Some content of this application is unavailable at the moment.
If this situation persist, please contact us atFeedback&Contact
1. (WO2012030712) POLYAXIAL PEDICLE SCREW
Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

What is claimed is:

1. A polyaxial bone anchor comprising:

a housing having an upper end, a lower end and a bore extending through the housing from the upper end to the lower end, the bore opening out at the lower end at a lower opening, the housing including a channel configured for receiving an elongate stabilization member therethrough which extends from a first side surface of the housing to a second side surface of the housing opposite the first side surface transverse to the bore;

a retainer positioned into the bore of the housing and having an outermost diameter greater than a diameter of the lower opening, the retainer including a plurality of alternating tabs and slots circumferentially arranged to define a cavity therein;

a bone screw including a head portion and a shank extending from the head portion, the head portion of the bone screw positionable in the cavity of the retainer with the shank extending from the lower end of the housing by deflecting the tabs radially outward to enlarge a lower opening of the retainer into the cavity from a diameter less than a diameter of the head portion to a diameter greater than or equal to the diameter of the head portion; and

means for applying a force to move the retainer toward the lower end of the housing while the retainer is positioned in the bore.

2. The polyaxial bone anchor of claim 1, wherein the means for applying a force biases the retainer toward the lower end of the housing.

3. The polyaxial bone anchor of claim 2, wherein the retainer is moved toward the upper end of the housing while being positioned in the bore in order to insert the head portion of the bone screw into the cavity of the retainer.

4. The polyaxial bone anchor of claim 3, wherein the retainer is insertable into the bore of the housing without the head portion of the bone screw positioned in the cavity of the retainer, yet with the head portion of the bone screw positioned in the cavity of the retainer, the retainer is prevented from being removed from the bore of the housing.

5. The polyaxial bone anchor of claim 2, wherein the means for applying a force is integral with the retainer.

6. The polyaxial bone anchor of claim 5, wherein the means for applying a force is a portion of the retainer including one or more circumferential or helical slots formed therein.

7. The polyaxial bone anchor of claim 2, wherein the means for applying a force is a wave washer.

8. The polyaxial bone anchor of claim 1, further comprising a spacer axially movable relative to the retainer, the spacer including a first portion extending from the retainer toward the upper end of the housing which is configured to engage an elongate stabilization member disposed in the channel of the housing and a second portion extending into a bore of the retainer which is configured to engage the head portion of the bone screw.

9. The polyaxial bone anchor of claim 1, wherein the housing includes an annular rim defining the lower opening, wherein the diameter of the lower opening at the annular rim is less than a diameter of the bore of the housing toward the upper end of the housing from the annular rim

10. The polyaxial bone anchor of claim 9, wherein the retainer includes a lower beveled surface which contacts the annular rim of the housing, thereby preventing the tabs of the retainer from deflecting radially outward in order to secure the head portion of the bone screw in the cavity of the retainer.

11. The polyaxial bone anchor of claim 1, wherein an upper portion of the retainer includes first and second legs defining a channel therebetween aligned with the channel of the housing for receiving an elongate stabilization member therethrough.

12. The polyaxial bone anchor of claim 1, wherein the retainer has an outermost diameter greater than a diameter of the lower opening and is insertable into the bore of the housing from the lower end of the housing by passing the retainer through the lower opening with the plurality of tabs deflected radially inward.

13. A polyaxial bone anchor comprising:

a housing having an upper end, a lower end and a bore extending through the housing from the upper end to the lower end, the bore opening out at the lower end at a lower opening, the housing including a channel configured for receiving an elongate stabilization member therethrough which extends from a first side surface of the housing to a second side surface of the housing opposite the first side surface transverse to the bore;

a retainer positionable in the bore of the housing, the retainer movable in the bore of the housing between a first position and a second position, the retainer being closer to the lower end of the housing in the first position and closer to the upper end of the housing in the second position; and

a bone screw including a head portion and a shank extending from the head portion, the head portion of the bone screw positionable in a cavity of the retainer with the shank extending from the lower end of the housing;

wherein the head portion of the bone screw is insertable into the cavity of the retainer from the lower end of the housing when the retainer is in the second position, but is not removable from the cavity of the retainer when the retainer is in the first position.

14. The polyaxial bone anchor of claim 13, further comprising a resilient spring means biasing the retainer toward the first position.

15. The polyaxial bone anchor of claim 14, wherein the resilient spring means is a wave washer.

16. The polyaxial bone anchor of claim 14, wherein the resilient spring means is integral with the retainer.

17. The polyaxial bone anchor of claim 16, wherein the resilient spring means is a portion of the retainer including one or more circumferential or helical slots formed therein.

18. The polyaxial bone anchor of claim 14, wherein during insertion of the head portion of the bone screw into the cavity of the retainer, the head portion of the bone screw exerts a force against the retainer to move the retainer to the second position.

19. The polyaxial bone anchor of claim 13, wherein an annular rim defining the lower opening of the housing contacts a lower beveled surface of the retainer to prevent radially outward deflection of a plurality of tabs of the retainer in order to secure the head portion of the bone screw in the cavity of the retainer.

20. A polyaxial bone anchor comprising:

a housing having an upper end, a lower end and a bore extending through the housing from the upper end to the lower end, a lower portion of the housing including a plurality of deflectable tabs arranged around a perimeter of the housing, the housing including a channel configured for receiving an elongate stabilization member therethrough which extends from a first side surface of the housing to a second side surface of the housing opposite the first side surface transverse to the bore;

a spacer positionable in the bore of the housing, the spacer movable in the bore of the housing between a first position and a second position, the spacer being closer to the lower end of the housing in the first position and closer to the upper end of the housing in the second position;

a bone screw including a head portion and a shank extending from the head portion, the head portion of the bone screw positionable in a cavity of the spacer with the shank extending from the lower end of the housing;

a collar positionable circumferentially exterior of the plurality of deflectable tabs to inhibit outward radial deflection of the plurality of tabs; and

a resilient spring means biasing the spacer toward the first position into engagement with the head portion of the bone screw;

wherein the head portion of the bone screw is insertable into the bore of the housing from the lower end of the housing by deflecting the plurality of tabs radially outward, but is not removable from the housing when the collar is positioned circumferentially exterior of the plurality of deflectable tabs.

21. A method of assembling a polyaxial bone anchor comprising:

providing a housing having an upper end, a lower end and a bore extending through the housing from the upper end to the lower end, the bore opening out at the lower end at a lower opening, the housing including a channel configured for receiving an elongate stabilization member therethrough which extends from a first side surface of the housing to a second side surface of the housing opposite the first side surface transverse to the bore;

inserting a retainer into the bore of the housing from the lower end of the housing by passing the retainer through the lower opening, the retainer having an outermost diameter greater than a diameter of the lower opening, the retainer including a plurality of alternating tabs and slots formed therein providing the retainer with sufficient flexibility to be urged through the lower opening from the lower end of the housing by radially compressing the retainer;

inserting a head portion of a bone screw into a cavity of the retainer from the lower end of the housing by moving the retainer toward the upper end of the housing allowing the plurality of tabs to splay radially outward to accommodate passage of the head portion of the bone screw into the cavity of the retainer; and

urging the retainer, with the head portion of the bone screw positioned in the cavity of the retainer, back toward the lower end of the housing to retain the head portion of the bone screw in the cavity of the retainer;

wherein the retainer is biased toward the lower end of the housing by a biasing spring means.

22. The method of claim 21, wherein an annular rim defining the lower opening of the housing contacts a lower beveled surface of the retainer to prevent radially outward deflection of the plurality of tabs of the retainer in order to secure the head portion of the bone screw in the cavity of the retainer.

23. The method of claim 22, wherein the head portion of the bone screw is not removable from the cavity of the retainer when the retainer is moved toward the lower end of the housing.

24. The method of claim 21, wherein the biasing spring means is a wave washer.

25. The method of claim 21, wherein the biasing spring means is integral with the retainer.

26. The method of claim 25, wherein the biasing spring means is a portion of the retainer including one or more circumferential or helical slots formed therein.