The normal ROM with ACL tear?

what is the normal range of motion pre op for an acl tear? We don't know if this is my acl or not, but i can bend my leg some. can BARLY get it to 90 degrees with out tons of pain. Don't really have that looseness feeling, although i did when it first happened, heard a REALLY loud pop followed by a smaller one. extreme pain afterwards and immedate swelling. does this sound like an acl tear? We're waiting on MRI results. or is this maybe an MCL tear? or meniscus?