What are ACL injuries?
Ligaments are tough bands of fibrous tissue that connect two bones. The anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) are inside the knee joint. These ligaments connect the thigh bone (femur) and the large bone of the lower leg (tibia) at the knee joint. The ACL and PCL form an "X" inside the knee that stabilizes the knee against front-to-back or back-to-front forces.
An ACL injury is a sprain or tear, in which the ligament is stretched beyond its normal range. When the ACL is torn, it's almost always due to at least one of the following patterns of injury:
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