A bone anchor is provided comprising an anchor member (1, 1) having an open first end (11) and a second end (12) and a tubular section (13) between the first end (11) and the second end (12), a longitudinal axis (L) extending from the first end to the second end, and a bone engagement structure (16) for engaging the bone in at least a portion of the tubular section (13) wherein the anchor member (1) is made of a first material a core member (2, 2) having a first end (21) and a second end (22) and being insertable into the anchor member and connectable thereto wherein the core member (2) is made of a second material that is different from the first material.
