A joint prosthesis, as a replacement for a ball and socket type joint, has a head (14) that allows for infinite adjustment rotationally and/or of angular orientation with respect to an implanted stem (12), particularly during a procedure for implanting the prosthesis. The angular orientation is positionable and fixed or locked in a set position without utilizing external or separate fasteners. An expandable conjoining member (30) associated with the prosthesis stem receives the head and allows for the positioning thereof. The expandable conjoining member is fixed in position through expansion of the expandable conjoining member to produce a friction fit (wedging) of the expandable conjoining member within a receiving socket of the stem. Expansion of the expandable conjoining member is achieved through coupling interaction of a stem of the head with the conjoining member.
