Symptoms of an ACL injury include hearing a “pop” and knee swelling, according to WebMD. Knee swelling is often a sign of bleeding inside the joint. Another symptom is an unstable knee joint.
When a person has an unstable joint, the knee suddenly buckles or gives out. This symptom is common for an ACL injury that is chronic, states WebMD. When a person suffers an ACL injury, he should abstain from activities that put an added strain on the knees to avoid further damage. The most recommended solution for someone with an ACL injury is to participate in a rehab program to rebuild muscle strength and flexibility.