The mechanism of injury for most meniscus injuries is a rotational, weight bearing load with a shift a-p or lateral. For the ACL, it is generally a deceleration and pivot load to unload injury. Most athletes or people feel the pop or injury during the unloading phase of the change in direction. If you had a healthy meniscus, and the form was spot on, i wouldn't think you would injure it. If that's what you injured? A meniscal injury will cause some swelling but an ACL rupture will cause near immediate diffuse swelling.(one less vascular than the other respectively)