The anterior cruciate ligament (ACL) is one of a pair of ligaments in
the center of the knee joint that form a cross, and this is where the
name "cruciate" comes from. There is both an anterior and a posterior
cruciate ligament (PCL). Both of these ligaments function to stabilize
the knee from front-to-back.
In medical terms, the ACL is the primary restraint to anterior displacement
of the tibia on the femur. This means that when the ACL is injured, the
shinbone can slide forward on the thighbone, causing the knee to "give
way".
