Closures with splay resisting threads for bone anchor receivers having horizontal radiused tool attachment grooves

1. A receiver assembly for securing an elongate rod to a bone anchor, the receiver assembly comprising:

a receiver having a longitudinal axis, a base, and a pair of opposed upright arms extending upwardly from the base to define an open channel therebetween configured to receive the elongate rod, the open channel opening onto top surfaces of the upright arms to define a top of the receiver and onto front side and back side faces of the upright arms and the base, the upright arms having interior surfaces with a discontinuous helically wound receiver guide and advancement structure formed therein and outer side surfaces opposite the interior surfaces, each upright arm having a horizontally-extending extending upper tool engaging groove formed into an upper portion of the outer side surface thereof, with each upper tool engaging groove further including an outward facing surface extending parallel with respect to the receiver longitudinal axis and a downwardly-facing surface spaced a fixed distance below the top surface of the upright arm and extending continuously along an entire length thereof to at least one of the front side face and the back side face; and

a closure configured to be positioned within the open channel to secure the elongate rod to the receiver in a locked configuration, the closure comprising a cylindrical body having a central axis and an outer surface with a mating continuous helically wound closure guide and advancement structure formed thereon, the closure guide and advancement structure being configured to resist a tendency toward splaying between the pair of receiver upright arms upon a screwing in of the closure within the open channel by rotatable engagement with the receiver guide and advancement structure, the closure guide and advancement structure having a lower clearance surface and an outer crest surface extending parallel to the closure central axis to form a right angle with respect to the lower clearance surface, the outer crest surface further including an upper edge and a lower edge spaced below the upper edge, the lower edge comprising one of a curvate or rounded surface extending between and connecting the lower clearance surface and the outer crest surface,

wherein when the receiver assembly is in the locked configuration, the closure does not extend over any part of the receiver upright arm top surfaces and the entire lower clearance surface and entire outer crest surface of the closure guide and advancement structure are spaced apart from the receiver guide and advancement structure.

2. The receiver assembly of claim 1 ,

wherein the closure guide and advancement structure further comprises an upper surface extending radially outward from and being perpendicular to the central axis of the closure, and

wherein the upper surface and the lower clearance surface each include a planar surface that is parallel with respect to the other.

3. The receiver assembly of claim 2 , wherein the outer crest surface is perpendicular to the planar surfaces on both of the upper surface and the lower clearance surface.

4. The receiver assembly of claim 2 , wherein the upper surface intersects the outer crest surface so as to form a right angle therebetween.

5. The receiver assembly of claim 1 , wherein the closure body further comprises a top end surface, a bottom end surface, and a plurality of tool engaging surfaces aligned parallel with the central axis and extending entirely through the closure body from the top end surface to the bottom end surface.

6. The receiver assembly of claim 1 ,

wherein the closure body further comprises a plurality of tool engaging surfaces spaced apart from and being parallel with the central axis, and

wherein a peripheral portion of each of the plurality of the tool engaging surfaces spaced furthest from the closure central axis has an inwardly-facing concave surface.

7. The receiver assembly of claim 6 , wherein the inwardly-facing concave surface on each of the plurality of tool engaging surfaces further comprises a radiused surface.

8. The receiver assembly of claim 1 , wherein the upper tool engaging grooves extend at least partially around a periphery of the upright arms and adjacent to the top surfaces.

9. The receiver assembly of claim 1 , wherein the upper tool engaging grooves intersect the open channel on the receiver front and back side faces.

10. The receiver assembly of claim 1 , wherein the upper tool engaging grooves are radiused with respect to the longitudinal axis of the receiver.

11. The receiver assembly of claim 1 , wherein the upper tool engaging groove downwardly-facing surfaces are located above a top surface of the elongate rod when the elongate rod is locked in the open channel by the closure.

12. The receiver assembly of claim 1 , wherein the downwardly-facing surface of each of the upper tool engaging grooves includes an undercut feature.

13. The receiver assembly of claim 1 , wherein

the front and back side faces on the receiver base and upright arms include front and back planar surfaces that are parallel with respect to each other,

the upright arm outer side surfaces include side planar surfaces that are parallel with respect to each other, and

each of the front and back planar surfaces and the side planar surfaces is parallel to the receiver longitudinal axis.

14. The receiver assembly of claim 1 , wherein the receiver guide and advancement structure and the closure guide and advancement structure cooperate to prevent the upright arms of the receiver from splaying when the receiver assembly is in the locked configuration.

15. The receiver assembly of claim 1 ,

wherein the closure guide and advancement structure further comprises a base integrally formed with the cylindrical body of the closure having a height extending between a lower edge adjacent a lower root surface below the guide and advancement structure and an upper edge adjacent an upper root surface above the guide and advancement structure, and

wherein the height from the lower edge to the upper edge of the base defines a first length therebetween and a distance from the upper edge to the lower edge of the outer crest surface defines a second length therebetween, with the first length being equal to the second length.

16. The receiver assembly of claim 1 , wherein the closure includes a centrally located bottom surface adjacent the central axis configured to engage the elongate rod.

17. The receiver assembly of claim 1 , wherein the closure includes one of a breakoff driving structure and non-breakoff internal driving structure centered around the central axis.

18. The receiver assembly of claim 1 , wherein the closure includes a central threaded bore for a threaded set screw to lock the elongate rod in place.

19. The receiver assembly of claim 1 , wherein the closure is one of a single part construction and a multi-part construction.

20. The receiver assembly of claim 1 , wherein the receiver further includes a central bore, a lower cavity in the base and a lower opening communicating with the cavity and a bottom surface on the receiver.

21. The receiver assembly of claim 1 , wherein the receiver further includes a central bore with a lower spherical seating surface.

22. The receiver assembly of claim 1 , wherein bone anchor comprises a polyaxial screw.

23. A receiver assembly for securing an elongate rod to a bone anchor, the receiver assembly comprising:

a receiver having a longitudinal axis, a base, and a pair of opposed upright arms extending upwardly from the base to define an open channel therebetween configured to receive the elongate rod, the open channel opening onto top surfaces of the upright arms to define a top of the receiver and onto front side and back side faces of the upright arms, the upright arms having interior surfaces with a discontinuous helically wound receiver guide and advancement structure formed therein and outer side surfaces opposite the interior surfaces, each upright arm having a horizontally-elongated upper tool engaging groove formed into an upper portion of the outer side surface thereof, with each upper tool engaging groove further including an outward facing surface extending parallel with respect to the receiver longitudinal axis and a downwardly-facing surface spaced a fixed distance below the upright arm top surfaces and extending continuously along an entire length thereof to at least one of the front side face and the back side face, each outer side surface having an outward facing planar surface extending below the upper tool engaging groove; and

a closure configured to be positioned within the open channel to secure the elongate rod to the receiver in a locked configuration, the closure comprising a cylindrical body having a central axis and an outer surface with a mating continuous helically wound closure guide and advancement structure formed thereon, the closure guide and advancement structure being configured to resist a tendency toward splaying between the pair of receiver upright arms upon a screwing in of the closure within the open channel by rotatable engagement with the receiver guide and advancement structure, the closure guide and advancement structure having a lower clearance surface and an outer crest surface extending parallel to the closure central axis, the closure body comprising a top end surface, a bottom end surface, and a plurality of tool engaging surfaces spaced radially apart from the central axis and extending downward from the top end surface,

wherein when the receiver assembly is in the locked configuration, the closure does not extend over any part of the receiver upright arm top surfaces and the entire lower clearance surface and entire outer crest surface of the closure guide and advancement structure are spaced apart from the receiver guide and advancement structure, and

wherein each of the plurality of tool engaging surfaces is aligned parallel with the central axis and includes a peripheral portion spaced furthest from the closure central axis having an inwardly-facing concave surface.

24. The receiver assembly of claim 23 , wherein the inwardly-facing concave surface on each of the plurality of tool engaging surfaces further comprises a radiused surface.

25. The receiver assembly of claim 23 , wherein the inwardly-facing concave surfaces of each of the plurality of tool engaging surfaces is configured as a portion of a bore hole.

26. The receiver assembly of claim 23 , wherein each of the plurality of tool engaging surfaces extends entirely through the closure body from the top end surface to the bottom end surface.

27. The receiver assembly of claim 23 ,

wherein the lower clearance surface and the outer crest surface of the closure guide and advancement structure form a right angle with respect to each other, and

wherein the outer crest surface further includes an upper edge and a lower edge spaced below the upper edge and having a rounded surface extending between and connecting the lower clearance surface and the outer crest surface.

28. A receiver assembly for securing an elongate rod to a bone anchor, the receiver assembly comprising:

a receiver having a longitudinal axis, a base, and a pair of opposed upright arms extending upwardly from the base to define an open channel therebetween configured to receive the elongate rod, the open channel opening onto top surfaces of the arms to define a top of the receiver and onto front side and back side faces of the upright arms and the base, the upright arms having interior surfaces with a discontinuous helically wound receiver guide and advancement structure formed therein and outer side surfaces opposite the interior surfaces, each upright arm having at least one horizontally extending upper tool engaging groove formed into an upper portion of the outer side surface thereof, with each upper tool engaging groove having a downwardly-facing top surface spaced a fixed distance below the upright arm top surfaces and extending to at least one of the front side face and the back side face; and

a closure configured for positioning within the open channel to engage and secure the elongate rod to the receiver in a locked position, the closure comprising a cylindrical body having a central axis, a bottom end surface having a solid central portion centered about the central axis and configured to engage the elongate rod, and an outer surface with a mating continuous helically wound closure guide and advancement structure formed thereon and configured to resist a tendency toward splaying between the pair of receiver upright arms upon a screwing in of the closure within the open channel by rotatable engagement with the receiver guide and advancement structure, the closure guide and advancement structure having an outer crest surface extending vertically along and being parallel with the central axis and a lower clearance surface extending radially outward and upward from the central axis so as to form an obtuse angle with respect to the outer crest surface,

wherein the closure body includes a plurality of tool engaging surfaces spaced radially outward and apart from the central axis, each of the plurality of tool engaging surfaces including a peripheral portion spaced furthest from the central axis having an inwardly-facing concave surface, and

wherein when the receiver assembly is in the locked configuration, the closure does not extend over any part of the receiver upright arm top surfaces.

29. The receiver assembly of claim 28 , wherein the closure guide and advancement structure further comprises:

a base having a height extending between a lower edge adjacent a lower root surface below the guide and advancement structure and an upper edge adjacent an upper root surface above the guide and advancement structure, and

the outer crest surface further includes an upper edge and a lower edge spaced below the upper edge,

wherein the upper edge of the outer crest surface is spaced radially outward and axially above the upper edge of the base.

30. The receiver assembly of claim 28 and further comprising the bone anchor, wherein the bone anchor comprises one of a hook or a screw.

31. The receiver assembly of claim 28 and further comprising the bone anchor, wherein the bone anchor comprises a shank having a shank body with a helically wound bone implantable thread.

32. The receiver assembly of claim 31 , wherein the shank is integrally formed with the receiver.

33. The receiver assembly of claim 31 , wherein the shank is separate from the receiver and configured for pivotal engagement with the receiver prior to a locking of the elongate rod within the receiver channel with the closure.

34. The receiver assembly of claim 33 , wherein the shank is cannulated along an entire length thereof so as to cooperate with a guide pin or wire for insertion into a patient bone.

35. The receiver assembly of claim 28 and further comprising a holding tool, wherein the holding tool includes an attachment structure sized and shaped to be received in the upper tool engaging grooves when the holding tool is coupled with the receiver of the bone anchor assembly.

36. A receiver assembly for securing an elongate rod to a bone anchor, the receiver assembly comprising:

a receiver having a longitudinal axis, a base, and a pair of opposed upright arms extending upwardly from the base to define an open channel therebetween configured to receive the elongate rod, the open channel opening onto top surfaces of the arms to define a top of the receiver and onto front side and back side faces of the upright arms and the base, the upright arms having interior surfaces with a discontinuous helically wound receiver guide and advancement structure formed therein and outer side surfaces opposite the interior surfaces, each upright arm having at least one horizontally extending upper tool engaging groove formed into an upper portion of the outer side surface thereof, with each upper tool engaging groove having a downwardly-facing top surface spaced a fixed distance below the upright arm top surfaces and extending to at least one of the front side face and the back side face, the outer side surfaces having planar surface portions beneath the upper tool engaging grooves that are parallel with respect to each other; and

a closure configured for positioning within the open channel to engage and secure the elongate rod to the receiver in a locked position, the closure comprising a cylindrical body having a central axis, a bottom end surface having a solid central portion centered about the central axis and configured to engage the elongate rod, and an outer surface with a mating continuous helically wound closure guide and advancement structure formed thereon and configured to resist a tendency toward splaying between the pair of receiver upright arms upon a screwing in of the closure within the open channel by rotatable engagement with the receiver guide and advancement structure, the closure guide and advancement structure further comprising:

a crest with an outer surface extending vertically along and being parallel with the central axis between an upper outer edge and a lower outer edge thereof;

a base having a height extending between a lower edge adjacent a lower root surface below the guide and advancement structure and an upper edge adjacent an upper root surface above the guide and advancement structure,

the upper outer edge of the outer surface of the crest being spaced radially outward and axially above the upper edge of the base; and

a lower clearance surface extending radially outward and upward from the lower edge of the base so as to form an obtuse angle with respect to the crest outer surface,

wherein the closure body includes a plurality of tool engaging surfaces spaced radially outward and apart from the central axis, each of the plurality of tool engaging surfaces including a peripheral portion spaced furthest from the central axis having an inwardly-facing concave surface, and

wherein when the receiver assembly is in the locked configuration, the closure does not extend over any part of the receiver upright arm top surfaces.

37. The receiver assembly of claim 36 and further comprising the bone anchor, wherein the bone anchor comprises one of a hook or a screw.

38. The receiver assembly of claim 36 and further comprising the bone anchor, wherein the bone anchor comprises a shank having a shank body with a helically wound bone implantable thread.

39. The receiver assembly of claim 38 , wherein the shank is integrally formed with the receiver.

40. The receiver assembly of claim 38 , wherein the shank is separate from the receiver and configured for pivotal engagement with the receiver prior to a locking of the elongate rod within the receiver channel with the closure.

41. The receiver assembly of claim 40 , wherein the shank is cannulated along an entire length thereof so as to cooperate with a guide pin or wire for insertion into a patient bone.