INTRAMEDULLARY NAIL

• US 20100174284A1
• Filed: 10/13/2009
• Published: 07/08/2010
• Est. Priority Date: 10/15/2008
• Status: Active Grant

• Current Assignee: Zimmer GmbH (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Zimmer GmbH (Zimmer Biomet Holdings, Inc.)
• Inventors: Schwammberger, Andy, Dittmann, Rolf, Velikov, Jordan, Senger, Reto
• Granted Patent: US 8,668,695 B2
• Time in Patent Office: Days
• US Class Current: 606/62
• CPC Class Codes: A61B 17/7283 with special cross-section of the nail
• CPC Class Codes: A61B 17/7291 for small bones, e.g. in the foot, ankle, hand or wrist
• CPC Class Codes: A61B 17/744 the longitudinal elements coupled to an intramedullary nail

Abstract

The present invention provides an intramedullary nail having a body with a transverse bore extending through the body and having an area of enhanced stress distribution on at least the lateral side of the transverse bore. In one exemplary embodiment, the intramedullary nail includes a cutout adjacent to the transverse bore, such as an oblique cutout, that enhances the stress distribution of the intramedullary nail in the region around the lateral opening of the transverse bore. In one exemplary embodiment, the cutout includes a ramp portion or area that defines the lateral opening of the transverse bore. In other exemplary embodiments, the cutout includes a runout or a substantially flat portion that defines the lateral opening of the transverse bore.

Claims

1. An intramedullary nail, comprising:

an elongate body including a proximal end defined by a proximal portion, a distal end defined by a distal portion, a medial side, a lateral side, and a longitudinal axis, said elongate body defining an elongate body periphery, said proximal portion of said elongate body having an interior wall defining a transverse bore extending therethrough, said transverse bore extending from said lateral side to said medial side of said elongate body in a direction transverse to said longitudinal axis of said elongate body, said proximal portion including a cutout positioned adjacent to said transverse bore on said lateral side of said elongate body, said cutout comprising;

a ledge portion extending in a substantially medial-lateral direction and positioned adjacent to a proximal most edge of said wall defining said transverse bore;

a ramp portion defining a substantially planar surface, said ramp portion forming a ramp angle with said longitudinal axis of said elongate body, said ramp angle being between zero degrees and thirty degrees, wherein said ramp portion extends along the longitudinal axis of the elongate body in a distal direction, said ramp portion terminating distally at said elongate body periphery, wherein said ramp portion terminates at a position spaced distally from a distal most edge of said wall defining said transverse bore; and

an intermediate portion positioned between said ledge portion and said ramp portion, said intermediate portion having an intermediate portion radius of curvature.

2. The intramedullary nail of claim 1, wherein said ramp angle is between approximately four degrees and approximately twelve degrees.

3. The intramedullary nail of claim 1, wherein said ramp angle is between approximately five degrees and approximately six degrees.

4. The intramedullary nail of claim 1, wherein said radius of curvature of said intermediate portion is substantially three millimeters.

5. The intramedullary nail of claim 1, wherein at least a portion of said ledge portion is positioned no more proximally than a proximal most portion of said wall defining said transverse bore, wherein said ledge portion defines a lateral support point for a lag screw received within said transverse bore of said elongate body.

6. The intramedullary nail of claim 1, wherein said cutout further comprises a longitudinal portion extending between said intermediate portion and said ramp portion, said longitudinal portion defining a substantially flat surface extending substantially parallel to said longitudinal axis of said elongate body.

7. The intramedullary nail of claim 6, wherein said longitudinal portion terminates distally at a position between a proximal most edge of said wall defining said transverse bore and a distal most edge of said wall defining said transverse bore.

8. The intramedullary nail of claim 6, wherein said longitudinal portion terminates distally at a position spaced distally from a distal most edge of said wall defining said transverse bore.

9. The intramedullary nail of claim 6, wherein said longitudinal portion defines flattened side surfaces on opposing anterior and posterior sides of said transverse bore, each of said flattened side surfaces having a width of at least substantially two millimeters.

10. The intramedullary nail of claim 1, wherein said ramp portion defines flattened side surfaces on opposing anterior and posterior sides of said transverse bore, each of said flattened side surfaces having a width of at least substantially two millimeters.

11. The intramedullary nail of claim 1, wherein said ledge portion forms a separation angle with said ramp portion, said separation angle being equal to substantially ninety degrees.

12. The intramedullary nail of claim 1, wherein said ramp portion defines a runout portion defining a substantially planar surface, said runout portion extending in a plane substantially parallel to both said longitudinal axis of said elongate body and a plane tangent to said elongate body periphery at a lateral point of said proximal portion.

13. The intramedullary nail of claim 12, wherein said elongate body further comprises a transition portion extending proximally from said distal portion along said longitudinal axis, said transition portion having a proximal end having a proximal diameter and a distal end having a distal diameter, said proximal diameter being greater than said distal diameter, wherein said runout portion is spaced from said longitudinal axis of said elongate body by a distance at least as great as one-half of said distal diameter of said transition portion.

14. The intramedullary nail of claim 13, wherein said distal portion has a distal portion periphery and said runout portion is substantially coplanar with a plane tangent to said distal portion periphery at a proximal most point of said distal portion periphery, whereby said runout portion terminates distally at said distal portion periphery.

15. The intramedullary nail of claim 13, wherein said runout portion is spaced from said longitudinal axis of said elongate body by a distance greater than one-half of said distal diameter of said transition portion and less than said proximal diameter of said transition portion, wherein said runout portion terminates distally at said transition portion periphery.

16. The intramedullary nail of claim 12, wherein said intermediate portion radius of curvature is equal to substantially three millimeters.

17. The intramedullary nail of claim 12, wherein said ledge portion forms a separation angle with said runout portion, said separation angle being equal to substantially ninety degrees.

18. The intramedullary nail of 12, wherein at least a portion of said ledge portion is positioned no more proximally than a proximal most portion of said wall defining said transverse bore, wherein said ledge portion defines a lateral support point for a lag screw received within said transverse bore of said elongate body.

19. The intramedullary nail of 12, wherein said runout portion defines flattened side surfaces on opposing anterior and posterior sides of said transverse bore, each of said flattened side surfaces have a width of at least substantially two millimeters.

20. An intramedullary nail, comprising:

an elongate body including a proximal end, a distal end, a medial side, a lateral side, and a longitudinal axis, said elongate body, comprising;

a distal portion defining said distal end of said elongate body;

a transition portion extending proximally from said distal portion along said longitudinal axis, said transition portion having a proximal end having a proximal diameter and a distal end having a distal diameter, said proximal diameter being greater than said distal diameter, said transition portion defining a transition portion periphery; and

a proximal portion extending proximally from said transition portion and defining a proximal end of said elongate body, said proximal portion defining a proximal portion periphery, said proximal portion having a diameter substantially equal to said proximal diameter of said transition portion, said proximal portion having an interior wall defining a transverse bore extending therethrough, said transverse bore extending from said lateral side of said elongate body to said medial side of said elongate body in a direction transverse to said longitudinal axis of said elongate body, said proximal portion having a cutout positioned adjacent to said transverse bore on said lateral side of said elongate body, said cutout defining a derivation from at least one of said proximal portion periphery and said transition portion periphery, said derivation having a volume of at least 100 cubic millimeters.

21. The intramedullary nail of claim 20, wherein said cutout defining said derivation from at least one of said proximal portion periphery and said transition portion periphery has a volume of between 105 and 120 cubic millimeters.

22. The intramedullary nail of claim 20, wherein said cutout defining said derivation from at least one of said proximal portion periphery and said transition portion periphery has a volume of substantially 106 cubic millimeters.

23. The intramedullary nail of claim 20, wherein said cutout further comprises:

a ledge portion extending in a substantially medial-lateral direction and positioned at a proximal edge of said wall defining said transverse bore;

a runout portion defining a substantially planar surface, said runout portion extending in a plane substantially parallel to both said longitudinal axis of said elongate body and a plane tangent to a lateral point of said proximal portion periphery, wherein said runout portion terminates at a position spaced distally from a distal edge of said wall defining said transverse bore; and

an intermediate portion positioned between said ledge portion and said runout portion, said intermediate portion having an intermediate portion radius of curvature.

24. The intramedullary nail of claim 20, wherein said cutout further comprises:

a ledge portion extending in a substantially medial-lateral direction and positioned adjacent to a proximal most edge of said wall defining said transverse bore;

a ramp portion defining a substantially planar surface, said ramp portion forming a ramp angle with said longitudinal axis of said elongate body, said ramp angle being between one-half degree and thirty degrees, wherein said ramp portion diverges from the longitudinal axis of the elongate body in a distal direction, said ramp portion terminating distally at one of said proximal portion periphery and said transition portion periphery, wherein said ramp portion terminates at a position spaced distally from a distal most edge of said wall defining said transverse bore; and

an intermediate portion positioned between said ledge portion and said ramp portion, said intermediate portion having an intermediate portion radius of curvature.