A partial or total shoulder replacement may be necessary after a bone fracture, severe arthritis, a rotator cuff tear, or when other conservative treatments for shoulder pain do not work. A total shoulder replacement is most common. This is when the ball of the shoulder joint is replaced by a metal ball and the socket of the joint is covered with plastic. A partial replacement is when only the ball of the joint is replaced by a metal ball and the socket remains the same. After a replacement surgery of this nature, physical therapy is usually prescribed to regain mobility of the shoulder, increase strength of the muscles supporting the joint, and to restore you back to your prior level of function.