A sudden “pop” in the knee at the time of injury
Immediate swelling within a few hours
Severe pain right after the injury
Feeling of the knee giving way or instability
Trouble bearing weight or walking
Loss of full range of motion
Difficulty straightening the knee
Tenderness around the knee
Swelling that makes the knee feel tight
Injury during pivoting, twisting, or sudden stopping
Feeling like the knee is shifting out of place
Bruising around the knee
Inability to continue sports or activity after the injury
A medical exam and imaging are needed to confirm an ACL tear