US20120209385A1 - Anterior intervertebral fusion with fixation system, device and method - Google Patents

Abstract

A system, device, and method are disclosed for anterior intervertebral fusion with fixation. An intervertebral fusion with fixation device includes a spacer configured to fit into a disc space between plural vertebrae, the spacer including through holes between and through plural sidewalls. A first fixating element is rigidly preloaded in a first portion of the spacer along a first linear trajectory. A second fixating element is rigidly preloaded in a second portion of the spacer along a second linear trajectory. An integrated drill and screwdriver instrument is adapted to extend through a cannula of the first fixating element and second fixating element and penetrate the vertebra. The instrument is further adapted to drive the head of the first fixating element and second fixating element into the vertebra and lock the first fixating element and second fixating element with respect to the spacer to prevent extrusion from the spacer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims the benefit of U.S. Provisional Application No. 61/463,239, filed on Feb. 15, 2011, and U.S. Provisional Application No. 61/517,717, filed on Apr. 25, 2011, which are incorporated herein by reference in their entirety.
FIELD
• The present disclosure relates to spinal implants and associated instrumentation. Various embodiments are directed to an anterior intervertebral fusion with fixation system, device and method.
DESCRIPTION OF RELATED ART
• A healthy spinal disc (intervertebral disc) is a fibroelastic structure with a non-compressible viscous center that articulates adjacent vertebrae. Due to its deformable geometry, the disc not only supports normal functional loads of the human body, but also evenly distributes the stresses applied during body movement and positioning. The disc interfaces with associated superior and inferior vertebrae via large surface areas known as vertebral endplates. Normally, vertebral endplates are thin regions of dense bone (e.g. 1 mm-3 mm) that support high stresses at articulating junctions.
• Intervertebral discs and adjacent articulations progressively deteriorate with age. This natural degenerative process results in various degrees of pathological changes, mostly affecting the geometry and elasticity of a vertebral disc. In severe cases, reduced disc volume results in foraminal compression that mechanically irritates nerve roots and causes neurocompressive syndrome. This often causes severe chronic pain that can only be resolved surgically.
• Historically, surgical treatment of degenerative spinal disc disease required fusion, which immobilizes two adjacent vertebral bodies (vertebrae) to prevent motion-sensitive pain and inflammation. This is accomplished by distracting the vertebrae to a healthy disc height, inserting a disc implant and allowing bone to grow between and through the disc implant until the vertebrae fuse into a solid bony structure. To facilitate proper healing under normal conditions of motion, the disc implant is used to maintain temporary positioning until the bone achieves fusion. The implant is secured to the vertebrae using fixation elements.
• The effectiveness of the disc implant can be evaluated with the following criteria: (i) its ability to restore and maintain normal disc height and curvature; (ii) its ease of delivery and fixation to the disc space; (iii) its ability to facilitate fusion of associated vertebrae; and (iv) its ability to restrict movement of associated vertebrae.
• Disc implants share the same fundamental characteristics to meet the effectiveness criteria. Implants aim to restore disc height through the use of variable geometries. Lordotic curvature is preserved through the use ergonomic designs that conform to spinal curvature and height between the vertebrae. Also, the disc implants are sufficiently porous or hollow to promote the growth of vertebral bone into and through the implant. However, independently, these implants can only restrict spinal flexion and intervertebral compression. Any excessive lateral, sliding, or extension motion may cause device failure and/or extrusion. To avoid this risk, it is customary to provide additional fixation of the disc implant to the vertebrae.
• Devices and systems may integrate fixating members directly into the disc implant. These implants have garnered the nickname “standalone” due to their ability to self-fixate without the use of secondary fixation elements. In the foregoing standalone implants, obtrusive fixation elements are delivered directly through implant pilot openings into the vertebra, which fixate the implant to the vertebrae and prevent implant failure under remaining ranges of motion (e.g., lateral, sliding, extension). Nevertheless, during these motions, connectivity between fixation elements and vertebrae may become weakened causing the fixation elements to slip or extrude out of the implant. To prevent unwanted fixation element slipping or extrusion, it is customary to include a locking mechanism for the implant.
SUMMARY
• In a particular embodiment, an intervertebral fusion with fixation device is disclosed. The device includes a spacer with an insertion wall, a trailing wall opposite to the insertion wall, a first lateral wall, a second lateral wall opposite to the first lateral wall, a top surface, and a bottom surface opposite to the top surface. The intervertebral fusion with fixation device further includes a first fixating element rigidly preloaded in a first portion of the spacer along a first linear trajectory, the first fixating element configured to penetrate and secure to a first vertebra by advancing along the first linear trajectory. The device also includes a second fixating element rigidly preloaded in a second portion of the spacer along a second linear trajectory that is different from the first linear trajectory, the second fixating element configured to penetrate and secure to a second vertebra by advancing along the second trajectory. Further, the intervertebral fusion with fixation device includes a through opening having an entrance proximate the top surface and an exit proximate the bottom surface to facilitate contact and in-growth of bone fusion material with the first vertebra and second vertebra.
• In another particular embodiment, an integrated drill and screwdriver instrument is disclosed. The integrated drill and screwdriver includes a handle, a driving element configured to engage a head of a bone screw and rotate the bone screw into a vertebra, and a drilling element extending from the from the driving element. The drilling element is configured to extend through a cannula of the bone screw and to penetrate the vertebra. The driving element is configured to engage the head of the bone screw as the drilling element penetrates through a vertebral endplate.
• In a further particular embodiment, an intervertebral fusion with fixation system is disclosed. The system includes an intervertebral fusion with fixation device configured to be implanted between plural vertebrae. The device includes a spacer with an insertion wall, a trailing wall opposite to the insertion wall, a first lateral wall, a second lateral wall opposite to the first lateral wall, a top surface, and a bottom surface opposite to the top surface. The device further includes a first fixating element rigidly preloaded in a first portion of the spacer along a first linear trajectory, the first fixating element configured to penetrate and secure to a first vertebra by advancing along the first linear trajectory. Additionally, the device also includes a second fixating element rigidly preloaded in a second portion of the spacer along a second linear trajectory that is different from the first linear trajectory, the second fixating element configured to penetrate and secure to a second vertebra by advancing along the second trajectory. The system also includes an integrated integrated drill and screwdriver instrument. The integrated instrument includes a handle, a driving element configured to engage a head of a bone screw and rotate the bone screw into a vertebra, and a drilling element extending from the from the driving element. The drilling element is configured to extend through a cannula of the bone screw and to penetrate the vertebra. The driving element is configured to engage the head of the bone screw as the drilling element penetrates through a vertebral endplate.
• In yet another particular embodiment, a method to secure plural vertebrae is disclosed. The method includes implanting an intervertebral fusion with fixation device between plural vertebrae. The fusion with fixation device includes a spacer, a first fixating element rigidly preloaded in a first portion of the spacer along a first linear trajectory, and a second fixating element rigidly preloaded in a second portion of the spacer along a second linear trajectory that is different from the first linear trajectory. The method further includes driving the first fixating element along the first linear trajectory to penetrate the first vertebra and to secure the spacer to a first vertebra, and driving the second fixating element along the second linear trajectory to penetrate the second vertebra and to secure the spacer to a second vertebra. The method also includes extending an integrated drill and screwdriver instrument through a cannula of the first fixating element and a cannula of the second fixating element, drilling the plural vertebrae with a drilling element, engaging the first fixating element and second fixating element with a driving element as the drilling element penetrates through a vertebral endplate of the plural vertebrae, and rotating the first fixating element and second fixating element via the driving element to penetrate the plural vertebrae and to secure the spacer to the plural vertebrae. The method further includes locking the first fixation element and second fixation element with respect to the spacer to prevent the first fixation element and second fixation element from extruding from the plural vertebrae and from the spacer.
• In a further embodiment, a method to assemble an intervertebral fusion with fixation device is disclosed. The method includes rigidly preloading a first fixating element in a first portion of a spacer along a first linear trajectory and a second fixating element in a second portion of the spacer along a second linear trajectory, the first linear trajectory being different from the second linear trajectory.
BRIEF DESCRIPTION OF DRAWINGS
• FIG. 1 is a perspective view of an example spacer of an intervertebral fusion with fixation device;
• FIG. 2 is a front view of the example spacer shown inFIG. 1;
• FIG. 3 is a side view of the example spacer shown inFIG. 1;
• FIG. 4 is a perspective view of an example fixation element of the intervertebral fusion with fixation device;
• FIG. 5 is a cross-sectional side view of the example fixation element show inFIG. 4;
• FIG. 6 is a side view of an example integrated drill and screwdriver driving instrument;
• FIG. 7 is a perspective exploded view of a tip of the example integrated drill and screwdriver drilling tip shown inFIG. 6;
• FIG. 8 is a perspective view of an example intervertebral fusion with fixation device with the example fixation elements shown inFIG. 4 preloaded in the example spacer shown inFIG. 1;
• FIG. 9 is a perspective view of the example intervertebral fusion with fixation device ofFIG. 8 with the example integrated drill and screwdriver ofFIG. 6 actuating a fixation element shown inFIG. 4.
• FIG. 10 is a translucent perspective view of an example intervertebral fusion with fixation device with the example fixation element ofFIG. 4 in a locked position within a vertebra.
DETAILED DESCRIPTION
• FIG. 1 is a perspective view of anexample spacer100 of an intervertebral fusion with fixation device. The intervertebral fusion with fixation device is illustrated inFIG. 8. Thespacer100 is made of a weight-bearing material, such as a polymer, metal, ceramic, biological material, or composite thereof, that is capable of withstanding the normal stresses of bodily movement and positioning, while also allowing sufficient elasticity. The material can have a flexural modulus and tensile strength comparable to bone. For example, thespacer100 can be made of polyetheretherketone (PEEK), a thermoplastic with a flexural modulus of 4.2 GPa and a tensile strength of 95 MPa. Another benefit of PEEK is its high level of biocompatibility in a dynamic and immunoreactive environment. Other materials and combinations of materials are possible.
• Thespacer100 includes aninsertion wall110, trailingwall112,lateral walls106,108,top surface102,bottom surface104, and throughopening114 extending between and through thetop surface102 andbottom surface104 for bone graft insert.
• In various embodiments, the dimensions of thespacer100 are approximately the following: the length of thespacer100 between aninsertion wall110 and trailingwall112 is between about 10 mm and 80 mm; the width of thespacer100 between a firstlateral wall106 and secondlateral wall108 is between about 10 mm and 80 mm; and the height of thespacer100 between atop surface102 andbottom surface104 is between about 4 mm and 30 mm. The foregoing dimensions are non-limiting and are intended to be adjusted depending on the specific spinal anatomy of the patient.
• Theopening114 can have a volume approximately between 0 cm³and 8 cm³. Other volumes can be provided. While theinsertion wall110, trailingwall112, andlateral walls106,108 are generally flat surfaces, thetop surface102 andbottom surface104 may be tapered or curved with respect to one another to conform to intervertebral lordosis or curvature. Thelateral walls106,108 can also have a tapered geometry to conform to intervertebral space. In some embodiments, the angle between thelateral surfaces106,108 can be from about 0 degrees to about 16 degrees.
• The trailingwall112 includes a plurality of through holes202 (shown inFIG. 2) extending from thecentral opening114 to the exterior of thespacer100 to receive, secure, and guide plural fixation elements400 (shown inFIG. 4). Each of the foregoing holes202 is oriented to provide a trajectory for a fixation element (shown inFIG. 4). The trajectories of theholes202 can be oriented in directions lateral, medial, superior, inferior, or any combination thereof to the spacer to provide multi-axial fixation to the vertebrae. In some embodiments, theholes202 can direct thefixation elements400 in divergent trajectories to counterbalance one another from any opposing torques or shear stresses initiated by vertebral motion. The dimensions of theholes202 are approximately the following: the medial and/or lateral angle in respect tolateral walls106,108 is between about 0 degrees and 25 degrees, and the superior and/or inferior angle in respect tosurfaces102,104 is between about 30 degrees and 50 degrees. The diameters of the foregoingholes202 are approximately between 0.5 mm and 10 mm.
• FIG. 2 is a front view of theexample spacer100 shown inFIG. 1. Now with reference toFIGS. 1 and 2, thespacer100 includesridges116 onsurfaces102,104 proximate theholes202 to reinforce thespacer100 during advancement of thefixation elements400. For example,ridges116 can be provided about the exits to the outside of thespacer100 and can be of various dimensions and tapers along thesurfaces102,104. In some embodiments, theridges116 can be omitted. Thespacer100 further includesridges118 along thesurfaces102,104 that penetrate surrounding vertebrae during implantation and provide stability to thespacer100 through micro-scale contact with the vertebral plates.
• Thespacer100 can include pluralradiopaque markers120 to enhance radiographic visualization of thespacer100. Themarkers120 can be made of a biocompatible radiopacic material, such as tantalum, platinum alloys, gold alloys, or palladium alloys. Other applicable materials may also be employed.Plural markers120 can be provided near thewalls106,108,110,112 and surfaces102,104 to provide additional visual references of thespacer100 for clinicians during radiographic imaging. Furthermore, themarkers120 can assume various geometries and volumes within thespacer100 depending on visualization requirements. In various embodiments, themarkers120 can be omitted.
• FIG. 3 is a side view of anexample spacer100 of an intervertebral fusion with fixation device ofFIG. 8. In a particular embodiment, the trailingheight302 gradually decreases to theinsertion height304 at a taper to approximate natural lordosis. Additionally, theridges116 can be also tapered to minimize friction during insertion and facilitate smooth entry of thespacer100 into the intervertebral space.
• FIG. 4 is a perspective view of anexample fixation element400. In a particular embodiment, thefixation element400 can be made of a biocompatible metal, such as a titanium alloy. Other applicable materials may also be employed. Thefixation element400 includes atip405 that locks into and interfaces with theholes202 during assembly to maintain a preloaded position, and penetrates bone during engagement with vertebral endplates. Thefixation element400 has aminor diameter402 that is between about 1 mm and 10 mm. Thefixation element400 also includes amajor diameter404 of threading that is between 2 mm and 15 mm to provide cutting during engagement.
• Additionally, thetip405 includesflutes406 to facilitate penetration into the vertebra during initial engagement. Thefixation element400 further includes ahead407 with a conically shapedbody408 to pressure-fit into theholes202 after advancement via aninstrument receiver410. Theinstrument receiver410 can interface with a driving instrument (shown inFIG. 6). In a particular embodiment, thehead407 includes ahook protrusion412 with a sharp edge that can cut into thehole202 after thefixation element400 is advanced (e.g., fully) into the vertebra and thehead407 is in contact with thespacer100. The contact between the sharp edge of thehook protrusion412 and thehole202 functions as a locking mechanism to prevent extrusion of thefixation element400.
• FIG. 5 is a cross-sectional side view of anexample fixation element400 ofFIG. 4. As illustrated, thefixation element400 includes acannula502 that allows a drilling tip of the driving instrument (shown inFIG. 6) to pass into and through thefixation element400 to facilitate vertebral endplate pre-drilling and preparation for advancement of thefixation element400. Thefixation element400 further includes aplatform504 that connects or interfaces the drivinginstrument receiver410 andcannula502 to contact and limit the depth of motion of the driving instrument (shown inFIG. 6) in relation to thefixation element400.
• FIG. 6 is a side view of an example integrated drill and screwdriver driving instrument (driving instrument)600. In a particular embodiment, the drivinginstrument600 can be made of a metal, such as titanium. Other applicable materials may also be employed. The drivinginstrument600 includes anintegrated tip614 that can penetrate and pre-drill vertebral endplates with adrill tip606 as well as engage the drivinginstrument receiver410 of afixation element400 with afixation element interface604.
• Thedrill tip606 of theintegrated tip614 can pass into and through thecannula502 of thefixation element400 in order to penetrate and pre-drill a vertebral endplate. Thefixation element interface604 can contact the drivinginstrument receiver410 once thedrill tip606 has penetrated through the vertebral endplate into the softer bony layer. In a particular embodiment, both thefixation element interface604 and corresponding drivinginstrument receiver410 are of a quadrilateral shape to facilitate rigid contact between the surfaces and allow engagement of thefixation element400.
• The drivinginstrument600 includes abody602 to increase operational distance from thespacer100 and provide access under various angulations. Thebody602 is smoothly mated to theintegrated tip614 with aconical transition element610. Furthermore, the drivinginstrument600 includes ahandle612 that can be operated manually or by an electrical or mechanical tool. In a particular embodiment, thehandle612 can be constructed as a hexagonal bit to fit a standard screwdriver. Thehandle612 is smoothly mated to thebody602 with aconical transition element603.
• FIG. 7 is an exploded perspective view of the example integratedtip614. Theintegrated tip614 includes cuttingblades702 to facilitate vertebral penetration during advancement. Theintegrated tip614 further includes arounded transition element704 between thefixation element interface604 and thedrill tip606 to allow smooth contact between thefixation element interface604 and drivinginstrument receiver410 during the initial engagement of thefixation element400.
• FIG. 8 is a perspective view of an example intervertebral fusion withfixation device800 with the pluralexample fixation elements400 ofFIG. 4 preloaded in theexample spacer100 ofFIG. 1. As illustrated, thefixation elements400 can be preloaded into thespacer100 viaholes202. Theflutes406 and threading404 cut into and secure thefixation elements400 to thespacer100 viaholes202 to maintain a preloaded assembly. This preloaded assembly ensures fixed trajectories for thefixation elements400 during delivery of thedevice800 and eliminates the need for alignment post-implantation.
• FIG. 9 is a perspective view of an example intervertebral fusion with fixation device ofFIG. 8 with anexample driving instrument600 ofFIG. 6 actuating afixation element400 ofFIG. 4. As illustrated, theintegrated tip614 is delivered into and through thecannula502 of thefixation element400 to pre-drill the vertebral endplate with thecutting blades702 of thefixation element400. The penetration of theintegrated tip614 through the vertebral endplate combined with the linear force applied to thehandle612 drives thefixation element interface604 into contact with the drivinginstrument receiver410 of thefixation element400. Simultaneously, the torque from thehandle612 engages thefixation element interface604, which in turn actuates the drivinginstrument receiver410 and advances thefixation element400 into vertebral endplate. Additionally, the fixation element flutes406 andmajor threading404 penetrate and secure thefixation element400 to the endplate of the vertebra.
• FIG. 10 is a translucent perspective view of an example intervertebral fusion withfixation device800 with the pluralexample fixation elements400 ofFIG. 4 in a locked position and secured to avertebra1001. In a particular embodiment, thehook protrusion412 of thefixation element400 pressure fits theholes202 of thespacer100 to prevent thefixation element400 from toggling and backing-out. Furthermore, thehook protrusion412 rigidly cut into thespacer100 via its sharp edge to limit the ability of thefixation element400 to torque towards the trailingwall112 of thedevice800 and away from thevertebra1001. Additionally, theridges118 penetrate adjacent vertebral endplates and provide ancillary stability.
• Other apparent modifications and configurations of the invention will be appreciated by those skilled in the art to allow varying applications of the disclosed embodiments without departing from the scope of the embodiments described herein. The disclosed specifications and principles are intended to be used for illustrative purposes only, with the true scope and spirit of the patent document being defined by the following claims.

Claims (14)

1. An intervertebral fusion with fixation device configured to be implanted between plural vertebrae, the device comprising:

a spacer with an insertion wall, a trailing wall opposite to the insertion wall, a first lateral wall, a second lateral wall opposite to the first lateral wall, a top surface, and a bottom surface opposite to the top surface;

a first fixating element rigidly preloaded in a first portion of the spacer along a first linear trajectory, the first fixating element configured to penetrate and secure to a first vertebra by advancing along the first linear trajectory; and

a second fixating element rigidly preloaded in a second portion of the spacer along a second linear trajectory that is different from the first linear trajectory, the second fixating element configured to penetrate and secure to a second vertebra by advancing along the second trajectory.

2. The intervertebral fusion with fixation device ofclaim 1, wherein the spacer includes a through opening having an entrance proximate the top surface and an exit proximate the bottom surface to facilitate contact and in-growth of bone fusion material with the first vertebra and second vertebra.

3. The intervertebral fusion with fixation device ofclaim 1, wherein the spacer is made of polyetheretherketone (PEEK), other polymers, metal, ceramics, or composites.

4. The intervertebral fusion with fixation device ofclaim 1, wherein at least one of the first fixating element and the second fixating element is a cannulated bone screw.

5. The intervertebral fusion with fixation device ofclaim 4, wherein the cannulated bone screw includes a head that is configured to integrate with a driving instrument.

6. The intervertebral fusion with fixation device ofclaim 4, wherein the cannulated bone screw includes a head that has a locking mechanism configured to penetrate and lock into spacer to prevent screw toggling and extrusion.

7. An integrated drill and screwdriver instrument, the instrument comprising:

a handle;

a driving element configured to engage a head of a bone screw and to rotate the bone screw into a vertebra,

a drilling element extending from the driving element, the drilling element configured to extend through a cannula of the bone screw and to penetrate the vertebra, the driving element engaging the head of the bone screw as the drilling element penetrates through a vertebral endplate.

8. An intervertebral fusion with fixation system, the system compromising:

an intervertebral fusion with fixation device configured to be implanted between plural vertebrae, the device comprising:

a spacer with an insertion wall, a trailing wall opposite to the insertion wall, a first lateral wall, a second lateral wall opposite to the first lateral wall, a top surface, and a bottom surface opposite to the top surface;

a first fixating element rigidly preloaded in a first portion of the spacer along a first linear trajectory, the first fixating element configured to penetrate and secure to a first vertebra by advancing along the first linear trajectory; and

a second fixating element rigidly preloaded in a second portion of the spacer along a second linear trajectory that is different from the first linear trajectory, the second fixating element configured to penetrate and secure to a second vertebra by advancing along the second trajectory; and

an integrated drill and screwdriver instrument, the instrument comprising:

a handle;

a driving element configured to engage a head of a bone screw and to rotate the bone screw into a vertebra; and

a drilling element extending from the driving element, the drilling element configured to extend through a cannula of the bone screw and to penetrate the vertebra, the driving element engaging the head of the bone screw as the drilling element penetrates through a vertebral endplate.

9. A method to secure plural vertebrae, the method comprising:

implanting an intervertebral fusion with fixation device between plural vertebrae, the device comprising:

a spacer with an insertion wall, a trailing wall opposite to the insertion wall, a first lateral wall, a second lateral wall opposite to the first lateral wall, a top surface, and a bottom surface opposite to the top surface;

a first fixating element rigidly preloaded in a first portion of the spacer along a first linear trajectory; and

a second fixating element rigidly preloaded in a second portion of the spacer along a second linear trajectory that is different from the first linear trajectory, the second fixating element configured to penetrate and secure to a second vertebra by advancing along the second trajectory;

driving the first fixating element along the first linear trajectory to penetrate the first vertebra and to secure the spacer to the first vertebra; and

driving the second fixating element along the second linear trajectory to penetrate the second vertebra and to secure the spacer to the second vertebra.

10. The method ofclaim 9, the method comprising:

introducing an integrated drill and screwdriver instrument to the first fixating element of the intervertebral fusion with fixation device, the instrument comprising:

a handle;

a driving element configured to engage a head of the first fixating element; and

a drilling element extending from the driving element, the drilling element configured to extend through a cannula of the first fixating element; and

drilling the first vertebra with the drilling element;

engaging the first fixating element with the driving element as the drilling element penetrates through a vertebral endplate of the first vertebra; and

rotating the first fixating element via the driving element to penetrate the first vertebra and to secure the spacer to the first vertebra.

11. The method ofclaim 10, the method comprising:

locking the first fixating element with respect to the spacer to prevent the first fixating element from extruding from the spacer.

12. The method ofclaim 9, the method comprising:

introducing the instrument to the second fixating element of the intervertebral fusion with fixation device;

drilling the second vertebra with the drilling element;

engaging the second fixating element with the driving element as the drilling element penetrates through a vertebral endplate of the second vertebra; and

rotating the second fixating element via the driving element to penetrate the second vertebra and to secure the spacer to the second vertebra.

13. The method ofclaim 12, the method comprising:

locking the second fixating element with respect to the spacer to prevent the second fixating element from extruding from the spacer.

14. A method to assemble an intervertebral fusion with fixation device, the method comprising:

providing a spacer that includes an insertion wall, a trailing wall opposite to the insertion wall, a first lateral wall, a second lateral wall opposite to the first lateral wall, a top surface, and a bottom surface opposite to the top surface;

preloading a first fixating element rigidly in a first portion of the spacer along a first linear trajectory, the first fixating element configured to penetrate and secure to a first vertebra by advancing along the first linear trajectory; and

preloading a second fixating element rigidly in a second portion of the spacer along a second linear trajectory that is different from the first linear trajectory, the second fixating element configured to penetrate and secure to a second vertebra by advancing along the second trajectory.

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