The anterior cruciate ligament (ACL) is one of four knee ligaments that connect the upper leg bone (femur) with the lower leg bone (tibia) by running crosswise inside the center of the knee joint. The ACL stabilizes knee movement in a forward and backward direction.
Specifically, the ACL prevents the tibia from sliding or twisting abnormally on the femur when the leg is straight or slightly bent. And the ACL prevents the knee from being stretched or straightened beyond its normal limits (hyperextended). It also supports other knee ligaments that keep the knee from bending sideways.
Current as of: May 23, 2016
Author: Healthwise Staff
Medical Review: William H. Blahd, Jr., MD, FACEP - Emergency Medicine & Freddie H. Fu, MD - Orthopedic Surgery
To learn more about Healthwise, visit Healthwise.org.
© 1995-2017 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
Donations to UW Health are managed by the University of Wisconsin Foundation, a publicly supported charitable organization under 501(c)(3) of the Internal Revenue Code.