A method and apparatus for proper sizing and centralization of a shoulder humerus implant are provided. The method and apparatus replicate the proper stem height and position for a shoulder humerus implant, and may be used during trialing and maintaining the proper height and orientation during implantation. The apparatus further assists in maintaining the shoulder humerus implant stem at the center of the humeral canal to allow for proper cementing technique, and facilitates selection of the appropriate humeral head replacement.
