ACL Tear Symptoms: Signs, Treatment And When Surgery Is Needed You twist your knee while playing football, running, or even stepping off a curb. You hear a "pop." Your knee swells and feels weak. Many people ignore this and hope it will heal on its own. But these could https://www.tumblr.com/healpedia/831974508011421696/acl-tear-symptoms-when-do-you-need-surgery