Christians tell me every knee shall bow, and every tongue shall confess Jesus is lord so:?

Just tell me: How do I make my knee bow? Can I make my elbow bow? And does it make a difference which knee? (you dont say knees....just knee). What if somebody lost both legs in an accident. They dont have any knees to bow. IS that a one way ticket to hell because you cant bow a knee? Or would it be acceptable to bow a prosthetic knee?