Anti-splay medical implant closure with multi-surface removal aperture

A closure for setting engagement with a structural member and comprising:

• (a) a substantially cylindrical body having an outer cylindrical surface relative to a central closure axis;
• (b) a guide and advancement flange extending helically about said outer cylindrical surface;
• said guide and advancement flange being sized and shaped to radially interlock with a mating guide and advancement flange on a receiving bone screw;
• said closure flange having a trailing surface relative to said forward advancement direction, and said receiving bone screw having a head with an upwardly facing interior flank surface that generally slopes upwardly and outwardly from said central closure axis;
• (c) said trailing surface being compound in contour and including a projection spaced from said body and extending outwardly from a remainder of the trailing surface in a direction generally parallel to the closure axis;
• the projection having an inward facing anti-splay surface component facing generally toward said closure axis;
• (d) said body having a multi-lobular aperture formed therein which is aligned on and elongated along said closure axis, said aperture including a plurality of circumferentially spaced lobes extending substantially parallel to said closure axis and said lobes circumferentially alternating with bore grooves extending substantially parallel to said closure axis to form a removal socket adapted to receive a removal tool;
• and
• (e) a break off installation head.

In a closure for setting engagement with a structural member and including a substantially cylindrical body having an outer cylindrical surface relative to a central closure axis, the improvement comprising:

• (a) said closure having a flange that has a leading surface and a trailing surface with at least one of said leading surface and said trailing surface having a projection extending axially outward thereon and said projection being spaced from said body;
• said selected one of said leading and trailing surfaces being generally outwardly linear between said body and said projection so as to form a substantially continuous guide and advancement flange extending helically about said outer surface;
• said projection including an inward facing anti-splay surface component facing generally toward said closure axis;
• said flange being sized and shaped to radially interlock with a mating guide and advancement flange on a receiving structure;
• said receiving structure guide and advancement flange having an upwardly facing interior flank surface that generally slopes upwardly and outwardly from said closure axis;
• (b) said body having a multi-surfaced aperture formed therein which is located and elongated along said closure axis, said aperture including a plurality of circumferentially spaced surfaces extending substantially parallel to said closure axis so as to form a removal socket adapted to receive a removal tool;
• and
• (c) a break off installation head.

A closure for setting engagement with a receiver and comprising:

• (a) a substantially cylindrical body having an outer cylindrical surface relative to a central closure axis;
• (b) a substantially continuous guide and advancement flange extending helically about said outer cylindrical surface and being sized and shaped to radially interlock with a mating guide and advancement flange on the receiver;
• said closure flange having a leading surface and a trailing surface relative to a direction of forward advancement;
• said flange leading surface facing downwardly and generally sloping downwardly and inwardly toward said central closure axis;
• said flange trailing surface having at least a substantially linear portion wherein a line drawn tangent to said portion intersects the closure axis at a constant angle along substantially the entire length of the flange extending helically about said outer cylindrical body;
• (c) at least one of said leading surface and said trailing surface being compound in contour and including a projection spaced from said body and extending outward in an axial direction from at least one leading and trailing surface and the projection having an inward facing receiver anti-splay surface component facing generally toward said closure axis and being on the side of the projection closest to the body;
• the projection and receiver anti-splay surface being sized and shaped to radially interlock with cooperating anti-splay structure on the receiver;
• (d) said body having a multi-surface aperture formed therein that is aligned with said closure axis and that is elongated along said closure axis, said aperture opening onto a trailing surface of said body and including a plurality of circumferentially spaced, centrally facing surfaces extending substantially parallel to said closure axis that are aligned to form a removal socket adapted to receive a removal tool;
• and
• (e) a break off installation head.