Pedicle screws and methods of using the same

1. A pedicle screw comprising:

a threaded screw body having a proximal end and a distal end, the proximal end comprising an enlarged head;

a housing having an upper portion with an upper opening and a lower portion with a lower opening extending along a first axis of the housing, the upper portion being internally threaded and an internal surface of the lower portion curving toward the lower opening, and a third opening and a fourth opening along a second axis transverse to the first axis adapted to receive an elongated rod;

one or more clamps positioned adjacent the lower portion of the housing and having an upper portion with a cylindrical outer surface and a lower portion with a curved outer surface, the curved outer surface of the lower portion adapted to engage the curved internal surface of the lower portion of the housing, the upper portion of the one or more clamps adapted to contact the elongated rod, and an inner surface of the lower portion of the one or more clamps adapted to engage the enlarged head, wherein a radius of curvature of the curved outer surface of the lower portion of the one or more clamps is different from a radius of curvature of the curved internal surface of the lower portion of the housing; and

a set screw configured to be received within the internally threaded first portion of the housing, wherein the set screw when engaged in the first portion applies a force onto the rod when received in the housing, the rod engaging the one or more clamps to frictionally engage the enlarged head against the inner surface of the one or more clamps.

2. The pedicle screw of claim 1 , wherein the inner surface of the lower portion of the one or more clamps comprises a plurality of grooves.

3. The pedicle screw of claim 2 , wherein the plurality of grooves are aligned horizontally on the inner surface.

4. The pedicle screw of claim 1 , wherein an outer dimension of the enlarged head is less than an inner dimension of the lower opening of the housing.

5. The pedicle screw of claim 1 , comprising no more than two clamps.

6. The pedicle screw of claim 1 , wherein the one or more clamps have an upper portion with an indentation shaped to receive the rod.

7. The pedicle screw of claim 1 , further comprising a crimp from an outside of the housing to hold the one or more clamps within the housing.

8. The pedicle screw of claim 1 , wherein the radius of curvature of the curved outer surface of the lower portion of the one or more clamps is less than the radius of curvature of the curved internal surface of the lower portion of the housing.

9. The pedicle screw of claim 1 , wherein the radius of curvature of the curved outer surface of the lower portion of the one or more clamps is greater than the radius of curvature of the curved internal surface of the lower portion of the housing.

10. A pedicle screw comprising:

a threaded screw body having a proximal end and a distal end, the proximal end comprising an enlarged head;

a housing having an upper portion having an upper opening and a lower portion having a lower opening extending along a first axis of the housing, the upper portion being internally threaded and the lower portion having a gradually decreasing dimension toward the lower opening, and a third opening and a fourth opening along a second axis transverse to the first axis adapted to receive an elongated rod;

two clamps completely separated from each other by a plane and positioned in the housing and having an upper surface adapted to engage the elongated rod such that the rod is oriented parallel to the plane and a lower surface adapted to engage the enlarged head, wherein the plane is parallel to the second axis of the housing; and

a set screw configured to be received within the internally threaded first portion, wherein the set screw when engaged in the first opening applies a force onto the rod when received in the housing, the rod engaging the clamps and causing the clamps to frictionally engage the enlarged head.

11. The pedicle screw of claim 10 , wherein the lower surface of the one or more clamps adapted to engage the enlarged head comprises a plurality of grooves aligned horizontally on the lower surface.

12. The pedicle screw of claim 10 , wherein the enlarged head comprises a roughened surface.

13. The pedicle screw of claim 10 , wherein the one or more clamps have an upper portion with a cylindrical outer surface and a lower portion with a curved outer surface.

14. The pedicle screw of claim 12 , wherein an outer dimension of the lower portion is less than or about equal to an outer dimension of the upper portion.

15. The pedicle screw of claim 12 , wherein an outer dimension of the lower portion gradually decreases toward a lower end of the lower portion.

16. The pedicle screw of claim 10 , each clamp further comprising an indentation configured to receive a crimp extending from an outside of the housing into engagement with the indentation to hold the clamp in the housing, wherein an axis extending from one indentation to the other is perpendicular to the plane separating the two clamps.

17. A pedicle screw comprising:

a threaded screw body having a proximal end and a distal end, the proximal end comprising an enlarged head;

a housing having an upper portion with an upper opening and a lower portion with a lower opening extending along a first axis of the housing, the upper portion being internally threaded and the lower portion having an internal surface, and a third opening and a fourth opening along a second axis transverse to the first axis adapted to receive an elongated rod;

two clamps completely separated from each other by a plane and positioned in the housing and having an upper portion and a lower portion, the upper portion of the clamps adapted to contact the elongated rod such that the rod is oriented parallel to the plane, and an inner surface of the lower portion of the clamps adapted to engage the enlarged head, wherein the plane is parallel to the second axis of the housing, and wherein the inner surface of the lower portion of one or more clamps comprises a plurality of horizontally-aligned grooves; and

a set screw configured to be received within the internally threaded first portion of the housing, wherein the set screw when engaged in the first portion applies a force onto the rod when received in the housing, the rod engaging the clamps to frictionally engage the enlarged head against the inner surface of the one or more clamps.

18. The pedicle screw of claim 17 , wherein the upper portion of the one or more clamps has a cylindrical outer surface and the outer surface of the lower portion is curved, the upper portion cylindrical outer surface gradually transitioning to the curved outer surface of the lower portion.

19. The pedicle screw of claim 17 , further comprising a crimp from an outside of the housing to hold the one or more clamps within the housing.