Hinged anterior cervical plate system

Abstract

A folding anterior cervical locking plate system for stabilizing the cervical spine in a spinal fusion procedure. The plate system has at least two plate sections hinged together by a hinge structure at adjacent ends for pivoting movement of the plate sections relative to one another through at least 90 in each of two directions. A first hole in each plate section enables visualization of the underlying graft. A locking plate spans adjacent ends of the plate sections and holes in the locking plate are aligned with holes in adjacent plate sections so pedicle screws inserted through the holes in the locking plates extend through the holes in the plate sections to secure the system to the vertebral bodies and stabilizes the cervical spine. In one embodiment the locking plate slides in guide channels on opposite side edges of the plate sections.

Claims

1. A folding plate system for stabilizing adjacent vertebral bodies in a cervical spine, said plate system comprising: at least two plate sections connected to one another via a uniaxial rotating hinge, the uniaxial rotating hinge having only a single axis of rotation which extends parallel to adjacent ends of the at least two plate sections such that the at least two plate sections are pivotable out of plane with one another about the single axis of rotation; a peripherally enclosed visualization hole in each of the at least two plate sections arranged and disposed for visualization of an underlying graft site; and a plurality of screw holes through each of the at least two plate sections for receiving screws inserted therethrough, each of the plurality of screw holes having a cross-sectional area less than the visualization hole.

2. The folding plate system of claim 1, wherein the at least two plate sections are made of titanium.

3. The folding plate system of claim 1, wherein each of the at least two plate sections measures 2-3 mm in thickness, 6-10 mm in width, and 20-30 mm in length.

4. The folding plate system of claim 1, further including a locking plate sized to extend between the at least two plate sections, the locking plate having a plurality of holes therethrough spaced to align with at least some of the plurality of screw holes in the at least two plate sections such that screws inserted through the plurality of holes in the locking plate and the at least some of the plurality of screw holes in the at least two plate sections fix the at least two plate sections so as to resist pivoting movement of the at least two plate sections relative to one another about the single axis of rotation.

5. The folding plate system of claim 4, wherein the locking plate extends across the uniaxial rotating hinge.

6. The folding plate system of claim 4, further including a guide channel extending longitudinally along each of opposite side edges of each of the at least two plate sections such that the locking plate is retained and guided at opposite side edges in the guide channels for sliding movement in the guide channels from an unlocked position on top of one of the at least two plate sections to a locked position spanning the uniaxial rotating hinge connecting the at least two plate sections.

7. The folding plate system of claim 1, wherein locking plate is made of titanium.

8. The folding plate system of claim 1, wherein the uniaxial rotating hinge includes a pair of support arms extending from a first plate section of the at least two plate sections, a pivot pin supported by the pair of support arms, and a bore extending transversely in a second plate section of the at least two plate sections, the pin being rotatably received in the bore to pivotally connect together said the plate section and the second plate section.

9. The folding plate system of claim 8, wherein: a slot extends longitudinally in the second plate section in angularly offset relation below a plane of the second plate section, said slot opening into the bore and enabling the pivot pin to be inserted endwise into the bore, the slot terminating in spaced relation to an adjacent side edge of the second plate section, wherein an end of the slot forms a stop that limits how far the pivot pin may be inserted into the bore; and notches formed in the second plate section in spaced locations corresponding to locations of the support arms on the first plate section when the pivot pin of said first plate section is fully inserted into the bore of the second plate section, the notches extending transversely to the slot and terminating at upper and lower extremities in upper and lower surfaces, respectively, of the second plate section such that the plate sections are pivotable up and down relative to one another.

10. The folding plate system of claim 1, wherein the at least two plate sections consist of a first plate section and a second plate section so as to form a two-level system.

11. The folding plate system of claim 1, wherein the at least two plate section includes a first plate section and a second plate section connected to one another via the uniaxial rotating hinge and a third plate section connected to the second plate section via a second uniaxial rotating hinge so as to form a three-level system.

12. The folding plate system of claim 1, wherein the at least two plate sections are pivotable out of plane with one another about the single axis of rotation via the uniaxial rotating hinge through at least 90 in each of two directions relative to one another.

13. The folding plate system of claim 1, wherein at least one of the at least two plate sections includes an end opposite the uniaxial rotating hinge which is free of a hinge-forming structure.

14. The folding plate system of claim 1, wherein the plurality of screw holes through each of the at least two plate sections includes four screw holes through each of the at least two plate sections.

15. The folding plate system of claim 14, wherein the four screw holes are disposed adjacent to four corners of each of the at least two plate sections.

16. The folding plate system of claim 1, wherein the visualization hole is disposed at a center of each of the at least two plate sections.

17. A method for stabilizing adjacent vertebral bodies in a cervical spine, comprising: inserting a folding plate system through an in incision into a position adjacent to an anterior surface of the cervical spine while the folding plate system is in a folded configuration, the folding plate system including: at least two plate sections connected to one another via a uniaxial rotating hinge, the uniaxial rotating hinge having only a single axis of rotation which extends parallel to adjacent ends of the at least two plate sections such that the at least two plate sections are pivotable out of plane with one another about the single axis of rotation; a peripherally enclosed visualization hole in each of the at least two plate sections arranged and disposed for visualization of an underlying graft site; and a plurality of screw holes through each of the at least two plate sections for receiving screws inserted therethrough, each of the plurality of screw holes having a cross-sectional area less than the visualization hole, then unfolding the folding plate system to a flattened configuration by rotating the at least two plate section relative to one another into a planar relationship; and attaching the folding plate system to the adjacent vertebral bodies with a plurality of screws.

18. The method of claim 17, further including positioning a locking plate extending between the at least two plate sections, and rotationally fixing the at least two plate sections with the locking plate so as to resist pivoting movement of the at least two plate sections relative to one another about the single axis of rotation.

19. The method of claim 18, wherein the locking plate includes a plurality of holes therethrough spaced to align with at least some of the plurality of screw holes in the at least two plate sections, and rotationally fixing the at least two plate sections with the locking plate includes inserting screws through the plurality of holes in the locking plate and the at least some of the plurality of screw holes.

20. The method of claim 19, wherein the locking plate is sized to extend across the uniaxial rotating hinge and the at least two locking plates include a guide channel extending longitudinally along each of opposite side edges of each of the at least two plate sections, and positioning the locking plate includes sliding the locking plate through the guide channel such that the locking plate is retained at opposite side edges in the guide channels in a locked position spanning the uniaxial rotating hinge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The foregoing as well as other objects and advantages of the invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings, wherein like reference characters designate like parts throughout the several views, and wherein:

[0032] FIG. 1 is a schematic front representation of the cervical spine.

[0033] FIG. 2 is a schematic side representation of the cervical spine.

[0034] FIG. 3 is a schematic cross sectional view of the cervical spine, showing a typical bone spur and herniated disc.

[0035] FIG. 4 is a fragmentary schematic front view of a patient's neck, showing a typical transverse incision made in an anterior fusion surgery procedure.

[0036] FIG. 5 is an enlarged fragmentary schematic front view of a patient's neck after retractors have been used to open the incision and move adjacent tissue aside to gain access to the cervical spine.

[0037] FIG. 6 is an isometric view of a prior art plate for single level fusion.

[0038] FIG. 7 is an isometric view of a prior art plate for two level fusion.

[0039] FIG. 8 is a schematic isometric representation of a prior art plate for single level fusion.

[0040] FIG. 9 is a schematic isometric representation of a prior art plate for two level fusion.

[0041] FIG. 10 is a schematic isometric representation of a prior art plate for three level fusion.

[0042] FIG. 11 is an isometric view of a first form of plate system according to the invention, wherein two plate sections are hinged together for use in a two level fusion.

[0043] FIG. 12 is an isometric view of the first form of plate system, wherein three plate sections are hinged together for use in a three level fusion.

[0044] FIG. 13 is an enlarged, fragmentary, top isometric view of one end of one of the plate sections in the first form of the invention.

[0045] FIG. 14 is an enlarged, fragmentary, bottom isometric view of the end shown in FIG. 13.

[0046] FIG. 15 is a top isometric view of the opposite end of the plate section shown in FIGS. 11-14.

[0047] FIG. 16 is a top plan view of one of the plate sections in FIGS. 11-14.

[0048] FIG. 17 is an enlarged fragmentary sectional view taken along line 17-17 in FIG. 16.

[0049] FIG. 18 is an enlarged fragmentary sectional view taken along line 18-18 in FIG. 16.

[0050] FIG. 19 is an exploded, fragmentary, top isometric view showing how two plate sections are oriented so that they can be assembled at the hinged ends.

[0051] FIG. 20 is a fragmentary top plan view showing two plate sections assembled together at the hinged ends.

[0052] FIG. 21 is an enlarged fragmentary view in elevation of two plate sections hinged together and illustrating the range of pivoting movement between them.

[0053] FIG. 22 is an exploded top isometric view of one of the screws and a locking plate that spans the hinged connection between two hinged together plate sections.

[0054] FIG. 23 is a top plan view of two hinged together plate sections and a locking plate slidably engaged at its opposite side edges in the channels on one of the plate sections prior to the locking plate being moved across the hinged connection between the two plate sections.

[0055] FIG. 24 is a top plan view showing the locking plate of FIG. 23 moved into operative position across the hinged connection between the two plate sections.

[0056] FIG. 25 is a fragmentary side view in elevation of the plate sections and locking plate of FIG. 24.

[0057] FIG. 26 is a schematic isometric view illustrating how three hinged together plate sections can be folded to shorten the overall length.

[0058] FIG. 27 is a fragmentary front view of a patient's neck, showing a transverse incision expanded with retractors and a single level plate section shown inn full lines in position on the cervical spine, with an additional plate shown in broken lines for a two level fusion.

[0059] FIG. 28 is a top isometric view of an alternate form of the invention for two level fusion, wherein the guide channels are omitted.

[0060] FIG. 29 is a top isometric view of the form of the invention shown in FIG. 28, but wherein an additional plate section is added for three level fusion.

[0061] FIG. 30 is an exploded top isometric view of two hinged together plate sections in that form of the invention shown in FIG. 28, and a locking plate in position to be secured to the plate sections in spanning relationship to the hinged connection.

[0062] FIG. 31 is a fragmentary side view of two plate sections and a locking plate secured to the face of two vertebrae.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0063] A representative front view of a cervical spine CS is shown in FIG. 1, and the anterior surface A and posterior surface P are indicated in the side view of FIG. 2.

[0064] A cross section of the cervical spine CS is shown in FIG. 3. The section is taken through a disc 10 and its associated annulus 11, with the annulus shown ruptured and a herniation 12 of the disc compressing a nerve 13 leading from the spinal cord 14. A bone spur 15 is also shown compressing the nerve 13.

[0065] A transverse incision 16, offset slightly to one side of the cervical spine, is made in the front of a patient's neck 17 in FIG. 4. It should be understood that depending upon the requirements of a particular procedure, the incision can be made either transversely, as shown, or longitudinally.

[0066] Retractors 18 are being used in FIG. 5 to spread open the incision and hold other tissue to the side to expose the vertebrae 19 and discs 20 at the anterior surface of the cervical spine.

[0067] FIGS. 6-10 depict prior art devices. A prior art plate for single level fusion is shown at 21 in FIG. 6, and a prior art plate for two level fusion is shown at 22 in FIG. 7. The two level plate 22 is a single unitary piece with portions 23 and 24 adapted to be positioned over adjacent discs, for example.

[0068] FIG. 8 is a schematic illustration of a prior art plate 25 for single level fusion. In this particular example, the plate has four holes 26 for receiving screws to fasten the plate to vertebral bodies and a single large hole 27 to enable visualization of the graft site and end plates.

[0069] FIG. 9 is a schematic illustration of a prior plate 28 for two level fusion. This plate is of one-piece construction and comprises two sections 29 and 30 adapted to overlie respective fusion sites. Each has holes 31 for receiving screws to fasten the plate to vertebral bodies, and a large centrally located hole 32 to enable visualization of the graft sites and end plates.

[0070] A prior art plate 33 for three level fusion is shown in FIG. 10. This plate is also of one-piece construction and has three sections 34, 35 and 36 adapted to overlie respective fusion sites. In this particular example, each section has four holes for receiving screws at 37 to fasten the plate to vertebral bodies, and a large centrally located hole 38 to enable visualization of the graft sites and end plates.

[0071] A two level plate system according to a first form of the invention is indicated generally at 40 in FIG. 11. This plate system comprises two plate sections 41 and 42 hinged together at 43 at adjacent ends for pivoting movement through at least 90 in each direction, and preferably through 120. Each plate section has four holes 44 in the specific example shown for receiving screws to fasten the plate system to vertebral bodies. A large central hole 45 is provided to enable visualization of the graft sites and end plates. Guide channels 46 extend along opposite side edges of each plate section on the upper surface thereof to receive and guide a locking plate as described hereinafter.

[0072] A three level plate system according to the first form of the invention is indicated generally at 50 in FIG. 12. This plate system comprises three plate sections 51, 52 and 53 hinged together at 43 at adjacent ends. Each plate section has four holes 44 in the specific example shown for receiving screws to fasten the plate system to vertebral bodies, and a large central hole 45 to enable visualization of the graft sites and end plates. Guide channels 46 extend along opposite side edges of each plate section on the upper surface thereof to receive and guide a locking plate as described hereinafter. Additional levels can be added, depending upon the requirements of a particular procedure. Cervical fusion surgery can involve up to seven levels.

[0073] It should be understood that a different number of holes 44 could be provided in the forms of invention described above, but four holes are typical and are illustrated and described in the specific examples disclosed herein.

[0074] In the forms of the invention shown in FIGS. 11 and 12, the manufacturer could supply sets of two, three, four, or more plate sections hinged together and the surgeon would select an appropriate set, depending upon the number of levels involved. In an alternate embodiment, some or all of the plate sections could have hinge-forming structures at both ends and the surgeon or surgical assistant could assemble as many plate sections as necessary for a particular procedure.

[0075] Details of the hinged ends are shown in FIGS. 13-19. Referring first to FIGS. 11, 13, 14, 17 and 18, the ends 60 and 61 of plate sections 41 and 42 are rounded and a cylindrical bore 62 (see FIGS. 13 and 14) extends transversely through end 60 of plate section 41 from one side of the plate section to the opposite side, which is optionally closed at 63 (see FIGS. 14 and 16). An annular groove 64 is formed in the wall of the bore near the open end (see FIGS. 14 and 20).

[0076] A slot 65 is formed in a lower portion of the rounded end 60, spaced counterclockwise at an angle A of about 30 from a vertical plane drawn through the longitudinal centerline of the bore 62 (see FIGS. 14 and 18). The slot opens into the bore 62 over most of the width of the plate section 41 except for a short section 66 where the slot terminates short of the closed end of the bore.

[0077] Notches 67 are formed in the rounded end 60 transversely to the slot 65 and intersect the slot at two spaced apart locations along the length of the bore 62. The notches terminate at their upper end 68 in the top of the plate section and at their lower end 69 in the bottom of the plate section, the terminal ends being spaced rearwardly at an angle B of about 30 from a vertical plane drawn through the longitudinal centerline of the bore 62 (see FIG. 17).

[0078] As seen best in FIGS. 15, 16, 19 and 20, a pair of support arms 70 extend from the rounded end 61 of plate section 42, supporting a cylindrically shaped hinge pin 71 in spaced relation to the end 61. An annular bead 72 on the outer surface of pin 71 near one end engages in groove 64 to restrain pin 71 against axial movement in the bore 62 when the pin is fully inserted into the bore. The closed end 63 of the bore limits insertion of the pin into the bore so that the bead 72 engages in the groove 64 when the parts are assembled into operative position.

[0079] To assemble the plate sections 41 and 42 or 51, 52 and 53 together, or other multiples of plate sections (not shown), the plate sections are angled relative to one another as shown in FIG. 19 so that plate section 42, for example, is at an angle A of 60 below the plane of plate section 41. The pin is inserted endwise into the bore 62 until one of the support arms 70 engages the closed end 66 of slot 65 (see FIG. 14), and/or, if provided, the end of the pin 71 abuts against closed end 63 of bore 62. This lines up the support arms 70 with notches 67 so that the plates 41 and 42 can be pivoted 120 in either direction (see FIG. 21). This also lines up the bead 72 with groove 64 which when engaged form a detent to prevent relative axial movement between pin 71 and bore 62 and prevent the two plate sections from unintentionally disconnecting from one another but permitting it when sufficient force is exerted.

[0080] As noted above, when connected the plate sections can pivot 120 in either direction relative to one another as shown in FIG. 21. This facilitates insertion of the plate system into position on the cervical spine without having to force it into surrounding tissue. When the plate system is in position on the anterior surface of the cervical vertebrae it is secured in place with screws passed through the holes 44 as explained hereinafter.

[0081] To lock the pivotally connected plate sections in their operative unfolded position and stabilize the spine to which they are attached, a locking plate 80 spans each hinged area 43. The locking plate is secured with screws 81 extended through openings 82 in the locking plate 80 and through the openings 44 in the plate sections 41 and 42 and then into the underlying vertebrae. In this regard, the holes 82 are located so that they line up with the holes 44 when the locking plate is in the positions shown in FIGS. 23 and 24.

[0082] In that embodiment of the invention shown in FIGS. 11-25, the locking plate is carried between the opposed pair of channels 46 on one or more of the plate sections, depending upon how many levels the plate system is intended to span. For a three level system as shown in FIG. 12, two locking plates would be required. In the two level plate system shown in FIGS. 11, 23 and 24, one locking plate 80 would be required and it would normally rest on either plate section 41 or plate section 42, depending upon how the plate system is oriented. After the plate sections are in position on the anterior surface of the cervical spine, the locking plate is slid across the hinged area 43 in the guide channels 46 and screws 81 are inserted through the openings 82 in the locking plate and openings 44 in the plate sections and into the vertebrae to secure all the components in place. Preferably, the locking plate is positioned at the caudal end of the plate system and pushed cranially to move it into locking position.

[0083] FIG. 26 is a schematic illustration of how a three level system 50 can be folded to shorten its length for easier insertion into place, and FIG. 27 shows the system in position on the anterior surface of the cervical spine.

[0084] An alternate embodiment of the invention for two level fusion is indicated generally at 40 in FIG. 28. In this form of the invention, the guide channels 46 are omitted, and as shown in FIGS. 30 and 31, the locking plate 80 is placed on top of the plate sections 41, 42 in spanning relationship to the hinged area 43 after the plate sections are positioned on the anterior face of the cervical spine. Screws 81 are then inserted through the holes 82 in the locking plate and through the aligned holes 44 in the plate sections 41 and 42 and into the vertebral bodies 19. In all other respects this form of the invention is identical to that form shown in FIGS. 11-27.

[0085] FIG. 29 shows a three level variation 50 of the system 40 illustrated in FIGS. 28 and 30. This system is identical to that shown in FIGS. 28 and 30 except that an additional level is added. In this regard, it should be understood that additional levels could similarly be added, depending upon the requirements of the procedure being performed.

[0086] While particular embodiments of the invention have been illustrated and described in detail herein, it should be understood that various changes and modifications may be made to the invention without departing from the spirit and intent of the invention as defined by the scope of the appended claims.