An improved modular rotational device includes a first and second threaded coupler for affixation along the stem of an endoprosthetic device, for example, a humeral prosthesis or a femoral prosthesis. The rotational device axis of rotation is coaxial with the stem, and its axis of rotation is located in close proximity to the intramedullary stem of the prosthesis or in close proximity to the distal articulation of the prosthesis. A housing has a proximal and distal end with an axial bore therethrough for receiving an elongated stem of the device. A lobe ring may be utilized to limit the axis of rotation of the device. Additional endoprosthetic devices may be attached to male or female threaded couplers, or to Morse tapers. A plurality of suture attachments facilitates attachment of soft tissue thereto.
