Fastener, spinal interbody system including same and method

A fastener having a first end, a second end, and a longitudinal axis extending from the first end to the second end, the fastener comprising:

• a head disposed at the first end of the fastener;
• a shaft connected to the head and extending to the second end of the fastener;
• at least one of the head and the shaft including a plurality of flat surfaces;
• a collar extending about the longitudinal axis and spaced in a longitudinal axis direction from the first end of the fastener, the collar including:
• a plurality of petals spaced about the longitudinal axis, each of the plurality of petals includes a root and a free end, the root is connected to the at least one of the head and the shaft, and the free end is spaced from the at least one of the head and the shaft such that an interior slot space is created between the free end of each of the petals and at the least one of the head and the shaft, wherein the free end is configured to flex into the slot space if force is applied the free end in a direction towards the longitudinal axis of the fastener,
• wherein the head includes a lip at a proximal most surface and a cylinder portion of the head extends downward away from the lip of the fastener along the longitudinal axis to a position directly opposing a proximal most portion of the plurality of petals, the cylinder portion of the head having a uniform outer diameter relative to the longitudinal axis, and a flat portion of the head extends downward away from a distal-most portion of the cylinder portion at a transverse angle relative to the outer diameter of the cylinder portion and adjacent to the petals.