Anterior Cruciate Ligament (ACL)
The ACL crosses from back of the femur to the front of the tibia. It acts as a strong support for your knee. But the ACL can be injured if you twist your knee too far or change direction too quickly.
A Sudden Twist
Your ACL can be injured when you twist your knee beyond its normal range of motion. When you’re on skis, for instance, and “catch an edge,” this causes you to twist your lower leg outward or inward. You might hear of feel a pop, and your knee may give away. Pain and swelling result. A complete tear of ACL is like rope fibers coming apart. A partial tear can also occur. Other parts of the knee may be injured at the same time that you injure the ACL.