Bone fixation system

A method of attaching a fixation element to an implant, the method comprising:

• inserting a shaft of the fixation element between respective inner surfaces of first and second wire segments of the implant along a transverse direction, wherein 1) the inner surfaces are curved as they extend along the transverse direction and define a first threaded region, and 2) the fixation element defines a head and the shaft extends from the head in a distal direction along a central axis of the fixation element;
• further inserting the fixation element between the inner surfaces along the transverse direction so as to cause a second threaded region of the fixation element to threadedly engage the first threaded region;
• and
• further inserting the fixation element between the inner surfaces along the transverse direction until 1) the second threaded region is disengaged from, and spaced in the distal direction from, the first threaded region, and 2) the first threaded region is aligned with an unthreaded groove of the head along a lateral direction that is perpendicular to the transverse direction,
• wherein the groove extends along the transverse direction between a 1) first ridge of the head, the first ridge extending out with respect to the central axis, and 2) a second ridge of the head, the second ridge extending out with respect to the central axis and defining the second threaded region.