ACL Tear Symptoms: Signs, Treatment And When Surgery Is Needed A knee injury can happen unexpectedly during sports, exercise, or everyday activities. You hear a "pop." Your knee swells and feels weak. It is easy to overlook these symptoms and expect the knee to recover naturally. But these could https://www.tumblr.com/healpedia/831974508011421696/acl-tear-symptoms-when-do-you-need-surgery