In a conventional shoulder replacement a metal ball is used on the top of the arm bone and a plastic socket is used on the shoulder blade. Our body is also designed in a similar fashion with a ball-and-socket shoulder joint.Likewise, the reverse shoulder replacement also uses a ball-and socket but in a reverse manner. Here the ball is put on the shoulder blade, and the socket is put above the arm bone. The name reverse shoulder replacement is thus used because it is a reverse method compared to our normal anatomy.