Low top bone fixation system and method for using the same

Abstract

An exemplary tulip assembly configured to be coupled to a head of a bone fixation device includes an inner tulip member including a lower portion configured to couple the head of the bone fixation device and an upper portion including a plurality of flexible protrusions extending from the lower portion. According to one exemplary embodiment the plurality of flexible protrusions are configured to provisionally couple a rod. The exemplary tulip assembly also includes an outer tulip member including a first position and a second position, the first position being configured to enable an expansion of the lower portion of the inner tulip member and the second position being configured to compressibly lock the lower portion of the inner member on the bone fixation device. Moreover, the present exemplary tulip assembly also includes a cap having a generally planar top and at least one locking member extending from the top. Wherein the at least one locking member is configured to compress the flexible protrusions to securely lock the rod within the tulip assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various exemplary embodiments of the present system and method and are a part of the specification. Together with the following description, the drawings demonstrate and explain the principles of the present system and method. The illustrated embodiments are examples of the present system and method and do not limit the scope thereof.

FIG. 1A and 1B are an axial view and a transverse view, respectively, of an assembled low top pedicle screw system, according to one exemplary embodiment.

FIG. 2 is an exploded axial view of a low top pedicle screw system, according to one exemplary embodiment.

FIG. 3 is a perspective view of a pedicle screw, according to one exemplary embodiment.

FIG. 4 is an axial exploded view of a tulip assembly of the low top pedicle screw system of FIG. 1, according to one exemplary embodiment.

FIG. 5 is a transverse exploded view of a tulip assembly of the low top pedicle screw system of FIG. 1, according to one exemplary embodiment.

FIG. 6 is an axial exploded cross-sectional side view of the low top pedicle screw system of FIG. 4, according to one exemplary embodiment.

FIGS. 7A-7D are axial, transverse, axial cross-sectional, and cut-away perspective views, respectively, of a tulip body, according to one exemplary embodiment.

FIGS. 8A-8C are axial, transverse, and cut-away perspective views, respectively, of an inner tulip member, according to one exemplary embodiment.

FIGS. 9A-9C are axial, transverse, and cut-away perspective views, respectively, of a compression cap, according to one exemplary embodiment.

FIG. 10 is a flow chart illustrating a method for securing a low top tulip assembly on a pedicle screw, according to one exemplary embodiment.

FIGS. 11A and 11B are an axial view and a cross-sectional side view, respectively, of the components of a low top pedicle screw system prior to assembly, according to one exemplary embodiment.

FIGS. 12A and 12B are an axial view and a cross-sectional side view, respectively, of the components of the low top pedicle screw system of FIG. 10 with the tulip assembly coupled to a head of a pedicle screw, according to one exemplary embodiment.

FIGS. 13A and 13B are an axial view and a cross-sectional side view, respectively, of the components of the low top pedicle screw system of FIG. 10 as a rod is snapped into the internal tulip member, according to one exemplary embodiment.

FIGS. 14A and 14B are an axial view and a cross-sectional side view, respectively, of the components of a low top pedicle screw system during provisional lock of the tulip assembly with respect to the pedicle screw, according to one exemplary embodiment.

FIGS. 15A and 15B are an axial view and a cross-sectional side view, respectively, of the components of a low top pedicle screw system as a compression cap is snapped into place, according to one exemplary embodiment.

FIGS. 16A and 16B are an axial view and a cross-sectional side view, respectively, of the components of a low top pedicle screw system in a fully assembled position, according to one exemplary embodiment.

Claims

1. A tulip assembly configured to be coupled to a head of a bone fixation device comprising: an inner tulip member including a lower portion configured to couple said head of said bone fixation device and an upper portion including a plurality of flexible protrusions extending from said lower portion, said plurality of flexible protrusions being configured to provisionally coupled a rod;an outer tulip member including a first position and a second position, said first position being configured to enable an expansion of said lower portion of said inner tulip member and said second position being configured to compressibly lock said lower portion of said inner member on said bone fixation device; anda cap including a generally planar top and at least one locking member extending from said top, said at least one locking member being configured to compress said flexible protrusions to securely lock said rod.

2. The tulip assembly of claim 1, wherein said plurality of flexible protrusions each comprise at least one rod engagement member, wherein said rod engagement member is configured to establish an area of engagement with said rod.

3. The tulip assembly of claim 2, wherein said plurality of flexible protrusions each comprise at least two rod engagement members, wherein said rod engagement members are configured to establish an area of engagement with said rod.

4. The tulip assembly of claim 1, wherein said lower portion of said inner tulip member further defines a plurality of expansion gaps configured to allow said rod engagement members to flex.

5. The tulip assembly of claim 1, wherein said inner tulip further defines a plurality of expansion gaps that extend from said lower portion into said flexible protrusions.

6. The tulip assembly of claim 5, further comprising a head receiving orifice defined by said lower portion of said inner tulip member, wherein said plurality of expansion gaps extending from said lower portion into said flexible protrusions are configured to allow said head receiving orifice to expand during a reception of said head of a bone fixation device.

7. The tulip assembly of claim 1, further comprising: at least one annular seating feature disposed on an outer surface of said lower portion of said inner tulip member; andat least one annular recess disposed on an internal wall of said outer tulip member;wherein said at least one annular seating feature mates with said at least one annular recess in said first position of said outer tulip member.

8. The tulip assembly of claim 7, further comprising: at least one annular compression feature disposed on an internal wall of said outer tulip member;wherein said at least one annular seating feature mates with said at least one annular compression feature in said second position of said outer tulip member.

9. The tulip assembly of claim 1, wherein said cap further comprises a generally planar rod mating surface formed substantially parallel with said generally planar top surface; wherein a height of said assembly above said rod is equal to a distance between said generally planar rod mating surface and said generally planar top surface.

10. The tulip assembly of claim 1, wherein said at least one locking member configured to compress said flexible protrusions is configured to be disposed between said flexible protrusions and said outer tulip member.

11. The tulip assembly of claim 1, wherein said inner tulip member and said outer tulip member are configured to provisionally lock an angular orientation of said tulip assembly relative to said bone fixation device independent of said cap.

12. A tulip assembly configured to be coupled to a head of a bone fixation device comprising: an inner tulip member including a lower portion configured to couple said head of said bone fixation device and an upper portion including a plurality of flexible protrusions extending from said lower portion, said plurality of flexible protrusions being configured to provisionally coupled a rod, wherein said plurality of flexible protrusions each comprise at least two rod engagement members, wherein said rod engagement members are configured to engage and retain said rod;an outer tulip member including a first position and a second position, said first position being configured to enable an expansion of said lower portion of said inner tulip member and said second position being configured to compressibly lock said lower portion of said inner member on said bone fixation device; anda cap including a generally planar top and at least one locking member extending from said top, said at least one locking member being configured to compress said flexible protrusions to securely lock said rod.

13. The tulip assembly of claim 12, wherein said lower portion of said inner tulip member further defines a plurality of expansion gaps configured to allow said rod engagement members to flex.

14. The tulip assembly of claim 12, wherein said inner tulip member further defines a plurality of expansion gaps that extend from said lower portion into said flexible protrusions.

15. The tulip assembly of claim 14, further comprising a head receiving orifice defined by said lower portion of said inner tulip member, wherein said plurality of expansion gaps extending from said lower portion into said flexible protrusions are configured to allow said head receiving orifice to expand during a reception of said head of a bone fixation device.

16. The tulip assembly of claim 12, further comprising: at least one annular seating feature disposed on an outer surface of said lower portion of said inner tulip member; andat least one annular recess disposed on an internal wall of said outer tulip member;wherein said at least one annular seating feature mates with said at least one annular recess in said first position of said outer tulip member.

17. The tulip assembly of claim 16, further comprising: at least one annular compression feature disposed on an internal wall of said outer tulip member;wherein said at least one annular seating feature mates with said at least one annular compression feature in said second position of said outer tulip member.

18. The tulip assembly of claim 12, wherein said cap further comprises a generally planar rod mating surface formed substantially parallel with said generally planar top surface; wherein a height of said assembly above said rod is equal to a distance between said generally planar rod mating surface and said generally planar top surface.

19. The tulip assembly of claim 12, wherein said inner tulip member and said outer tulip member are configured to provisionally lock an angular orientation of said tulip assembly relative to said bone fixation device independent of said cap.

20. A method of fixing a tulip assembly to a pedicle screw comprising: inserting said pedicle screw into a bone, said pedicle screw including a head portion;expanding an inner tulip member within an outer tulip member to receive a head portion of said pedicle screw after said pedicle screw is inserted into a bone;fixing an angle of said tulip assembly relative to said pedicle screw with said first inner tulip member by exerting a force on said outer tulip member;inserting a rod into said tulip assembly by engaging said rod with a plurality of rod engagement members; andpositionally locking said rod in said tulip assembly after said angle is fixed by compressing said rod engagement members with a frictionally engaged cap.