

What is the Primary Function of an ACL?

  • An ACL prevents the tibia(shine bone) from excessive forward motion in front of the femur(thigh bone), as well as provides rotational stability to the knee. – AAOS
  • An ACL prevents hyperextension of the knee

 What is the Primary Function of a PCL?

  • The PCL prevents the knee from excessive backwards motion of the tibia(shin bone). The PCL also pays a role as a centric axis controlling and imparting rotational stability to the knee. –Medscape

As we can see, the ACL is a very important ligament to protect and prevent from knee injuries. Of course, we cannot forget the PCL , even if it is the strongest of the four knee ligaments. So, now that you know what the ACL and PCL are, let’s take a look at the other two ligaments covered here.

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