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.

The improved endoprosthetic device surface treatment encourages soft tissue attachment thereto. A porous mesh surface treatment creates on an outer surface of the endoprosthetic device a three-dimensional surface structure similar to cancellous bone. Suture attachment features are provided at various locations around the treated surface structure to initially affix a vascularized soft tissue to the treated surface. As the patient heals the soft tissue grows and infiltrates the porous mesh surface to achieve an attachment strength substantially equal to the surrounding tissue.

A humeral implant component connectable to another humeral implant component, the humeral implant component comprising: a longitudinal axis, a first end and a second end, the first end and the second end opposing each other along the longitudinal axis of the humeral implant component, and an interface part for connecting the humeral implant component to the other humeral implant component, wherein the interface part is tapered along the longitudinal axis in a direction from the second end to the first end, the interface part being engageable with a tapered interface part of the other humeral implant component to form a tapered connection between the humeral implant component and the other humeral implant component, wherein the humeral implant component further comprises a through hole extending along the longitudinal axis for locking the tapered connection by a longitudinal fastener.