An implantable intramedullary fixation structure adapted to be received in the intramedullary canal of a long bone is disclosed comprising a plurality of elongated segments. Each segment has a first end and a complementarily-shaped second end such that the first end of a segment cooperatively engages the second end of an adjacent segment. The segments define a guide aperture so as to be receivable over a guide for positioning in the intramedullary canal.