BI-DIRECTIONAL DRILL POINT SCREW

Abstract

The present invention provides for a joint fixation device and method utilizing a bone screw having a bi-directional drill point that is constructed and arranged to cut and form a hole in a bone when the screw is rotated or oscillated in both directions around the longitudinal axis of the screw. The screw can then be rotated into a final position by rotation in a single direction; and removed by rotating the screw in an opposite direction.

Claims

1. A bi-directional drill point bone screw (10) comprising; a shank (12) including a central longitudinal axis (13), a proximal end (31) and a distal end (15), at least one helical thread (28) extending around and along a portion of an outer surface (53) of the shank (12), the at least one helical thread (28) adapted for interlocking cooperation with a bone, the proximal end (31) of the shank (12) includes a bi-directional drill point (30), the bi-directional drill point (30) having at least two web components (32) separated by open flutes (34), each web component (32) including a cutting face (50) at the most proximal end of the shank (12), each cutting face (50) including at least one cutting edge (40) arranged to rotate around the central longitudinal axis (13), wherein at least one cutting edge (40) is arranged to cut when the bi-directional drill point bone screw (10) is rotated in a clockwise direction, and at least one cutting edge (40) is arranged to cut when the bi-directional drill point bone screw (10) is rotated in a counter-clockwise direction, wherein rotary oscillation of the bi-directional drill point bone screw (10) about the longitudinal axis (13) of the shank (12) is suitable to form a predetermined diameter aperture in a bone.

2. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein each cutting edge (40) includes a face rake (42), the face rake (42) arranged perpendicularly with respect to the cutting face (50) extending along a respective web component (32).

3. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein each cutting edge (40) includes a face rake (42), the face rake (42) arranged to be at an angle of less than ninety degrees with respect to the cutting face (50) extending along a respective web component (32).

4. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein each cutting edge (40) includes a face rake (42), the face rake (42) arranged to be at an angle of more than ninety degrees with respect to the cutting face (50) extending along a respective web component (32).

5. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein the bi-directional drill point includes at least three web components (32) separated by open flutes (34), each web component including a cutting face (50) at the most proximal end of the shank (12), each cutting face (50) including at least one cutting edge (40) arranged to rotate around the central longitudinal axis (13), wherein at least one cutting edge (40) is arranged to cut when the bi-directional drill point bone screw (10) is rotated in a clockwise direction and at least one cutting edge (40) is arranged to cut when the bi-directional drill point bone screw (10) is rotated in a counter-clockwise direction.

6. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein the bi-directional drill point includes four or more web components (32) separated by open flutes (34), each web component (32) including a cutting face (50) at the most proximal end of the shank (12), each cutting face (50) including at least one cutting edge (40) arranged to rotate around the central longitudinal axis (13), wherein at least two cutting edges (40) are arranged to cut when the bi-directional drill point bone screw (10) is rotated in a clockwise direction and at least two cutting edges (40) are arranged to cut when the bi-directional drill point bone screw (10) is rotated in a counter-clockwise direction.

7. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein each cutting face (50) includes at least two cutting edges (40) arranged to rotate around the central longitudinal axis (13), wherein at least one cutting edge (40) on each cutting face (50) is arranged to cut when the bi-directional drill point bone screw (10) is rotated in a clockwise direction and at least one cutting edge (40) on each cutting face (50) is arranged to cut when the bi-directional drill point bone screw (10) is rotated in a counter-clockwise direction.

8. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein each web component (32) comprises a radiused root (44) and a web (36), each web (36) terminating at the outer periphery with a land (38), the land (38) constructed and arranged to control the diameter of the aperture created by the bi-directional drill point bone screw (10).

9. The bi-directional drill point bone screw (10) as claimed in claim 8 wherein the land (38) is constructed and arranged to burnish the bone surface as the aperture is sized.

10. The bi-directional drill point bone screw (10) as claimed in claim 9 wherein the land (38) is constructed and arranged to compress the bone surface as the aperture is sized.

11. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein each cutting face (50) is a planar surface.

12. The bi-directional drill point bone screw (10) as claimed in claim 11 wherein each cutting face (50) is arranged at an angle with respect to the longitudinal axis (13) to create a point angle (52), the point angle (52) reducing the longitudinal pressure required to start an aperture.

13. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein the flutes (34) are sized and shaped to channel bone fragments and shavings away from the proximal end (31) as the bi-directional drill point bone screw (10) is oscillated.

14. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein the at least one helical thread (28) is adapted to cut threads in the aperture as the bi-directional drill point bone screw (10) is rotated into the aperture.

15. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein the at least one helical thread (28) is adapted to compression form threads in the aperture as the bi-directional drill point bone screw (10) is rotated into the aperture.

16. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein the distal end (15) of the shank (12) includes a tool socket (17) for cooperation with a driving tool (14) for rotation and/or oscillation of the shank (12).

17. The bi-directional drill point bone screw (10) as claimed in claim 1 wherein the distal end (15) of the shank (12) includes a portion of a spherical ball (16), the portion of the spherical ball (16) formed integral with the shank (12).

18. The bi-directional drill point bone screw (10) as claimed in claim 17 including a polyaxial connector assembly (18), the polyaxial connector assembly (18) including a socket (21) for receiving the portion of a spherical ball (16) therein, the portion of the spherical ball (16) and the polyaxial connector assembly (18) cooperating to allow the connector longitudinal axis (54) and the shank (12) to be positioned at angles relative to one another.

19. The bi-directional drill point bone screw (10) as claimed in claim 18 wherein the polyaxial connector assembly (18) is constructed and arranged to cooperate with a rod member (56) for securing a first bi-directional drill point bone screw (10) to a second bi-directional drill point bone screw (10).

20. The bi-directional drill point bone screw (10) as claimed in claim 18 wherein the polyaxial connector assembly (18) is constructed and arranged to cooperate with a plate member (58) for securing a first bi-directional drill point bone screw (10) to a second bi-directional drill point bone screw (10).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0021] FIG. 1 is a perspective view of one embodiment of the bi-directional drill point bone screw;

[0022] FIG. 2 is a perspective view of the embodiment shown in FIG. 1, illustrating the bi-directional drill point bone screw secured to an oscillating surgical tool;

[0023] FIG. 3 is a partial fragmentary view of the bi-directional drill point bone screw as shown in FIG. 2;

[0024] FIG. 4 is a side view partially in section illustrating the bi-directional drill point bone screw secured to an alternative oscillating tool;

[0025] FIG. 5 is a side view partially in section illustrating the bi-directional drill point bone screw secured to an alternative oscillating tool;

[0026] FIG. 6A is a perspective view of the bi-directional drill point bone screw;

[0027] FIG. 6B is a partial enlarged view taken along lines 6B-6B of FIG. 6A;

[0028] FIG. 7A is a perspective view illustrating the bi-directional drill point bone screw in cooperation with a driving tool; and

[0029] FIG. 7B is a partial enlarged view taken along lines 7B-7B of FIG. 7A.

DETAILED DESCRIPTION

[0030] While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described presently preferred, albeit not limiting, embodiments with the understanding that the present disclosure is to be considered exemplifications of the present invention and are not intended to limit the invention to the specific embodiments illustrated.

[0031] As used herein, “pedicle screw” or “pedicle screw assembly” is used to describe commonly used orthopedic or spinal surgical instrumentation, individually or as units, such as described in U.S. Pat. No. 7,066,937. The disclosure of this patent regarding the construction of a pedicle screw is incorporated herein by reference in its entirety. While many embodiments of a pedicle screw exist commercially, the typical pedicle screw assembly consists generally of the pedicle screw containing a threaded portion which is inserted into a bone or spinal vertebrae. Connected to the screw is a housing unit having upwardly shaped arms which form a U-shape unit, which is often called a “tulip”. At the base of the tulip is a saddle that cooperates with both the tulip and the spherical head of the screw to lock the assembly together using a set screw inserted threadably between the two upright elements of the tulip. The housing unit is generally constructed to receive a longitudinal or spinal rod. The longitudinal or spinal rod is set to the housing through use of the set screw, which can be designed to screw into a threaded portion of the housing or tulip to lock the rod into place. This general construction scheme allows the surgeon to connect and secure adjacent bones or bone fragments together through use of the pedicle screw assembly, thereby providing stability temporarily until the bones heal or fuse, or if needed, permanently.

[0032] As used herein, the term “proximate end” defines the end closest to the user, i.e., patient, when in use.

[0033] As used herein, the “distal end” is defined as the end located farthest from the user when in use.

[0034] FIGS. 1-5 illustrate a bi-directional drill point bone screw 10 suitable for use as a portion of a spinal fixation system (not shown). The spinal fixation system may include spinal rods or plates (not shown) connecting a plurality of the oscillating drill point bone screws 10. The present oscillating drill point bone screw 10 may alternatively be utilized in other surgical procedures including, but not limited to, bone fractures, head injuries, or the like. The bi-directional drill point bone screw 10 includes a shank 12 including at least one helical thread 28 extending along at least a portion of an outer surface 53 of the shank that is adapted for insertion into a bone, such as a vertebra. The distal end 15 of the shank 12 has a spherical ball 16, or a portion of a spherical ball, preferably integral therewith, and a tool socket 17 (FIG. 3) therein for the receipt of a tool 14 to install the threaded shank 12 into the bone by rotation thereof. The spherical ball 16 cooperates with a connector 20 to provide a polyaxial connector assembly 18 having a socket 21 receiving the spherical ball 16 therein. The spherical ball 16 and the socket 21 allow the longitudinal axes of the connector assembly 20 and the threaded shank 12, 13 and 54 respectively, to be positioned at angles relative to one another. The connector 20 may also be provided with a pair of opposed channel components 22, which can receive a portion of a rod 56 for securement therein. The rod member is secured in the connector 20 between the two channel components 22, as with a set screw threadably engaging an interior threaded surface 24 of the connector 20. Alternatively, the bi-directional drill point bone screw 10 may be utilized to secure a bone plate 58 across one or more bones to secure the bone(s) in a desired position. The proximal end 31 of the shank 12 includes the bi-directional drill point 30; the bi-directional drill point 30 having at least two, and optionally 3, 4 or more, web components 32 separated by open flutes 34 forming a plurality of webs 36 extending to the proximal tip; each web 36 terminating at the periphery with a land 38. The proximal tip of each web component including a cutting face 50 having at least one, more preferably two or more, cutting edge(s) 40 that is/are constructed and arranged to cut when the screw is rotationally oscillated about the longitudinal axis 13 of the shank 12. Thus, in a preferred embodiment, the cutting face 50 is planar and there is a cutting edge 40 on each side of each flute 34. Each cutting edge 40 preferably includes a face rake 42 which reduces the rotational force required to cut bone. The face rake 42 may be arranged perpendicularly with respect to the cutting face 50 extending along a respective web component 32; or alternatively, the face rake 42 may be arranged to be an angle of less than ninety degrees with respect to the cutting face 50 extending along a respective web component 32. In yet another embodiment, the face rake 42 may be arranged to be an angle of more than ninety degrees with respect to the cutting face extending along a respective web component 32. In at least one embodiment, each cutting face 50 is arranged at an angle with respect to the longitudinal axis 13 to create a point angle 52. The point angle 52 is constructed and arranged to make starting the drill point into a bone easier by not walking across the bone surface when oscillated and reducing the longitudinal pressure required to start an aperture by increasing the force per square inch of surface area. Once the proximal tip 31 of the bi-directional drill point 30 enters the bone, the land 38, which may also include cutting tips, size the hole formed in the bone. In some embodiments, the land 38 may be constructed and arranged to burnish the bone surface as it is sized to create a precision diameter and a smooth bore. In some embodiments, the burnishing may include compression of the cut bone surface. The flutes 34 are sized and shaped to channel away bone fragments and shavings as they are cut. In a preferred embodiment, the flutes 34 include a radiused root 44 that adds strength and rigidity to the bi-directional drill point 30, while still channeling the chips and shavings out of the hole that's being formed.

[0035] Referring to FIGS. 2-5, the bi-directional drill point bone screw 10 is illustrated secured to a surgical tool 51 that is constructed and arranged to oscillate the screw shank about its longitudinal axis 13 until the bi-directional drill point 30 penetrates the bone, and thereafter rotate the screw 10 into its final position in a single direction. Removal of the screw 10 is completed by rotating the screw 10 in an opposite direction with a driving tool 14. FIGS. 4 and 5 illustrate alternative devices for oscillating the screw 10, and thereafter providing standard rotation for placing the screw 10 in its final position.

[0036] All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains.

[0037] It is to be understood that while certain forms of the invention are illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein.

[0038] One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary, and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.