CA2289089C

CA2289089C - Articulating toggle bolt bone screw

Info

Publication number: CA2289089C
Application number: CA002289089A
Authority: CA
Inventors: Thomas S. Mullane
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-05-08
Filing date: 1997-05-08
Publication date: 2007-03-27
Anticipated expiration: 2017-05-08
Also published as: EP1405606A2; DE69734615D1; DE69734615T2; CA2289089A1; ES2216147T3; DE69727978T2; DE69727978D1; EP1405606B1; EP0981300A1; WO1998049961A1; ES2252609T3; US5628740A; EP1405606A3; EP0981300B1

Abstract

An articulation toggle bolt bone screw for use in surgical implants having particular usefulness in the stabilization of the human spine by fixation of vertebra. The apparatus employs a self-tapping anchoring screw having a ball joint socket for receip t of a rotatable threaded bolt. The ball joint allows angular placement of the bolt which is secured into position by an attachment nut coupling directly to the anchoring screw. An upper surface of the attaching nut is rounded allowing engagement of component devices. A rod clamp is disclosed for use in combination with the device providing attachment to support rods and serving to bias the bolt into a permanent fixed position upon attachment. An alternative embodiment is disclosed of the rod clamp providing a single support rod attachment system.

Description

3 Field of the Invention 4 This invention relates generally to threaded anchoring bolts and, more particularly to bone screws used in 6 stabilization of human vertebrae.
7 Background of the Invention 8 The use of fixation devices for the treatment of vertebrae 9 injuries and deformities is well known in the art. Various fixation devices correct curvatures, treat trauma, amend 11 deformities, and remedy various degenerative spinal conditions.
12 Implants typically consist of strategically placed screws used 13 to anchor various component pieces such as support rods, cross 14 links, caudal facing hooks, cranial facing hooks and the like components all of which form a spinal implant system.
16 Common to spinal implant systems is the necessity for 17 proper anchoring to the bone so ws to provide support for the 18 aforementioned components. While bone screws are commonly used 19 for anchoring, they are limited in their positioning due to the design of component pieces. Numerous patents are directed to 21 component design in order to accommodate the bone screw, yet few 22 patents are directed to bone screws that will accommodate 23 existing component design. In many instances the combination of 24 existing component design and bone screw design inhibits application to a particular spinal injury. For example, bone 26 structure of the sacrum is typically soft, and often 27 osteoporotic in the elderly. Perpendicular placement of a bone 28 screw therein may not be possible and placement at an angle 29 thereto may cause undue stress further affecting adjoining bones. Thus, if a common bone screw is employed, the component 31 connector will be of special design.
32 For this and other reasons, screws located in bone 33 structure typically use a specially designed clamp to attach to 34 a component such as an alignment rod. A problem with specially designed clamps is that bone structure cannot be determined 1 until the patient's bone is exposed causing the necessity of a 2 large inventory of various sized clamps to be on hand during 3 surgery, of which the surgeon must search to find the right 4 combination. Even if a clamp combination is predicted, insertion of the screw may still require angular insertion due 6 to muscle or tender nerve locations. The result is a bone screw 7 which exerts unpredictable forces upon attachment to component 8 connectors. Further, any movement of muscle and other tissue 9 increases the difficulty of the operation and can be a major trauma to a person.
11 A conventional bone screw consists of a single shaft with 12 a coarse thread at one end for threading into the bone and a 13 machine thread at the other end for coupling to components.
14 Another type of bone screw has a U-shaped top which acts as a saddle for attachment to an alignment rod. If the screw is 16 placed incorrectly for any reason, the rod clamp must be made to 17 accommodate the position.
18 A number of patents exist which demonstrate the reliance on 19 the saddle type screw support and various designs to accommodate the problem.
21 U.S. Patent No. 5,133,717 sets forth a sacral screw with a 22 saddle support. Disclosed is the use of an auxiliary angled 23 screw to provide the necessary support in placing the screw in 24 an angular position for improved anchoring.
U.S. Patent No. 5,129,900 sets forth an attachment screw 25 and connector member that is adjustably fastened to an alignment 27 rod. An oblong area provided within each connector member 28 allows minute displacement of the alignment rod.
29 U.S. Patent 5,129,900 discloses an apparatus which utilizes a screw having a lower portion adapted for insertion into the 31 bone and a second portion of the screw including a means for 32 adjusting vertical placement of an alignment rod.
33 U.S. Patent 4,887,595 discloses a screw that has a first 34 externally threaded portion for engagement with the bone and a 1 second externally threaded portion for engagement with a locking 2 nut. The disclosure illustrates the use of a singular fixed 3 shaft.
- 4 U.S. Patent 4,946,458 discloses a screw which employs a spherical portion which is adapted to receive a locking pin so 6 as to allow one portion of the screw to rotate around the 7 spherical portion. A problem with the screw is the need for the 8 locking pin and the inability of the base screw to accommodate 9 a threaded extension bolt.
U.S. Patent 5,002,542 discloses a screw clamp wherein two 11 horizontally disposed sections are adapted to receive the head 12 of a pedicle screw for use in combination with a hook which 13 holds a support rod at an adjustable distance.
14 U.S. Patent 4,854,304 discloses the use of a screw with a top portion that is adaptable for use with a specially designed 16 alignment rod to permit compression as well as distraction.
17 U.S. Patent 4,887,596 discloses a pedicle screw for use in 18 coupling an alignment rod to the spine wherein the screw 19 includes a clamp permitting adjustment of the angle between the alignment rod and the screw.
21 U.S. Patent 4,836,196 discloses a screw with an upper 22 portion design for threadingly engaging a semi-spherical cup for 23 use with a specially designed alignment rod. The alignment rod 24 having spaced apart covertures for receipt of a spherical disc allowing a support rod to be placed at angular positions.
26 Therefore, what is lacking in the art is an articulated toggle 27 bolt having a screw base for anchoring into bone and a means for 28 top loading of spinal implant components.
2 9 SU1~IARY OF THE INVENTION
The instant invention is directed to an articulating toggle . 31 bolt bone screw having particular usefulness with a clamping 32 mechanism for anchoring aligning rods used in a vertebra . 33 fixation system. The apparatus consists of a rigid shank having 34 a self-taping coarse thread formed along a length of the shank for attachment to bone and a spherical shaped socket disposed at 36 the opposite end. A toggle bolt attaches to the shank by use of 1 a ball shaped end that fits within the socket. An attachment 2 cap having a centrally disposed aperture and rounded top 3 threadingly engages the socket portion of the anchoring 'screw to 4 secure the ball shaped end to the socket. The aperture allows toggle bolt articulation providing the surgeon with the ability 6 to attach the screw to bone structure and place the toggle bolt 7 in a precise position for subsequent attachment to component 8 pieces.
9 Once the screw is anchored into the bane an alignment rod can be coupled to the toggle bolt by use of a rod clamp which is 11 formed from a bifurcated compressible sleeve. The clamp :has an 12 aperture for insertion of the bolt and a. perpendicularly 13 disposed opening for placement of the alignment rod. A lower 14 portion of the clamp includes a rounded surface that corresponds to a rounded surface of the attachment cap.
16 In operation the screw is threaded into bone structure of 17 a patient. The rod clamp is attached to the alignment rod and 18 positioned onto the toggle bolt. The toggle bolt is then moved 19 into a position so as to avoid stress on components which could force associated bones into improper positioning. A nut is used 21 to fasten the clamp to the screw wherein the compression causes 22 the toggle bolt to fictionally engage the attachment cap for 23 permanent positioning of the toggle bolt and alignment rad.
24 Accordingly, an aspect of the instant invention :is to provide a top-loading bone screw which provides an adjustable 26 range of motion for subseguent attachment of components.
27 Still another aspect is to provide a screw that c:an be 28 placed in an angular position and permanently fixed in said 29 position.
Yet still another aspect is to provide a rod clamp for 31 use in combination With the bone screw of the instant invention 32 using a curvature surface that provides mounting stability 33 despite the angle of attachment.
34 Still another aspect of this invention is to provide a anchoring base and rod clamp system that permits the use of a 36 single support rod.

1 Other aspects and advantages of this invention will become 2 apparent from the following description taken in conjunction 3 with the accompanying drawings wherein set forth, by way of 4 illustration and example, certain embodiments of this invention.

5 The drawings constitute a part of this specification and include 6 exemplary embodiments of the instant invention and illustrate 7 various objects and features thereof.

8 HRIEh' D1PSCR~PTION OF TH8 DRAWINGS

9 Figure 1 is a side view of the articulating toggle bolt bone screw of the instant invention;
11 Figure 2 is a cross sectional side view of the bone screw 12 with; the toggle bolt shown in an offset posit~ton;
13 ~~ Figure 3 is a top view of a hex shaped embodiment of the 14 bone screw;
Figure 4 is an exploded view of the bone screw w:lth rod 16 clamp;
17 Figure 5 is a perspective view of a spinal implant 18 illustrating the angular adjustment of individual bone screws 19 and setting forth an alternative embodiment using half size rod clamps for a single support rod system; and 21 Figure 6 is an exploded perspective view of the hex shaped 22 embodiment of the bone screw with rod clamp.

24 As required, detailed embodiments of the present invention are disclosed herein, however, it is to be understood that the 26 disclosed embodiments are merely exemplary of the invention 27 Which may be embodied in various forms. Therefore, specific 28 functional and structural details discloBed herein are not to be 29 interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the 31 art to variously employ the present invention in virtually any 32 appropriately detailed structure.
33 Now referring to Figure 1, the articulating togg7.e bolt 34 bone screw 10 of the instant invention is defined by an anchoring base 12 formed from stainless steel, titanium, 36 thermoplastic, composite, bovine, coral, POLYSORB, or the like 1 rigid material. The anchoring base provides fixed placement in 2 bone structure by use of a threaded shaft 14 having a coarse 3 self-taping thread disposed along a length thereof. An upper 4 portion of the anchoring base 12 forms a spherical shaped receptacle socket 16 to engage the foundation 18 of a toggle 6 bolt shaft 20 can also be formed from the aforementioned rigid 7 materials. The toggle bolt 20 provides a predetermined range of 8 rotation in conjunction with a centrally disposed aperture 22 9 found on attachment cap 24. Machine or english threads along the length of the bolt extend outwardly from the cap 24 for use 11 in securing various components to the bolt and permanent 12 attachment thereafter when a locking nut is installed. As 13 depicted in the drawings, bolt 20 may include a notch along the 14 length thereof allowing the bolt to be broken off at a predetermined position once installed so as to reduce the 16 profile of implantation.
17 It is noted that the apparatus can be formed from various 18 thermoplastic polyamides such as nylon. In addition to the 19 commonly known advantages of plastic, the material provides the surgeon with the ability to customize a bone screw installation.
21 For instance, if the spinal reconstruction requires an offset 22 angular attachment with an unusually large extension, the use of 23 an oversized plastic toggle bolt will allow the surgeon to 24 insert spacers, cross connects, or rod attachment, not shown, to conform to an individual patient's requirement. Once installed, 26 the surgeon can easily cut the remaining portion of the toggle 27 bolt that is not necessary.
28 Figure 2 sets forth a cross sectional side view of the bone 29 screw 10 clearly depicting the spherical socket chamber 26. The chamber 26 is defined by a cup shaped opening having an internal 31 thread 28 engaging the external thread 30 on the attachment cap 32 24. The socket 16 and attachment cap 24 form a ball shaped 33 chamber allowing the rotational movement of a ball shaped end 32 34 of toggle bolt base 18. Tabs 34 are positioned on either side of end 32 to prevent spinning within the chamber by engagement 36 of diametrically opposed slots that run both perpendicular and 1 vertical providing a slidable point of rotation. Median which 2 provides transition between shaft 20 and end 32 is operatively 3 associated with the aperture 22 setting forth a diameter smaller 4 than the diameter of the bolt end 32. The median 36 has a curved surface that engages the side wall of aperture 22 6 providing up to twenty five degrees of motion range over a 360 7 degree pattern from a longitudinal axis defined along the length 8 of said shank 14. The inner edge of aperture 22 is sized to 9 prevent passage of end 32. In addition, a preferred embodiment of the invention allows deformation of the aperture edge 38 11 during engagement of the toggle bolt 20 so as to permanently 12 wedge the end 32 and inner edge 38 together to prevent any 13 rotation or angular movement once the surgeon has determined the 14 optimum fixation position. Permanent positioning can be enhanced by use of roughened surfaces such as shot blasted or 16 striated surfaces. Further, material selection or construction 17 of wedge shaped ball tabs which allow deformation concomitantly 18 with the aperture inner edge 38 permit additional fixation.
19 Figure 3 is a top view of the bone screw 10 illustrating the attachment cap 24 having centrally disposed aperture 22.
21 Toggle bolt 20 can be angled by rotation of the shaft within the 22 confines of the aperture. Tabs 34 engage slots within the side 23 wall of the chamber allowing a pivot and slid movement of the 24 bolt. The anchoring base and attachment cap can be made in the form of a conventional hex head allowing ease of installation, 26 see Fig. 6, or use a round body. In either embodiment, it has 27 been found that forming a hex head 40 on the end of the bolt 20 28 facilitates attachment, holding, or removal by use of a 29 conventional torque wrench.
Now referring to Figure 4, an exploded view of the 31 articulating toggle bolt bone screw sets forth the anchoring 32 base 12 with threaded shaft 14 and the spherical socket chamber 33 26 with internal thread 28. Threaded toggle bolt base 12 has 34 ball shaped end 32 with tabs 34 to prevent spinning of the bolt in socket 26. The median 36 clearly shows an hourglass shape 36 operatively associated with the aperture 22 of attachment cap 1 24. External threads 30 of cap 24 provide engagement with 2 anchoring base 12. It should be obvious to one skilled in the 3 art that low profile applications can be obtained by various cap 4 attachment methods including welding or press fit, not shown, but within the scope of the instant invention. The upper 6 surface 42 of the cap 24 is rounded, i.e. convex, for engaging 7 the lower surface 44 of a rod clamp 46. Rod clamp 46 is formed 8 from a bifurcated compressible sleeve having a longitudinal slot 9 with an aperture 54 disposed perpendicular thereto for insertion of rod supports. A spaced apart upper section 50 and lower 11 section 52 provides an area for compression by removal of said 12 slot 48 allowing the clasping of a rod placed in aperture 54.
13 In operation, rod clamp 46 is coupled to the toggle bolt 20 by 14 the use of a conventional locking nuts 56 shown in duplicate as the preferred method of preventing unintentional loosening. The 16 rod aperture 54 permits coupling to a conventional support rod, 17 not shown, wherein tightening of the nuts 56 to the bolt 20 18 causes compression of the rod aperture 54 when the upper section 19 50 and lower section 52 are forced together. The lower section 52 has a curvature 44 to allow broad surface area contact with 21 the upper surface 42 of the cap 24 throughout the range of 22 angular bolt motion. To increase support of the rod and 23 attachment to the bolt 20, the surface of the aperture 54 and 24 joining surfaces 44 and 42 can be knurled or otherwise roughened providing a texture for increased gripping ability. As 26 previously noted, it is deemed within the scope of this 27 invention to use spacers between attachment cap 24 and rod clamp 28 46 as well as variations of the clamping mechanism for 29 attachment to devices such as cross links and the like ancillary devices.
31 Figure 5 sets forth a pictorial view of the bone screws 32 ready for attachment to a spine. In this example, support rod 33 58 is shown in a straight axis over a parallel plane to the 34 longitudinal axis of spine 60. Screw 62 to be threaded into the bone 64 perpendicular to the support rod. As previously 36 described the screw 62 utilizes the threaded shaft 66 for 1 attachment to bone. The toggle bolt 68 is positioned within the 2 socket 70 and projects through the cap aperture for attachment 3 to alternative embodiment clamp 72 which frictionally engages 4 the support rod 58 by use of the locking nuts 74. Mirror image anchoring screws and rod clamps are depicted but not numbered so 6 as to provide drawing clarity. In this particular embodiment, 7 the rod clamp 72 has a reduced area of attachment to the rod 58 8 providing a singular rod implant system. Unique to this 9 invention is the ability to use a single support rod yet find proper pedicle anchoring. Screw 62' is threaded into the bone 11 76 at approximately a seven degree angle to the support rod 58.
12 The screw 62' utilizes the threaded shaft 66' for attachment to 13 the~bone wherein toggle bolt 68' is positioned within the socket 14 70'and slightly offset for which the cap and clamp surface provide a compensating surface area for attachment. Alternative 16 embodiment clamp 72' is then engaged to the support rod 56 by 17 use of the locking nuts 74'. Screw 62~' threaded into the bone 18 ?8 at approximately a fifteen degree angle to the support rod 19 56. The screw 62" utilizes the threaded shaft 66" for attachment to the bone wherein toggle bolt 68~' is positioned 21 within the socket ,70~' and slightly offset for which the cap and 22 clamp surface compensate . Alternative rod clamp 72 ~' i.~ then 23 engaged to the support rod 56 by use of the locking nut. 74".
24 Now referring to Figure 6, an exploded perspec'~ive view of the articulating toggle bone screw of the preferrLd embodiment 26 sets forth the anchoring base 82 with threaded shaft 84 and the 27 hex shaped socket chamber 86 with internal thread 88. The hex 28 shaped housing allows the use of leverage tools for insertion of 29 the anchoring base 82 in strong bone structure. Threaded goggle bolt base 90 has ball shaped end 92 with tab 94 to help prevent 31 spinning of the bolt 90 in socket 86. Attachment cap 96 is 32 shown with aperture 98 using external threads 100 for engagement 33 with threads 88 anchoring base 86 . As with the rounded body 34 embodiment, the upper surface 102 of the cap is made ava9.lable for engaging the lower surface 104 of conventional implant 36 devices such as rod clamp 106. The rod clamp 106 is formed from 1 a bifurcated compressible sleeve having a longitudinal slot 108 2 defined by a spaced apart upper section 110 and lower section 3 112 with an aperture 114 disposed perpendicular thereto. The 4 rod clamp 106 is coupled to the toggle bolt 90 by insertion of 5 the bolt 90 through bolt hole 116 for coupling to conventional 6 locking nuts 118 shown in duplicate as the preferred method of 7 preventing unintentional loosening.
8 It is to be understood that while we have illustrated and 9 described certain forms of our invention, it is not to be 10 limited to the specific forms or arrangement of components 11 herein described and shown. It will be apparent to those 12 skilled in the art that various changes may be made without 13 departing from the scope of the invention and the invention is 14 not to be considered limited to what is shown in the drawings and described in the specification.

Claims

WHAT IS CLAIMED IS:

1. An articulating toggle bolt bone screw for surgical implantation comprising:
an anchoring base having a rigid shank with a self-taping threaded first end for securing into human bone and a cylindrical shaped second end having an enlarged sidewall forming a socket;
a bolt constructed of rigid material having a first spherically shaped end insertable into said socket and a threaded second end receptive to a locking nut;
and an attachment cap frictionally engaging an inner surface of said enlarged sidewall of said anchoring base forming a receptacle for holding said first end of said bolt in a fixed position relative to said anchoring base, said attachment cap having a rounded upper inner surface and a centrally disposed sized aperture allowing said second end of said bolt to articulate over a predetermined range of motion;
whereby said anchoring base is adapted to be screwed into human bone wherein said second end of said bolt is available for attachment to conventional implant component devices, wherein tightening of the locking nut to said second end of said bolt frictionally engages said first spherically shaped end against said inner surface of said attachment cap securing said bolt in position.

2. The screw according to claim 1 wherein said attachment cap includes a curved upper outer surface.

3. The screw according to claim 1 wherein said predetermined range of motion is approximately twenty five degrees throughout a 360 degree pattern from a longitudinal axis defined along a length of said shank.

4. The screw according to claim 1 wherein said bolt includes at least one tab extending outwardly from a surface of said spherically shaped first end to prevent circular rotation about an axis formed along a length of said bolt.

5. The screw according to claim 1 wherein said anchoring base and bolt are constructed from steel.

6. The screw according to claim 1 wherein said anchoring base and bolt are constructed from plastic.

7. The screw according to claim 1 wherein said second end of said anchoring base and an outside surface of said attachment cap have a symmetrical hex shaped diameter.

8. The screw according to claim 1 wherein said bolt includes a tab extending outwardly from a surface of said spherically shaped first end for wedging said bolt in a fixed position relative to said anchoring base.

9. A surgically implantable rod attachment apparatus comprising:
an anchoring base constructed from a steel shank having a shank longitudinal axis with a first end forming a self-taping thread available for insertion into rigid bone structure and a second end having an enlarged sidewall forming a first spherical shaped socket; a bolt constructed from a single piece of rigid material having a bolt longitudinal axis with a first spherically shaped end insertable into said socket and a threaded second end receptive to a lock nut; an attachment cap frictionally engaging an inner surface of said enlarged sidewall of said anchoring base forming a receptacle for holding said first end of said bolt in a fixed position relative to said anchoring base, said attachment cap having rounded upper inner and outer surfaces and a centrally disposed sized aperture allowing said bolt to articulate over a predetermined range of motion; a bifurcated compressible clamp having a spaced apart upper clamp sleeve section and lower clamp sleeve section forming a longitudinal slot with a clamp aperture disposed perpendicular thereto, said clamp aperture available for insertion of a conventional support rod, said lower clamp sleeve section having a concave surface for frictional engagement of said upper, outer surface of said attachment cap; and at least one lock nut engagable with said threaded second end of said bolt for securing said lower clamp sleeve to said bolt;
whereby said anchoring base is securable to said bone structure by screwing said anchoring base into said bone structure wherein said bolt is available for angular rotation within said aperture for proper positioning of the support rod having said conventional support rod placed through said clamp aperture allowing securement to said anchoring base by tightening said at least one lock nut frictionally engaging said first end of said bolt to said inner surface of said attachment cap.

10. The attachment apparatus according to claim 9 wherein said attachment cap is screwed to said anchoring base.

11. The attachment apparatus according to claim 9 wherein said attachment cap is welded to said anchoring base.

12. The apparatus attachment according to claim 9 wherein said attachment cap is press fit to said anchoring base.