An injury to the ACL when the joint is carried through a range of motion greater than normal, but without dilocation or fracture; or an injury resulting from tensile force to muscle or tendon of the ACL.
Symptoms:
Knee instability
Knee swelling
Severe pain when bending the knee
Causes:
Knee hyperextension
The lower leg is forced forward in relation to the upper leg
Direct impact from the front of the thigh while the lower leg is in a stable position