Pain in the knee is not necessarily indicative of an injured ACL, even though knee pain is a common indicator of an ACL sprain or tear. A torn ACL would potentially have the following symptoms: • A popping sound can be heard, or a popping sensation felt in the knee at the time of the knee injury. Many patients report hearing or feeling their knee pop when describing their knee injury to a medical professional. • Intense pain in the knee at the time of injury, could be sudden and intense, or a searing, burning sensation. • The injured knee may start to swell, getting particularly worse about 5-6 hours after the initial injury was sustained. • A knee with a torn ACL may not be able to be bent or straightened after injury. Depending on the severity of the tear, it may be impossible to put weight on the knee that was injured.