Bone connector with pivotable joint

1. A bone screw, comprising:

a first screw element and a second screw element each including an external thread for threaded engagement with bone, the screw elements being connected by a pivotable joint that traps a cylindrical protuberance of the first screw element in a cylindrical cavity of the second screw element to block removal of the cylindrical protuberance from the cylindrical cavity,

wherein the cylindrical protuberance and the cylindrical cavity are formed by a leading end region of one of the screw elements and a trailing end region of the other screw element, and

wherein the cylindrical protuberance is movable in the cylindrical cavity to permit (a) the screw elements to be twisted relative to one another about a longitudinal axis defined by one of the screw elements and (b) the bone screw to be bent about a transverse axis of the bone screw and to an angle of at least about 5 degrees from a coaxial arrangement of the screw elements.

2. The bone screw of claim 1 , wherein the cylindrical cavity includes a tapered region that blocks removal of the cylindrical protuberance from the cylindrical cavity.

3. The bone screw of claim 1 , wherein the cylindrical cavity includes a mouth that is narrower than a diameter of the cylindrical protuberance such that withdrawal of the protuberance from the cylindrical cavity is resisted.

4. The bone screw of claim 1 , wherein the pivotable joint permits the bone screw to be bent to an angle of about 5 to 40 degrees.

5. The bone screw of claim 4 , wherein the pivotable joint permits the bone screw to be bent to an angle of about 5 to 20 degrees.

6. The bone screw of claim 1 , wherein the screw elements are a leading screw element and a trailing screw element, wherein the trailing screw element defines a central channel extending longitudinally through the trailing screw element, and wherein the leading screw element includes a driver engagement structure that is accessible to mate with a corresponding driver advanced to the driver engagement structure via the central channel.

7. The bone screw of claim 6 , wherein the cylindrical protuberance is provided by the trailing screw element and forms a portion of the central channel.

8. The bone screw of claim 6 , wherein the cylindrical protuberance is formed by the leading screw element and defines an opening that communicates with the central channel.

9. The bone screw of claim 6 , wherein the external thread of the leading screw element has a larger pitch than the external thread of the trailing screw element, thereby providing compression when the screw elements are driven into bone.

10. The bone screw of claim 6 , wherein the leading screw element is smaller in diameter on average than the trailing screw element.

11. The bone screw of claim 1 , wherein each of the screw elements is only one discrete piece.

12. The bone screw of claim 1 , wherein the screw elements are movable relative to one another via axial motion of the cylindrical protuberance in the cylindrical cavity.

13. A method of connecting bones with a pair of screw elements connected by a pivotable joint that traps a cylindrical protuberance of one of the screw elements in a cylindrical cavity of the other screw element to block removal of the cylindrical protuberance from the cylindrical cavity, with the cylindrical protuberance and the cylindrical cavity being formed by a leading end region of a first of the screw elements and a trailing end region of a second of the screw elements, the cylindrical protuberance being movable in the cylindrical cavity to permit (a) the screw elements to be twisted relative to one another about a longitudinal axis defined by one of the screw elements and (b) the bone screw to be bent about a transverse axis of the bone screw and to an angle of at least about 5 degrees from a coaxial arrangement of the screw elements, the method comprising:

driving the bone screw into a pair of bones such that an external thread of each screw element is disposed in threaded engagement with a different bone.

14. The method of claim 13 , wherein the pair of bones are a scaphoid bone and a lunate bone.

15. The method of claim 13 , wherein the cylindrical cavity includes a tapered region that blocks removal of the cylindrical protuberance from the cylindrical cavity.

16. The method of claim 13 , wherein the pivotable joint permits the bone screw to be bent to an angle of about 5 to 40 degrees.

17. The method of claim 13 , wherein the screw elements are a leading screw element and a trailing screw element, wherein the trailing screw element defines a central channel extending longitudinally through the trailing screw element, and wherein the leading screw element includes a driver engagement structure that is accessible to mate with a corresponding driver advanced to the driver engagement structure via the central channel.

18. The method of claim 17 , wherein the cylindrical protuberance is provided by the trailing screw element and forms a portion of the central channel.

19. The method of claim 17 , wherein the cylindrical protuberance is formed by the leading screw element and defines an opening that communicates with the central channel.

20. The method of claim 17 , wherein the external thread of the leading screw element has a larger pitch than the external thread of the trailing screw element, thereby providing compression when the bone screw is driven into the pair of bones.