Patent ID: 12251317

DETAILED DESCRIPTION

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

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. Looking atFIG.1, an exemplary embodiment of an expandable fusion device10is shown between adjacent vertebral bodies2and3. The fusion device10engages the endplates4and5of the adjacent vertebral bodies2and3and, in the installed position, maintains normal intervertebral disc spacing and restores spinal stability, thereby facilitating an intervertebral fusion. The expandable fusion device10can be manufactured from a number of materials including titanium, stainless steel, titanium alloys, non-titanium metallic alloys, polymeric materials, plastics, plastic composites, PEEK, ceramic, and elastic materials. In an embodiment, the expandable fusion device10can be configured to be placed down an endoscopic tube and into the disc space between the adjacent vertebral bodies2and3.

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

With reference toFIGS.2-7, an embodiment of the fusion device10is shown. In an exemplary embodiment, the fusion device10includes a first endplate14, a second endplate16, a central ramp18, and a driving ramp260. In an embodiment, the expandable fusion device10can be configured to be placed down an endoscopic tube and into the disc space between the adjacent vertebral bodies2and3. One or more components of the fusion device10may contain features, such as through bores, that facilitate placement down an endoscopic tube. In an embodiment, components of the fusion device10are placed down the endoscopic tube with assembly of the fusion device10in the disc space.

Although the following discussion relates to the second endplate16, it should be understood that it also equally applies to the first endplate14as the second endplate16is substantially identical to the first endplate14in embodiments of the present invention. Turning now toFIGS.2-7and10, in an exemplary embodiment, the second endplate16has a first end39and a second end41. In the illustrated embodiment, the second endplate16further comprise an upper surface40connecting the first end39and the second end41, and a lower surface42connecting the first end39and the second end41. In an embodiment, the second endplate16further comprises a through opening44, as seen onFIG.11. The through opening44, in an exemplary embodiment, is sized to receive bone graft or similar bone growth inducing material and further allow the bone graft or similar bone growth inducing material to be packed in the central opening in the central ramp18.

As best seen inFIGS.7and10, the lower surface42includes at least one extension46extending along at least a portion of the lower surface42, in an embodiment. In an exemplary embodiment, the extension46can extend along a substantial portion of the lower surface42, including, along the center of the lower surface42. In the illustrated embodiment, the extension46includes a generally concave surface47. The concave surface47can form a through bore with the corresponding concave surface47(not illustrated) of the first endplate14, for example, when the device10is in an unexpanded configuration. In another exemplary embodiment, the extension46includes at least one ramped surface48. In another exemplary embodiment, there are two ramped surfaces48,50with the first ramped surface48facing the first end39and the second ramped surface facing the second end41. In an embodiment, the first ramped surface48can be proximate the first end39, and the second ramped surface50can be proximate the second end41. It is contemplated that the slope of the ramped surfaces48,50can be equal or can differ from each other. The effect of varying the slopes of the ramped surfaces48,50is discussed below.

In one embodiment, the extension46can include features for securing the endplate16when the expandable fusion device10is in an expanded position. In an embodiment, the extension46includes one or more protuberances49extending from the lateral sides51of the extension. In the illustrated embodiment, there are two protuberances49extending from each of the lateral sides51with each of the sides53having one of the protuberances49extending from a lower portion of either end. As will be discussed in more detail below, the protuberances49can be figured to engage the central ramp18preventing and/or restricting longitudinal movement of the endplate16when the device10is in an expanded position.

As illustrated inFIGS.2-5, in one embodiment, the upper surface40of the second endplate16is flat and generally planar to allow the upper surface40of the endplate16to engage with the adjacent vertebral body2. Alternatively, as shown inFIG.15, the upper surface40can be curved convexly or concavely to allow for a greater or lesser degree of engagement with the adjacent vertebral body2. It is also contemplated that the upper surface40can be generally planar but includes a generally straight ramped surface or a curved ramped surface. The ramped surface allows for engagement with the adjacent vertebral body2in a lordotic fashion. While not illustrated, in an exemplary embodiment, the upper surface40includes texturing to aid in gripping the adjacent vertebral bodies. Although not limited to the following, the texturing can include teeth, ridges, friction increasing elements, keels, or gripping or purchasing projections.

Referring now toFIGS.2-8, in an exemplary embodiment, the central ramp18has a first end20, a second end22, a first side portion24connecting the first end20and the second end22, and a second side portion26(best seen onFIG.5) on the opposing side of the central ramp12connecting the first end20and the second end22. The first side portion24and the second side portion26may be curved, in an exemplary embodiment. The central ramp18further includes a lower end28, which is sized to receive at least a portion of the first endplate14, and an upper end30, which is sized to receive at least a portion of the second endplate16.

The first end20of the central ramp18, in an exemplary embodiment, includes an opening32. The opening32can be configured to receive an endoscopic tube in accordance with one or more embodiments. The first end20of the central ramp18, in an exemplary embodiment, includes at least one angled surface33, but can include multiple angled surfaces. The angled surface33can serve to distract the adjacent vertebral bodies when the fusion device10is inserted into an intervertebral space.

The second end22of the central ramp18, in an exemplary embodiment, includes an opening36. The opening36extends from the second end22of the central ramp18into a central guide37in the central ramp18.

In an embodiment, the central ramp18further includes one or more ramped surfaces33. As best seen inFIG.8, the one or more ramped surfaces33positioned between the first side portion24and the second side portion26and between the central guide37and the second end22. In an embodiment, the one or more ramped surfaces33face the second end22of the central ramp18. In one embodiment, the central ramp18includes two ramped surfaces33with one of the ramped surfaces33being sloped upwardly and the other of the ramped surfaces33being sloped downwardly. The ramped surfaces33of the central ramp can be configured and dimensioned to engage the ramped surface48in each of the first and second endplates14,16.

Although the following discussion relates to the second side portion26of the central ramp18, it should be understood that it also equally applies to the first side portion24in embodiments of the present invention. In the illustrated embodiment, the second side portion26includes an inner surface27. In an embodiment, the second side portion26further includes a lower guide35, a central guide37, and an upper guide38. In the illustrated embodiment, the lower guide35, central guide37, and the upper guide38extend out from the inner surface27from the second end22to the one or more ramped surfaces31. In the illustrated embodiment, the second end22of the central ramp18further includes one or more guides38. The guides38can serve to guide the translational movement of the first and second endplates14,16with respect to the central ramp18. For example, protuberances49on the second endplate16may be sized to be received between the central guide37and the upper guide38. Protuberances49of the first endplate16may be sized to be received between the central guide37and the lower guide35. A first slot29may be formed proximate the middle of the upper guide38. A second slot31may be formed between end of the upper guide38and the one or more ramped surfaces33. The protuberances49may be sized to be received within the first slot29and/or the second slot31when the device10is in the expanded position.

Referring now toFIGS.4-7and9, the driving ramp260has a through bore262. In an embodiment, the driving ramp260is generally wedge-shaped. As illustrated, the driving ramp260may comprise a wide end56, a narrow end58, a first side portion60connecting the wide end56and the narrow end58, and a second side portion62connecting the wide end56and the narrow end58. The driving ramp260further may comprise ramped surfaces, including an upper ramped surface64and an opposing lower ramped surface66. The upper ramped surface64and the lower ramped surface66may be configured and dimensioned to engage the ramped surface50proximate the second end41in of the first and the second endplates14,16. The first and second side portions60,62may each include grooves68that extend, for example, in a direction parallel to the longitudinal axis of the through bore262. The grooves68may be sized to receive the central guide37on the interior surface27of each of the side portions24,26of the central ramp18. In this manner, the grooves68together with the central guide37can surface to guide the translational movement of the driving ramp260in the central ramp18.

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

After the fusion device10has been inserted into the appropriate position in the intervertebral disc space, the fusion device10can then be expanded into the expanded position. To expand the fusion device10, the driving ramp260may move in a first direction with respect to the central ramp18. Translational movement of the driving ramp260through the central ramp18may be guided by the central guide37on each of the first and second side portions24,26of the central ramp18. As the driving ramp260moves, the upper ramped surface64pushes against the ramped surface50proximate the second end41of the second endplate16, and the lower ramped surface66pushes against the ramped surface50proximate the second end41of the first endplate14. In addition, the ramped surfaces33in the central ramp18push against the ramped surface48proximate the first end41of the first and second endplates14,16. In this manner, the first and second endplates14,16are pushed outwardly into an expanded configuration. As discussed above, the central ramp16includes locking features for securing the endplates14,16.

It should also be noted that the expansion of the endplates14,16can be varied based on the differences in the dimensions of the ramped surfaces48,50and the angled surfaces62,64. As best seen inFIG.16, the endplates14,16can be expanded in any of the following ways: straight rise expansion, straight rise expansion followed by a toggle into a lordotic expanded configuration, or a phase off straight rise into a lordotic expanded configuration.

Turning back toFIGS.2-7, in the event the fusion device10needs to be repositioned or revised after being installed and expanded, the fusion device10can be contracted back to the unexpanded configuration, repositioned, and expanded again once the desired positioning is achieved. To contract the fusion device10, the central ramp18is moved with respect to the central ramp260away from the central ramp260. As the central ramp18moves, the ramped surfaces33in the central ramp18ride along the ramped surfaces48of the first and second endplates14,16with the endplates14,16moving inwardly into the unexpanded position.

With reference now toFIG.17, fusion device10is shown with an exemplary embodiment of artificial endplates100. Artificial endplates100allows the introduction of lordosis even when the endplates14and16of the fusion device10are generally planar. In one embodiment, the artificial endplates100have an upper surface102and a lower surface104. The upper surfaces102of the artificial endplates100have at least one spike106to engage the adjacent vertebral bodies. The lower surfaces104have complementary texturing or engagement features on their surfaces to engage with the texturing or engagement features on the upper endplate14and the lower endplate16of the fusion device10. In an exemplary embodiment, the upper surface102of the artificial endplates100have a generally convex profile and the lower surfaces104have a generally parallel profile to achieve lordosis. In another exemplary embodiment, fusion device10can be used with only one artificial endplate100to introduce lordosis even when the endplates14and16of the fusion device10are generally planar. The artificial endplate100can either engage endplate14or engage endplate16and function in the same manner as described above with respect to two artificial endplates100.

With reference toFIGS.11-14, an embodiment for placing an expandable fusion device10into an intervertebral disc space is illustrated. The expandable fusion device10can be introduced into the intervertebral space down an endoscopic tube utilizing a tool70that is attached to endplate16, with the second endplate16being first placed down the tube with tool70and into the disc space, as seen inFIG.11. After insertion of the second endplate16, the first endplate14can be placed down the same endoscopic tube with tool72and into the disc space, as shown onFIG.12. Following the first endplate14, the central ramp12can be placed down the same endoscopic tube and into the disc space guided by tools70and72, as shown onFIGS.13and14.

Referring now toFIGS.18-23, an alternative embodiment of the expandable fusion device10is shown. In an exemplary embodiment, the fusion device10includes a first endplate14, a second endplate16, a central ramp18, and an actuator assembly200. As will be discussed in more detail below, the actuator assembly200drives the central ramp18which forces apart the first and second endplates14,16to place the expandable fusion device in an expanded position. One or more components of the fusion device10may contain features, such as through bores, that facilitate placement down an endoscopic tube. In an embodiment, components of the fusion device10are placed down the endoscopic tube with assembly of the fusion device10in the disc space.

Although the following discussion relates to the second endplate16, it should be understood that it also equally applies to the first endplate14as the second endplate16is substantially identical to the first endplate14in embodiments of the present invention. With additional reference toFIG.24, in an exemplary embodiment, the second endplate16has a first end39and a second end41. In the illustrated embodiment, the second endplate16further comprise an upper surface40connecting the first end39and the second end41, and a lower surface42connecting the first end39and the second end41. While not illustrated, in an embodiment, the second endplate16further comprises a through opening. The through opening, in an exemplary embodiment, is sized to receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface40of the second endplate16is flat and generally planar to allow the upper surface40of the endplate16to engage with the adjacent vertebral body2. Alternatively, as shown inFIG.15, the upper surface40can be curved convexly or concavely to allow for a greater or lesser degree of engagement with the adjacent vertebral body2. It is also contemplated that the upper surface40can be generally planar but includes a generally straight ramped surface or a curved ramped surface. The ramped surface allows for engagement with the adjacent vertebral body2in a lordotic fashion. While not illustrated, in an exemplary embodiment, the upper surface40includes texturing to aid in gripping the adjacent vertebral bodies. Although not limited to the following, the texturing can include teeth, ridges, friction increasing elements, keels, or gripping or purchasing projections.

In one embodiment, the second endplate16further comprises a first side portion202connecting the first end39and the second end41, and a second side portion204connecting the first end39and the second end41. In the illustrated embodiment, the first and second side portions202,204are extensions from the lower surface42. In an exemplary embodiment, the first and second side portions202,204each include ramped surfaces206,208. In the illustrated embodiment, the ramped surfaces206,208extend from the first end39of the second endplate16to bottom surfaces210,212of each of the side portions202,204. In one embodiment, the ramped surfaces206,208are forward facing in that the ramped surfaces206,208face the first end39of the second endplate. As previously discussed, the slope of the ramped surfaces206,208may be varied as desired for a particular application.

In an embodiment, the first and second side portions202,204each comprise at least one protuberance214. In an exemplary embodiment, the first and second side portions202,204each comprise a first protuberance214, a second protuberance216, and a third protuberance218. In one embodiment, the protuberances214,216,218extend from the interior surface220of the first and second side portions202,204. In an exemplary embodiment, the protuberances214,216,218extend at the lower side of the interior surface220. As best seen inFIG.24, the first and the second protuberances214,216form a first slot222, and the second and third protuberances216,218form a second slot224.

As best seen inFIG.24, the lower surface42of the second endplate16, in an embodiment, includes a central extension224extending along at least a portion of the lower surface. In the illustrated embodiment, the central extension224extends between the first and second side portions202and204. In an exemplary embodiment, the central extension224can extend from the second end41of the endplate16to the central portion of the endplate. In one embodiment, the central extension224includes a generally concave surface226configured and dimensioned to form a through bore with the corresponding concave surface226(not illustrated) of the first endplate14. The central extension224can further include, in an exemplary embodiment, a ramped surface228. In the illustrated embodiment, the ramped surface228faces the first end39of the endplate16. The ramped surface228can be at one end of the central extension224. In an embodiment, the other end of the central extension224forms a stop230. In the illustrated embodiment, the stop230is recessed from the second end41of the second endplate16.

Referring toFIGS.25-27, in an exemplary embodiment, the central ramp18includes a body portion232having a first end234and a second end236. In an embodiment, the body portion232includes at least a first expansion portion238. In an exemplary embodiment, the body portion232includes a first expansion portion238and a second expansion portion240extending from opposing sides of the body portion with each of the first and second expansion portions238,240having a generally triangular cross-section. In one embodiment, the expansion portions238,240each have angled surfaces242,244configured and dimensioned to engage the ramped surfaces206,208of the first and second endplates14,16and force apart the first and second endplates14,16. In an embodiment, the engagement between the angled surfaces242,244of the expansion portions238,240with the ramped surfaces206,208of the first and second endplates14,16may be described as a dovetail connection.

The second end236of the central ramp18, in an exemplary embodiment, includes opposing angled surfaces246. The angled surfaces246can be configured and dimensioned to engage the ramped surface228in the central extension224in each of the first and second endplates14,16. In other words, one of the angled surfaces246can be upwardly facing and configured, in one embodiment, to engage the ramped surface228in the central extension224in the second endplate16. In an embodiment, the engagement between the angled surfaces246of the second end236of the central ramp18with the ramped surface228in the first and second endplates14,16may be described as a dovetail connection.

The second end236, in an exemplary embodiment, can further include an extension252. In the illustrated embodiment, the extension252is generally cylindrical in shape with a through bore254extending longitudinally therethrough. In one embodiment, the extension252can include a beveled end256. While not illustrated, at least a portion of the extension252can be threaded.

Referring still toFIGS.25-27, the central ramp18can further include features for securing the first and second endplates14,16when the expandable fusion device10is in an expanded position. In an embodiment, the body portion232of the central ramp18includes one or more protuberances248,250extending from opposing sides of the body portion232. As illustrated, the protuberances248,250, in one embodiment, can be spaced along the body portion232. In an exemplary embodiment, the protuberances248,250can be configured and dimensioned for insertion into the corresponding slots222,224in the first and second endplates14,16when the device10is in an expanded position, as best seen inFIGS.19and21. The protuberances248,250can engage the endplates14,16preventing and/or restricting movement of the endplates14,16with respect to the central ramp18after expansion of the device10.

With reference toFIGS.20-23, in an exemplary embodiment, the actuator assembly200has a flanged end253configured and dimensioned to engage the stop232in the central extension224of the first and the second endplates14,16. In an embodiment, the actuator assembly200further includes an extension254that extends from the flanged end253. In a further embodiment, the actuator assembly200includes a threaded hole256that extends through the actuator assembly200. It should be understood that, while the threaded hole256in the actuator assembly200is referred to as threaded, the threaded hole256may only be partially threaded in accordance with one embodiment. In an exemplary embodiment, the threaded hole256is configured and dimensioned to threadingly receive the extension252of the central ramp18.

With additional reference toFIGS.28-32, a method of installing the expandable fusion device10ofFIGS.18-27is now discussed in accordance with one embodiment of the present invention. Prior to insertion of the fusion device, the disc space may be prepared as described above and then one or more endoscopic tubes may then inserted into the disc space. The expandable fusion device10can then be inserted into and seated in the appropriate position in the intervertebral disc space, as best seen inFIGS.28-32. The expandable fusion device10can be introduced into the intervertebral space down an endoscopic tube (not illustrated), with the central ramp18being first placed down the tube and into the disc space, as seen inFIG.28. After insertion of the central ramp, the first endplate14can be placed down an endoscopic tube, as shown onFIG.29, followed by insertion of the second endplate16, as shown onFIG.30. After the second endplate16, the actuator assembly200can then be inserted to complete assembly of the device10, as best seen inFIG.31.

After the fusion device10has been inserted into and assembled in the appropriate position in the intervertebral disc space, the fusion device10can then be expanded into the expanded position. To expand the fusion device10, the actuator assembly200can be rotated. As discussed above, the actuator assembly200is in threaded engagement with the extension250of the central ramp18. Thus, as the actuator assembly200is rotated in a first direction, the central ramp18moves toward the flanged end253of the actuator assembly200. In another exemplary embodiment, the actuator assembly200can be moved in a linear direction with the ratchet teeth as means for controlling the movement of the central ramp18. As the central ramp18moves, the angled surfaces242,244in the expansion portions238,240of the central ramp18push against the ramped surfaces206,208in the first and second side portions202,204of the first and second endplates14,16. In addition, the angled surfaces246in the second end236of the central ramp18also push against the ramped surfaces228in the central extension224of each of the endplates14,16. This is best seen inFIGS.22-23.

Since the expansion of the fusion device10is actuated by a rotational input, the expansion of the fusion device10is infinite. In other words, the endplates14,16can be expanded to an infinite number of heights dependent on the rotational advancement of the actuator assembly200. As discussed above, the central ramp16includes locking features for securing the endplates14,16.

In the event the fusion device10needs to be repositioned or revised after being installed and expanded, the fusion device10can be contracted back to the unexpanded configuration, repositioned, and expanded again once the desired positioning is achieved. To contract the fusion device10, the actuator assembly200can be rotated in a second direction. As discussed above, actuator assembly200is in threaded engagement with the extension250of the central ramp18; thus, as the actuator assembly200is rotated in a second direction, opposite the first direction, the central ramp18moves with respect to the actuator assembly200and the first and second endplates14,16away from the flanged end253. As the central ramp18moves, the first and second endplates are pulled inwardly into the unexpanded position.

Referring now toFIGS.33-38, an alternative embodiment of the expandable fusion device10is shown. In the illustrated embodiment, the fusion device includes a first endplate14, a second endplate16, a central ramp18, and an actuator assembly200. The fusion device10ofFIGS.33-38and its individual components are similar to the device10illustrated onFIGS.18-23with several modifications. The modifications to the device10will be described in turn below.

Although the following discussion relates to the second endplate16, it should be understood that it also equally applies to the first endplate14as the second endplate16is substantially identical to the first endplate14in embodiments of the present invention. With additional reference toFIG.39, in an exemplary embodiment, the lower surface42of the second endplate16has been modified. In one embodiment, the central extension224extending from the lower surface42has been modified to include a second ramped surface258rather than a stop. In an exemplary embodiment, the second ramped surface258faces the second end41of the second endplate16. In contrast, ramped surface228on the central extension228faces the first end39of the second endplate. The concave surface228connects the ramped surface228and the second ramped surface258.

With reference toFIGS.35-38, in an exemplary embodiment, the actuator assembly200has been modified to further include a driving ramp260. In the illustrated embodiment, the driving ramp260has a through bore262through which the extension254extends. In an embodiment, the driving ramp260is generally wedge-shaped. As illustrated, the driving ramp260may comprise a blunt end264in engagement with the flanged end253. In an exemplary embodiment, the driving ramp260further comprises angled surfaces266configured and dimensioned to engage the second ramped surface258of each of the endplates14,16and force apart the first and second endplates14,16.

Referring now toFIGS.40-44, an alternative embodiment of the expandable fusion device10is shown. In the illustrated embodiment, the fusion device10includes a first endplate14, a second endplate16, a central ramp18, an actuator assembly200, and a driving ramp300. As will be discussed in more detail below, the actuator assembly200functions, in an embodiment, to pull the central ramp18and the driving ramp300together, which forces apart the first and second endplates14,16. In an embodiment, the expandable fusion device

Although the following discussion relates to the first endplate14, it should be understood that it also equally applies to the second endplate16as the second endplate16is substantially identical to the first endplate14in embodiments of the present invention. With reference toFIGS.40-45, in an exemplary embodiment, the first endplate14has a first end39and a second end41. In the illustrated embodiment, the first endplate14further comprises an upper surface40connecting the first end39and the second end41, and a lower surface42connecting the first end39and the second end41. While not illustrated, in an embodiment, the first endplate14may comprise further comprises a through opening. The through opening, in an exemplary embodiment, is sized to receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface40of the first endplate14is flat and generally planar to allow the upper surface40of the endplate14to engage with the adjacent vertebral body2. Alternatively, as shown inFIG.15, the upper surface40can be curved convexly or concavely to allow for a greater or lesser degree of engagement with the adjacent vertebral body2. It is also contemplated that the upper surface40can be generally planar but includes a generally straight ramped surface or a curved ramped surface. The ramped surface allows for engagement with the adjacent vertebral body2in a lordotic fashion. While not illustrated, in an exemplary embodiment, the upper surface40includes texturing to aid in gripping the adjacent vertebral bodies. Although not limited to the following, the texturing can include teeth, ridges, friction increasing elements, keels, or gripping or purchasing projections.

In one embodiment, the first endplate14further comprises a first side portion202connecting the first end39and the second end41, and a second side portion204connecting the first end39and the second end41. In the illustrated embodiment, the first and second side portions202,204are extensions from the lower surface42. In an embodiment, the first and second side portions each have an interior surface302and an exterior surface304. In an exemplary embodiment, the first and second side portions202,204each include one or more ramped portions. In the illustrated embodiment, the first and second side portions202,204include first ramped portions306,308at the first end39of the endplate14and second ramped portions310,312at the second end41of the endplate. The first and second side portions202,204each can include a bridge portion314connecting the first ramped portions306,308and the second ramped portions310,312. In an embodiment, the first ramped portions306,308abut the exterior surface304of the respective side portions202,204, and the second ramped portions310,312abut the interior surface302of the respective side portions202,204. As illustrated, the first ramped portions306,308may include tongue portions316,318with the tongue portions316,318extending in an oblique direction with respect to the upper surface40of the endplate14. As further illustrated, the second ramped portions310,312may include tongue portions320,322that extend in an oblique direction with respect to the upper surface40of the endplate14.

As best seen inFIG.45, the lower surface42of the second endplate16, in an embodiment, includes a central extension224extending along at least a portion of the lower surface. In the illustrated embodiment, the central extension224extends between the first and second side portions202and204. In an exemplary embodiment, the central extension224can extend generally between the first ramped portions306,308and the second ramped portions310,312. In one embodiment, the central extension224includes a generally concave surface226configured and dimensioned to form a through bore with the corresponding concave surface226(not illustrated) of the second endplate16.

With reference toFIGS.43and44, the actuator assembly200includes a head portion324, a rod receiving extension326, and a connecting portion328that connecting portions that connects the head portion324and the rod receiving extension326. As illustrated, the head portion324may include one or more instrument gripping features330that can allow it to be turned by a suitable instrument. In addition, the head portion324has a larger diameter than the other components of the actuator assembly200to provide a contact surface with the driving ramp300. In the illustrated embodiment, the head portion324includes a rim332that provides a surface for contacting the driving ramp300. As can be seen inFIG.44, in an exemplary embodiment, the rod receiving extension326includes an opening sized and dimensioned to receive the extension336of the central ramp18. In an embodiment, the rod receiving extension326includes threading for threadingly engaging the extension336. In another embodiment, the rod receiving extension326includes ratchet teeth for engaging the extension336. In the illustrated embodiment, the head portion324and the rod receiving extension326are connected by connecting portion328which can be generally cylindrical in shape.

With reference toFIGS.43,44, and46, the central ramp18includes expansion portion334and extension336. As best seen inFIG.46, the expansion portion334may include an upper portion338and side portions340,342that extend down from the upper portion338. In an embodiment, each of the side portions340,342include dual, overlapping ramped portions. For example, side portions340,342each include a first ramped portion344that overlaps a second ramped portion346. In the illustrated embodiment, the first ramped portion344faces the extension336while the second ramped portion344faces away from the extension336. In one embodiment, angled grooves348,350are formed in each of the first and second ramped portions344,346. In another embodiment, the angled grooves348,350are sized to receive the corresponding tongues316,318,320,322in the first and second endplates with angled grooves348receiving tongues320,322in the second endplate16and angled grooves350receiving tongues316,318in the first endplate14. Although the device10is described with tongues316,318,320,322on the endplates14,16and angled grooves348,350on the central ramp18, it should be understood that that device10can also be configured with grooves on the endplates14,16and tongues on the central ramp18, in accordance with one embodiment of the present invention.

In an exemplary embodiment, the extension336is sized to be received within the rod receiving extension326of the actuator assembly200. In one embodiment, the extension336has threading with the extension336being threadingly received within the rod receiving extension326. In another embodiment, the extension336has ratchet teeth with the extension336being ratcheted into the rod receiving extension336. In an embodiment, the extension336include nose352at the end of the extension336.

With reference toFIGS.47-49, in an exemplary embodiment, the driving ramp300includes an upper portion354having an upper surface356and an oblique surface358. In an embodiment, the driving ramp300further includes side portions360,362that extend from the upper portion354connecting the upper portion354with the lower portion364of the driving ramp300. As best seen inFIGS.48-49, the driving ramp300further includes a bore366, in an exemplary embodiment, sized to receive the connection portion328of the actuator assembly200. In one embodiment, the driving ramp300moves along the connection portion328when the actuator assembly200is pushing the driving ramp300. In an exemplary embodiment, the driving ramp300further includes contact surface368that engages the rim332of the head portion324of the actuator assembly200. In the illustrated embodiment, the contact surface368has a generally annular shape.

In an exemplary embodiment, the side portions360,362of the driving ramp300each include overlapping ramped portions. For example, the side portions360,362each include first ramped portions370that overlap second ramped portions372. In the illustrated embodiment, the first ramped portions370face central ramp18while the second ramped portions372face the opposite direction. In one embodiment, angled grooves374,376are formed in each of the first and second ramped portions370,372.FIG.48is a perspective view of the driving ramp300that shows the top ends of the angled grooves374in ramped portions370.FIG.49is a perspective view of the driving ramp300that shows the top ends of the angled grooves376in ramped portions372. In an exemplary embodiment, the angled grooves374,376are sized to receive corresponding tongues316,318,320,322in the first and second endplates14,16with angled grooves370receiving tongues316,318in the second endplate16and angled grooves372receiving tongues320,322in the first endplate14. Although the device10is described with tongues316,318,320,322in the first and second endplates14,16and angled grooves370,372,374,376on the driving ramp300, it should be understood that that device10can also be configured with grooves on the second endplate16and tongues on the driving ramp300, in accordance with one embodiment of the present invention.

Turning now toFIGS.40-42, a method of installing the expandable fusion device10ofFIGS.40-49is now discussed in accordance with one embodiment of the present invention. Prior to insertion of the fusion device, the disc space may be prepared as described above. The expandable fusion device10can then be inserted into and seated in the appropriate position in the intervertebral disc space. The expandable fusion device10is then introduced into the intervertebral space, with the end having the expansion portion334of the central ramp18being inserted. In an exemplary method, the fusion device10is in the unexpanded position when introduced into the intervertebral space. In an exemplary method, the intervertebral space may be distracted prior to insertion of the fusion device10. The distraction provide some benefits by providing greater access to the surgical site making removal of the intervertebral disc easier and making scraping of the endplates of the vertebral bodies2,3easier.

With the fusion device10inserted into and seated in the appropriate position in the intervertebral disc space, the fusion device can then expand into the expanded position, as best seen inFIG.42. To expand the fusion device10, an instrument is engaged with the head portion324of the actuator assembly200. The instrument is used to rotate actuator assembly200. As discussed above, actuator assembly200is threadingly engaged with the extension336of the central ramp18; thus, as the actuator assembly200is rotated in a first direction, the central ramp18is pulled toward the actuator assembly200. In an exemplary embodiment, the actuator assembly200is moved in a linear direction with the ratchet teeth engaging as means for controlling the movement of the actuator assembly200and the central ramp18. As the central ramp18is pulled towards the actuator assembly200, the first ramped portions344of the central ramp18push against the second ramped portions310,312of the second endplate16and the second ramped portions346of the central ramp18push against first ramped portions306,308of the first endplate14. In this manner, the central ramp18acts to push the endplates14,16outwardly into the expanded position. This can best be seen inFIGS.40-42. As the endplates14,16move outwardly the tongues316,318,320,322in the endplates14,16ride in the angled grooves348,350with the tongues320,322in the second endplate16riding in angled grooves348and the tongues316,318in the first endplate14riding in angled grooves350.

As discussed above, the actuator assembly200also engages driving ramp300; thus, as the actuator assembly200is rotated in a first direction, the actuator assembly200pushes the driving ramp300towards the central ramp18in a linear direction. As the driving ramp300is pushed towards the central ramp18, the first ramped portions370of the driving ramp300push against the first ramped portions306,308of the second endplate16and the second ramped portions372of the driving ramp300push against the second ramped portions310,312of the first endplate14. In this manner, the driving ramp300also acts to push the endplates14,16outwardly into the expanded position. This can best be seen inFIGS.40-42. As the endplates14,16move outwardly the tongues316,318,320,322in the endplates14,16ride in the angled grooves370,372with the tongues316,318in the second endplate16riding in angled grooves370and the tongues320,322in the first endplate14riding in angled grooves372.

Since the expansion of the fusion device10is actuated by a rotational input, the expansion of the fusion device10is infinite. In other words, the endplates14,16can be expanded to an infinite number of heights dependent on the rotational advancement of the actuator assembly200.

Referring now toFIGS.50-54, an alternative embodiment of the expandable fusion device10is shown. In the illustrated embodiment, the fusion device10includes a first endplate14, a second endplate16, a central ramp18, an actuator assembly200, and a driving ramp300. As will be discussed in more detail below, the actuator assembly200functions, in an embodiment, to pull the central ramp18and the driving ramp300together, which forces apart the first and second endplates14,16. In an embodiment, the expandable fusion device may contain features, such as a through bore, that facilitate placement down an endoscopic tube. In an embodiment, the assembled fusion device10may be placed down the endoscopic tube and then expanded.

Although the following discussion relates to the first endplate14, it should be understood that it also equally applies to the second endplate16as the second endplate16is substantially identical to the first endplate14in embodiments of the present invention. It should be understood that, in an embodiment, the first endplate14is configured to interlock with the second endplate16. With additional reference toFIG.55, in an exemplary embodiment, the first endplate14has a first end39and a second end41. As illustrated, the first end39may be wider than the second end41. In the illustrated embodiment, the first endplate14further comprises an upper surface40connecting the first end39and the second end41, and a lower surface42connecting the first end39and the second end41. As best seen inFIG.54, the lower surface42can be curved concavely such that the first and second endplates14,16form a through bore when the device10is in a closed position. In an embodiment, the first endplate14may comprise a through opening44. The through opening44, in an exemplary embodiment, is sized to receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface40of the first endplate14is flat and generally planar to allow the upper surface40of the endplate14to engage with the adjacent vertebral body2. Alternatively, as shown inFIG.15, the upper surface40can be curved convexly or concavely to allow for a greater or lesser degree of engagement with the adjacent vertebral body2. It is also contemplated that the upper surface40can be generally planar but includes a generally straight ramped surface or a curved ramped surface. The ramped surface allows for engagement with the adjacent vertebral body2in a lordotic fashion. As illustrated, in an exemplary embodiment, the upper surface40includes texturing to aid in gripping the adjacent vertebral bodies. For example, the upper surface40may further comprise texturing400to engage the adjacent vertebral bodies. Although not limited to the following, the texturing can include teeth, ridges, friction increasing elements, keels, or gripping or purchasing projections.

In one embodiment, the first endplate14further comprises a first side portion202connecting the first end39and the second end41, and a second side portion204connecting the first end39and the second end41. In the illustrated embodiment, the first and second side portions202,204are extensions from the lower surface42. In an embodiment, the first and second side portions202,204each include an interior surface302and an exterior surface304. In an embodiment, the first end39of the first endplate14is generally designed and configured to fit over the second end41of the second endplate16when the device10is in a closed position. As illustrated, the first and second side portions202,204each may include first ramped portions306,308, second ramped portions310,312, and/or central ramped portion402.

In an embodiment, the first ramped portions306,308are proximate the first end39of the endplate14. In accordance with embodiment of the present invention, the first ramped portions306,308of the first endplate14are generally designed and configured to fit over the second ramped portions310,312of the second endplate16when the device10is in a closed position. In an exemplary embodiment, the first ramped portions306,308generally face the first end39and can extend in an oblique direction with respect to the upper surface40, for example. As illustrated, the first ramped portions306,308may include tongue portions316,318extending in an oblique direction with respect to the upper surface40of the endplate14.

In an embodiment, the second ramped portions310,312are proximate the second end41of the endplate14. In an exemplary embodiment, the second ramped portions310,312can extend in an oblique direction with respect to the upper surface40and generally face the second end41. The first and second side portions202,204, in an embodiment, each can include a bridge portion314connecting the first ramped portions306,308and the second ramped portions310,312. As further illustrated, the second ramped portions310,312may include tongue portions320,322that extend in an oblique direction with respect to the upper surface40of the endplate14.

In an embodiment, the endplate14further may include a central ramped portion402proximate the bridge portion314. In the illustrated embodiment, the endplate14includes a central ramped portion402proximate the bridge portion314of the second side portion204. In an exemplary embodiment, the central ramped portion402can extend in an oblique direction with respect to the upper surface40and face the first end39of the endplate14. As illustrated, the first ramped portions306,308may include tongue portions316,318with the tongue portions316,318extending in an oblique direction with respect to the upper surface40of the endplate14.

With reference toFIGS.50-52and54, in an embodiment, the actuator assembly200includes a head portion324, an extension404, and a through bore406that extends longitudinally through the actuator assembly200. As illustrated, the head portion324may include one or more instrument gripping features330that can allow it to be turned by a suitable instrument. In addition, the head portion324has a larger diameter than the other components of the actuator assembly200to provide a contact surface with the driving ramp300. In the illustrated embodiment, the head portion324includes a rim332that provides a surface for contacting the driving ramp300. In an embodiment, the extension404is a generally rod-like extension. In another embodiment, the extension404includes ratchet teeth for engaging the extension336.

With reference toFIGS.51,52, and56, the central ramp18has a first end408and a second end410. In an embodiment, the central ramp18includes a first expansion portion412, a second expansion portion414, a rod-receiving extension416, and a through bore418that extends longitudinally through the central ramp18. In an exemplary embodiment, first expansion portion412can be proximate the first end408of the central ramp18. As best seen inFIG.56, the first expansion portion412may include side portions420,422. In an embodiment, each of the side portions420,422includes dual, overlapping ramped portions that extend in oblique directions with respect to the through bore418. For example, side portions420,422each include a first ramped portion424that overlaps a second ramped portion426. In the illustrated embodiment, the first ramped portion424faces the rod-receiving extension416while the second ramped portion426faces the opposite direction. In one embodiment, angled grooves428,430are formed in each of the first and second ramped portions424,426. In an exemplary embodiment, the angled grooves428,430are sized to receive the corresponding tongues316,318,320,322in the first and second endplates14,16with angled grooves428receiving tongues320,322in the second endplate16and angled grooves430receiving tongues316,318in the first endplate14. Although the device10is described with tongues316,318,320,322on the endplates14,16and angled grooves428,430on the central ramp18, it should be understood that that device10can also be configured with grooves on the endplates14,16and tongues on the central ramp18, in accordance with one embodiment of the present invention.

In an embodiment, the second expansion portion414is located on the rod-receiving extension416between the first end408and the second end410of the central ramp18. In an exemplary embodiment, the second expansion portion414includes central ramped portions432. In one embodiment, the second expansion portion414includes two central ramped portions432on opposite sides of the rod-receiving extension416. In an exemplary embodiment, the central ramped portions424extend in an oblique direction with respect to the through bore418and face the second end410of the central ramp18.

The rod-receiving extension416extends from the first expansion portion412and has an opening434at the second end of the central ramp18. In an embodiment, the rod-receiving extension416is sized and configured to receive the extension404of the actuator assembly200. In an embodiment, the rod-receiving extension416has threading with the rod-receiving extension416threadingly receiving extension404of the actuator assembly200. In another embodiment, the rod-receiving extension416has ratchet teeth with the extension404being ratcheted into the rod-receiving extension416.

With reference toFIGS.50-52and57, in an exemplary embodiment, the driving ramp300includes an upper portion354having an upper surface356and an oblique surface358. In an embodiment, the driving ramp300further includes a bore366, in an exemplary embodiment, sized to receive the extension404of the actuator assembly200. In the illustrated, embodiment, the upper portion354has a hole436that extends through the upper surface356to the bore366. Set screw438may be inserted through the hole436to secure the driving ramp300to the actuator assembly200. In one embodiment, the driving ramp300further includes contact surface368that engages the rim332of the head portion324of the actuator assembly200. In the illustrated embodiment, the contact surface368has a generally annular shape.

In an embodiment, the driving ramp300further includes side portions360,362that extend from the upper portion354connecting the upper portion354with the lower portion364of the driving ramp300. In an exemplary embodiment, the side portions360,362of the driving ramp300each include a ramped portion438. In the illustrated embodiment, the ramped portion438faces central ramp300. In an embodiment, the ramped portion438is configured and dimensioned to engage the ramped portions306,308at the first end39of the second endplate16. In one embodiment, angled grooves440are formed in the ramped portions316,318. In an exemplary embodiment, the angled grooves440are sized to receive the corresponding tongues316,318in the second endplate16. Although the device10is described with tongues316,318on the second endplate16and angled grooves440on the driving ramp300, it should be understood that that device10can also be configured with grooves on the second endplate16and tongues on the driving ramp300, in accordance with one embodiment of the present invention.

A method of installing the expandable fusion device10ofFIGS.50-57is now discussed in accordance with one embodiment of the present invention. Prior to insertion of the fusion device, the disc space may be prepared as described above. The expandable fusion device10can then be inserted into and seated in the appropriate position in the intervertebral disc space. In an embodiment, the device10is assembled prior to insertion. The expandable fusion device10can be introduced into the intervertebral space, with the end having the first end408of the central ramp18being inserted. In an exemplary method, the fusion device10is in the unexpanded position when introduced into the intervertebral space. In an exemplary method, the intervertebral space may be distracted prior to insertion of the fusion device10. The distraction provide some benefits by providing greater access to the surgical site making removal of the intervertebral disc easier and making scraping of the endplates of the vertebral bodies2,3easier.

With the fusion device10inserted into and seated in the appropriate position in the intervertebral disc space, the fusion device can then expand into the expanded position. To expand the fusion device10, an instrument is engaged with the head portion324of the actuator assembly200. The instrument is used to rotate actuator assembly200. As discussed above, actuator assembly200is threadingly engaged with the rod receiving extension416of the central ramp18; thus, as the actuator assembly200is rotated in a first direction, the central ramp18is pulled toward the actuator assembly200. In an exemplary embodiment, the actuator assembly200is moved in a linear direction with the ratchet teeth engaging as means for controlling the movement of the actuator assembly200and the central ramp18.

As the central ramp space18is pulled towards the actuator assembly200, the central ramp18acts to push endplates14,16outwardly into the expanded position. By way of example, the first ramped portions424, second ramped portions426, and central ramped portions432push against the corresponding ramped portions in the first and second endplates14,16. The first ramped portions424in the first expansion portion412of the central ramp18push against the second ramped portions310,312of the second endplate16with the corresponding tongues320,322in the second ramped portions310,312of the second endplate16riding in angled grooves428in the first ramped portions424in the first expansion portion412. The second ramped portions426in the first expansion portion412push against the first ramped portions316,318of the first endplate14with the corresponding tongues316,318in first ramped portions316,318of the first endplate14riding in angled grooves430in the second ramped portions426in the first expansion portion412. The central ramped portions432in the second expansion portion414push against the central ramped portion402in the first and second endplates14,16.

As discussed above, the actuator assembly200also engages driving ramp300; thus, as the actuator assembly200is rotated in a first direction, the actuator assembly200pushes the driving ramp300towards the central ramp18in a linear direction. As the driving ramp300is pushed towards the central ramp18, the driving ramp300also acts to push the endplates14,16outwardly into the expanded position. By way of example, the ramped portions438of the driving ramp300push against ramped portions306,308at the first end39of the second endplate16. As the endplates14,16move outwardly, the tongues316,318in the ramped portions306,308of the second endplate16ride in the angled grooves440in the ramped portions438of the driving ramp300.

It should also be noted that the expansion of the endplates14,16can be varied based on the differences in the dimensions of the various ramped portions in the central ramp18, the driving ramp300, and the first and second endplates14,16. As best seen inFIG.16, the endplates14,16can be expanded in any of the following ways: straight rise expansion, straight rise expansion followed by a toggle into a lordotic expanded configuration, or a phase off straight rise into a lordotic expanded configuration.

In the event the fusion device10needs to be repositioned or revised after being installed and expanded, the fusion device10can be contracted back to the unexpanded configuration, repositioned, and expanded again once the desired positioning is achieved. To contract the fusion device10, the instrument can be used to rotate the actuator assembly200in a second direction that is opposite the first direction. Rotation of the actuator assembly200results in movement of the central ramp18and the driving ramp300away from one another. As the central ramp18and the driving ramp300move, the endplates14,16move inwardly into the unexpanded position.

Although the preceding discussion only discussed having a single fusion device10in the intervertebral space, it is contemplated that more than one fusion device10can be inserted in the intervertebral space. It is further contemplated that each fusion device10does not have to be finally installed in the fully expanded state. Rather, depending on the location of the fusion device10in the intervertebral disc space, the height of the fusion device10may vary from unexpanded to fully expanded. It should be noted that, as well as the height being varied from an unexpanded state to an expanded state, the fusion10may be positioned permanently anywhere between the expanded state and the unexpanded state.

Referring now toFIGS.58-65, an alternative embodiment of the expandable fusion device10is shown. In the illustrated embodiment, the fusion device10includes an upper endplate480, a lower endplate485, and actuator assembly445. The actuator assembly445comprises a front sloped height actuator450, a rear sloped height actuator455, and a linear actuator460. In an embodiment the linear actuator460functions to pull the front sloped actuator450and the rear sloped actuator455together, which forces apart the upper endplate480and lower endplate485.

With reference toFIGS.58-59, in an exemplary embodiment of fusion device10, the actuator assembly445comprises a front sloped actuator450, a rear sloped actuator455, and a linear actuator460. As illustrated, the linear actuator460may comprise a head portion465and an extension466. In an embodiment, the extension466is a generally rod-like extension that comprises surface threads470. It should be understood that, while the surface threads470of the linear actuator460are referred to as threaded, the surface threads470may only be partially threaded in accordance with one embodiment. The linear actuator460of the actuator assembly445may extend through an opening456in the rear sloped actuator455where the surface threads470of the linear actuator460engage the complimentary threads500of the extension475of the front sloped actuator450. Thus, as the linear actuator460is rotated in a first direction, the actuator assembly445pulls the front sloped actuator450towards the rear sloped actuator455and consequently also towards the head portion465of the linear actuator460in a linear direction. As the front sloped actuator450is pulled towards the rear sloped actuator455, the sloped surfaces454,459respectively, of the front sloped actuator450and the rear sloped455actuator push the upper480and lower485endplates outwardly into the expanded position.

With reference toFIGS.58-59and63, in an exemplary embodiment, the upper and lower endplates480,485may comprise two portions, such as two opposing mirrored halves. Both the upper endplate480and lower endplate485may comprise a front end481and a rear end482. The front and rear ends481,482of each portion of each endplate may be substantially similar to the front and rear ends481,482of every other portion of every other endplate. It should be understood that that references to the front and rear ends481,482of each endplate are with respect to the front and rear of the expandable fusion device10, which is with respect to the direction of placement into an intervertebral disc space with the front of the expandable fusion device10placed into the space first, followed by the rear of the expandable fusion device10. Each portion of the upper and lower endplates480,485further may comprise front ramped surface483and rear ramped surface484, as a component of the front and rear ends481,482of each portion of the upper and lower endplate480,485. The front ramped surface483may be located on the front end481of each half of the upper and lower endplates480,485. The rear ramped surface484may be located on the rear end482of each half of the upper and lower endplates485. With additional reference toFIGS.60and61, in the illustrated embodiment, the front and rear ends481,482of each portion of upper and lower endplates480,485contains a slot490that engages the corresponding elevated and angled tongues495of the front sloped actuator450and the rear sloped actuator455. The elevated and angled tongues495may be substantially identical in design and function for both the front sloped actuator450and the rear sloped actuator455. Because the elevated and angled tongues495are angled at a slant that directs away from the center of the expandable fusion device, as the front sloped actuator450is pulled towards the rear sloped actuator455by rotation of the linear actuator460, the ramped sections454,459of the front and rear sloped actuators450,455, in conjunction with the elevated and angled tongues495of the front and rear sloped actuators450,455pushes both portions of the upper and lower endplates480,485outward simultaneously in both horizontal and vertical directions.

With reference toFIGS.58-62, front sloped actuator450may comprise a front end451and a rear end453. The front end451may comprise opposing sloped surfaces452. In some embodiments, the front end451of the front sloped actuator450is the section of the expandable fusion device10that is first inserted into an intervertebral disc space. The front sloped actuator450may also comprise a rear end453connected to extension475from the front slope actuator450. The rear end453of the front sloped actuator450also may comprise opposing sloped surfaces454. The opposing sloped surfaces454of the rear end453of the front sloped actuator450may be sloped towards the rear sloped actuator455. The opposing sloped surfaces454of the rear end453of the front sloped actuator450also comprises the elevated and angled tongues495that engage the slots490of the halves of the upper and lower endplates480,485, as described in the preceding paragraph. The front sloped actuator450also comprises a threaded screw opening463. As illustrated, the extension475from the front sloped actuator450may comprise extending threaded prongs476a,476b. The extension475is generally located in the center of the actuator assembly445, and with respect to the front end451of the front sloped actuator450, the extension475extends longitudinally towards the rear sloped actuator455and the linear actuator460. The extension475may be sized and configured to receive the extension466of the linear actuator460. The extension475may comprise threads500that engage with the threads470of the extension466of the linear actuator460. Turning the linear actuator460, rotates the threads470of the linear actuator460, which are threadingly engaged to the threads500of the extension475of the front sloped actuator450, and consequently can push or pull the extension475and therefore the front sloped actuator450towards or away from the rear sloped actuator455and the linear actuator460, dependent upon which direction the linear actuator460is rotated.

With continued reference toFIGS.58-62, rear sloped actuator455may comprise an opening456. The opening456may be disposed in the center of the rear sloped actuator455and may run longitudinally throughout the entirety of the rear sloped actuator455. The opening456may be sized to receive the extension of the475of the front sloped actuator450with the extension466of the linear actuator460disposed therein. The rear sloped actuator455also contains a front side458which faces the extension475of the front sloped actuator450. The front side458of the rear sloped actuator455has opposing sloped surfaces459, that are sloped towards the extension475and consequently the front sloped actuator450. The front side458of the rear sloped actuator455also comprises the elevated and angled tongues495that engage the slots490of the halves of the upper480and lower485endplates, as described above. As best seen inFIGS.61and63, in an exemplary embodiment, the rear sloped actuator455comprises tool engagement surfaces510. Tool engagement surface510is a surface for engagement of a placement and positioning tool (not shown) which allows for insertion and adjustment of the fusion device10into an intervertebral space as best shown inFIG.1. Tool engagement surfaces510may be located horizontally on opposing sides of sloped rear actuator455.

As discussed above, the linear actuator460may comprise a head portion465and an extension466. Surface threads470may be disposed on the extension466of the linear actuator460. Surface threads470are complimentary to and engage the threads500of the extension475of the front sloped actuator450. In another embodiment, the extension466includes ratchet teeth for engaging the front sloped actuator450. Linear actuator460also comprises opening468in the head portion465of linear actuator460. In the illustrated embodiment, the opening468includes one or more instrument gripping features472that can allow it to be turned by a suitable instrument. Linear actuator460may be disposed in the opening456of the rear sloped actuator455with the extension466running through the opening456. The head portion465may be of a diameter that is too large to pass through the opening456and thus allows the linear actuator460to reach an endpoint where it, or from another perspective the front sloped actuator450, cannot be drawn closer through rotation of the linear actuator460.

As best seen inFIGS.60-62, in an exemplary embodiment, the front sloped actuator450comprises an extension475further comprising threads500that engage the surface threads470of the linear actuator460. Thus, as the linear actuator460is rotated in a first direction by a threaded instrument (not shown), the front sloped actuator450moves toward the flanged end465of the linear actuator460. In the event the fusion device10needs to be repositioned or revised after being installed and expanded, the fusion device10can be contracted back to the unexpanded configuration, repositioned, and expanded again once the desired positioning is achieved. To contract the fusion device10, the thread locking screw460can be rotated in a second direction. As discussed above, actuator assembly445is in threaded engagement with the extension475of the front sloped actuator450; thus, as linear actuator460is rotated in a second direction, opposite the first direction, the front sloped actuator450moves with respect to the actuator assembly445and the upper and lower endplates480,485away from the flanged end465.

With reference toFIGS.58-59, and63, in an exemplary embodiment the upper and lower endplates480,485may further comprise endplate pins515. As illustrated, the upper and lower endplates480,485may each comprise two endplate pins515. Endplate pins515may rest in slots disposed in each portion of the upper and lower endplates480,485. In the illustrated embodiment, the endplate pins515connect the portions of the upper endplate480and the portions of the lower endplate485. Endplate pins515can provide for even and simultaneous movement of endplate portions. With specific reference toFIGS.64(a) and64(b), endplate pins515can be seen in both the unexpanded fusion device configuration as shown inFIG.64(a)and the expanded fusion device configuration as shown inFIG.64(b).

In an exemplary embodiment,FIG.65depicts bone graft hole520, which is shown disposed in upper endplate480. Bone graft hole520in conjunction with threaded hole470of the linear actuator460provides space for bone grafts that may be used in the intervertebral fusion procedure.

A method of installing the expandable fusion device10ofFIGS.58-65is now discussed in accordance with one embodiment of the present invention. Prior to insertion of the fusion device10, the disc space may be prepared as described above. The expandable fusion device10can then be inserted into and seated in the appropriate position in the intervertebral disc space. In an embodiment, the device10is assembled prior to insertion. The expandable fusion device10can be introduced into the intervertebral space, with the end having the first end of the front sloped actuator450being inserted. In an exemplary method, the fusion device10is in the unexpanded position when introduced into the intervertebral space. In an exemplary method, the intervertebral space may be distracted prior to insertion of the fusion device10. The distraction provide some benefits by providing greater access to the surgical site making removal of the intervertebral disc easier and making scraping of the endplates of the vertebral bodies2,3easier as depicted inFIG.1.

With the fusion device10inserted into and seated in the appropriate position in the intervertebral disc space, the fusion device10can then expand into the expanded position. To expand fusion device10, an instrument may be engaged with the instrument gripping features472the linear actuator460. The threaded instrument may rotate the linear actuator460in the first direction, drawing the front sloped actuator450and the rear sloped actuator455together and contracting the actuator assembly455. In an exemplary embodiment the front sloped actuator450and the linear actuator460may be drawn together in a linear fashion with the threads500of the extension475of the front sloped actuator450engaging the surface threads470of the linear actuator460as a means for controlling the movement of the contraction of the actuator assembly445and consequently the expansion of the upper and lower endplates480,485, which expand horizontally and vertically with contraction of the actuator assembly445.

It should also be noted that the expansion of the upper and lower endplates480,485may be varied based on the differences in the dimensions of the sloped surfaces454and459and the direction of the angle in the elevated and angled tongues495. As best seen inFIG.16, the upper and lower endplates480and485can be expanded in any of the following ways: straight rise expansion, straight rise expansion followed by a toggle into a lordotic expanded configuration, or a phase off straight rise into a lordotic expanded configuration.

Although the preceding discussion only discussed having a single fusion device10in the intervertebral space, it is contemplated that more than one fusion device10can be inserted in the intervertebral space. It is further contemplated that each fusion device10does not have to be finally installed in the fully expanded state. Rather, depending on the location of the fusion device10in the intervertebral disc space, the height of the fusion device10may vary from unexpanded to fully expanded. It should be noted that, as well as the height being varied from an unexpanded state to an expanded state, the fusion10may be positioned permanently anywhere between the expanded state and the unexpanded state.

Referring now toFIGS.66-73, an alternative embodiment of the expandable fusion device10is shown. In the illustrated embodiment, the fusion device10includes an upper endplate570, a lower endplate580, and a collective actuator assembly520. The collective actuator assembly520comprises a front sloped actuator assembly530, a rear sloped actuator assembly540, and threaded locking screws550. In an embodiment a threaded instrument560functions to pull the front sloped actuator assembly530and the rear sloped actuator assembly540together, which forces apart the upper endplate570and lower endplate580.

With reference toFIGS.66-68and71, in an exemplary embodiment of fusion device10, the collective actuator assembly520comprises a front sloped actuator assembly530, a rear sloped actuator assembly540, and threaded locking screws550. The threaded locking screws550have flanged ends551and surface threads552that extend at least partially through the collective actuator assembly520. It should be understood that, while the surface threads552of the threaded locking screws550are referred to as threaded, the surface threads552may only be partially threaded in accordance with one embodiment. The threaded locking screws550of the collective actuator assembly520may rest in an opening541in the rear width actuator542of the rear sloped actuator assembly540where the surface threads552of the threaded locking screws550engage threaded screw openings595of the front height actuator532of the front sloped actuator assembly530. The threaded instrument560(FIG.72) may extend through an instrument opening561in the rear width actuator542of the rear sloped actuator assembly540. As the threaded instrument560is rotated in a first direction, the collective actuator assembly520pulls the front sloped actuator assembly530towards the rear sloped actuator assembly540and consequently also towards the flanged ends551of the threaded locking screws550in a linear direction. As the front sloped actuator assembly530is pulled towards the rear sloped actuator assembly540, the front width actuator536and the rear width actuator542are pulled together. As they are pulled together, the front and rear width actuators536,542drive apart the portions of the upper endplate570and the portions of the lower endplate575. More particularly, the front and rear width actuators536542engage the front height actuators532and the rear height actuators546to force them horizontally outward, which in turn engage the upper and lower endplates570,575to force them horizontally outward. The front stop pins533may have one end disposed in the retaining bores534of the front height actuator532and opposite ends disposed in the front stop pint track535of the front width actuator536. The front stop pins533may slide in the front stop pin track535of the front width actuator536until they reach the end of the front stop pin track535and movement of the front width actuator536is stopped, thus restricting lateral expansion of the device10, as best seen onFIG.68. Simultaneously, the rear stop pins543disposed in the retaining bores544of the rear width actuator542, slide in the rear stop pin tracks545of the rear height actuators546until they reach the end of the rear stop pin tracks545and movement of the rear width actuator542is stopped, as best seen onFIGS.68and71. When the front width actuator536is stopped, the front sloped actuator assembly530may be pulled towards the rear sloped actuator assembly540, by simultaneously turning threaded locking screws550. As threaded locking screws550are rotated simultaneously in a first direction, the sloped surfaces537,547respectively, of the front height actuators532and the rear height actuator546push the upper570and lower580endplates vertically outward into the expanded position.

With reference toFIGS.66-68, in an exemplary embodiment, the upper and lower endplates570,580may split into two portions, such as being bifurcated into two opposing mirrored halves. The portions of the upper endplate570maybe substantially identical to the portions of the lower endplate580in embodiments of the present invention. Both the upper and lower endplates570,580may comprise front and rear ends571,572. The front and rear ends571,572of each portion of each endplate may be substantially similar to the front and rear ends571,572of every other portion of every other endplate. It should be understood that that references to the front and rear ends571,572of each endplate are with respect to the front and rear of the expandable fusion device10, which is with respect to the direction of placement into an intervertebral disc space with the front of the expandable fusion device10placed into the space first, followed by the rear of the expandable fusion device10. Each portion of the upper and lower endplates570,580further comprises front and rear ramped surface portions573,574, as a component of the front and rear ends571,572of each portion of the upper and lower endplate570,580respectively. The front ramp surface573is located on the front end571of each portion of the upper and lower endplates570,580. The rear ramp surface574is located on the rear end572of each portion of the upper and lower endplates570,580. The front and rear ends571,572of each half of upper endplate570contains a slot575that engages the corresponding elevated tongues590of the front height actuator532and the rear height actuator546of the front sloped actuator assembly530and the rear sloped actuator assembly540respectively. The elevated tongues590may be substantially identical in design and function for both the front height actuator532and the rear height actuator546.

As best seen inFIGS.66-67and69, the front sloped actuator assembly530may comprise a front width actuator536. As illustrated, the front width actuator536may be wedge-shaped. The front width actuator536may further comprise a sloped front end538. The sloped front end538may be the section of the expandable fusion device10that is first inserted into an intervertebral disc space. The front width actuator536may further comprise a front stop pin track535that is complimentary to the front stop pins533. The front width actuator536may also comprise a threaded instrument opening539. The threaded instrument opening539also comprises threads that engage the threaded instrument560. The front sloped actuator assembly530may also comprise a pair of front height actuators532. The front height actuators532may be mirrored analogues that have substantially the same function. The front width actuator536may be disposed between the pair of front height actuators532. The front height actuators532comprise a sloped surface537and elevated tongues590that vertically expand the upper570and lower580endplates. The front height actuators532additionally comprise a threaded screw opening595. The threaded screw opening595engages the threaded locking screws550. When threaded locking screws550are turned in a first direction, upper570and lower580endplates are expanded vertically, due to the contraction of the front sloped actuator assembly530and the rear sloped actuator assembly540. Front height actuators532may additionally comprise retaining bores534, wherein the front stop pins533are disposed.

Rear sloped actuator assembly540may comprise a rear width actuator542. As illustrated, the rear width actuator542may be generally wedge-shaped. The rear width actuator542may further comprise an instrument opening561wherein the threaded instrument560may be inserted to operate the expandable fusion device10. The rear width actuator542may additionally comprise openings541. Threaded locking screws550may be inserted into openings541of the rear width actuator542and run through the collective actuator assembly520to connect to the threaded screw openings595in the front height actuators532. Rear width actuator542may additionally comprise retaining bores544which house the rear stop pins543. The rear stop pins543are fixed in the retaining bores544and do not move relative to and apart from the retaining bores544. The rear stop pins543and retaining bores544may be present in pairs, located on the top and bottom of the rear width actuator542. Rear stop pins543connect the rear width actuator542to the rear height actuators546. Rear height actuators546comprise rear stop pin tracks545in which the rear stop pins543may be disposed. When the threaded instrument560is turned in a first direction to contract the collective actuator assembly520and draw the front sloped actuator assembly530and the rear sloped actuator540, the rear stop pins543slide in the rear stop pin tracks545to expand the upper and lower endplates570,580horizontally, until the rear stop pins543contact the end of the rear stop pin tracks545. The rear sloped actuator assembly540may also comprise a pair of rear height actuators546. The rear height actuators546may be mirrored analogues that have substantially the same function. The rear width actuator542may be disposed between the pair of rear height actuators546. Rear height actuators546may comprise a sloped surface547and elevated tongues590that vertically expand the upper570and lower580endplates. Sloped surface547is sloped towards the front sloped actuator assembly530. Elevated tongues590engage the corresponding slots575of the upper570and lower580endplates.

As discussed above, the threaded locking screws550of the collective actuator assembly520, may each comprise a flanged end551and surface threads552. Surface threads551are disposed on the front end553of the threaded locking screws. The front end553of the threaded locking screws550are longitudinally opposite the flanged ends551of the threaded locking screws550. Surface threads551are complimentary to and engage the threads of the threaded screw openings595of the front height actuators532of the front sloped actuator assembly530. Threaded locking screws550also comprise an instrument opening554in the flanged ends551of the threaded locking screws550. In an exemplary embodiment, the instrument opening554is configured and dimensioned to receive a locking screw instrument (not shown). Threaded locking screws550are disposed in the threaded screw openings541of the rear width actuator542with the front end553running through the threaded screw openings541. The flanged ends551may be of a diameter that is too large to pass through the threaded screw openings541and thus allows the threaded locking screws550to reach an endpoint where it, or from another perspective the front sloped actuator assembly530, cannot be drawn closer through rotation of the threaded locking screws550.

As best seen inFIG.68, as the threaded locking screws550are rotated in a first direction by a locking screw instrument (not shown), the front height actuators532are pulled towards the flanged ends551of the threaded locking screws550. In the event the fusion device10needs to be repositioned or revised after being installed and expanded, the upper570and lower580endplates of fusion device10can be contracted back to the unexpanded configuration, repositioned, and expanded again once the desired positioning is achieved. To contract the endplates570,580of fusion device10, the threaded instrument560and the threaded locking screws550can be rotated in a second direction. As discussed above, rear sloped actuator assembly540is in threaded engagement with the front sloped actuator assembly530; thus, as the threaded instrument560is rotated in a second direction, opposite the first direction, the front sloped actuator assembly530is pushed away from the rear sloped actuator assembly540and the upper570and lower580endplates are pulled inward horizontally, this may continue until the front stop pins533and the rear stop pins543reach the end of their collective stop pin tracks535and545respectively. When the upper570and lower580endplates have been contracted to their initial unexpanded horizontal positions, the threaded locking screws550can be turned in a second direction opposite the first direction. Rotating the threaded locking screws550in a second direction will continue to push the front sloped actuator assembly530away from the rear sloped actuator assembly540. This can continue, until the endplates570,580are fully contracted into the default unexpanded configuration.

With reference toFIGS.66-68, in an exemplary embodiment the upper and lower endplates570,580each comprise endplate pins600. As illustrated, the upper and lower endplates570,580each comprise two endplate pins600. Endplate pins600rest in slots disposed in each half of the upper and lower endplates605,610. Endplate pins600connect the halves of the upper endplate470and the halves of the lower endplate580. Endplate pins600provide for even and simultaneous movement of endplate halves.

In an exemplary embodiment,FIGS.71(a)-71(c)depict bone graft hole615in the upper and lower endplates570,580. Bone graft hole615in conjunction with the threaded instrument opening561provides space for bone grafts that may be used in the intervertebral fusion procedure.

A method of installing the expandable fusion device10ofFIGS.66-72is now discussed in accordance with one embodiment of the present invention. Prior to insertion of the fusion device, the disc space may be prepared as described above. The expandable fusion device10can then be inserted into and seated in the appropriate position in the intervertebral disc space. In an embodiment, the device10is assembled prior to insertion. The expandable fusion device10can be introduced into the intervertebral space, with the end having the first end of the front sloped actuator450being inserted. In an exemplary method, the fusion device10is in the unexpanded position when introduced into the intervertebral space. In an exemplary method, the intervertebral space may be distracted prior to insertion of the fusion device10. The distraction provide some benefits by providing greater access to the surgical site making removal of the intervertebral disc easier and making scraping of the endplates of the vertebral bodies2,3easier as depicted inFIG.1.

With the fusion device10inserted into and seated in the appropriate position in the intervertebral disc space, the fusion device10can then expand into the expanded position. To expand fusion device10, a threaded instrument is inserted into the threaded instrument opening561and the threaded instrument opening539of the rear sloped actuator assembly540and the front sloped actuator assembly530respectively. The threaded instrument is rotated in the first direction, drawing the front sloped actuator assembly530and the rear sloped actuator540together and contracting the collective actuator assembly520. In an exemplary embodiment the front sloped actuator assembly530and the rear sloped actuator assembly540are drawn together in a linear fashion with the threads of the threaded instrument opening539of the front sloped actuator assembly530engaging the surface threads561of the threaded instrument560as a means for controlling the movement of the contraction of the collective actuator assembly520and consequently the horizontal expansion of the upper570and lower580endplates, which expand horizontally with contraction of the collective actuator assembly520. When horizontal expansion of endplates570and580has reached its maximum, threaded locking screws550may be rotated in a first direction simultaneously to further draw the front actuator assembly530towards the rear actuator assembly540. This contraction of the collective actuator assembly520expands the upper570and lower580endplates until they reach their maximum vertical expansion.

It should also be noted that the expansion of the upper570and lower580endplates may be varied based on the differences in the dimensions of the sloped surfaces537and547. As best seen inFIG.16, the upper570and lower580endplates may be expanded in any of the following ways: straight rise expansion, straight rise expansion followed by a toggle into a lordotic expanded configuration, or a phase off straight rise into a lordotic expanded configuration.

Turning now toFIGS.74-84, an expandable fusion device or implant700is shown according to one embodiment. The expandable fusion device700, similar to other embodiments of fusion device10, may include left and right side portion assemblies702,704configured to expand in width to increase the overall footprint of the device700and expand in height to correct disc height restoration, lordosis, and/or sagittal balance. The expandable fusion device700extends along a central longitudinal axis A between front and rear ends of the device700.FIG.74(a)shows the expandable fusion device700in a fully collapsed configuration with the left and right side portions702,704collapsed in both width and height.FIG.74(b)shows the expandable fusion device700in an expanded configuration with the left and right side portions702,704expanded in width and in height. It should be understood that references to the front and rear ends and left and right side portions702,704are described with respect to the direction of placement into an intervertebral disc space with the front of the expandable fusion device700placed into the disc space first, followed by the rear of the expandable fusion device700. The implant700may be suitable for a transforaminal lumbar interbody fusion (TLIF) through a posterior approach or other suitable surgical procedure.

With emphasis on the exploded view inFIG.75, movement of the first half or left side portion702and the second half or right side portion704of the implant700is controllable by a central drive screw706. The central drive screw706may be positioned along the central longitudinal axis A of the device700. The central drive screw706is positioned into and threadedly engaged with a central drive sleeve728. The central drive sleeve728is attached to a front distal block or plate708and the central drive screw706is attached to a rear proximal block or plate710. For example, the central drive sleeve728may be attached to the front distal plate708with a lock nut730and the central drive screw706may be retained within the rear proximal plate710with a locking ring or retaining ring732. The drive screw706is configured to pull the front distal plate708towards the rear proximal plate710and push the left and right side portions702,704outwards and away from one another using a plurality of arms or linkages712,714,716,718.

Once the left and right side portion assemblies702,704are fully expanded in width, the distal plate708may continue to travel to allow for vertical expansion of the left and right side portions702,704, thereby increasing the height of the device700. For example, the left and right side portion assemblies702,704may each include upper and lower endplates720,722, an actuator724, and a front ramp726. Both of the front ramps726are actuated when the central drive screw706is turned. Rotation of the drive screw706pulls the front ramps726toward the actuators724, which then expands the top and bottom endplates720,722via ramps776,778,780along the endplates720,722, actuators724, and front ramps726, and slots790in the actuators724and pins792coupling the endplates720,722to the actuators724and the front ramps726.

As best seen inFIG.76, the drive screw706extends from a proximal end740to a distal end742. The proximal end740may include an enlarged head portion configured to be received in a bore744defined through the rear proximal plate710. The bore744in the rear plate710may be internally threaded to provide for a threaded connection to the rear plate710, for example, allowing for a rigid connection to an insertion instrument. The proximal end740of the drive screw706may define an instrument recess748configured to receive an instrument, such as a driver, to rotate or actuate the drive screw706. The instrument recess748may include a tri-lobe recess or other suitable recess configured to engage with a driver instrument. The drive screw706may include a shaft with an exterior threaded portion746extending along its length. The drive screw706is receivable through the bore744in the rear plate710such that the proximal head portion740of the drive screw706is receivable in the rear plate710. A friction ring736, such as a polyether ether ketone (PEEK) ring, may be assembled onto the drive screw706, for example, below the enlarged head, to increase friction or drag on the drive screw706during rotation. The central drive screw706may be retained within the rear proximal plate710with retaining ring732. For example, the retaining ring732may include a split ring with a plurality of inner teeth734or various reliefs to allow the retaining ring732to compress and enter the bore744of the rear plate710and engage an internal groove in the plate710. When the retaining ring732is positioned around the drive screw706and within the bore744in the rear plate710, the teeth734are configured to engage with the central drive screw706, thereby locking the screw706in position in the plate710. The rear plate710may include one or more slots738configured to be engaged by an instrument. For example, opposite sides of the rear plate710may include two opposed slots738configured to be engaged with an instrument to aid insertion and removal of the retaining ring732.

As best seen inFIGS.77-78, the threaded shaft746of the drive screw706may be receivable through the body of the drive sleeve728. The drive sleeve728may have a tubular body with an inner bore750that is internally threaded to allow for threaded engagement with the threaded shaft746of the drive screw706. The drive sleeve728may have an exterior threaded portion752at its distal end. The distal threaded portion752may fit into a bore754defined through the front distal plate708. After being positioned through the bore754in the front plate708, the drive sleeve728may be secured to the front distal plate708with the lock nut730. The lock nut730may include a ring with a central bore defining internal threads. The drive sleeve728may be secured to the front distal plate708by coupling the internally threaded lock nut730to the distal threaded portion750of the drive sleeve728.

The drive sleeve728may be keyed to the bore754through the front plate708with one or more keying portions756configured to ensure the orientation of the drive sleeve728relative to the front plate708. For example, the keying portions756may include a pair of protrusions or keys on an outer surface of the sleeve728configured to mate with a corresponding pair of recesses or keyways in the bore754. The proximal end of the drive sleeve728may also include one or more keying portions758configured to ensure the orientation of the drive sleeve728relative to the rear plate710. For example, the keying portions758may include a pair of protrusions or keys extending proximally from the proximal end of the sleeve728configured to mate with a corresponding pair of recesses or keyways in the rear plate710. It will be appreciated that any suitable number, type, or configuration of keying portions756,758may be selected to align the sleeve728with the front and rear plates708,710. For example, although rectangular keys and notches are shown, it will be appreciated that the keying portions756,758may include a dovetail interface, finger joint, pin(s), or other suitable keying feature(s) to ensure the desired orientation. When the drive screw706is rotated or actuated, the drive sleeve728and attached front plate708is drawn toward the rear plate710, thereby providing for expansion of the device700. The keying portions756prevent the drive sleeve728from rotating.

With emphasis onFIGS.79-82, the left and right side portion assemblies702,704may each include upper and lower endplates720,722configured to expand away from one another to increase the vertical height of the expandable fusion device700. The upper and lower endplates720,722may be mirror images of one another. Although described with reference to the upper endplate720, the discussion herein applies equally to the lower endplate722. The upper endplate720includes an upper or outer facing surface760configured to interface with the vertebral endplate(s) of the adjacent vertebral bodies when implanted in the disc space. The outer surface760may include a plurality of teeth, ridges, roughened surfaces, keels, gripping or purchasing projections, or other friction increasing elements configured to retain the device700in the disc space. The endplates720,722may be 3D printed, for example, using additive manufacturing to provide a natural roughened surface to promote boney on growth or may be machined and blasted to achieve a roughened surface. The upper endplate720includes a lower or inner facing surface762. The inner facing surface762may define an elongate channel766positioned between two parallel side walls768. The elongate channel766may be configured to receive the body of the actuator724therein. One or more openings764may extend vertically through the body of the endplate720. In the collapsed position, as shown inFIG.74(a), portions of the actuator724may be received in the openings764. In the expanded position, as shown inFIG.74(b), the openings764may be open and free to receive bone-graft or other suitable bone forming material. One or more openings or bores769may extend horizontally through the sidewalls768of the endplate720. The through bores769are configured to receive horizontal pins792, which help to expand the endplates720,722in height.

As best seen inFIGS.79-80, the left and right side portion assemblies702,704may include first and second actuators724positioned between the upper and lower endplates720,722of the left and right side portions702,704, respectively. The actuators724may include a planar body having a proximal end770and a distal end772. The proximal end770may define an enlarged triangular-shaped portion774defining one or more first and second ramps776,778. The first ramp(s)776may be upward front-facing ramped surface(s) configured to interface with corresponding ramp(s)780at the rear end of the upper endplate720and the second ramp(s)778may be downward front-facing ramped surface(s) configured to interface with corresponding ramp(s)780at the rear end of the lower endplate722. It will be appreciated that the first ramps776may include a pair of spaced apart upper ramped surfaces configured to mate with a pair of ramped surfaces780on the rear side walls768of the upper endplate720and the second ramps778may include a pair of spaced apart lower ramped surfaces configured to mate with a pair of ramped surfaces780on the rear side walls768of the lower endplate722. The triangular-shaped portion774may define a horizontal notch784which bifurcates the proximal end770of the actuator724. The notch784is configured to receive a portion of the rear linkage716,718therein. A vertical bore786extends through the triangular-shaped portion774and is in fluid communication with the notch784. The vertical bore786is configured to receive a vertical pivot pin788to thereby secure the actuator724to the respective rear linkage716,718and allow for pivotable movement.

With emphasis onFIG.80, the planar body of the actuator724may include a plurality of slots790configured to receive the horizontal pins792, which help to guide expansion of the endplates720,722in height. For example, the actuator724may define four slots790: two upper slots790for receiving pins792coupled to the upper endplate720and two lower slots790for receiving pins792coupled to the lower endplate722. In this embodiment, the first upper slot790, toward the proximal end770, may include a diagonal or angled portion794in communication with a straight portion796aligned with the longitudinal axis A of the device10. The first lower slot790, toward the proximal end770, may be a mirror image of the first upper slot790. The angled portions794of the first upper and lower slots790may be generally aligned in parallel with the corresponding ramps776,778of the triangular-shaped portion774of the actuator724.

The second upper slot790, toward the distal end772, may include a diagonal or angled portion798in communication with a relief cut802. The angled portion798may be tapered toward the relief cut802to guide the pin792toward a desired location in the slot790. The relief cut802may form a spring tab804configured to retain the pin792in its desired position until a force from continued rotation of the drive screw706disengages the pin792to allow for expansion in height. The second lower slot790, toward the proximal end770, may be a mirror image of the second upper slot790. The second upper and lower slots798may be generally aligned in parallel with the first upper and lower slots794, respectively. The length of the angled slots798, near the distal end772, may be generally longer than the length of the angled slots794, near the proximal end770, thereby providing for angulation of the upper and lower endplates720,722, for example, for adjusting lordosis and/or sagittal balance. Although the upper and lower slots790are shown as mirror images of one another, it will be appreciated that any of the slots790may be the same or different from one another depending on the desired expansion.

As shown inFIG.82, the left and right side portions702,704may each include front ramp726. The front ramp726may be configured to expand the distal or front ends of the upper and lower endplates720,722. The front ramp726may define one or more first and second ramps806,808. The first ramp(s)806may be upward rear-facing ramped surface(s) configured to interface with a corresponding ramp810at the front end of the upper endplate720and the second ramp(s)808may be downward rear-facing ramped surface(s) configured to interface with a corresponding ramp810at the front end of the lower endplate722. It will be appreciated that the first ramps806may include a pair of spaced apart upper ramped surfaces configured to mate with a pair of ramped surfaces810on the front side walls768of the upper endplate720and the second ramps808may include a pair of spaced apart lower ramped surfaces configured to mate with a pair of ramped surfaces810on the front side walls768of the lower endplate722. The front ramp726may include a bifurcated body with a notch814configured to receive a portion of the front linkage712,714. A vertical bore816, in fluid communication with the notch814, extends through the body of the front ramp726. A vertical pivot pin818is receivable through the bore816to secure the respective front linkage712,714to the front ramp726and allow for pivotable movement.

With emphasis onFIGS.83(a)-83(c), the front ramps726and actuators724are joined to the front and rear plates708,710, respectively, via front and rear arms or linkages712,714,716,718, which permit pivotable movement to expand the width of the left and right halves702,704of the expandable fusion device700. Although described with reference to linkage712, the description of linkage712herein applies equally to all of the linkages712,714,716,718. The linkage712may include a frame with a U-shaped rectangular body, which acts a joint between the front or rear plate708,710and the left or right half702,704, respectively. The linkage712may include a tab or base820coupled to an upper arm portion822and a lower arm portion824via a connecting bar826. The upper and lower arm portions822,824may be separated by a gap. The upper and lower arm portions822,824of the linkage712may be aligned generally parallel to one another and may be received in recessed portions840in the upper and lower faces of the plates708,710. The recessed portions840in the top and bottom surfaces of the plates708,710may be generally shaped to mimic the outer shape of the arm portions822,824of the linkages712,714,716,718. The connecting bar826may be oriented generally perpendicular to the base820and upper and lower arm portions822,824.

With emphasis onFIG.84, each linkage712,714,716,718may form a pivotable joint, for example, utilizing one or more pins788,818,832, to expand the width of the first and second side portions702,704. The base820of the linkage712may define a vertical through bore828configured to receive the vertical pivot pin788,818, thereby connecting the linkage712,714,716,718to the actuator724or front ramp726, respectively. For each front ramp726, the tab or base820of the front linkage712,714is positioned in the notch814of the front ramp726, the pin818extends through the opening816in the front ramp726, into the opening828through the base820of the linkage712,714, and into the remainder of the opening816in the front ramp726. Similarly, for each actuator724, the tab or base820of the rear linkage716,718is positioned in the notch784of the actuator724, the pin788extends through the opening786in the actuator724, through the opening828through the base820, and into the remainder of the opening786in the actuator724. In this manner, the left and right halves702,704are free to pivot about the axes of the respective pins788,818.

The upper and lower arm portions822,824of each linkage712,714,716,718defines a vertical through bore830configured to receive a vertical pin832, thereby connecting the linkage712,714,716,718to the front and rear plates708,710, respectively. For the front plate708, the base of the front plate708is positioned in between the upper and lower arms822,824of the front linkage712,714, the pin832extends through the opening830in the upper arm822, through the opening836through the front plate708, and into the opening830in the lower arm824. Similarly, for the rear plate710, the base of the rear plate710is positioned in between the upper and lower arms822,824of the rear linkage716,718, the pin832extends through the opening830in the upper arm822, through the opening838through the rear plate710, and into the opening830in the lower arm824. In this manner, each linkage712,714,716,718is free to pivot about the axes of the respective pins832to widen the footprint of the device700.

With further emphasis onFIGS.83(a)-83(c), the upper and lower arm portions822,824of each linkage712,714,716,718may define a plurality of gear teeth834configured to intermesh with gear teeth834of the adjacent linkage712,714,716,718. The gear teeth834on each arm portion822,824may include a partial set of rotary teeth, such as up to four intermeshing teeth. For example, the gear teeth834of the upper arm portion822of the front left linkage712is configured to intermesh with the gear teeth834of the upper arm portion822of the adjacent front right linkage714and the gear teeth834of the upper arm portion822of the rear left linkage716is configured to intermesh with the gear teeth834of the upper arm portion of the adjacent rear right linkage718. The gear teeth834of the adjacent lower arm portions824intermesh in a similar fashion. These intermeshing gears teeth834are configured to engage with each other to ensure adjacent linkages712,714,716,718pivot together concurrently.

The implant700may be assembled in the following manner. As shown inFIG.76, the drive screw706is inserted into the rear plate710and may be retained using the retaining ring732. The retaining ring732may include inner reliefs734to allow the ring732to compress and enter the bore744of the rear plate710and engage an internal groove, thereby securing the drive screw706in the rear plate710. The PEEK friction ring736may be pre-assembled onto the drive screw706, which is then inserted into rear plate710, threaded into the drive sleeve728and retained by the retaining ring732. As shown inFIG.77, the drive sleeve728may be inserted into the front plate708and secured with the lock nut730. The keying features756on the screw sleeve728and front plate708may be aligned to lock the sleeve728from rotation. After the sleeve728is inserted into the front plate708, the sleeve728is retained by threading the lock nut730onto the distal threaded portion752of the sleeve728. As shown inFIG.78, the drive screw706is threaded into the proximal end of the drive sleeve728. Once fully assembled, actuation of the drive screw706is configured to push or pull the front plate708. When the front plate708is pulled toward the rear plate710, the implant700first expands in width and then expands in height.

Each of the left and right sides702,704may be assembled as follows. As shown inFIG.79, the upper endplate720may be placed onto the top of the actuator724and secured using two horizontal endplate pins792. Bump outs for slots709on the top of the actuator724may be received in the openings764through the endplate720. Two endplate pins792are inserted into the upper endplate720from one side, through the slot790of the actuator724and through the opposite side of upper endplate720. The slots790may be configured to secure the pin(s)792in a specific location in the slot790, for example, with the spring tab804. As shown inFIG.81, the lower endplate722is placed onto the bottom of the actuator724and secured using two more horizontal endplate pins792. Bump outs for slots709on the bottom of the actuator724may be received in the openings764through the endplate722. Two endplate pins792are inserted into the lower endplate722from one side, through slot790of the actuator724and through the opposite side of the lower endplate722. Similarly, the slots790may be configured to secure the pin(s)792in a specific location in the slot790, for example, with the spring tab804. As shown inFIG.82, the front ramp726is placed into the front of the set of assembled endplates720,722and secured using two horizontal front ramp pins792.

The left and right sides702,704are assembled to the front and rear plates708,710with the linkages712,714,716,718. As shown inFIG.83(a), the adjacent rear linkages716,718are placed into position on the rear plate710and secured with two vertical pivot pins832. The rear linkages716,718may include the gears834configured to engage with each other to ensure both adjacent linkages716,718pivot together concurrently. As shown inFIG.83(b), the adjacent front linkages712,714may be placed into position on the front plate708and secured with two additional vertical pivot pins832. The front linkages712,714may have gears834configured to engage with each other to ensure both adjacent linkages712,714pivot together concurrently. As shown inFIG.84, the holes828through the base820of the rear linkages716,718are aligned with the holes786in the actuators724and secured using two vertical pivot pins788. The holes828through the base820of the front linkages712,714are aligned with the holes816in the front ramps708and secured using two vertical pivot pins818. Once assembled, the left and right sides702,704are able to pivot about the linkages712,714,716,718to increase the width of the device700.

The implant700may be attached to a multi-component instrument. The instrument may include a driving component configured to engage with the drive screw706, for example, with a tri-lobe interface. When the drive screw706is rotated, the screw706pulls or translates proximally the screw sleeve728, front plate708, and front linkages712,714. When doing so, the drive screw706forces the sets of linkages712,714,716,718to pivot outwardly and expand in width. The linkages712,714,716,718may be keyed to each other with gears834so the linkages712,714,716,718pivot together. Width expansion may be in parallel or in a Y shape, for example, where only the distal portion expands in width. Height expansion may not occur yet because of the retaining features in the actuator724that holds the pins792in place until a greater force disengages the pins792and allows for height expansion. Once the linkages712,714,716,718pivot outward and full width expansion occurs, the front ramps726then begin to translate proximally with the screw sleeve728, front plate708, front linkages712,714. This forces the pins792up the ramps794,798of the actuators724, which translate the endplates720,722upward and downward, thereby increasing the vertical height of the implant700. In this manner, the implant700is able to expand in width for an increased footprint or surface area to aid in overall stability and minimize subsidence. The implant700is then able to expand in height to adjust lordosis, correct sagittal balance, and adjust the overall height for a precise patient fit.

In order to improve access, verify desired expansion, and/or monitor the procedure, robotic and/or navigation guidance may be used to install and expand the implant700. The implant700may be suitable for a transforaminal lumbar interbody fusion (TLIF) through a posterior approach, for example. A minimally invasive surgical (MIS) procedure may be utilized to access the disc space and perform the procedure. The orientation and position of the implant700in its final implanted position may be optimized with pre-op and intra-op scans utilizing robotic and/or navigational systems. Robotic and/or navigation guidance may be used to correctly orient the implant and align the implant for the desired lateral and vertical expansion. Further details of robotic and/or navigational systems can be found in U.S. Pat. Nos. 10,675,094, 9,782,229, and U.S. Patent Publication No. 2017/0239007, which are incorporated herein by reference in their entireties for all purposes.

Although the preceding discussion only discussed having a single fusion device10,700in the intervertebral space, it is contemplated that more than one fusion device10,700can be inserted in the intervertebral space. It is further contemplated that each fusion device10,700does not have to be finally installed in the fully expanded state. Rather, depending on the location of the fusion device10,700in the intervertebral disc space, the height of the fusion device10,700may vary from unexpanded to fully expanded. It should be noted that, as well as the height being varied from an unexpanded state to an expanded state, the fusion device10,700may be positioned permanently anywhere between the expanded state and the unexpanded state.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. Although individual embodiments are discussed, the invention covers all combinations of all those embodiments.