A proximal humeral prosthesis includes a humeral head having a distal end and a proximal end adapted to be coupled to a glenoid cavity of a scapula; a humeral stem core having an outer surface, a distal end, and a proximal end adapted to be coupled to the distal end of the humeral head; a humeral stem graft having an inner surface adapted to be coupled to at least a portion of the outer surface of the humeral stem core, a distal end, a proximal end, and an outer surface including at least one tendon attachment site; and an intramedullary stem having a proximal end adapted to be coupled to the distal end of the humeral stem core and a distal end adapted to be coupled to at least one bone of a skeleton. The prosthesis can be rendered modular and can further include a spacer segment. Resorption of bone from the humeral stem graft can be inhibited by compression of the humeral stem graft. Further, the prosthesis can include sites for attachment of soft tissues to the prosthesis, soft tissues for attachment to soft or bony tissues of the recipient, or both, which can improve function of the shoulder joint.