Variable lordosis spacer and related methods of use

An expandable fusion device may include a first endplate, and a second endplate. The expandable fusion device also may include a first ramp configured to mate with both the first and second endplates. The first ramp may be a wedge with an incline extending along a longitudinal axis of the expandable fusion device, and also may be a wedge having an incline extending along a lateral axis of the expandable fusion device. A second ramp may be configured to mate with both the first and second endplates. The first ramp may be a wedge having an incline extending along the longitudinal axis of the expandable fusion device, and also may be wedge having an incline extending along the lateral axis of the expandable fusion device.

FIELD OF THE INVENTION

Various embodiments of the present disclosure relate generally to variable lordosis spacers and related systems and methods. More specifically, the present disclosure relates to devices, systems, and methods for correcting lordosis and/or other spinal abnormalities.

BACKGROUND

A common procedure for handling pain associated with intervertebral discs that have become degenerated due to various factors such as trauma or aging is the use of intervertebral fusion devices for fusing one or more adjacent vertebral bodies. Generally, to fuse the adjacent vertebral bodies, the intervertebral disc is first partially or fully removed. An intervertebral fusion device is then typically inserted between neighboring vertebrae to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion.

There are a number of known conventional fusion devices and methodologies in the art for accomplishing the intervertebral fusion. These include screw and rod arrangements, solid bone implants, and fusion devices which include a cage or other implant mechanism which, typically, is packed with bone and/or bone growth inducing substances. These devices are implanted between adjacent vertebral bodies in order to fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventional fusion devices and methodologies. For example, present methods for installing a conventional fusion device often require that the adjacent vertebral bodies be distracted to restore a diseased disc space to its normal or healthy height prior to implantation of the fusion device. In order to maintain this height once the fusion device is inserted, the fusion device is usually dimensioned larger in height than the initial distraction height. This difference in height can make it difficult for a surgeon to install the fusion device in the distracted intervertebral space.

Further, lordosis refers to a curvature of the spine, and in particular a curvature that is posteriorly concave. In certain patients, this curvature may, for example, be larger than desired. Traditional vertebral fusion procedures and devices do not adequately account for this curvature. As such, traditional devices do not properly align with adjacent vertebral bodies. To ensure proper fit of traditional devices, bone may be removed from the vertebral bodies, increasing procedure and healing time.

As such, there exists a need for a fusion device capable of being installed inside an intervertebral disc space at a minimum distraction height and for a fusion device that can maintain a normal distance between adjacent vertebral bodies when implanted.

SUMMARY OF THE DISCLOSURE

The present disclosure relates to embodiments of expandable fusion devices and related methods of use.

In one aspect, the present disclosure is directed to an expandable fusion device that may include a first endplate, and a second endplate. The expandable fusion device also may include a first ramp configured to mate with both the first and second endplates. The first ramp may be a wedge with an incline extending along a longitudinal axis of the expandable fusion device, and also may be a wedge having an incline extending along a lateral axis of the expandable fusion device. A second ramp may be configured to mate with both the first and second endplates. The first ramp may be a wedge having an incline extending along the longitudinal axis of the expandable fusion device, and also may be wedge having an incline extending along the lateral axis of the expandable fusion device.

Various examples of the present disclosure may include one or more of the following aspects: wherein the first and second endplates may each include at least one first mating feature configured to mate with at least one corresponding first mating feature disposed on the first ramp; wherein the at least one mating feature of the first and second endplates may be slidable with respect to the corresponding first mating feature disposed on the first ramp; wherein the first and second endplates may each include a second mating feature configured to mate with a corresponding second mating feature disposed on the first ramp; wherein the second mating feature and the corresponding second mating feature may each be C-shaped, V-shaped, or U-shaped; wherein the first and second endplates may each include a third mating feature configured to mate with a corresponding third mating feature disposed on the second ramp; wherein the third mating feature and the corresponding third mating feature may each be C-shaped, V-shaped, or U-shaped; wherein each of the first and second endplates may have an inner surface configured to mate with the first ramp, wherein the inner surface of each of the first and second endplates may be shaped as a concave curve, the concave curve being formed about a longitudinal axis of the expandable fusion device; wherein the expandable fusion device may be movable between a collapsed configuration and an expanded configuration; wherein the first ramp may be coupled to the second ramp by an actuating mechanism, and the expandable fusion device may be configured to transition from the collapsed configuration to the expanded configuration via actuation of the actuating mechanism to move the second ramp and the first ramp toward one another; wherein, in the expanded configuration, the expandable fusion device may be a wedge having an incline extending along the lateral axis of the expandable fusion device; and wherein the first and second endplates each may have an outer surface configured to contact a respective vertebral body, wherein each outer surface of the first and second endplates may have one or more of teeth, ridges, friction increasing elements, keels, or gripping or purchasing projections.

In another aspect, the present disclosure may be directed to an expandable fusion device. The expandable fusion device may include a first endplate and a second endplate, and both the first and second endplates may extend from a first side of the expandable fusion device to a second side of the expandable fusion device. The expandable fusion device also may include a first ramp and a second ramp. Both the first ramp and the second ramp may be configured to mate with both the first and second endplates, and both the first ramp and the second ramp may extend from the first side of the expandable fusion device to the second side of the expandable fusion device. At least one of the first and second sides of the expandable fusion device may pivotally expand about a pivot point.

Various examples of the present disclosure may include one or more of the following aspects: wherein both of the first and second sides of the expandable fusion device may pivotally expand about the same pivot point; wherein the same pivot point may be a point disposed outside of the expandable fusion device; wherein the pivot point may be disposed along the first side or between the first and second sides of the expandable fusion device; and wherein only the second side of the expandable fusion device may pivot about the pivot point.

In yet another aspect, the present disclosure may be directed to an expandable fusion device. The expandable fusion device may include a first endplate and a second endplate, and both the first and second endplates may extend from a first side of the expandable fusion device to a second side of the expandable fusion device. The expandable fusion device also may include a first ramp and a second ramp, and both the first ramp and the second ramp may be configured to mate with both the first and second endplates, and both the first ramp and the second ramp may extend from the first side of the expandable fusion device to the second side of the expandable fusion device. The first and second side of the expandable fusion device may form concentric arcs about a pivot point.

Various examples of the present disclosure may include one or more of the following aspects: wherein the expandable fusion device may be movable between a collapsed configuration and an expanded configuration, and both of the first and second sides of the expandable fusion device may have same angular rate of change when moving between the collapsed configuration and the expanded configuration; and wherein the first side of the expandable fusion device may be defined by a first radius, the second side of the expandable fusion device may be defined by a second radius, and the first radius may be smaller than the second radius.

DETAILED DESCRIPTION

A spinal fusion is typically employed to eliminate pain caused by the motion of degenerated disk material. Upon successful fusion, a fusion device becomes permanently fixed within the intervertebral disc space. Referring toFIG. 1, an expandable fusion device10is shown between adjacent vertebral bodies2and3. Expandable fusion device10may extend from a first side22(e.g., a posterior side) to a second side24(e.g., an anterior side). Expandable fusion device10may engage the endplates of adjacent vertebral bodies2and3and, in an installed position, maintain normal intervertebral disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. In some embodiments, expandable fusion device10may provide indirect decompression (e.g., by reducing the pressure of vertebral bodies2and3on adjacent nerves) while still providing lordosis correction. Expandable fusion device10may be formed from any suitable material or combination of materials, including, but not limited to, titanium, stainless steel, titanium alloys, non-titanium metallic alloys, polymeric materials, plastics, plastic composites, PEEK, ceramic, and elastic materials, among others.

In an embodiment, the expandable fusion device10may be configured and sized to be placed down an insertion tube and into the disc space between the adjacent vertebral bodies2and3. For example, expandable fusion device10may be configured for insertion through an insertion tube, such as, e.g., a cannula. It should be noted, however, that the insertion tube may alternatively have any suitable diameter. In one embodiment, expandable fusion device10may be inserted through a cannula having a diameter of about 8.5 mm. In some embodiments, the expandable fusion device10may have a width in a range of from about 8 mm to about 26 mm, and a length in a range from about 20 mm to about 65 mm, or may have other suitable dimensions. Expandable fusion device10may be inserted into a patient via a direct lateral procedure, although anterior, anterolateral, posterolateral or posterior procedures alternatively may be utilized.

Expandable fusion device10may be generally wedge shaped, and may have a height that increases from first side22toward second side24. In some embodiments, the expandable fusion device10may be expanded to a height that is equal to or greater than about 150% of its initial height. In one embodiment, the expandable fusion device10may be expanded to a height that is equal to or greater than about 200% of its initial height, or another suitable percentage of its initial height.

As shown inFIG. 10, expandable fusion device10may include one or more openings26to accommodate bone growth along the longitudinal length of the expandable fusion device10. In some embodiments, openings26may have the same dimensions, or may alternatively have different dimensions. In the embodiment shown, expandable fusion device10has two openings26, although other suitable numbers and dimensions of openings are also contemplated. Openings26may be sufficiently large to facilitate bone growth after installation of expandable fusion device10between vertebral bodies2and3.

In an exemplary embodiment, bone graft or similar bone growth inducing material may be introduced around and within the expandable fusion device10to further promote and facilitate the intervertebral fusion. The expandable fusion device10, in one embodiment, may be packed with bone graft (e.g., autograft or allograft) or similar bone growth inducing material to promote the growth of bone through and around the expandable fusion device10. The bone graft may be packed between the endplates of the adjacent vertebral bodies prior to, subsequent to, or during implantation of the fusion device.

In one embodiment, expandable fusion device10may be treated with a titanium and/or hydroxyapatite plasma spray coating to encourage bony on-growth, improving the strength and stability of the connection between the respective component and the underlying bone (e.g., a vertebral body). Any other suitable coating also may be provided on expandable fusion device10. Such coatings may include therapeutic agents, if desired. Expandable fusion device10also may include radiopaque markings to facilitate in vivo visualization. In some embodiments, portions of expandable fusion device10may be formed of a radiolucent material, while other portions of expandable fusion device10may be formed of radiopaque materials to facilitate imaging of the radiopaque portions of expandable fusion device10, such as, e.g., actuating mechanisms, endplates, ramps, or the like.

With reference toFIGS. 2-12, an embodiment of the expandable fusion device10is shown. In an exemplary embodiment, the expandable fusion device10may include a first endplate14, a second endplate16, a first ramp18, and a second ramp20. Expandable fusion device10may be movable between a collapsed configuration shown inFIGS. 2-4 and 8, and an expanded configuration shown inFIGS. 5-7 and 9. The ability of expandable fusion device10to reciprocally move between the collapsed and expanded configurations may provide numerous benefits. For example, because expandable fusion device10can be inserted between the vertebral bodies2and3in a collapsed configuration that is smaller than the expanded configuration, the large impaction forces needed to install traditional fusion devices are not required to install expandable fusion device10. In one embodiment, expandable fusion device10may be in a lordotic state in the collapsed configuration, although other suitable configurations, such as, e.g., parallel or other starting angles, are also contemplated.

Expandable fusion device10may expand and collapse about a set pivot point P, shown inFIGS. 8 and 9. Expandable fusion device10may be constructed to alter the position of pivot point P. That is, first ramp18, second ramp20, and endplates14,16may be constructed to exhibit a curvature (e.g., may have a radius of curvature) about pivot point P, as further described below. In the collapsed configuration shown inFIGS. 2-4 and 8, expandable fusion device10may maintain an angle α (shown only inFIG. 8) with respect to pivot point P. In the expanded configuration shown inFIGS. 5-7 and 9, expandable fusion device10may maintain an angle β (shown only inFIG. 9) with respect to pivot point P. The construction of expandable fusion device10also may select the rate of change between angles α and β in the transition of expandable fusion device10between the collapsed and expanded configurations. In some embodiments, expandable fusion device10may experience a linear increase in the lordotic angle during the transition from the collapsed configuration to the expanded configuration (i.e., through an expansion range). In some embodiments, expandable fusion device10may be constructed to set pivot point P closer to the expandable fusion device10(or even within the perimeter of expandable fusion device10). As pivot point P moves toward expandable fusion device10(or further toward a midline204shown inFIGS. 8 and 9), the rate of angle change per height change exhibited by expandable fusion device10may increase. Because second side24has a larger distance from Pivot point P than first side22, second side24may increase in height faster than first side22in the transition of expandable fusion device10from the collapsed configuration to the expanded configuration. Thus, expandable fusion device10may be constructed in various configurations to set different α and β angles (i.e., different ramp angles on the anterior and posterior sides of expandable fusion device10).

The position of pivot point P may be dependent or independent upon the inclination of expandable fusion device10between first side22and second side24. That is, as the difference in height between first side22and second side24increases, pivot point P may be set closer to expandable fusion device10, or even within the perimeter of expandable fusion device10. Thus, as pivot point P is set closer to expandable fusion device10(or further toward midline204), angles α and β may become larger. On the contrary, as the pivot point P is set further from expandable fusion device10, a smaller rate of angle change per height change, and smaller α and β angles will be present in expandable fusion device10.

In one embodiment, α may be about 10.4°, β may be about 22.5°, and a distance d between pivot point P and first side22, may be about 17 mm although other suitable values are also contemplated.

First and second sides22,24or expandable fusion device10may thus be formed as arcs (e.g., concentric arcs) about pivot point P. In the collapsed configuration, first side22may be oriented at angle α with respect to pivot point P, and may have a radius rpc. In the collapsed configuration, second side24also may be oriented at angle α with respect to pivot point P, but may have a radius racthat is larger than radius rpc, as second side24may be oriented at a further distance from pivot point P than first side22. In the expanded configuration, first and second sides22,24of expandable fusion device10may expand at a substantially similar angular rate, and may both become oriented at angle β with respect to pivot point P. In the expanded configuration, first side22may have a radius rpcthat is constant with radius rpc.

The curvatures of first ramp18, second ramp20, and endplates14,16, may determine the location of pivot point P. As shown inFIGS. 8 and 9, the curvatures of first ramp18, second ramp20, and endplates14,16may cause first and second sides22,24of expandable fusion device10to be curved about pivot point P to form portions of the aforementioned concentric arcs. The curvature of first and second sides22,24, may set the distance of pivot point P from first and second sides22,24. That is, if expandable fusion device10is constructed so as to position pivot point P relatively farther from first and second sides22,24, each of first and second sides22,24may have shallower curvatures. On the contrary, if expandable fusion device10is constructed so as to position pivot point P relatively closer to first and second sides22,24(or even between first and second sides22,24), each of first and second sides22,24may have steeper curvature.

Referring toFIGS. 11 and 12, endplates14,16may have a first end30and a second end32. In the illustrated embodiment, the endplates14,16may include an outer surface40connecting the first end30and the second end32, and an inner surface42connecting the first end30and the second end32. Outer surface40and inner surface42may both be defined by first and second ends30,32, and by a first side44and a second side45. First side44of endplates14,16may be disposed at first side22of expandable fusion device10. Similarly, second side45of endplates14,16may be disposed at second side24of expandable fusion device10. First and second sides44,45may define a plurality of mating features configured to engage with one or more mating features of first ramp18and second ramp20. In one embodiment, both first and second sides44,45may extend from inner surface42. Second side45may extend further from inner surface42than first side44.

First side44may include a mating feature46at first end30, at least one mating feature47at an intermediate portion, and a mating feature48at second end32.

Mating feature46may be substantially C-shaped, V-shaped, U-shaped, or otherwise suitably shaped. In the embodiment shown, mating feature46may form a slidable joint with a corresponding mating feature (e.g., one of mating features77or146described in further detail below). The slidable joint may be, e.g., a tabled splice joint, or another suitable joint. That is, mating feature46and its corresponding mating feature77or146may be similarly shaped to have a groove disposed between two shoulders. One shoulder of mating feature46may slide within the groove of the corresponding mating feature77or146, while one shoulder of the corresponding mating feature77or146may slide within the groove of mating feature46. In some embodiments, It should be understood that mating feature46and its corresponding mating feature77or146may be formed in any other suitable manner. For example, mating feature46and its corresponding mating feature77or146may form another splice joint, a tongue and groove joint, another suitable joint, or be related to each other in another suitable manner. In some embodiments, mating feature46and its corresponding mating feature77or146may be slidable and/or interlocking with one another. In some embodiments, mating feature46may be inclined along longitudinal axis200from first end30of endplates14,16toward an intermediate portion of endplates14,16.

In the embodiment shown byFIGS. 11 and 12, mating features47are shown as defining inwardly facing recesses or grooves. The recesses of mating features47may accept a protrusion or tongue of a corresponding mating feature (e.g., mating features84and86described in further detail below). Thus, mating features47and its corresponding mating features84or86may form a tongue and groove joint. That is, the tongue of the corresponding mating feature84or86may be slidable within the groove of mating feature47. It is also contemplated that mating feature47and its corresponding mating feature84or86may form another type of joint, such as, e.g., a splice joint, another suitable joint, or be related to each other in another suitable manner. In some embodiments, mating features47and their corresponding mating features84or86may be slidably interlocking with one another. In some embodiments, mating features47may be inclined along longitudinal axis200from a respective intermediate portion of endplates14,16toward first end30of endplates14,16. Thus, the inclinations of mating feature46and mating features47may generally oppose one another. Alternatively, mating features47may be inclined in any other suitable direction, such as, e.g., from a respective intermediate portion of endplates14,16toward second end32of endplates14,16.

Mating feature48and its corresponding mating feature (e.g., mating features78and148described in further detail below) may be substantially similar to mating feature46described above. In some embodiments, mating feature48may be inclined along longitudinal axis200from second end32of endplates14,16toward an intermediate portion of endplates14,16. Thus, the inclinations of mating features46and48may oppose one another, but the inclinations of mating features47and48may be generally aligned (e.g., substantially parallel).

Second side45may include a mating feature49at first end30, at least one mating feature50at an inner (or intermediate) portion, and a mating feature51at second end32. Mating feature49may be similar to mating feature46described above, except that mating feature49may have different (e.g., larger) dimensions than mating feature46. Similar to mating feature46, mating feature49may be inclined along longitudinal axis200from first end30of endplates14,16toward an intermediate portion of endplates14,16.

Mating features50may be similar to mating features47, except that mating features50may have different (e.g., larger) dimensions than mating features47. Similar to mating features47, mating features50may be inclined along longitudinal axis200from a respective intermediate portion of endplates14,16toward first end30of endplates14,16. Thus, the inclinations of mating feature49and mating features50may generally oppose one another. Alternatively, mating features50may be inclined in any other suitable direction, such as, e.g., from a respective intermediate portion of endplates14,16toward second end32of endplates14,16.

Mating feature51may be substantially similar to mating feature46described above. However, in some embodiments, mating feature51may have different (e.g., larger) dimensions than mating feature46. Similar to mating feature46, mating feature51may be inclined along a longitudinal axis200(referring toFIG. 10) from second end32of endplates14,16toward an intermediate portion of endplates14,16. Thus, the inclinations of mating features46and48may oppose one another, but the inclinations of mating features50and51may be generally aligned (e.g., substantially parallel).

Mating features46-51may be configured to mate with a corresponding mating feature on one of first and second ramps18and20in a slidable and/or interlocking relationship.

Outer surface40and/or inner surface42may be curved about one or more axes. For example, outer surface40and/or inner surface42may be curved about longitudinal axis200. Thus, in one embodiment, outer surface40may be convex, while inner surface42may be concave about the longitudinal axis200. In some embodiments, material can be added to or removed from outer surface40to modify the interaction between outer surface40and vertebral bodies2and3. For example, material can be added to give outer surface40a generally flat configuration while maintaining the concavity of inner surface42.

The respective mating features of endplates14,16may be curved in order to impart a curvature to first and second sides22,24of assembled expandable fusion device10as set forth above. As best seen inFIG. 13, first and second sides44and45may be curved (e.g., may have a radius of curvature) about pivot point P, and thus mating features46-51that are disposed in one of first and second sides44,45may be similarly curved with respect to pivot point P.

In some embodiments, the outer surface40of endplates14,16may be flat and generally planar to allow the outer surface40engage with an adjacent vertebral body. Alternatively, the outer surface40may be curved convexly or concavely to allow for a greater or lesser degree of engagement with the adjacent vertebral body. It is also contemplated that the outer surface40may be generally planar but include a generally straight ramped surface or a curved ramped surface. The ramped surface may allow for engagement with the adjacent vertebral body in a further lordotic fashion. In one embodiment, the outer surface40may include texturing to aid in gripping the adjacent vertebral bodies. Although not limited to the following, the texturing may include teeth, ridges, friction increasing elements, keels, or gripping or purchasing projections.

Referring now toFIGS. 11, 12, and 16, the first ramp18may have a first end70, a second end72, a first side portion74connecting the first end70and the second end72, and a second side portion76on the opposing side of the first ramp18connecting the first end70and the second end72. The first ramp18may further include a third end (e.g., an upper end)28, which is sized to receive at least a portion of the first endplate14, and an fourth end (e.g., a lower end)29, which is sized to receive at least a portion of the second endplate16.

The first end70of the first ramp18, in an exemplary embodiment, may include four mating features77,78,80, and82(mating feature82shown only inFIG. 16). Each of mating features77,78,80,82may be shaped to mate with a respective mating feature disposed on one of endplates14,16. Mating feature77may be configured to mate with, and may be similarly shaped as mating feature46of endplate14. Mating feature78may be configured to mate with, and may be similarly shaped as mating feature48of endplate16. Mating feature80may be configured to mate with, and may be similarly shaped as mating feature49of endplate14. Mating feature82may be configured to mate with, and may be similarly shaped as mating feature51of endplate16. Each of mating features77,78,80, and82may have substantially similar inclinations (with respect to an assembled expandable fusion device10) their respective and corresponding mating features set forth above. In one embodiment, each of mating features77,78,80, and82are inclined from an intermediate portion of first ramp18toward first end70of first ramp18, although other suitable configurations are also contemplated. In one embodiment, mating features77and78extend from third end28, while mating features78and82extend from fourth end29.

First side portion74may include mating features84and86that are configured to mate with various mating features of endplates14,16.

Mating features84may be protrusions extending from an intermediate portion of first side portion74toward first end70. In one embodiment, mating features84may have a surface that is inclined from the intermediate portion of first side portion74toward first end70. The inclined surface of mating features84also may extend laterally outward from first side portion74. Mating features84also may extend from third end28of first ramp18. The inclined surface of mating features84may extend toward a generally flattened surface that is substantially parallel to longitudinal axis200of expandable fusion device10. In one embodiment, first ramp18may include at least two mating features84that are staggered along first side portion74, although other suitable numbers of mating features84may alternatively be utilized. In the embodiment shown, mating features84are substantially similar to one another, although it is contemplated that mating features84may be different than one another. Mating features84may be configured to mate with mating features47of endplate14. In the embodiment shown inFIGS. 11 and 12, mating features47and84may form a slidable and interlocking (e.g., a tongue and groove) joint that allows expandable fusion device10to move between the collapsed and expanded configurations. However, it is contemplated that mating features47and84may be modified to other suitable configurations that allow expandable fusion device10to move between the collapsed and expanded configurations. For example, in one alternative embodiment, mating features47may be formed as protrusions, while mating features84are formed as recesses. In another alternative embodiment, each of mating features47and84may be formed as grooves disposed between two shoulders such that mating features47and84form a splice joint (e.g., similar to the tabled splice joints described above).

Mating features86may be protrusions extending from an intermediate portion of first side portion74toward first end70. In one embodiment, mating features86may have a surface that is inclined from the intermediate portion of first side portion74toward first end70. The inclined surface of mating features86also may extend laterally outward from first side portion74. Unlike mating features84, mating features86may extend from fourth end29of first ramp18. Thus, mating features84and86may extend in generally opposite vertical directions from first side portion74. The inclined surface of mating features86may extend toward a generally flattened surface that is substantially parallel to longitudinal axis200of expandable fusion device10. In one embodiment, first ramp18may include at least two mating features86that are staggered along first side portion74, although other suitable numbers of mating features86may alternatively be utilized. In some embodiments, each of mating features84and86may be staggered from one another, although other suitable configurations are also contemplated. In the embodiment shown, mating features86are substantially similar to one another, although it is contemplated that mating features86may be different than one another. Mating features86may be configured to mate with mating features47of endplate16. In the embodiment shown inFIGS. 11 and 12, mating features47and86may form a slidable and interlocking (e.g., a tongue and groove) joint that allows expandable fusion device10to move between the collapsed and expanded configurations. However, it is contemplated that mating features47and86may be modified to other suitable configurations that allow expandable fusion device10to move between the collapsed and expanded configurations (e.g., in a substantially similar manner as described above with reference to mating features47and84).

Second side portion76may include mating features88and90that are configured to mate with various mating features of endplates14,16.

Mating features88may be protrusions extending from an intermediate portion of second side portion76toward first end70. In one embodiment, mating features88may have a surface that is inclined from the intermediate portion of second side portion76toward first end70. The inclined surface of mating features88also may extend laterally outward from second side portion76. Mating features88also may extend from third end28of first ramp18. The inclined surface of mating features88may extend toward a generally flattened surface that is substantially parallel to longitudinal axis200of expandable fusion device10. In one embodiment, first ramp18may include at least two mating features88that are staggered along second side portion76, although other suitable numbers of mating features88may alternatively be utilized. In the embodiment shown, mating features88are substantially similar to one another, although it is contemplated that mating features88may be different than one another. Mating features88may be configured to mate with mating features50of endplate14. In the embodiment shown inFIGS. 11 and 12, mating features50and88may form a slidable and interlocking (e.g., a tongue and groove) joint that allows expandable fusion device10to move between the collapsed and expanded configurations. However, it is contemplated that mating features50and88may be modified to other suitable configurations that allow expandable fusion device10to move between the collapsed and expanded configurations (e.g., in a substantially similar manner as described above with reference to mating features47and84).

Mating features90may be protrusions extending from an intermediate portion of second side portion76toward first end70. In one embodiment, mating features90may have a surface that is inclined from the intermediate portion of second side portion76toward first end70. The inclined surface of mating features90also may extend laterally outward from second side portion76. Unlike mating features88, mating features90may extend from fourth end29of first ramp18. Thus, mating features88and90may extend in generally opposite vertical directions from second side portion76. The inclined surface of mating features90may extend toward a generally flattened surface that is substantially parallel to longitudinal axis200of expandable fusion device10. In one embodiment, first ramp18may include at least two mating features90that are staggered along second side portion76, although other suitable numbers of mating features90may alternatively be utilized. In some embodiments, each of mating features88and90may be staggered from one another, although other suitable configurations are also contemplated. In the embodiment shown, mating features90are substantially similar to one another, although it is contemplated that mating features90may be different than one another. Mating features90may be configured to mate with mating features50of endplate16. In the embodiment shown inFIGS. 11 and 12, mating features50and90may form a slidable and interlocking (e.g., a tongue and groove) joint that allows expandable fusion device10to move between the collapsed and expanded configurations. However, it is contemplated that mating features50and90may be modified to other suitable configurations that allow expandable fusion device10to move between the collapsed and expanded configurations (e.g., in a substantially similar manner as described above with reference to mating features47and84).

The respective mating features of first ramp18may be curved in order to impart the curvature to first and second sides22,24of assembled expandable fusion device10as set forth above. That is, the mating features of first ramp18may have a radius of curvature about pivot point P. Further, as the mating features of first ramp18may be complimentary to corresponding mating features along endplates14,16, the mating features of endplates14,16also may have a radius of curvature about pivot point P. Referring toFIG. 17, mating features77,78,80,82,84,86,88, and90may each have a radius of curvature about pivot point P. Thus, all or a portion of first ramp18may be bent about pivot point P. The geometry of first ramp18(e.g., any of the aforementioned radii of curvature) may be approximated with simpler features for manufacturing ease.

As shown inFIG. 11, first ramp18may include both a bore418and a bore515. In some embodiments, the bore418may be threaded and configured to receive a threaded member302of an actuating mechanism300. The central longitudinal axis of the bore418may be off-center from the central longitudinal axis of the first ramp18in order to accommodate the bore515.

The adjacent bore515may serve as an access port to allow graft material to be delivered through the first ramp18, either prior to insertion or even in situ, if desired. The bore418may align with a bore366in second ramp20and bore515may align with an additional bore512in the second ramp20, as discussed below.

Second ramp20may be disposed adjacent to first ramp18in expandable fusion device10. Second ramp20may include four mating features146,148,149, and151. Each of mating features146,148,149, and151may be substantially similar to mating feature46described above, and may be configured to mate with a respective mating feature disposed on one of endplates14,16. Mating feature146may be configured to mate with mating feature46of endplate16. Mating feature148may be configured to mate with mating feature48of endplate14. Mating feature149may be configured to mate with mating feature49of endplate16. Mating feature151may be configured to mate with mating feature51of endplate14.

The respective mating features of second ramp20may be curved in order to impart the curvature to first and second sides22,24of assembled expandable fusion device10as set forth above. Further, as the mating features of second ramp20may have a radius of curvature about pivot point P, the mating features of endplates14,16also may have a radius of curvature about pivot point P. Mating features146,148,149, and151may be all curved about pivot point P. Thus, all or a portion of second ramp20may be bent about pivot point P. The geometry of second ramp20(e.g., any of the aforementioned radii of curvature) may be approximated with simpler features for manufacturing ease.

In one alternative embodiment, expandable fusion device10may be formed so as to locate pivot point P within lateral width of the expandable fusion device10along first side22of expandable fusion device10. In this alternative embodiment, all mating features (e.g., tracks, protrusions, grooves, shoulders, and the like) disposed along first side22of expandable fusion device10(e.g., along endplates14,16, and first and second ramps18and20) may be replaced by linkage or pivoting mechanisms. When pivot point P is located within lateral width of the expandable fusion device10along first side22of expandable fusion device10, only second side24may pivot about pivot point P during expansion and collapse of expandable fusion device10.

As described above, the second ramp20may include a bore366adjacent bore512. The bore366may be configured to receive an actuating mechanism300therethrough, and may be aligned with the bore418in the first ramp18. Accordingly, the bore366may have a central longitudinal axis that is off-set from the central longitudinal axis of the second ramp20to accommodate the adjacent bore512. The bore512of the second ramp20may be aligned with the bore515of the first ramp18to allow graft material to be inserted into the implant, either prior to or even after insertion of the implant.

First and second ramps18and20may each be a wedge having an incline extending in at least two planes. That is, each of first and second ramps18and20may be a wedge having an incline extending along a plane defined by longitudinal axis200(i.e., may be inclined along the longitudinal axis200), while also being a wedge having an incline extending along a plane defined a lateral axis202(i.e., may be inclined along the lateral axis202). The inclination of first and second ramps18and20(and their associated mating features) along the longitudinal axis200of expandable fusion device10may allow for the expansion/compression of endplates14and16as first and second ramps18and20translate with respect to one another along the longitudinal axis200. The inclination of first and second ramps18and20along the lateral axis202of expandable fusion device10may accommodate the uneven lengths of first and second sides44,45of endplates14,16.

A method of installing the expandable fusion device10ofFIG. 1is now discussed in accordance with one embodiment of the present disclosure. Prior to insertion of the expandable fusion device10, the intervertebral space may be prepared. In one method of installation, a discectomy may be performed where the intervertebral disc, in its entirety, may be removed. Alternatively, only a portion of the intervertebral disc can be removed. The endplates of the adjacent vertebral bodies2,3may be then scraped to create an exposed end surface for facilitating bone growth across the intervertebral space. One or more introduction sheaths then can be inserted into the disc space. The expandable fusion device10can then be introduced into the intervertebral space down an insertion sheath and seated in an appropriate position in the intervertebral disc space.

After the expandable fusion device10has been inserted into the appropriate position in the intervertebral disc space, the expandable fusion device10can then be transitioned from the collapsed configuration to the expanded configuration. To expand the expandable fusion device10, the second ramp20may be moved toward the first ramp18. As the first and second ramps18and20move toward one another, the respective mating features of first and second ramps18and20may push against corresponding mating features disposed on endplates14and16to move expandable fusion device10into the expanded configuration. In some embodiments, one or more of endplates14,16, and first and second ramps18,20may include locking features for securing expandable fusion device10in the expanded configuration.

In the event the expandable fusion device10needs to be repositioned or revised after being installed and expanded, the expandable fusion device10can be contracted back to the collapsed configuration, repositioned, and expanded again once the desired positioning is achieved. To contract the expandable fusion device10, the first ramp18is moved away from the second ramp20via the actuating mechanism300.

Actuating mechanism300may include any suitable actuating mechanism configured to translate first and second ramps18and20toward and away from each other along the longitudinal axis200. Referring toFIGS. 4 and 7, actuating mechanism300may include a threaded member302(e.g., a screw) that, when rotated in a first direction, directs first and second ramps18and20toward each other, moving expandable fusion device10from the collapsed configuration to the expanded configuration. When threaded member202is rotated in a second direction that is opposite to the first direction, first and second ramps18and20may be moved away from each other, causing expandable fusion device10to move back toward the collapsed configuration. In one embodiment, threaded member302may be partially disposed through bore515of first ramp18, and may further extend through bore515as expandable fusion device10is moved from the collapsed configuration to the expanded configuration. In this embodiment, threaded member302may push second ramp20toward first ramp18, and may move coextensively with second ramp20during the transition of expandable fusion device10from the collapsed configuration to the expanded configuration, and from the expanded configuration to the collapsed configuration.

In an alternative embodiment shown inFIG. 19, threaded member302may be at least partially disposed within bore515in the collapsed configuration. However, to transition from the collapsed configuration to the expanded configuration, threaded member302may be actuated through second ramp20. Unlike the embodiment shown inFIGS. 4 and 7, in the embodiment ofFIG. 19, threaded member302may pull first ramp18toward second ramp20, and may move coextensively with first ramp18during the transition of expandable fusion device10from the collapsed configuration to the expanded configuration, and from the expanded configuration to the collapsed configuration. Any other suitable actuating mechanism may utilized, such as, e.g., sliders, pushers, ratchets, or the like.

In some embodiments, threaded member302may be rotated directly to actuate the actuating mechanism300. In some embodiments, an inserter (not shown) may be configured to thread into or be otherwise coupled to threaded member302. In such embodiments, the inserter may be actuated by suitable mechanisms (e.g., tools, ratchets, or the like) to rotate threaded member302and adjust the relative position of the first and second ramps18and20.

In some embodiments, only one of bores366and418may be threaded, such that expandable fusion device10may be actuated by linear movement of actuating mechanism300. For example, in one embodiment, bore366may be threaded while bore418may not be threaded. In such an embodiment, threaded member302may be threaded into bore366, and may be slidable through bore418. After threaded member302is threaded through bore366, threaded member302can be selectively pushed through bore418to move expandable fusion device10from the collapsed configuration to the expanded configuration (e.g., by moving first ramp18and second ramp20closer to one another). Additionally, threaded member302may be pulled in the opposite direction to move expandable fusion device10from the collapsed configuration to the expanded configuration (e.g., by moving first ramp18and second ramp20away from one another). In this embodiment, second ramp20may be pushed toward first ramp18to move expandable fusion device10from the collapsed configuration to the expanded configuration.

In an alternative embodiment, bore418may be threaded and bore366may not be threaded. In such an embodiment, threaded member302may be disposed through bore366and threaded into bore418(e.g., referring toFIG. 19). Threaded member302may be pulled linearly to move expandable fusion device10from the collapsed configuration to the expanded configuration (e.g., by moving first ramp18and second ramp20closer to one another). Additionally, threaded member302may be pushed to move expandable fusion device10from the expanded configuration back to the collapsed configuration (e.g., by moving first ramp18and second ramp20away from one another). In this embodiment, first ramp18may be pulled toward second ramp20to move expandable fusion device10from the collapsed configuration to the expanded configuration.

In one embodiment, a locking member (e.g., a screw not shown) may be disposed separately of expandable fusion device10during the transition between the collapsed and expanded configurations. Once the final position is achieved (e.g., the expanded configuration of expandable fusion device10), the locking member may be advanced to lock expandable fusion device10into a desired configuration. In some embodiments, the locking member may be integral with expandable fusion device10, or may be alternatively introduced after expansion. In some embodiments, the locking member may be captured within the expandable fusion device10so that it is not lost. In some embodiments, peening the tip of the locking member may prevent the locking member from becoming lost.

Once expandable fusion device10has been moved to the expanded configuration and locked via the locking member, bores366and418, previously used to expand the expandable fusion device10via actuating mechanism300may be utilized to pack graft or other bone growth inducing substances into expandable fusion device10. That is, bores366and418may be utilized to pack graft into the expandable fusion device10to fill any potential gaps that formed during expansion of expandable fusion device10.

Any aspect set forth in any embodiment may be used with any other embodiment set forth herein. Every device and apparatus set forth herein may be used in a suitable medical procedure, such as, e.g., a vertebral disc replacement procedure, and may be advanced through any suitable body lumen and body cavity.

It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed systems and processes without departing from the scope of the disclosure. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only. The following disclosure identifies some other exemplary embodiments.