http://orthoinfo.aaos.org/topic.cfm?topic=a00549
One of the most common knee injuries is an anterior cruciate ligament sprain or tear.
An anterior cruciate ligament (ACL) injury often is called a sprain. A sprain occurs when the threads or fibers of the ligament stretch or are torn.
http://www.webmd.com/fitness-exercise/t ... c-overview
























