A dead persons. I’m personally on my fourth person’s ACL (My original, and three other people’s). I do wish I could have found out who I got my second one from and how they died tho. Cause like two weeks after the surgery I started have this extremely vivid and recurring dreams of dying in a pretty bad car crash and I had never died in a dream until then. Stopped have the recurring dreams after I tore that ACL and had it replaced with a new one.