Patent Publication Number: US-2022226125-A1

Title: Intervertebral spacer and plate

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. patent application Ser. No. 17/326,840, filed on May 21, 2021, which is a continuation of U.S. patent application Ser. No. 16/505,045 filed on Jul. 8, 2019, which is a continuation of U.S. patent application Ser. No. 15/729,825 filed on Oct. 11, 2017, which is a continuation-in-part of patent application Ser. No. 15/144,054, filed May 2, 2016, which is a continuation-in-part of patent application Ser. No. 15/097,466, filed Apr. 13, 2016, which is a continuation-in-part application of patent application Ser. No. 14/802,229, filed Jul. 17, 2015, all of which are hereby incorporated by reference in their entirety herein. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to intervertebral devices and methods used to install these devices. 
     BACKGROUND OF THE INVENTION 
     Many types of spinal irregularities can cause pain, limit range of motion, or injure the nervous system within the spinal column. These irregularities can result from, without limitation, trauma, tumor, disc degeneration, and disease. One example of a spinal irregularity that may result from disc degeneration is spinal stenosis, the narrowing of a spinal canal, which can result in the compression of spinal nerves such as the spinal cord or cauda equina. In turn, the nerve compression can result in pain, numbness, or weakness. Other examples of conditions that can result from disc degeneration are osteoarthritis and disc herniation. 
     Often, these irregularities can be treated by performing a discectomy and/or immobilizing a portion of the spine. For example, treatment can include a surgical procedure that involves removal and replacement of an affected intervertebral disc with a prosthesis and the subsequent fusion of adjacent vertebrae. The prosthesis, such as an interbody cage or spacer, may be used either alone or in combination with one or more additional devices such as rods, screws, and/or plates. 
     SUMMARY OF THE INVENTION 
     Some embodiments herein are directed a vertebral fusion device that can include a spacer member comprising a first mating element; and a fixation member comprising a first bore extending therethrough and a second mating element, the second mating element configured to articulably engage the first mating element. 
     Other embodiments herein are directed to a vertebral fusion device that can include a first endplate comprising a first extension portion, the first extension portion comprising a first bore extending therethrough; a second endplate comprising a second extension portion, the second extension portion comprising a second bore extending therethrough; a first ramp configured to mate with the first and second endplates; a second ramp configured to mate with the first and second endplates; wherein the first and second bores each comprise an axis wherein at least one of the axes intersects a vertical, longitudinal plane of the device; and wherein the vertebral fusion device comprises an adjustable height. 
     Yet other embodiments herein are directed to a vertebral fusion device that can include a first endplate comprising a first extension portion, the first extension portion comprising a first bore extending therethrough; a second endplate comprising a second extension portion, the second extension portion comprising a second bore extending therethrough; a first ramp configured to mate with the first and second endplates; a second ramp configured to mate with the first and second endplates; wherein the first and second bores each comprise an axis wherein at least one of the axes intersects a vertical, longitudinal plane of the device. 
     Some embodiments herein are directed to a method of installing a vertebral fusion device that can include providing a vertebral fusion device in a collapsed configuration, comprising: a first endplate comprising a first extension portion and a second endplate comprising a second extension portion, both the first and second endplates extending from a first side of the device to a second side of the device; and a first ramp and a second ramp, both the first ramp and the second ramp being configured to mate with the first and second endplates, and both the first ramp and the second ramp extending from the first side of the device to the second side of the device, wherein at least one of the first and second sides of the device is configured to pivotably expand about a pivot point; wherein the device defines a first angle with respect to the pivot point. The method can also include transitioning the fusion device from the collapsed configuration to an expanded configuration, comprising: pivotably expanding at least one of the first and second sides of the device about the pivot point until the device defines a second angle with respect to the pivot point, wherein the second angle is greater than the first angle; and inserting a first fastener into a bore in the first extension portion and inserting a second fastener into a bore in the second extension portion. 
     Other embodiments herein are directed to a method of installing a vertebral fusion device that can include providing a vertebral fusion device in a collapsed configuration, comprising: a first endplate comprising a first extension portion and a second endplate comprising a second extension portion, both the first and second endplates extending from a first side of the device to a second side of the device; and a first ramp and a second ramp, both the first ramp and the second ramp being configured to mate with the first and second endplates, and both the first ramp and the second ramp extending from the first side of the device to the second side of the device, wherein at least one of the first and second sides of the device is configured to pivotably expand about a pivot point; wherein the device defines a first angle with respect to the pivot point. The method can also include transitioning the fusion device from the collapsed configuration to an expanded configuration, comprising: pivotably expanding at least one of the first and second sides of the device about the pivot point until the device defines a second angle with respect to the pivot point, wherein the second angle is greater than the first angle; and inserting a first fastener into the first extension portion along a first axis and inserting a second fastener into the second extension portion along a second axis, wherein at least one of the first and second axes is offset from a vertical, longitudinal plane of the vertebral fusion device. 
     Still other embodiments herein are directed to a method of installing a vertebral fusion device that can include providing a vertebral fusion device in a collapsed configuration, comprising: a first endplate comprising a first extension portion and a second endplate comprising a second extension portion, both the first and second endplates extending from a first side of the device to a second side of the device; and a first ramp and a second ramp, both the first ramp and the second ramp being configured to mate with the first and second endplates, and both the first ramp and the second ramp extending from the first side of the device to the second side of the device, wherein at least one of the first and second sides of the device is configured to pivotably expand about a pivot point; wherein the device defines a first angle with respect to the pivot point. The method can also include transitioning the fusion device from the collapsed configuration to an expanded configuration, comprising: pivotably expanding at least one of the first and second sides of the device about the pivot point until the device defines a second angle with respect to the pivot point, wherein the second angle is greater than the first angle; adjusting a position of at least one of the first and second extension portions relative to a body portion of at least one of the first and second endplates; and inserting a first fastener into the first extension portion along a first axis and inserting a second fastener into the second extension portion along a second axis, wherein at least one of the first and second axes is offset from a vertical, longitudinal plane of the vertebral fusion device. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating certain embodiments, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1A  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIG. 1B  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIGS. 2A-C  illustrate perspective views of one embodiment of a vertebral fusion device described herein; 
         FIG. 2D  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIG. 3A  illustrates a perspective view of one embodiment of a vertebral fusion device described herein; 
         FIG. 3B  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIG. 4  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIG. 5  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIG. 6  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIG. 7A  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIG. 7B  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIGS. 8A-B  illustrate schematic views of one embodiment of a vertebral fusion device described herein; 
         FIG. 9  illustrates a schematic view of one embodiment of a vertebral fusion device described herein; 
         FIGS. 10A-B  illustrate schematic views of one embodiment of a vertebral fusion device described herein; 
         FIGS. 11A-B  illustrate schematic views of one embodiment of a vertebral fusion device described herein; 
         FIGS. 12A-B  illustrate exploded views of one embodiment of a vertebral fusion device described herein; 
         FIGS. 12C-D  illustrate perspective views of one embodiment of a vertebral fusion device described herein; 
         FIG. 12E  illustrates a cross-sectional view of one embodiment of a vertebral fusion device described herein; 
         FIG. 12F  illustrates a perspective view of one embodiment of a vertebral fusion device described herein; 
         FIG. 13A  illustrates an exploded view of one embodiment of a vertebral fusion device described herein; 
         FIGS. 13B-E  illustrate perspective views of one embodiment of a vertebral fusion device described herein; 
         FIGS. 14A-B  illustrate perspective views of an inserter engaging a vertebral fusion device in accordance with some embodiments; 
         FIGS. 15A-D  illustrate different views of an inserter and particular components in accordance with some embodiments; 
         FIGS. 16A-E  illustrate different views of an alternative inserter and particular components in accordance with some embodiments; 
         FIG. 17  illustrates a cross-sectional view of an alternative inserter in accordance with some embodiments; 
         FIG. 18  illustrates a view of an exemplary vertebral fusion device with mounting anchors consistent with the present disclosure; 
         FIG. 19  illustrates a different view of the exemplary vertebral fusion device of  FIG. 18  with mounting anchors consistent with the present disclosure; 
         FIG. 20  illustrates a different view of the exemplary vertebral fusion device of  FIG. 19  with mounting anchors consistent with the present disclosure; 
         FIG. 21  illustrates a different view of the exemplary vertebral fusion device of  FIG. 19  with mounting anchors consistent with the present disclosure; and 
         FIGS. 22A-C  illustrate exemplary anchors consistent with the present disclosure. 
         FIG. 23  illustrates a view of an exemplary vertebral fusion device with mounting anchors consistent with the present disclosure; 
         FIG. 24  illustrates a different view of the exemplary vertebral fusion device of  FIG. 23  with mounting anchors consistent with the present disclosure; 
         FIG. 25  illustrates a different view of the exemplary vertebral fusion device of  FIG. 23  with mounting anchors consistent with the present disclosure; and 
         FIG. 26  illustrates a different view of the exemplary vertebral fusion device of  FIG. 23  with mounting anchors consistent with the present disclosure. 
         FIG. 27  illustrates a top perspective view of an alternative inserter in accordance with some embodiments; 
         FIG. 28  illustrates a close-up view of a distal end of the inserter of  FIG. 27  engaging a vertebral fusion device; 
         FIG. 29  illustrates a close-up view of a distal end of the inserter of  FIG. 27  without the vertebral fusion device; 
         FIG. 30  illustrates a cross-sectional view of a distal end of the inserter of  FIG. 27  engaging a vertebral fusion device; 
         FIG. 31  illustrates a side view of a funnel and plunger system in accordance with some embodiments; 
         FIG. 32  illustrates a side view of the funnel of  FIG. 31 ; 
         FIG. 33  illustrates a perspective view of a distal end of the funnel of  FIG. 31 ; 
         FIG. 34  illustrates a side view of the plunger of  FIG. 31 ; and 
         FIG. 35  illustrates a cross-sectional view of the funnel and plunger system of  FIG. 31  engaging a vertebral fusion device in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In a spinal fusion procedure, affected tissue between adjacent vertebrae may be removed and replaced with a prosthesis, such as an interbody cage, spacer, or other spinal implant. A plate and/or screws may also be used to secure the prosthesis within the intervertebral disc space. The intervertebral disc space can be accessed via various approaches (e.g., anterior, posterior, transforaminal, and/or lateral). In a lateral procedure, the prosthesis may be inserted through an incision on a patient&#39;s side; advantageously, this type of approach may generally avoid muscles and nerves that may otherwise be encountered in an anterior, posterior, and/or transforaminal approach. However, a lateral approach may be difficult in a patient&#39;s lumbar spine (e.g., between the L4 and L5 vertebrae), as the patient&#39;s bones, nerves, and/or musculature, such as the iliac crest, lumbar plexus, and/or psoas, can inhibit the trajectory of the screws. Accordingly, disclosed herein are vertebral fusion devices that can include an interbody spacer and a plate configured for use in lateral lumbar interbody fusion (LLIF) procedures, and that can enable implant and screw placement even in the vicinity of the iliac crest and other anatomy. 
     Some embodiments herein may be directed to vertebral fusion devices that can be configured for insertion between adjacent vertebrae via a lateral procedure (e.g., lateral lumbar interbody fusion). For example, the device may have a length (e.g., as measured between a leading end and a trailing end) that is about 100-300% greater than a width thereof (e.g., as measured in the anterior-posterior direction). The device may also have a length that is configured to laterally span a vertebral endplate. For example, the device may have a length in the range of from about 35 mm to about 65 mm. The device may also have a width in the range of from about 15 mm to about 30 mm. Some embodiments herein may be directed to expandable vertebral fusion devices that can be configured for use in lateral procedures. The expandable vertebral fusion devices described herein may have a variable height and may be configured to collapse to a smaller height prior to insertion and/or expand to a larger height after insertion. In some embodiments, the expanded height can be from about 25% to about 200% greater than the collapsed height. In other embodiments, the expanded height can be from about 100% to about 150% greater than the collapsed height. In some embodiments, the collapsed height can be in the range of from about 5 mm to about 10 mm, and/or the expanded height can be in the range of from about 15 mm to about 20 mm. In some embodiments, the expandable vertebral fusion devices may also have a variable lordotic angle. These devices may include one or more members configured to pivot about a pivot point. These devices may be configured to collapse to a smaller angle (e.g., 10.4°) prior to insertion and/or expand to a larger angle (e.g., 22.5°) after insertion. Accordingly, these devices may be configured for use in minimally-invasive surgery (MIS). For example, they may be inserted through a relatively small incision and/or through a cannula, thereby reducing trauma to the patient. Conversely, the expandable vertebral fusion devices described herein may be configured to expand to a width greater than that of other implants in the art, without requiring a larger incision. Furthermore, the height and/or lordotic angle of the expandable vertebral fusion devices may be adjusted after insertion, thereby providing a customized fit within the intervertebral space. 
     Components of all of the devices and systems disclosed herein can be made of materials known to those skilled in the art, including metals (e.g., titanium), metal alloys (e.g., stainless steel, titanium alloys, and/or cobalt-chromium alloys), ceramics, polymers (e.g., poly ether ether ketone (PEEK), polyphenylene sulfone (PPSU), polysulfone (PSU), polycarbonate (PC), polyetherimide (PEI), polypropylene (PP), polyacetals, or mixtures or co-polymers thereof), allograft, and/or combinations thereof. For example, a spacer member as described herein may include a polymeric material and a fixation member as described herein may include a metallic material. In some embodiments, the systems and devices may include radiolucent and/or radiopaque materials. In other embodiments, one or more components may be coated with a bone growth-enhancing material, such as hydroxyapatite. The components can also be machined and/or manufactured using techniques known to those skilled in the art. For example, polymeric components may be injection-molded or blow-molded. Additionally, the devices disclosed herein may be used together with materials that encourage bone growth, such as bone graft material, demineralized bone matrix, bone chips, and/or bone morphogenetic proteins. In some embodiments, these materials may advantageously be packed into hollow areas of the devices described herein. 
     As described herein, the spinal implants of the present disclosure may be configured for placement between two adjacent vertebrae, for example, as part of a spinal fusion procedure. These spinal implants may be referred to as, without limitation, interbody spacers, interbody fusion devices, vertebral fusion devices, interbody cages, and/or intervertebral cages. Each of the spinal implants described herein may include superior and/or inferior surfaces that are configured to engage and/or contact a vertebral endplate or other vertebral surface. In some embodiments, the superior and/or inferior surfaces may be convex, corresponding to the topography of the endplates. Additionally, the superior and/or inferior surfaces of each of the spinal implants described herein may include one or more texturizing members. Examples of such texturizing members include, but are not limited to, projections, bumps, teeth, grooves, peaks, spikes, and/or knurling. These texturizing features may advantageously enhance the interaction or friction, and/or reduce movement, between the implant and the vertebrae. The spinal implants of the present disclosure may be configured for insertion between adjacent vertebrae. In some embodiments, the spinal implants described herein may be configured for insertion between lumbar vertebrae (e.g., between L4-L5 vertebrae). The spinal implants described herein may be configured for insertion using a minimally-invasive procedure (e.g., through a cannula). The spinal implants described herein may be configured for insertion using a variety of approaches. In some embodiments, the spinal implants may be configured for lateral insertion. In other embodiments, the spinal implants of the present disclosure may be configured for anterior, posterior, and/or transforaminal insertion. Those skilled in the art may appreciate that directional terms such as “anterior,” “posterior,” “superior,” “inferior,” “top,” and “bottom,” and the like may be used herein for descriptive purposes and do not limit the orientation(s) in which the devices may be used. For example, those skilled in the art may appreciate that, in use, a “superior” surface may be installed adjacent an inferior vertebra, and vice versa. Accordingly, a feature described as being on top may actually be oriented towards the bottom after installation. 
     Some embodiments disclosed herein are directed to a vertebral fusion device that can include a spacer member and a fixation member (e.g., plate). The spacer member and the fixation member can be separate, or they can be integrated. In some embodiments, the device can include two or more fixation members and/or a multi-piece fixation member. In some embodiments, the fixation member(s) may be configured to move relative to the spacer member along one or more paths. The fixation member can include a bore configured to receive a fastener (e.g., bone screw, anchor, and/or staple) therethrough. These embodiments can advantageously direct the trajectory of a fastener, and/or can enable a user to alter the trajectory of a fastener, so as to avoid anatomical structures such as the lumbar plexus, psoas major, and/or iliac crest. In some embodiments, the spacer member can be expandable. For example, the spacer member can include a variable height and/or a variable lordotic angle. 
     Turning now to  FIGS. 1A-B , some embodiments herein are directed to a vertebral fusion device that can include a spacer member and a fixation member. With respect to  FIG. 1A , vertebral fusion device  10  can include a spacer member  2  and a fixation member (or plate)  4 , wherein the fixation member  4  may be configured to be offset from a vertical, longitudinal plane  6  of the spacer member  2 . The spacer member  2  may be configured for insertion between adjacent vertebrae via a lateral procedure (e.g., lateral lumbar interbody fusion). For example, the spacer member  2  may have a length (e.g., as measured between a leading end  14  and a trailing end  16 ) that is about 100-300% greater than a width thereof (e.g., as measured in the anterior-posterior direction). The spacer member  2  may also have a length that is configured to laterally span a vertebral endplate. For example, the spacer member  2  may have a length in the range of from about 40 mm to about 60 mm. The fixation member  4  may include at least one bore  8  configured to receive a fastener  12  therethrough. The fastener  12  may be, for example, a bone screw, anchor, staple, or spike. In some embodiments, the fixation member  4  may include two, three, four, or more bores configured to receive a fastener therethrough. In some embodiments, at least two bores may be horizontally and/or vertically displaced from each other. The fixation member  4  may have a height that is greater than a height of the spacer member  2 . For example, the fixation member  4  may have a height that is greater than a distance between two adjacent vertebrae. In some embodiments that include two bores, the two bores may be spaced apart by a distance that is greater than a distance between two adjacent vertebrae. The fixation member  4  may be configured to be offset (e.g., anteriorly) from the vertical, longitudinal plane  6  by an angle α, for example, in the range of from about 5° to about 90°. In some embodiments, α may be in the range of from about 5° to about 45°. In other embodiments, a may be in the range of from about 20° to about 30°. 
     Other embodiments herein are directed to methods of installing the vertebral fusion device  10 . In these embodiments, the spacer member  2  may be inserted along a first trajectory (e.g., laterally). The first trajectory may be along and/or parallel to the vertical, longitudinal plane  6 . The fixation member  4  may be inserted along a second trajectory that intersects the first trajectory (e.g., obliquely and/or anterolaterally). The first and second trajectories may intersect to form the angle α, for example, in the range of from about 5° to about 90°. Fastener  12  may be inserted into bore  8  along a third trajectory that intersects the first trajectory (e.g., obliquely and/or anterolaterally). In some embodiments, the third trajectory may be parallel to the second trajectory. 
     An alternative embodiment is illustrated in  FIG. 1B . As illustrated therein, vertebral fusion device  30  may include some or all of the features of vertebral fusion device  10 , unless expressly described otherwise. Additionally, vertebral fusion device  30  may include a securing member  32 . The securing member  32  may include a head  34  and an elongate body  36 . The head  34  may be configured to engage a tool such as an inserter and/or a driver. The elongate body  36  may include an engagement feature such as threading or ratcheting. For example, in some embodiments the securing member  32  may be a screw. The securing member  32  may be configured to couple the spacer member  2  and/or the fixation member  4 . For example, the elongate body  36  may be configured to engage a threaded opening  31  in the fixation member  4  and/or a threaded opening  33  in the spacer member  2 . In use, after the spacer member  2 , the fixation member  4 , and/or the fastener  12  are inserted, the fixation member  4  may be coupled with the spacer member  2 . In some embodiments, this step can include coupling the securing member  32  with the fixation member  4  and the spacer member  2 , for example, by threading the securing member  32  therein. The securing member  32  may also be inserted along a trajectory (e.g., a fourth trajectory) that is offset from the vertical, longitudinal plane  6 . The fourth trajectory may be parallel to the second and/or third trajectories, as described herein with respect to vertebral fusion device  10 . 
     Some embodiments herein are directed to a vertebral fusion device that can include a spacer member and a fixation member, wherein the fixation member is configured to move relative to the spacer member when it is coupled thereto. Turning to  FIGS. 2A-C , some embodiments herein are directed to a vertebral fusion device  50  that can include a spacer member  52  and a fixation member  54 . As illustrated in  FIG. 2B , the spacer  52  can include a first (e.g., leading) end  56 , a second (e.g., trailing) end  58 , a first (e.g., anterior) side  66 , and a second (e.g., posterior) side  68 . The spacer member  52  may include an upper (e.g., superior) surface  60 , a lower (e.g., inferior) surface (not shown), and an outer side surface  62  along an outer perimeter thereof. The spacer member  52  may be generally rectangular. In some embodiments, the outer side surface  62  can include at least one curved portion  70 , as illustrated, for example, in  FIG. 2C . The curved portion  70  may appear curved (e.g., concave) when viewed from the upper surface  60  and/or the lower surface. The curved portion  70  may be located at the trailing end  58  and/or anterior side  66  of the spacer member  52 . As illustrated in  FIGS. 2A-C , the curved portion may extend at least partially along the trailing end  58  and/or anterior side  66 . As illustrated in  FIGS. 2A-B , the spacer member  52  can include a central cavity  64 . In some embodiments, the central cavity  64  may be configured to receive bone growth material therein. The spacer member  52  may be configured for insertion between adjacent vertebrae via a lateral procedure (e.g., lateral lumbar interbody fusion). For example, the spacer member  52  may have a length (e.g., as measured between the leading end  56  and the trailing end  58 ) that is about 100-300% greater than a width thereof (e.g., as measured in the anterior-posterior direction). The spacer member  52  may also have a length that is configured to laterally span a vertebral endplate. For example, the spacer member  52  may have a length in the range of from about 40 mm to about 60 mm. 
     In some embodiments, the spacer member  52  can include a first mating element  72 , as illustrated in  FIG. 2B . As illustrated in  FIG. 2B , the first mating element  72  can include a groove, slot, notch, channel, and/or recess. In some embodiments, the groove, slot, notch, channel, and/or recess may include a tapered cross-section. In other embodiments, it may include a T-shaped cross-section, and may be referred to as a T-slot. In yet other embodiments, the first mating element  72  can include a protrusion, projection, lip, and/or overhang. The protrusion and/or projection can also include a tapered cross-section. The first mating element  72  can extend along a curved path. The first mating element may be disposed on the curved portion  70  of the outer side surface  62 . In some embodiments, the first mating element  72  may be disposed on at least a portion of the trailing end  58  and at least a portion of the anterior side  66 . 
     The fixation member  54  can include a second mating element  74 . As illustrated in  FIG. 2C , the second mating element  74  can be disposed on a coupling portion  80  of the fixation member. The coupling portion  80  may be configured to be at least partially disposed between the upper and lower surfaces of the spacer member  52 . The coupling portion  80  may be generally perpendicular to a fixation portion  82  of the fixation member  54 . In some embodiments, the second mating element  74  can include a groove, slot, notch, channel, and/or recess. The groove, slot, notch, channel, and/or recess may include a tapered cross-section. In other embodiments, it may include a T-shaped cross-section, and may be referred to as a T-slot. In yet other embodiments, the second mating element  74  can include a protrusion, projection, lip, and/or overhang. The protrusion and/or projection can also include a tapered cross-section. The first and/or second mating elements  72 ,  74  may each extend along a curved path. In some embodiments, the first and second mating elements  72 ,  74  may include the same radius of curvature. 
     In some embodiments, the first mating element  72  can include a groove and the second mating element  74  can include a protrusion, or vice versa. Those skilled in the art may appreciate that when the first and second mating elements  72 ,  74  are engaged, they may form a joint (e.g., a dovetail joint, a tongue and groove joint, and/or a splice joint). Accordingly, the fixation member  54  may be configured to jointedly couple to the spacer member  52 . The second mating element  74  may be configured to articulably, pivotably, and/or slideably engage the first mating element  72 . The second mating element  74  may be disposed on a leading side of the fixation member  54 . For example, the fixation member  54  may be configured to articulate at least partially about the spacer member  52  by translating the second mating element  74  along the first mating element  72 . 
     The fixation member  54  may include at least one bore  76 , as illustrated in  FIG. 2A . The bore  76  may be disposed on the fixation portion  82  of the fixation member  54 . The bore  76  may be configured to receive a fastener therethrough. The fastener may be, for example, a bone screw, anchor, staple, or spike. In some embodiments, the fixation member  54  may include two, three, four, or more bores configured to receive a fastener therethrough. In some embodiments, at least two bores may be horizontally and/or vertically offset from each other. As illustrated in  FIG. 2A , the fastener member  54  can include two bores  76  that are horizontally and vertically offset from each other. The fixation member  54  may be configured to extend beyond the upper surface  60  and/or the lower surface of the spacer member  52 . In some embodiments, at least one bore  76  may be located above the upper surface  60  of the spacer member  52  when the spacer member  52  and the fixation member  54  are articulably coupled. The fixation member  54  may have a height that is greater than a height of the spacer member  52  (e.g., as measured between the upper surface  60  and the lower surface). For example, the fixation member  4  may have a height that is greater than a distance between two adjacent vertebrae. In some embodiments that include two bores, the two bores may be spaced apart by a distance that is greater than a distance between two adjacent vertebrae. The fixation member  54  can also include a receptacle  78  therethrough. The receptacle  78  can include a threaded interior. In some embodiments, the receptacle  78  can be configured to threadably receive an inserter or implant holder therein. The fixation portion  82  of the fixation member  54  can also include one or more notches  84 , as illustrated in  FIG. 2A . The notches  84  may each be configured to engage a protrusion, such as a tab, on the inserter. In use, the protrusion may key into the notch  84  and/or the spacer member  52 , advantageously inhibiting motion of the fixation member  54  during insertion. 
     In some embodiments, the vertebral fusion device  50  can also include a locking member (not shown). The locking member can be configured to reversibly engage the spacer member  52  and/or the fixation member  54 . In some embodiments, the locking member can include a clamp, clasp, and/or catch. The locking member can be configured to inhibit movement of the fixation member  54  relative to the spacer member  52  when in a locked configuration. When in an unlocked configuration, the locking member can allow movement of the fixation member  54  relative to the spacer member  52 . The vertebral fusion device  50  can reversibly transition between the locked and unlocked configuration. 
     Also described herein are methods for installing the vertebral fusion device  50 . These methods can include providing the vertebral fusion device  50 , wherein the spacer member  52  and the fixation member  54  are articulably, pivotably, and/or slideably engaged (e.g., the first and second mating elements  72 ,  74  may be articulably, pivotably, and/or slideably engaged). In embodiments that include a locking member, the vertebral fusion device  50  may be provided in the locked configuration as described herein. In some embodiments, the vertebral fusion device  50  may be provided (e.g., inserted) between two adjacent vertebrae (e.g., between the L4 and L5 vertebrae), for example, along a lateral approach. In some embodiments, an inserter may be coupled to the vertebral fusion device  50  during the insertion process, for example, by threadably engaging the receptacle  78  and/or keying into the notches  84 . In some embodiments, the inserter may be coupled to both the fixation member  54  and the spacer member  52 . Advantageously, the inserter may inhibit movement of the fixation member  54  during insertion and/or placement. In embodiments that include a locking member, the device  50  may then be unlocked, e.g., by releasing the locking member. A position (e.g., orientation) of the fixation member  54  (e.g., the position of bore  76 ) may then be adjusted relative to the spacer member  52 . The position of the fixation member  54  may be adjusted, for example, by articulating, pivoting, and/or sliding the fixation member  54  along the path defined by the first mating element  72 . The method can also include inserting a first fastener member into the bore  76 . In some embodiments, the first fastener member may be inserted along an anterolateral trajectory. In other embodiments, the first fastener member may be inserted along an upwards trajectory (e.g., towards a superior vertebra). In use, those skilled in the art may appreciate that the vertebral fusion device  50  may advantageously enable a user to adjust the position of the bore  76 , thereby adjusting fastener placement. Accordingly, a user may be able to position the bore  76  to avoid certain anatomical structures such as the psoas major, lumbar plexus, and/or iliac crest. 
     An alternative embodiment, vertebral fusion device  100 , is illustrated in  FIG. 2D . Unless expressly described otherwise, vertebral fusion device  100  may include some or all of the features of vertebral fusion device  50 . For example, vertebral fusion device  100  may include a spacer member  114  which includes some or all of the same features as spacer member  52 . Vertebral fusion device  100  can include a modified fixation member  102 . The fixation member  102  can include a threaded post  104 , a coupling portion  106 , and a fixation portion  108 . The fixation portion  108  can include one or more bores (not shown) as described with respect to fixation member  54 . The coupling portion  106  can include some or all of the features of coupling portion  80  (e.g., a mating element as described herein). The threaded post  104  can extend, e.g., proximally, from the coupling portion  106 . The fixation portion  108  can include a through-hole  110  configured to receive at least a portion of the threaded post  104  therethrough. The through-hole  110  may include a smooth (e.g., non-threaded) interior surface. The fixation portion  108  may be coupled to an actuator  112 . The actuator  112  may include a threaded hole configured to mate with the threaded post  104 . The actuator  112  can also include an exterior tool-engaging surface. In some embodiments, the actuator  112  can include a nut. In use, the fixation portion  108  may be configured to translate along an axis defined by the threaded post  104 , towards and/or away from the spacer member  114 . 
     Also described herein are methods for installing the vertebral fusion device  100 . These methods can be the same or similar to those described with respect to the vertebral fusion device  50 . Additionally, the step of adjusting a position (e.g., orientation) of the fixation member  102  can include adjusting (e.g., increasing and/or reducing) a distance between the spacer member  114  and the fixation member  102 . The distance can be measured horizontally. The step of adjusting the fixation member  102  can include engaging the actuator  112 . In embodiments where the actuator  112  includes a nut, this step can include threading or unthreading the nut along the threaded post  104 . As the nut travels along the threaded post  104 , it may advantageously also cause translational motion of the fixation member  102  in the same direction (e.g., proximally and/or distally). Advantageously, the ability to adjust the position of the fixation member  102  (e.g., the bore(s)) by translation and articulation can provide increased freedom to a user with regards to fastener placement. 
     Other embodiments herein are directed to a vertebral fusion device that can include a movable (e.g., articulable and/or translatable) fixation member as described herein and that can also include an expandable spacer member. The expandable spacer member can include a variable height (e.g., as measured between an upper surface and a lower surface). The expandable spacer member may be generally rectangular, and in some embodiments may be configured for lateral insertion as described herein. Turning to  FIGS. 3A-B , vertebral fusion device  150  can include expandable spacer member  152 . The expandable spacer member  152  can include a first (e.g., upper) endplate  156 , a second (e.g., lower) endplate  158 , a frame  160 , an articulating screw support  162 , a link  164 , and a nut  166 . The expandable spacer member  152  may also include a drive link (not shown). The drive link may be configured to engage the first and second endplates  156 ,  158  and may be configured to pull and/or displace the endplates  156 ,  158  relative to the frame  160 . The expandable spacer member  152  may also include a first (e.g., distal and/or leading) end  170  and a second (e.g., proximal and/or trailing) end  172 . In some embodiments, vertebral fusion device  150  may include one or more features of the devices described in U.S. Patent Publication No. 2014/0249628, entitled “ARTICULATING EXPANDABLE INTERVERTEBRAL IMPLANT,” published on Sep. 4, 2014, which is hereby incorporated by reference herein in its entirety for all purposes. 
     The frame  160  can include one or more lift ramps  168  on the upper and/or lower surfaces thereof. Each lift ramp  168  may have a surface that is inclined from an intermediate portion of the frame  160  towards the proximal end  172 . Each lift ramp  168  may be configured to slideably engage an expansion ramp  174  on the first and/or second endplates  156 ,  158 . Each expansion ramp  174  may have a surface that is inclined from an intermediate portion of the first and/or second endplates  156 ,  158  towards the distal end  170 . In use, the spacer member  152  may be expanded by translating the frame  160  relative to the first and second endplates  156 ,  158 . The lift ramps  168  may engage the expansion ramps  174  and urge the first and second endplates  156 ,  158  apart, thereby increasing the height of the spacer member  152 . 
     The nut  166  can include internal threads that may be configured to mate with external threads of the link  164 . The nut  166  can also include one or more tool-engaging portions  176  disposed on an outer surface thereof. The nut  166  may be rotatably retained along a fixed axial orientation within the articulating screw support  162 . In use, a tool (e.g., a driver) may engage and rotate the nut  166 . As the nut  166  rotates, link  164  may be advanced or withdrawn with respect to the frame  160 , thereby moving endplates  156 ,  158  with respect to the frame  160  and causing an expansion or contraction of the height of the expandable spacer member  152 . 
     The articulating screw support  162  may be movably (e.g., slideably, articulably, and/or pivotably) coupled to the frame  160 . The frame  160  can also include a first mating element  178 . The first mating element  178  can include a groove, slot, notch, channel, and/or recess. In some embodiments, the groove, slot, notch, channel, and/or recess may include a tapered cross-section. In other embodiments, it may include a T-shaped cross-section, and may be referred to as a T-slot. In yet other embodiments, the first mating element  178  can include a protrusion, projection, lip, and/or overhang. The protrusion and/or projection can also include a tapered cross-section. The first mating element  178  may be disposed on a curved portion of the trailing end  172 . In some embodiments, the first mating element  178  may be disposed on at least a portion of the trailing end  172  and/or at least a portion of an anterior side. 
     The articulating screw support  162  can include a second mating element  180 . The second mating element  180  may be disposed on an inner surface of the articulating screw support  162 . In some embodiments, the second mating element  180  can include a groove, slot, notch, channel, and/or recess. The groove, slot, notch, channel, and/or recess may include a tapered cross-section. In other embodiments, it may include a T-shaped cross-section, and may be referred to as a T-slot. In yet other embodiments, the second mating element  180  can include a protrusion, projection, lip, and/or overhang. The protrusion and/or projection can also include a tapered cross-section. The first and/or second mating elements  178 ,  180  may each extend along a curved path. In some embodiments, the first and second mating elements  178 ,  180  may include the same radius of curvature. 
     In some embodiments, the first mating element  178  can include a groove and the second mating element  180  can include a protrusion, or vice versa. Those skilled in the art may appreciate that when the first and second mating elements  178 ,  180  are engaged, they may form a joint (e.g., a dovetail joint, a tongue and groove joint, and/or a splice joint). Accordingly, the articulating screw support  162  may be configured to jointedly couple to the expandable spacer member  152 . The second mating element  180  may be configured to articulably, pivotably, and/or slideably engage the first mating element  178 . For example, the articulating screw support  162  may be configured to articulate at least partially about the expandable spacer member  152  by translating the second mating element  180  along the first mating element  178 . 
     In some embodiments, the articulating screw support  162  can be configured to engage a fixation member, such as fixation member  154 , illustrated in  FIG. 3B , or any other fixation members described herein. The fixation member  154  can be directly or indirectly attached, mounted, and/or coupled to the articulating screw support  162 . In some embodiments, the fixation member  154  can be mechanically coupled to the articulating screw support  162 . In use, the nut  166  can be movable, thereby enabling expansion and/or contraction of the expandable spacer member  152  from a variety of approaches. Additionally, the fixation member can also be movable, thereby enabling a user to position the fixation member in an orientation that avoids certain anatomical structures as described herein. 
     As illustrated in  FIG. 3B , in some embodiments, the fixation member  154  can be indirectly engaged with the articulating screw support  162 . The vertebral fusion device  150  can include a threaded post  182 . In some embodiments, the threaded post  182  may be an axial extension of link  164  (e.g., the threaded post  182  may extend lengthwise along axis  186 ). The fixation member  154  can include some or all of the features of fixation member  102 . For example, fixation member  154  can include a through-hole  184  configured to receive at least a portion of the threaded post  182  therethrough. The through-hole  184  may include a smooth (e.g., non-threaded) interior surface. The vertebral fusion device  150  may also include an actuator  188 . The actuator  188  may include a threaded hole configured to mate with the threaded post  182 . The actuator  188  may also include an exterior tool-engaging surface. In some embodiments, the actuator  188  can include a nut. In use, the fixation member  154  may advantageously be configured to translate along the axis  186 , towards and/or away from the expandable spacer member  152 . 
     Also described herein are methods for installing the vertebral fusion device  150 . These methods can include providing the vertebral fusion device  150  in a collapsed configuration, wherein the device  150  has a first height (e.g., as measured from an upper surface of endplate  156  to a lower surface of endplate  158 ). In some embodiments, this step can include inserting the vertebral fusion device between two adjacent vertebrae (e.g., between the L4 and L5 vertebrae), for example, along a lateral, oblique, or anterolateral approach. These methods can also include adjusting a position (e.g., orientation) of the link  164  and/or the fixation member  154  relative to the expandable spacer member  152 . The position of the link  164  and/or fixation member  154  can be adjusted, for example, by articulating, pivoting, and/or sliding the articulating screw support  162  along the path defined by the first mating element  178 . These methods can also include expanding the vertebral fusion device  150  to an expanded configuration, wherein the device  150  has a second height that is greater than the first height. This step can include rotating the nut  166 , thereby applying a force to the frame  160  and separating the endplates  156 ,  158  as described herein. In some embodiments, this step can also include inserting a tool (e.g., a driver) which engages and rotates the nut  166 . The tool can be inserted along a lateral, oblique, or anterolateral approach. Advantageously, a curved path of the first mating element  178  can enable actuation of nut  166  at an angle with respect to a longitudinal axis of spacer  152 . In this manner, spacer member  152  may be inserted into the body along a non-linear path, for example during a transforaminal, posterior, and/or lateral insertion, and articulating screw support  162  may be positioned to be more readily accessible along the insertion path (e.g., oblique and/or anteriolateral) to a tool end which engages nut  166  for rotation, thereby minimizing disturbance of body tissue. In some embodiments, the device  150  can be inserted along a lateral path and the tool can be inserted along an oblique and/or anteriolateral path. In other embodiments, the device  150  can be inserted along an oblique and/or anteriolateral path and articulated into a lateral position (e.g., the expandable spacer member  152  can articulate relative to the link  164  and/or fixation member  154 ). 
     The method can also include inserting a first fastener member into a bore on the fixation member  154 . In some embodiments, the first fastener member may be inserted along an anterolateral and/or oblique trajectory. In other embodiments, the first fastener member may be inserted along an upwards trajectory (e.g., towards a superior vertebra). In use, those skilled in the art may appreciate that the vertebral fusion device  150  may advantageously enable a user to adjust the position of the bore, thereby adjusting fastener placement. Accordingly, a user may be able to position the bore to avoid certain anatomical structures such as the psoas major, lumbar plexus, and/or iliac crest. 
     In some embodiments, for example, those relating to the vertebral fusion device illustrated in  FIG. 3B , the step of adjusting a position (e.g., orientation) of the fixation member  154  can include adjusting (e.g., increasing and/or reducing) a distance between the spacer member  152  and the fixation member  154 . The distance can be measured along axis  186 . The step of adjusting the fixation member  154  can include engaging the actuator  188 . In embodiments where the actuator  188  includes a nut, this step can include threading or unthreading the nut along the threaded post  182 . As the nut travels along the threaded post  182 , it may advantageously also cause translational motion of the fixation member  154  in the same direction (e.g., proximally and/or distally). Advantageously, the ability to adjust the position of the fixation member  154  (e.g., the bore(s)) by translation and articulation can provide increased freedom to a user with regards to fastener placement. 
     Turning to  FIG. 4 , some embodiments herein are directed to a vertebral fusion device  200  that can include a spacer member  202  and a first movable fixation member  204 . The first movable fixation member  204  can be configured to be moveably (e.g., articulably, pivotably, and/or slideably) coupled and/or engaged to the spacer member  204 , as described herein with respect to, e.g., vertebral fusion devices  50 ,  100 , and/or  150 . For example, the first movable fixation member  204  can include a second mating element configured to engage a corresponding first mating element on the spacer member  202 . In some embodiments, the first movable fixation member  204  can be configured to translate towards and/or away from the spacer member  202 , for example, as described herein with respect to vertebral fusion device  100 . The first movable fixation member  204  can include a height that, when coupled to the spacer member  202 , extends from a central portion  206  of the spacer member to a position above and/or beyond an upper or lower surface  208 ,  210  of the spacer member  202 . As illustrated in  FIG. 4 , the height of the first movable fixation member  204  can extend beyond/above the upper surface  208  of the spacer member  202 . In these embodiments, the first movable fixation member  204  may be referred to as an upper fixation member. In other embodiments, the height of the first movable fixation member  204  can extend beyond/below the lower surface  210  of the spacer member. In these embodiments, the first movable fixation member  204  may be referred to as a lower fixation member. 
     As illustrated in  FIG. 4 , in some embodiments, the first movable fixation member  204  can include a single bore  212 . The bore  212  can be configured to receive a fastener (e.g., a bone screw, anchor, and/or staple) therethrough. In other embodiments, the first movable fixation member  204  can include two or more bores. The two or more bores may be horizontally displaced relative to each other (e.g., displaced along a width of the fixation member  204 ). In some embodiments, the two or more bores may be vertically aligned (e.g., aligned along the height of the fixation member  204 ). 
     As illustrated in  FIG. 4 , the vertebral fusion device  200  can include a second fixation member  214 . The second fixation member  214  may be movable or stationary. In embodiments where the second fixation member  214  is movable, it may include some or all of the same features as first fixation member  204 . In these embodiments, the spacer member  202  may include an additional mating element (e.g., curved tongue or groove) configured to engage a corresponding mating element on the second fixation member  214 . In embodiments where the second fixation member  214  is stationary, it may be coupled (e.g., attached) to the spacer member  202 . In some embodiments, the second fixation member  214  and the spacer member  202  can together make up a unitary body. The second fixation member  214  can include a height that, when coupled to the spacer member  202 , extends from the central portion  206  of the spacer member  202  to a position above and/or beyond an upper or lower surface  208 ,  210  of the spacer member  202 . As illustrated in  FIG. 4 , the height of the second fixation member  214  can extend beyond/below the lower surface  210  of the spacer member  202 . In these embodiments, the second fixation member may be referred to as the lower fixation member. In other embodiments, the height of the second fixation member  214  can extend beyond/above the upper surface  208  of the spacer member  202 . In these embodiments, the second fixation member may be referred to as the upper fixation member. As illustrated in  FIG. 4 , the second fixation member  214  may extend away from the spacer member  202  in a direction opposite that of the first fixation member  204 . 
     Embodiments herein are also directed to methods of installing the vertebral fusion device  200 . These methods can include some or all of the steps described herein with respect to vertebral fusion devices  50 ,  100 , and  150 , for example. These methods can include providing the vertebral fusion device  200 , wherein the spacer member  202  and the fixation member  204  are articulably, pivotably, and/or slideably engaged (e.g., the first and second mating elements (not shown) may be articulably, pivotably, and/or slideably engaged). In embodiments that include a locking member, the vertebral fusion device  200  may be provided in a locked configuration. The locking member may inhibit movement of the movable fixation member(s). In some embodiments, the vertebral fusion device  200  may be provided (e.g., inserted) between two adjacent vertebrae (e.g., between the L4 and L5 vertebrae), for example, along a lateral approach. In embodiments that include a locking member, the device  200  may then be unlocked, e.g., by releasing the locking member. A position (e.g., orientation) of the first movable fixation member  204  (e.g., the position of bore  212 ) may then be adjusted relative to the spacer member  202 . The position of the first movable fixation member  204  may be adjusted, for example, by articulating, pivoting, and/or sliding the fixation member  204  along the path defined by the first mating element. In some embodiments, this step can also include axially translating the fixation member  204  towards and/or away from the spacer member  202 . The method can also include inserting a first fastener member into the bore  212 . In some embodiments, the first fastener member may be inserted along an anterolateral trajectory. In other embodiments, the first fastener member may be inserted along an upwards trajectory (e.g., towards a superior vertebra). 
     In embodiments where the second fixation member  214  is stationary, a second fastener member can be inserted into bore  216  either before or after the first fastener member is inserted into bore  212 . Advantageously, the second fixation member  214 , when stationary, can provide stability to the device  200  while the first fixation member  204  can provide adjustable fastener placement. In embodiments where the second fixation member  214  is movable, methods herein can also include the steps of adjusting a position (e.g., orientation) of the second fixation member  214  relative to the spacer member  202  and inserting a fastener member into a bore thereof. In these embodiments, the first and second fixation members  204 ,  214  may advantageously be independently adjustable. Accordingly, each of the first and second fixation members  204 ,  214  may be positioned differently to accommodate the particular anatomical features of a patient and/or the planned trajectory of the associated fastener (e.g., towards the inferior vertebra or towards the superior vertebra). 
     Other embodiments herein are directed to vertebral fusion devices that can include a spacer member and a fixation member, wherein the fixation member is configured to translate (e.g., telescope, extend, and/or retract) relative to the spacer member. In some embodiments, the fixation member may be configured to translate along a horizontal axis. In other embodiments, the fixation member may be configured to translate along a vertical axis. In yet other embodiments, the fixation member may be configured to translate along an axis that defines an angle in the range of from about 0° to about 180° relative to a side surface of the spacer member. 
     As illustrated in  FIG. 5 , vertebral fusion device  250  can include a spacer member  252  and a fixation member  254 , wherein the fixation member  254  can be translatably coupled to and/or engaged with the spacer member  252 . The spacer member  252  can include a first (e.g, distal and/or leading) side  256 , a second (e.g., proximal and/or trailing) side  258 , a third (e.g., anterior) side  260 , and/or a fourth (e.g., posterior) side  262 . The four sides can define a generally rectangular shape. The spacer member  252  can include a vertical, longitudinal plane  274 . The spacer member  252  can also include a cavity  264 . The cavity  264  can include an opening  266  on the third side  260  of the spacer member  252 . The spacer member  252  can also include a first mating element (not shown). The first mating element of the spacer member  252  can be configured to engage the second mating element  268  of the fixation member  254 , described herein. In some embodiments, the spacer member  252  can include two or more first mating elements. The first mating element may be disposed within the cavity  264 . The first mating element can include, for example, a ramp, rack, and/or track. In some embodiments, the first mating element can define a curved, angled, and/or straight path. The path may extend generally transversely towards and/or away from the opening  266 . In some embodiments, the path may be parallel to a horizontal plane of the spacer member  252 . In other embodiments, the path may be perpendicular or skewed to the horizontal plane. 
     The fixation member  254  can include a second mating element  268 . The fixation member  254  can include two or more second mating elements  268 . The second mating element  268  may be configured to be disposed within the cavity  264  of the spacer member  252 . The second mating element  268  can include, for example, a ramp, rail, rod, pinion, and/or other element configured to engage with and translate relative to the mating element of the spacer member  252 . As illustrated in  FIG. 5 , the two second mating elements  268  can each include a rail. The second mating element  268  may also define a path. The path of the second mating element  268  may be parallel to the path of the first mating element. The second mating element(s)  268  may each have different features (e.g., length, curvature, and/or angle). The second mating element  268  may be coupled perpendicularly to the fixation member  254 . In other embodiments, the second mating element  268  may be at a non-perpendicular angle (e.g., less than 90°) relative to the fixation member  254 . The fixation member  254  may be angled in any direction relative to the second mating element(s)  268  and/or spacer member  252 . For example, the fixation member  254  may be angled towards the second side  258  (e.g., obliquely and/or anterolaterally), as illustrated in  FIG. 5 . In other embodiments, the fixation member  254  may be angled towards an upper surface  270  or a lower surface (not shown) of the spacer member  252 . The fixation member  254  can include one or more bores  278  extending therethrough, wherein each may be configured to receive a fastener therein. Each bore  278  can include an axis  276 . When the device  250  is in an assembled configuration, the axis  276  can be offset (e.g., anterolaterally and/or obliquely) from the vertical, longitudinal plane  274  by an angle β, for example, in the range of from about 5° to about 90°. In some embodiments, β may be in the range of from about 5° to about 45°. In other embodiments, β may be in the range of from about 20° to about 30°. The second mating element  268  may be statically or dynamically (e.g., pivotably and/or articulably) coupled to the fixation member  254 . In use, the fixation member  254  may be configured to translate at least partially into and out of the cavity  264  of the spacer member  252 . This may occur as the mating elements of the spacer member  252  and the fixation member  254  engage each other (e.g., two rails coupled to the fixation member  254  may slide along two tracks within the cavity  264  of the spacer member  252 ). 
     In some embodiments, the device may further include an actuator (not shown). The actuator may be configured to urge translation of the fixation member  254  relative to the spacer member  252 . In some embodiments, the actuator may be configured to engage a tool, such as a driver. In other embodiments, the device  250  may further include a locking member (not shown). The locking member may be configured to maintain the position of the fixation member  254  relative to the spacer member  252 . In some embodiments, the locking member may be configured to inhibit retraction of the fixation member  254  towards the cavity  264 . In other embodiments, the mating elements may be configured to inhibit retraction of the fixation member  254 . For example, the mating elements may include teeth and/or ratcheting. 
     Embodiments herein are also directed to methods of installing the vertebral fusion device  250 . These methods can include providing the vertebral fusion device  250  in a collapsed configuration. In some embodiments, this step can include inserting the vertebral fusion device  250  between adjacent vertebrae along a lateral trajectory as described herein. In the collapsed configuration, the vertebral fusion device  250  may include a first width. In some embodiments, the first width may be equal to a width of the spacer member  252  as measured from third side  260  to the fourth side  262 . An outer surface  272  of the fixation member  254  may be a first distance from the third surface  260  of the spacer member  252 . Additionally, when in the collapsed configuration, at least a portion of the mating element  268  may be located within the cavity  264  of the spacer member  252 . In some embodiments, the fixation member  254  may also be partially or completely located within the cavity  264 . Furthermore, when in the collapsed configuration, the vertebral fusion device  250  may include outer dimensions (e.g., length, width, and/or height) that are not greater than the outer dimensions of the spacer member  252  alone. When in the collapsed configuration, the device  250  may also be fully contained within the intervertebral disc space of a patient. 
     These methods can also include the step of transitioning the vertebral fusion device  250  from the collapsed configuration to an expanded configuration. In the expanded configuration, the device  250  can include a second width that is greater than the first width. The outer surface  272  of the fixation member  254  may be at a second distance from the third surface  260 , wherein the second distance is greater than the first distance. A portion of the mating element  268  may be located outside the cavity  264 . The transitioning step can include translating (e.g., extending) the fixation member  254  away from the spacer member  252  (e.g., anteriorly). This step can be performed by directly urging the fixation member  254  away from the spacer member  252 , or indirectly by engaging the actuator. In some embodiments, this step can include sliding the mating element  268  of the fixation member  254  along the mating element of the spacer member  252 . In some embodiments, the fixation member  254  may translate along an axis that is not parallel to the horizontal plane of the spacer member  252 . In other embodiments, the fixation member  254  may translate, rotate, and/or pivot away from the spacer member  252 . In embodiments that include a locking member, these methods can also include locking the fixation member  254  in the expanded configuration. 
     Some methods can further include inserting a fastener into bore  278  along axis  276 . In some embodiments, this step can include inserting the fastener at an angle, relative to the vertical, longitudinal plane  274 , in the range of from about 5° to about 90°. In other embodiments, this step can include inserting the fastener along an anterolateral and/or oblique trajectory. Advantageously, a user may be able to install the spacer member  252  and fixation member  254  along a first trajectory, and may be able to install the fastener(s) along a second trajectory. In use, when the fastener is installed along an anterolateral and/or oblique trajectory, various anatomical structures may advantageously be avoided, as described herein. 
     Turning to  FIG. 6 , some embodiments herein are directed to a vertebral fusion device  300  that can include a spacer member  302  and a fixation member  304 . The spacer member  302  can include features of the other spacer members described herein. For example, the spacer member  302  may be configured for insertion between adjacent vertebrae via a lateral procedure (e.g., lateral lumbar interbody fusion). The spacer member  302  may have a length (e.g., as measured between a leading end  306  and a trailing end  308 ) that is about 100-300% greater than a width thereof (e.g., as measured in the anterior-posterior direction). The spacer member  302  may also have a length that is configured to laterally span a vertebral endplate. For example, the spacer member  302  may have a length in the range of from about 40 mm to about 60 mm. 
     The fixation member  304  can include a base element  310  and a movable element  312 . The base element  310  can include a first (e.g., superior) end  314 , a second (e.g., inferior) end  316 , a distal surface  318 , and a proximal surface  320 . The base element  310  can also include at least one bore  322  configured to receive a fastener  323  therethrough. The base element  310  can be configured to engage the spacer member  302 , for example, at the trailing end  308  thereof. For example, the base element  310  can be statically or dynamically (e.g., pivotably and/or articulably) engaged with the spacer member  302 . In some embodiments, the base element  310  can be integrated with the spacer member  302 . In other embodiments, a coupling member, such as a set screw, can be configured to couple the base element  310  with the spacer member  302 . In yet other embodiments, the base element  310  may not be engaged with the spacer member  302 . 
     The movable element  312  can include a fastener portion  330  extending from a coupler portion  328 . In some embodiments, when assembled, the fastener portion  330  may be superior to the coupler portion  328 , or vice versa. The fastener portion  330  can include a bore  332  configured to receive a fastener  333  therethrough. The coupler portion  328  can be configured to couple and/or engage the base element  310 . In some embodiments, the coupler portion  328  can be configured to be at least partially received within the base element  310 . In other embodiments, the coupler portion  328  may be coupled to the distal surface  318  or proximal surface  320  of the base element  310 . 
     The base element  310  may be configured to be movably coupled with the movable element  312 . Accordingly, the base element  310  can include a first coupling feature  324  that can be configured to engage a second coupling feature  326  on the movable element  312 . In some embodiments, the first coupling feature  324  may be disposed at the first end  314  of the base element  310 . In other embodiments, the first coupling feature  324  may be disposed at the second end  316  of the base element  310 . The second coupling feature  326  may be disposed on the coupler portion  328  of the movable element  312 . In some embodiments, the first coupling feature  324  can include a protrusion, such as a prong, pin, bump, tongue, and/or rail, and the second coupling feature  326  can include a receptacle, such as a slot, channel, hole, groove, ledge, and/or track. In other embodiments, the first coupling feature  324  can include a receptacle and the second coupling feature  326  can include a protrusion. In yet other embodiments, the first and second coupling features  324 ,  326  may be coupled via a joint (e.g., a dovetail joint, a tongue and groove joint, and/or a splice joint). In some embodiments, the second coupling feature  326  may be configured to translate (e.g., slide) along the first coupling feature  324 . In other embodiments, the second coupling feature  326  may be configured to pivot about the first coupling feature  324 . As illustrated in  FIG. 6 , the first coupling feature  324  can include a slot at the first end  314  of the base element, and the second coupling feature  326  can include a flange extending from the coupler portion  328  of the movable element  312 . In some embodiments, the slot at the first end  314  of the base element  310  can include the first coupling feature  324  therein. In other embodiments, the fixation member  304  can include two or more movable elements engaged with the base element  310 . For example, the fixation member  304  can include an upper movable element configured to translate superiorly and/or a lower movable element configured to translate inferiorly. 
     In use, the fixation member  304  may be configured to reversibly transition between an extended configuration and a retracted configuration. In the retracted configuration, the fixation member  304  may have a first height. In some embodiments, the height may be measured from the fastener portion  330  of the movable element  312  to the second end  316  of the base element  310 . The fastener portion  330  may be separated from the second end  316  by a first distance. In some embodiments, at least a section of the coupler portion  328  may be disposed within the base element  310 . In the extended configuration, the fixation member  304  may have a second height that is greater than the first height. The fastener portion  300  may be separated from the second end  316  by a second distance that is greater than the first distance. In some embodiments, the section of the coupler portion  328  that was disposed within the base element  310  may be outside of the base element  310 . In some embodiments, the device  300  may also include a locking member (not shown). In these embodiments, the locking member may be configured to inhibit extension and/or contraction of the movable element  312 . For example, the locking member may include teeth, ratcheting, a fastener, and/or other blocking features. 
     Also described herein are methods for installing the vertebral fusion device  300 . These methods can include providing the vertebral fusion device  300  in a retracted configuration as described herein. In some embodiments, this step can include inserting the device  300  between adjacent vertebrae (e.g., L4-L5 vertebrae) along a lateral trajectory. These methods can also include transitioning the fixation member  304  from the retracted configuration to the extended configuration, for example, by extending the movable element  312 . In some embodiments, the movable element  312  can translate (e.g., slide) relative to the base element  310 . For example, the movable element  312  can telescope at least partially out of the base element  310 . In other embodiments, this step can include pivoting the movable element  312  away from the base element  310 . This step can be performed by directly urging the movable element  312  away from the base element  310 , for example, by sliding the movable element  312  at least partially out of the slot on the base element  310 . In other embodiments, this step can be performed indirectly by activating an actuator engaged with the movable element  312 . In embodiments that include a locking member, the method can also include locking the fixation member  304  in the extended configuration. 
     Some methods can further include inserting fastener  323  into bore  322  and/or inserting fastener  333  into bore  332 . Those skilled in the art may appreciate that the dynamic capability of the movable element  312  can advantageously enable a user to adjust a position of the fastener  333  based on the particular anatomy of an individual patient. Accordingly, some methods can further include extending and/or retracting the movable element  312  multiple times so as to calibrate and/or improve the location of fastener placement. 
     The vertebral fusion devices described herein can be used with one or more fasteners (e.g., bone screw, anchor, and/or staple). In any of these embodiments, a curved fastener can be used. One example is illustrated in  FIG. 7A . Turning now to  FIG. 7A , some embodiments herein are directed to a vertebral fusion device  350  that can include a spacer member  352 , a fixation member  354 , and a curved fastener  356 . In some embodiments, the device  350  can also include a straight fastener  374 . The spacer member  352  and fixation member  354  can include some or all of the features of the spacer members and fixation members described herein. For example, the spacer member  352  may be configured for insertion between adjacent vertebrae via a lateral procedure (e.g., lateral lumbar interbody fusion). The spacer member  352  may have a length (e.g., as measured between a leading end  306  and a trailing end  308 ) that is about 100-300% greater than a width thereof (e.g., as measured in the anterior-posterior direction). The spacer member  352  may also have a length that is configured to laterally span a vertebral endplate. For example, the spacer member  352  may have a length in the range of from about 40 mm to about 60 mm. 
     The fixation member  354  can include a first (e.g., superior) end  362 , a second (e.g., inferior) end  364 , a distal surface  366 , and a proximal surface  368 . The fixation member  354  can also include at least one bore configured to receive a fastener therethrough. As illustrated in  FIG. 7A , the first end  362  can include a first bore  370  and the second end  364  can include a second bore  372 . The first and/or second bores  370 ,  372  can each include an axis (not shown). In some embodiments, at least one axis (e.g., the axis of first bore  370 ) can be perpendicular to the fixation member  354 . In other embodiments, at least one axis can be configured to be parallel to a vertical, longitudinal plane  351  of the spacer member  352 . In some embodiments, the fixation member  354  can include a height (e.g., as measured from the first end  362  to the second end  364 ) that is greater than a height of the base member  352 . In other embodiments, the height of the fixation member  354  can be less than or equal to the height of the base member  352 . In yet other embodiments, the device  350  may have a height that is configured to fit within a disc space. 
     The fixation member  354  can be configured to engage the spacer member  352 , for example, at the trailing end  360  thereof. For example, the fixation member  354  can be statically or dynamically (e.g., pivotably and/or articulably) engaged with the spacer member  352 . In some embodiments, the fixation member  354  can be integrated with the spacer member  352 . In other embodiments, a coupling member, such as a set screw, can be configured to couple the fixation member  354  with the spacer member  352 . In yet other embodiments, the fixation member  354  may not be engaged with the spacer member  352 . 
     The curved fastener  356  can include a curved, elongate body  376  extending from a head  378 . The elongate body  376  can be curved along a longitudinal axis thereof. In use, the elongate body  376  may be configured to curve away from the spacer member  352 . The elongate body  376  may be configured to pass through a bore (e.g., first bore  370  and/or second bore  372 ). Accordingly, the body  376  may have a diameter and/or width that is less than a diameter of first bore  370 . The curved fastener  356  can be any suitable fastener member configured to couple an implant to a bone. For example, the curved fastener  356  can include an anchor, staple, and/or screw. In some embodiments, the body  376  can be threaded. In other embodiments, the body  376  can include one or more backout-prevention members, such as teeth and/or ratcheting. The body  376  can include a tapered tip. In some embodiments, the curved fastener  356  can be cannulated. The head  378  may be enlarged and/or rounded. In other embodiments, the head  378  may be cylindrical, conical, and/or frustoconical. The head  378  may be configured to engage the fixation member  354 . For example, the head may be configured to rest within one of the bores. As illustrated in  FIG. 7A , curved fastener  356  can be engaged with the first (e.g., superior) bore  370  and straight fastener  374  can be engaged with the second (e.g., inferior) bore  372 . In other embodiments, curved fastener  356  can be engaged with the second (e.g., inferior) bore  372  and straight fastener  374  can be engaged with the first (e.g., superior) bore  370 . 
     Embodiments herein are also directed to methods of installing the vertebral fusion device  350 . These embodiments can include providing the device  350  as described herein with respect to other vertebral fusion devices. For example, in some embodiments, this step can include inserting the device  350  into a space, such as between adjacent vertebrae (e.g., L4-L5 vertebrae), along a lateral trajectory. In some embodiments, the spacer member  352  and the fixation member  354  may be coupled prior to insertion. In other embodiments, the spacer member  352  and the fixation member  354  may be coupled after insertion (e.g., in situ). The method can also include inserting the curved fastener  356  into the first bore  370  at the first (e.g., superior) end  362  of the fixation member  354 . Furthermore, the curved fastener  356  can be inserted along a curved trajectory that is coaxial with the longitudinal axis of the body  376 . In some embodiments, this step can include inserting the body  376  into a superior vertebra. Those skilled in the art may appreciate that this curved trajectory in the superior vertebra may advantageously be configured to avoid certain anatomical structures as described herein. 
     The vertebral fusion devices described herein may include a fastener configured to follow a trajectory that has been selected and/or altered to avoid certain anatomical structures as described herein. As described herein with respect to vertebral fusion device  350 , in some embodiments, a curved fastener may be included. In an alternative embodiment, illustrated in  FIG. 7B , the vertebral fusion device  350  can include one, two, or more fasteners  380  configured for lateral insertion along a posterior angle. The fastener  380  can include an elongate body  382  extending from a head  384 . The elongate body  382  can extend along axis  386  in a straight line. The elongate body  382  can include a length configured for insertion through bore  370  at an angle to the vertical, longitudinal plane  351 . In some embodiments, the elongate body  382  may have a length that is less than that of other fasteners (e.g., curved fastener  356  and/or straight fastener  374 ). Those skilled in the art may appreciate that fastener insertion along a posterior angle may entail the risk of injury to various anatomical structures. However, the shorter length of elongate body  382  may advantageously enable insertion in a posterior direction while inhibiting possible injury that may be caused by a fastener protruding into the body. 
     In use, after the spacer member  352  and the fixation member  354  have been installed, the fastener  380  may be inserted into the first bore  370  in a posterior and/or posterolateral direction (e.g., towards posterior side  388  of spacer member  352 ). The fastener  380  may also be inserted into a superior vertebra (e.g., an L4 vertebra). As illustrated in  FIG. 7B , the fastener  380  may be inserted along a trajectory such that the axis  386  intersects the vertical, longitudinal plane  351  of the spacer member  352 . The axis  386  and the plane  351  may intersect to form an angle γ that can be in the range of from about 5° to about 90°. In other embodiments, γ can be in the range of from about 5° to about 45°. In yet other embodiments, γ can be in the range of from about 20° to about 30°. In some embodiments, the fastener  380  may be inserted along a trajectory such that the distal tip  390  of the fastener  380  does not protrude beyond the posterior side  388  of the spacer member  352 . Those skilled in the art may appreciate that the use of fastener  380  along this posterior approach may enable placement of the fastener while avoiding certain anatomical structures as described herein. In some embodiments, a fastener (e.g., curved fastener  356 , straight fastener  374 , and/or fastener  380 ) may be also inserted into the second bore  372  and/or an inferior vertebra (e.g., an L5 vertebra). 
     In some embodiments, one or more bores of a fixation member may be angled to direct the trajectory of a fastener. As illustrated in  FIGS. 8A-B , vertebral fusion device  400  can include a spacer member  402  and a fixation member  404 . The spacer member  402  and the fixation member  404  can include some or all of the features of the spacer members and fixation members described herein, unless described otherwise. As illustrated in  FIG. 8B , the fixation member  404  can include a first (e.g., superior) end  406 , a second (e.g., inferior) end  408 , a distal surface  410 , and a proximal surface  412 . The first end  406  can include a first bore  414  and the second end  408  can include a second bore  416 . In some embodiments, the first and/or second ends  406 ,  408  can include two or more bores. As illustrated in  FIG. 8A , for example, the first end  406  can include first bore  414  and bore  418 . The first bore  414  can include an axis  420  that can be non-perpendicularly angled relative to the spacer member  402  and/or the fixation member  404 . As illustrated in  FIG. 8A , axis  420  can be configured to intersect a vertical, longitudinal plane  422  of the spacer member  352 . Axis  420  may extend in a posterior and/or posterolateral direction (e.g., towards posterior side  426  of spacer member  402 ). The axis  420  and the plane  422  may intersect to form an angle (not shown) that can be in the range of from about 5° to about 90°. In other embodiments, the angle can be in the range of from about 5° to about 45°. In yet other embodiments, the angle can be in the range of from about 20° to about 30°. As illustrated in  FIG. 8B , axis  420  can also be configured to intersect a horizontal, longitudinal plane  424  of the spacer member  352 . Axis  420  may extend in an upward or superior direction (e.g., away from superior surface  428  of the spacer member  402 ). The axis  420  and the plane  424  may intersect to form an angle δ that can be in the range of from about 5° to about 90°. In other embodiments, δ can be in the range of from about 5° to about 45°. In yet other embodiments, δ can be in the range of from about 20° to about 30°. Any other bores disposed on the fixation member  404  (e.g., bore  418 ) can include an axis having a similar trajectory as described with respect to axis  420 . 
     In use, after the spacer member  402  and the fixation member  404  have been installed, a fastener  430  may be inserted into the first bore  414  along axis  420 . As illustrated in  FIGS. 8A-B , a curved fastener (e.g., curved fastener  356 ) may be inserted therein. In other embodiments, a straight fastener may be used. The fastener may be a screw, anchor, and/or staple. The fastener may be inserted from an anterolateral and/or oblique position, and may extend posteriorly and/or posterolaterally. Advantageously, the angled axis  420  of bore  414  can direct a fastener away from certain anatomical structures as described herein, including, without limitation, the iliac crest, psoas major, dura, and/or lumbar plexus. 
     Turning now to  FIG. 9 , an alternative embodiment of a vertebral fusion device is illustrated. Vertebral fusion device  450  can include a spacer member  452 , a fixation member  454 , and a clamp member  456 . The spacer member  452  and fixation member  454  can include some or all of the features of the spacer members and fixation members described herein. For example, the spacer member  452  may be configured for insertion between adjacent vertebrae via a lateral procedure (e.g., lateral lumbar interbody fusion). The spacer member  452  may have a length (e.g., as measured between a leading end and a trailing end) that is about 100-300% greater than a width thereof (e.g., as measured in the anterior-posterior direction). The spacer member  452  may also have a length that is configured to laterally span a vertebral endplate. For example, the spacer member  452  may have a length in the range of from about 40 mm to about 60 mm. The spacer member  452  can also include a plurality of horizontal grooves at a trailing end thereof. In some embodiments, the grooves can be disposed on a proximal surface and/or on an inner surface of the spacer member  452 . Each groove can include a non-symmetrical slope. For example, each groove can be slanted, tapered, and/or sawtooth-shaped. The grooves can be configured to engage the clamp member  456  as described further herein. 
     In some embodiments, the spacer member  452  may be configured to engage the fixation member  454 . The fixation member  454  can include a first (e.g., superior) end  458  and a second (e.g., inferior) end  460 . The fixation member  454  can also include at least one bore configured to receive a fastener therethrough. As illustrated in  FIG. 9 , the second end  460  can include a single bore  462  therethrough. In some embodiments, the fixation member  454  may include only one bore. In other embodiments, the first end  458  may not include any bores. In yet other embodiments, the second end  460  may not include any bores. In some embodiments, the fixation member  454  can include a height (e.g., as measured from the first end  458  to the second end  460 ) that is greater than a height of the spacer member  452 . In other embodiments, the height of the fixation member  454  can be less than or equal to the height of the spacer member  452 . In yet other embodiments, the device  450  may have a height that is configured to fit within a disc space (e.g., between two adjacent vertebrae). 
     The clamp member  456  can include first and second prongs  464 ,  466  extending generally perpendicularly from a body portion  468 . The body portion  468  can be straight or curved. In some embodiments, the body portion  468  may be curved. In some embodiments, the body portion  468  may include a radius of curvature that is greater than that of a fastener body and not larger than that of a fastener head. The body portion  468  and first and second prongs  464 ,  466  may define a U-shaped opening  470 . Each prong  464 ,  466  can include a tip  472 ,  474  having a retention feature  476 ,  478  thereon. The retention feature  476 ,  478  may include a projection angled away from the tip, such as a sawtooth, barb, or ratchet. The retention feature  476 ,  478  may be configured to engage the grooves on the spacer member  452 . 
     Also described herein are methods for installing the vertebral fusion device  450 . These embodiments can include providing the device  450  as described herein with respect to other vertebral fusion devices. For example, in some embodiments, this step can include inserting the device  450  into a space, such as between adjacent vertebrae (e.g., L4-L5 vertebrae), along a lateral trajectory. In some embodiments, the spacer member  452  and the fixation member  454  may be coupled prior to insertion. In other embodiments, the spacer member  452  and the fixation member  454  may be coupled after insertion (e.g., in situ). A fastener  480  can be inserted into the bore  462  on the second end  460  of the fixation member  454 . Any of the fasteners described herein can be used. In some embodiments, this step can include inserting the fastener  480  into an inferior vertebra. 
     Methods described herein can also include placing the clamp member  456  above the fixation member  454 . In some embodiments, this step can include superficially placing the clamp member  456  on a surface (e.g., a lateral surface) of a superior vertebra. A fastener  482  can then be inserted within the U-shaped opening  470  of the clamp member  456 . The fastener  482  may also be inserted above the fixation member  454 . Those skilled in the art may appreciate that the fastener  482  may not be inserted into a bore in the fixation member. Advantageously, this feature may provide a user with greater flexibility with regarding fastener placement. The methods can also include translating (e.g., compressing) the clamp member  456  towards the spacer member  452  until the retention features  476 ,  478  of the clamp member  456  engage the grooves on the spacer member  452 . Those skilled in the art may appreciate that features of the clamp member  456  and the spacer member  452  may form a ratcheting mechanism, wherein the grooves of the spacer member  452  enable translation of the clamp member  456  towards spacer member (e.g., in an inferior and/or downward direction) and inhibit translation of the clamp member  456  in the reverse direction (e.g., superior and/or upward). Additionally, the head of the fastener member  482  may inhibit lateral motion of the clamp member  456 . In other embodiments, those skilled in the art may appreciate that the fixation member  454  can include a bore at the first end  458  only, and the clamp member  456  can be placed below the fixation member  454  (e.g., on an inferior vertebra). 
     Turning to  FIGS. 10A-B , an alternative embodiment of a vertebral fusion device is illustrated. Vertebral fusion device  500  can include a spacer member  502 . The vertebral fusion device  500  can also include a fastener  506 . The spacer member  502  can include some or all of the features of the spacer members described herein, unless described otherwise. As illustrated in  FIGS. 10A-B , the spacer member  502  can include a leading end  508 , a trailing end  510 , a first (e.g., anterior) side  512 , a second (e.g., posterior) side  514 , an upper (e.g., superior) side  516 , and a lower (e.g., inferior) side  518 . The spacer member  502  may be configured for insertion between adjacent vertebrae via a lateral procedure (e.g., lateral lumbar interbody fusion). The spacer member  502  may have a length (e.g., as measured between leading end  508  and trailing end  510 ) that is about 100-300% greater than a width thereof (e.g., as measured in the anterior-posterior direction). The spacer member  502  may also have a length that is configured to laterally span a vertebral endplate. For example, the spacer member  502  may have a length in the range of from about 40 mm to about 60 mm. 
     The spacer member  502  may also include a receptacle  520  (e.g., a bore and/or channel) configured to receive at least a portion of fastener  506  therethrough, as illustrated in  FIG. 10B . In some embodiments, the receptacle  520  can include an opening on the upper and/or lower sides  516 ,  518 . In other embodiments, the receptacle  520  can include an opening on the first and/or second sides  512 ,  514 . The receptacle  520  can include an axis  526 . In some embodiments, the axis  526  can be generally straight; in other embodiments, the axis  526  can be generally curved. As illustrated in  FIG. 10B , the axis  526  can be offset from a vertical plane (e.g., longitudinal vertical plane  522  and/or transverse vertical plane  524 ) of the spacer member  502 . The axis  526  may be offset from a vertical plane of the spacer member  502  by an angle in the range of from about 5° to about 90°. In some embodiments, the axis  526  may be offset from a vertical plane of the spacer member  502  by an angle in the range of from about 5° to about 45°. In other embodiments, the axis  526  may be offset from a vertical plane of the spacer member  502  by an angle in the range of from about 20° to about 30°. In some embodiments, the axis  526  can intersect a vertical plane of the spacer member  502 . The spacer member  502  can include a locking member and/or a retention member, such as ratcheting, teeth, barbs, and/or blades, which can be configured to retain the fastener  506  therein. 
     The vertebral fusion device  500  may or may not include a fixation member (not shown). In some embodiments, the spacer member  502  may be configured to engage a fixation member. In some embodiments, the fixation member may be configured to engage one or more areas of the spacer member  502 , such as the leading end  508 , trailing end  510 , first side  512 , second side  514 , upper side  516 , and/or lower side  518 . In some embodiments, the fixation member may be configured to engage an outer surface of the spacer member  502 . In other embodiments, the fixation member may be configured to engage an inner surface of the spacer member  502 . The fixation member can include one or more dimensions (e.g., length, width, and/or height) that are not larger than that of the spacer member  500 . The fixation member may be generally flat and/or planar. The fixation member may include a bore passing therethrough, and may be configured to receive the fastener  506  therein. 
     The spacer member  502  may be configured to engage (e.g., receive) the fastener  506 . As illustrated in  FIG. 10A , the fastener  506  can include an elongate body  528  extending from a head  530 . The fastener  506  can include a screw, anchor, and/or staple. The fastener  506  can include one or more features of the fasteners described herein. The elongate body  528  can be threaded. The elongate body  528  can be configured to pass through the bore  520  of the spacer member  502 . The elongate body  528  can have a length that can be configured to be greater than an intervertebral space, as illustrated in  FIG. 10A . The length of the elongate body  528  can be greater than the height of the spacer member  502 . As illustrated in  FIG. 10A , the elongate body  528  can be configured to engage two adjacent vertebral bodies. 
     Embodiments herein are also directed to methods of installing the vertebral fusion device  500 . These methods can include providing the device  500  as described herein with respect to other vertebral fusion devices. For example, in some embodiments, this step can include inserting the device  500  into a space, such as between adjacent vertebrae (e.g., L4-L5 vertebrae), along a lateral trajectory. Methods described herein can also include the step of inserting the fastener  506  through the bore  520  of the spacer member  502 . In some embodiments, when the fastener  506  is inserted, it can extend above and below the device  500  (e.g., beyond upper and lower sides  516 ,  518 ). In other embodiments, when the fastener  506  is inserted, it can be located within a perimeter of the device  500  (e.g., within the leading end  508 , trailing end  510 , first side  512 , and second side  514 ). In some embodiments, this step can include inserting the fastener  506  through an inferior vertebra, the device  500 , and a superior vertebra. In other embodiments, this step can include inserting the fastener  506  through a superior vertebra, the device  500 , and an inferior vertebra. In some embodiments, the fastener  506  can be inserted from an anterolateral and/or oblique position (e.g., between a direct lateral and direct anterior point of entry). In other embodiments, the fastener  506  can be inserted from a position anterior to the iliac crest. Advantageously, those skilled in the art may appreciate that these approaches may enable retention of the device  500  between adjacent vertebral bodies while avoiding certain anatomical structures. Some embodiments can also include locking the fastener  506  relative to the spacer member  502 . This step can include actuating the locking member. In other embodiments, a retention member may retain the fastener  506  relative to the spacer member  502  without a separate actuation step. 
     Turning now to  FIGS. 11A-B , an alternative embodiment of a vertebral fusion device is illustrated. Vertebral fusion device  550  can include a spacer member  552  and a fixation member  554 . The spacer member  552  and the fixation member  554  can include some or all of the features of the spacer members and fixation members herein, unless described otherwise. For example, the spacer member  552  may be configured for insertion between adjacent vertebrae via a lateral procedure (e.g., lateral lumbar interbody fusion). The spacer member  552  may have a length (e.g., as measured between a leading end and a trailing end) that is about 100-300% greater than a width thereof (e.g., as measured in the anterior-posterior direction). The spacer member  552  may also have a length that is configured to laterally span a vertebral endplate. For example, the spacer member  552  may have a length in the range of from about 40 mm to about 60 mm. As illustrated in  FIGS. 11A-B , the spacer member  552  can also include one or more retention members  556 . In some embodiments, the spacer member  552  can include a plurality of retention members  556 . Each retention member  556  can be configured to urge, encourage, and/or retain the vertebral fusion device  550  within an intervertebral space. In some embodiments, each retention member  556  can include a spike, anchor, and/or shim. Advantageously, the retention member(s)  556  can be deployable, extendable, and/or expandable. In some embodiments, the retention member(s)  556  may be located within the spacer member  552 . Each retention member  556  may be configured to transition between a retracted state, wherein the retention member  556  is contained within the spacer member  552 , to a deployed state, wherein at least a portion of the retention member  556  is protruding beyond the spacer member  552 . In some embodiments, the spacer member  552  can include one or more holes, for example, on upper surface  558 , through which the retention member(s)  556  can pass. In other embodiments, the device  550  can further include an actuator (not shown) that can be configured to deploy and/or retract the retention member(s)  556 . 
     In some embodiments, the spacer member  552  may be configured to engage the fixation member  554 . In these embodiments, the fixation member  554  may be configured to statically or dynamically (e.g., pivotably and/or articulably) engage the spacer member  552  as described herein. The fixation member  554  can include a first (e.g., superior) end  560  and a second (e.g., inferior) end  562 . The fixation member  554  can also include at least one bore configured to receive a fastener therethrough. As illustrated in  FIGS. 11A-B , the second end  562  can include a single bore  564  therethrough. In some embodiments, the fixation member  554  may include only one bore. In other embodiments, the first end  560  may not include any bores. In yet other embodiments, the second end  562  may not include any bores. In some embodiments, the fixation member  554  can include a height (e.g., as measured from the first end  560  to the second end  562 ) that is greater than a height of the spacer member  552  (e.g., as measured between the upper surface  558  and lower surface  559 ). In other embodiments, the height of the fixation member  554  can be less than or equal to the height of the spacer member  552 . When in an assembled configuration, as illustrated in  FIGS. 11A-B , the first end  560  may not extend beyond the upper surface  558  of the spacer member  552 , while the second end  562  may extend beyond the lower surface  559  of the spacer member  552 . 
     Also described herein are methods for installing the vertebral fusion device  550 . These embodiments can include providing the device  550  as described herein with respect to other vertebral fusion devices. For example, in some embodiments, this step can include inserting the device  550  into a space, such as between adjacent vertebrae (e.g., L4-L5 vertebrae), along a lateral trajectory. In some embodiments, the spacer member  552  and the fixation member  554  may be coupled prior to insertion. In other embodiments, the spacer member  552  and the fixation member  554  may be coupled after insertion (e.g., in situ). The vertebral fusion device  550  may be provided with the retention member(s)  556  in a retracted configuration. In this configuration, the retention member(s)  556  may be retained within the spacer member  552 . A fastener  566  can be inserted into the bore  564  on the second end  562  of the fixation member  554 . Any of the fasteners described herein can be used. In some embodiments, this step can include inserting the fastener  566  into an inferior vertebra. The methods can also include transitioning the retention member(s)  556  from the retracted configuration to the deployed configuration. This step can include deploying, extending, and/or expanding the retention member(s)  556  so that they are at least partially protruding beyond an outer surface (e.g., upper surface  558 ) of the spacer member  552 . This step can also include engaging (e.g., gripping, biting, penetrating, and/or piercing) a superior vertebra with the retention member(s)  556 . Those skilled in the art may appreciate that because the device  550  uses internal retention member  556  to engage the superior vertebra, a user advantageously may avoid interference from the iliac crest and other anatomical features. 
     Turning now to  FIGS. 12A-F , alternative embodiments of a vertebral fusion device according to some embodiments are illustrated. Unless otherwise described herein, vertebral fusion device  600  can include some or all of the features of the vertebral fusion devices described in U.S. patent application Ser. No. 14/449,428, entitled “VARIABLE LORDOSIS SPACER AND RELATED METHODS OF USE,” filed Aug. 1, 2014, U.S. Patent Publication No. 2014/0163683, entitled “EXPANDABLE VERTEBRAL IMPLANT,” published Jun. 12, 2014, and U.S. Patent Publication No. 2013/0023993, entitled “EXPANDABLE FUSION DEVICE AND METHOD OF INSTALLATION THEREOF,” published Jan. 23, 2013, all of which are hereby incorporated by reference herein in their entireties for all purposes. Vertebral fusion device  600  can include a first (e.g., upper and/or superior) endplate  602 , a second (e.g., lower and/or inferior) endplate  604 , a first engagement, angled, or ramped body  606 , and a second engagement, angled or ramped body  608 . As illustrated in  FIG. 12C , the device  600  can also include a first side  601  and a second side  603 . As described further herein, vertebral fusion device  600  can include an adjustable height and/or lordotic angle. In these embodiments, the first and/or second endplates  602 ,  604  may be configured to pivot about a pivot point, as described herein with respect to vertebral fusion device  800 . The vertebral fusion device  600  may be wedge-shaped along a latitudinal axis. For example, the device  600  may have a height that increases from the first side  601  to the second side  603 . In some embodiments, the first and/or second ramped bodies  606 ,  608  may be wedge-shaped. 
     First endplate  602  can include a body portion that can include a first (e.g., leading and/or distal) end  610  a second (e.g., trailing and/or proximal) end  612 , a first (e.g., posterior) side  618 , and a second (e.g., anterior) side  620 . The body portion of the first endplate  602  can also include an outer surface  614 , an inner surface  616 , an upper surface  622 , and a lower surface  628 . As illustrated in  FIG. 12A , the upper surface  622  can include a plurality of protrusions (e.g., bumps, teeth, and/or peaks) configured to engage a vertebral body. The upper surface  622  can be generally planar, concave, and/or convex. The first endplate  602  can include one or more mating features  624 . In some embodiments, the mating feature(s)  624  may be located on the inner surface  616 . In other embodiments, the first side  618  may include at least one mating feature  624 , and the second side  620  may include at least one mating feature  624 . In yet other embodiments, the first and/or second sides  618 ,  620  can each include a mating feature at the first end  610 , a mating feature at an intermediate portion, and a mating feature at the second end  612 . 
     As illustrated in  FIG. 12A , the first endplate  602  can also include a first extension portion  648 . The first extension portion  648  can extend, e.g., vertically, from the second end  612  of the body portion of the first endplate  602 . The first extension portion  648  can have a height that is greater than a height of the body portion of the first endplate  602 . For example, the first extension portion  648  may extend beyond the upper surface  622 . In some embodiments, the first extension portion  648  may be coupled (e.g., attached, joined, and/or connected) to the first endplate  602 . In some embodiments, the first extension portion  648  may be moveably (e.g., articulably) coupled to the body portion of the first endplate  602 , for example, as described herein with respect to vertebral fusion device  50 . For example, the body portion of the first endplate  602  and the extension portion  648  may together form a dovetail joint. In some embodiments, the first extension portion  648  and the body portion of first endplate  602  may each include a different material (e.g., a metal and/or a polymer). In other embodiments, the first extension portion  648  and the body portion of the first endplate  602  may form a unitary body. The first extension portion  648  can include a bore  650  passing therethrough. The bore  650  can be configured to receive a fastener  651  therein. The first extension portion  648  can also include a receptacle  654 . The receptacle  654  may at least partially overlap the bore  650 . The receptacle  654  may be configured to receive a retention member  656  therein. 
     As illustrated in  FIG. 12B , the bore  650  can include an axis  652 . In some embodiments, axis  652  may be generally parallel to a longitudinal axis (e.g., midline)  626  of the first endplate  602 . In other embodiments, axis  652  may be skewed relative to the longitudinal midline  626 . In yet other embodiments, axis  652  may be configured to intersect a vertical, longitudinal plane  658  of the assembled device  600 , as illustrated in  FIG. 12C . In some embodiments, the axis  652 , bore  650 , and/or first extension portion  648  may be horizontally offset from the longitudinal midline  626  and/or vertical, longitudinal plane  658 . In some embodiments, the axis  652 , bore  650 , and/or first extension portion  648  may be horizontally offset towards the second side  620 . As illustrated in  FIG. 12C , the axis  652  can intersect the plane  658  by an angle ε. In some embodiments, ε can be in the range of from about 0° to about 90°. In other embodiments, ε can be in the range of from about 5° to about 45°. In yet other embodiments, ε can be in the range of from about 20° to about 30°. In some embodiments, another angle γ can be provided, as shown in  FIG. 12B . In some embodiments, axis  652  can be arranged from 0-90 degrees off angle γ. 
     Second endplate  604  can include some or all of the same features as the first endplate  602 . In some embodiments, the first and second endplates  602 ,  604  may be symmetrical with respect to each other. As illustrated in  FIG. 12A , second endplate  604  can include a body portion that can include a first (e.g., leading and/or distal) end  630 , a second (e.g., trailing and/or proximal) end  632 , a first (e.g., posterior) side  634 , and a second (e.g., anterior) side  636 . The body portion of the second endplate  604  can also include an outer surface  638 , an inner surface  640 , an upper surface  642 , and a lower surface  644 . The lower surface  644  can include a plurality of protrusions (e.g., bumps, teeth, and/or peaks) configured to engage a vertebral body. The lower surface  644  can be generally planar, concave, and/or convex. The second endplate  604  can include one or more mating features  646 . In some embodiments, the mating feature(s)  646  may be located on the inner surface  640 . In other embodiments, the first side  634  may include at least one mating feature  646 , and the second side  636  may include at least one mating feature  646 . In yet other embodiments, the first and/or second sides  634 ,  636  can each include a mating feature at the first end  630 , a mating feature at an intermediate portion, and a mating feature at the second end  632 . 
     As illustrated in  FIG. 12A , the second endplate  604  can also include a second extension portion  660 . The second extension portion  660  can extend, e.g., vertically, from the second end  632  of the body portion of the second endplate  604 . The second extension portion  660  can have a height that is greater than a height of the body portion of the second endplate  604 . For example, the second extension portion  660  may extend beyond the lower surface  644 . In some embodiments, the second extension portion  660  may be coupled (e.g., attached, joined, and/or connected) to the body portion of the second endplate  604 . In some embodiments, the second extension portion  660  may be articulably coupled to the body portion of the second endplate  604 , for example, as described herein with respect to vertebral fusion device  50 . For example, the body portion of the second endplate  604  and the second extension portion  660  may together form a dovetail joint. In some embodiments, the second extension portion  660  and the body portion of the second endplate  604  may each include a different material (e.g., a metal and/or a polymer). In other embodiments, the second extension portion  660  and the body portion of the second endplate  604  may form a unitary body. The second extension portion  660  can include a bore  662  passing therethrough. The bore  662  can be configured to receive a fastener  663  therein. The second extension portion  660  can also include a receptacle  664 . The receptacle  664  may at least partially overlap the bore  662 . The receptacle  664  may be configured to receive a retention member  666  therein. 
     As illustrated in  FIG. 12B , the bore  662  can include an axis  668 . In some embodiments, axis  668  may be generally parallel to a longitudinal axis (e.g., midline)  670  of the second endplate  604 . In other embodiments, axis  668  may be skewed relative to the longitudinal midline  670 . In yet other embodiments, axis  668  may be configured to intersect a vertical, longitudinal plane (not shown) of the second endplate  604 , which may be coplanar with the vertical, longitudinal plane  658  of the first endplate  602 . In some embodiments, the axis  668 , bore  662 , and/or second extension portion  660  may be horizontally offset from the longitudinal midline  670  and/or vertical, longitudinal plane. In some embodiments, the axis  668 , bore  662 , and/or second extension portion  660  may be horizontally offset towards the second side  636 . In some embodiments, the axis  668  can intersect the plane (e.g., including plane  658 ) by an angle. In some embodiments, the angle can be in the range of from about 0° to about 90°. In other embodiments, the angle can be in the range of from about 5° to about 45°. In yet other embodiments, the angle can be in the range of from about 20° to about 30°. In still other embodiments, the angle can be equal to c as described herein. 
     As illustrated in  FIG. 12B , mating feature  624  of the first endplate  602  may be inclined (e.g., may extend from lower surface  628  towards upper surface  622 ) along longitudinal axis  626  in a direction from the second end  612  towards the first end  610 . In some embodiments, mating feature  624  may be angled, e.g., towards the first end  610 . In other embodiments, mating feature  624  may be inclined along the longitudinal axis  626  in a direction from the first end  610  towards the second end  612 . In some embodiments, mating feature  646  of the second endplate  604  may be declined (e.g., may extend from upper surface  642  towards lower surface  644 ) along longitudinal axis  670  in a direction from the second end  632  towards the first end  640 . In some embodiments, mating feature  646  may be angled, e.g., towards the first end  630 . In other embodiments, mating feature  646  may be declined along the longitudinal axis  670  from the first end  630  towards the second end  632 . 
     As described further herein, the first and/or second endplates  602 ,  604  may be configured to engage (e.g., mate with) the first ramped body  606 . As illustrated in  FIG. 12A , the first ramped body  606  can include a first (e.g., leading and/or distal) end  672 , a second (e.g., trailing and/or proximal) end  674 , a first (e.g., posterior) side portion  676 , and a second (e.g., anterior) side portion  678 . As illustrated in  FIG. 12B , the first ramped body  606  can also include a third (e.g., superior) end  680  and a fourth (e.g., inferior) end  682 . The third end  680  may include one or more mating features  684  configured to engage the first endplate  602  and the fourth end  682  may include one or more mating features  686  configured to engage the second endplate  604 . The first side portion  676  and/or the second side portion  678  can include one or more mating features  684 ,  686  configured to engage the first and/or second endplates  602 ,  604 . In some embodiments, the first end  672  can include two or more mating features  684  on the third end  680  and two or more mating features  686  on the fourth end  682 . Each of the mating features of the first ramped body  606  may be configured (e.g., shaped) to mate with a corresponding mating feature  624 ,  646  on the first and/or second endplates  602 ,  604 . Mating features  684 ,  686  may have substantially similar inclinations, when in an assembled configuration, as their corresponding mating features  624 ,  646 . In some embodiments, each mating feature  684  is inclined towards the first end  672  of the first ramped body  606 , and each mating feature  686  is declined towards the first end  672  of the first ramped body  606 . In other embodiments, mating feature  684  and mating feature  686  may diverge from each other along a longitudinal axis from a position relatively adjacent to the second end  674  to a position relatively adjacent to the first end  672 . In yet other embodiments, the mating features  684 ,  686  may be angled, e.g., towards the first end  672 . In still other embodiments, one or more mating features  684  may be inclined towards the second end  674  of the ramped body  606  and/or one or more mating features  686  may be declined towards the second end  674  of the ramped body  606 . In some embodiments, one or more mating features  684 ,  686  can include a protrusion (e.g., a tongue, rail, and/or shoulder). In other embodiments, one or more mating features  684 ,  686  can include a recess (e.g., a groove, track, and/or channel). In some embodiments, for example, as illustrated in  FIG. 12B , the mating features  684 ,  686  can alternate longitudinally along the first and/or second sides  676 ,  678 . In other embodiments, for example, as illustrated in  FIG. 12  B, the mating features  684 ,  686  can alternate transversely along the first and/or second sides  676 ,  678 . Each mating feature  684  on the first ramped body  606  can be generally the same. Each mating feature  686  may be generally the same. In some embodiments, at least one mating feature  684  and/or  686  may include different properties as compared to the other mating features  684 ,  686 . 
     The mating features  624 ,  646  on the first and/or second endplates  602 ,  604  as described herein may be configured to form a slidable joint with a corresponding mating feature  684 ,  686  on the first ramped body  606 . Accordingly, the first ramped body  606  may be configured to slideably engage the first and/or second endplates  602 ,  604 . The slideable joint may advantageously enable the vertebral fusion device  600  to transition reversibly between expanded and contracted configurations. The slidable joint may include, for example, a tabled splice joint, a dovetail joint, a tongue and groove joint, or another suitable joint. In some embodiments, one or more mating features on the first and/or second endplates  602 ,  604  can include a recess (e.g., a groove, track, and/or channel), and one or more mating features on the first ramped body  606  can include a protrusion (e.g., a tongue, rail, and/or shoulder) configured to slide within the groove. In other embodiments, one or more mating features on the first and/or second endplates  602 ,  604  can include a protrusion and one or more mating features on the first ramped body  606  can include a recess. 
     As illustrated in  FIG. 12A , the second end  674  of the first ramped body  606  can include a first threaded bore  688  passing longitudinally therethrough. The first threaded bore  688  may be configured to receive (e.g., threadably engage) a threaded member  704  of an actuator  702 . As illustrated in  FIG. 12A , the threaded member  704  of the actuator  702  can include a proximal end having a tool-engaging recess  710 . As illustrated in  FIGS. 12A-B , the actuator  702  can also include a washer  706  and/or a snap ring  708 . The second end  674  of the first ramped body  606  can also include a second bore  690  passing longitudinally therethrough. In some embodiments, the second bore  690  may be threaded. The second bore  690  may be configured to engage an inserter In other embodiments, the second bore  690  can advantageously be configured for use as an access port to enable graft material to be delivered into a cavity  692  (illustrated in  FIG. 12C ) of the device  600 . The second bore  690  may be laterally displaced from the first threaded bore  688 . In some embodiments, the first threaded bore  688  may be located adjacent to the second side  678  of the first ramped body  606  and the second bore  690  may be located adjacent to the first side  676 , or vice versa. In other embodiments, the first threaded bore  688  may be anteriorly offset relative to the second bore  690 , or vice versa. In some embodiments, as shown in  FIGS. 12A-12D , the second bore  690  for engaging an inserter is substantially straight and parallel relative to a central longitudinal axis that extends through the fusion device  600 . In alternative embodiments, illustrated in  FIGS. 12E and 12F , the second bore  690  for engaging an inserter can be located adjacent to the second side  678  and/or anteriorly offset relative to the first threaded bore  688 . In these embodiments, the device  600  may be advantageously configured to engage an inserter at an angle offset from the plane  658 , thereby enabling a user to position the device  600  in a direct lateral orientation, e.g., in a patient&#39;s lumbar spine, while reducing interaction with the psoas muscle. 
     The first threaded bore  688  and/or the second bore  690  can include an axis that is horizontally offset from the vertical, longitudinal plane  658 . In some embodiments, the axis (e.g., of the first threaded bore  688  and/or the second bore  690 ) can be horizontally offset towards the second side  678 . In some embodiments, the axis of the first threaded bore  688  and/or the second bore  690  can intersect the plane  658  to form an angle. In some embodiments, the angle can be in the range of from about 0° to about 90°. In other embodiments, the angle can be in the range of from about 5° to about 45°. In yet other embodiments, the angle can be in the range of from about 20° to about 30°. In still other embodiments, the angle can be equal to c as described herein. 
     When in an assembled configuration, the second ramped body  608  can be disposed adjacent to the first ramped body  606 . Second ramped body  608  can include one or more mating features configured to engage corresponding mating features  624 ,  646  on the first and/or second endplates  602 ,  604 . The mating features on the second ramped body  608  can include some or all of the same features as the mating features  684 ,  686  of the first ramped body  606 . As illustrated in  FIG. 12A , the second ramped body  608  can include a first bore  694 . The first bore  694  can be configured to be coaxial with the first threaded bore  688  of the first ramped body  606  when in an assembled configuration. The first bore  694  may be configured to receive the head portion of the actuator  702  therein. In use, the head portion may be configured to rotate within the first bore  694 . The second ramped body  608  can also include a second bore  696 . The first and/or second bores  694 ,  696  may be threaded. In some embodiments, the second bore  696  can be configured to engage an inserter. The second bore  696  can be configured to be coaxial with the second bore  690  of the first ramped body  606  when in an assembled configuration. The second bore  696  can be laterally displaced from the first bore  694 . In some embodiments, the first bore  694  may be located adjacent to a second side  698  of the second ramped body  608  and the second bore  696  may be located adjacent to a first side  697 , or vice versa. In other embodiments, the first bore  694  may be anteriorly offset relative to the second bore  696 , or vice versa. In some embodiments, illustrated in  FIG. 12E , the second bore  696  can be located adjacent to the second side  698  and/or anteriorly offset relative to the first bore  694 . In these embodiments, the device  600  may be advantageously configured to engage an inserter at an angle offset from the plane  658 , thereby enabling a user to position the device  600  in a direct lateral orientation, e.g., in a patient&#39;s lumbar spine, while reducing interaction with the psoas muscle. 
     The first bore  694  and/or the second bore  696  can include an axis that is horizontally offset from the vertical, longitudinal plane  658 . In some embodiments, the axis of the first bore  694  and/or the second bore  696  can be horizontally offset towards the second side  698 . In some embodiments, the axis of the first bore  694  and/or the second bore  696  can intersect the plane  658  to form an angle. In some embodiments, the angle can be in the range of from about 0° to about 90°. In other embodiments, the angle can be in the range of from about 5° to about 45°. In yet other embodiments, the angle can be in the range of from about 20° to about 30°. In still other embodiments, the angle can be equal to c as described herein. 
     The vertebral fusion device  600  can advantageously include an adjustable height and/or lordotic angle. In some embodiments, the device  600  may be expandable. The vertebral fusion device  600  may advantageously be configured to reversibly transition between a collapsed configuration and an expanded configuration. In a collapsed configuration, for example, as illustrated in  FIG. 12D , the vertebral fusion device  600  can include a first height (e.g., as measured from the upper surface  622  of the first endplate  602  to the lower surface  644  of the second endplate  604 ). In an expanded configuration, for example, as illustrated in  FIG. 12F , the vertebral fusion device  600  can include a second height that is greater than the first height. In some embodiments, the second height can be from about 25% to about 200% greater than the first height. In other embodiments, the second height can be from about 100% to about 150% greater than the first height. In some embodiments, the first height can be in the range of from about 5 mm to about 10 mm, and/or the second height can be in the range of from about 15 mm to about 20 mm. In some embodiments, the change in height can be caused by movement of the first and second endplates  602 ,  604  towards and/or away from each other. In these embodiments, the first and second endplates  602 ,  604  can be separated by a first distance when in the collapsed configuration and a second distance when in the expanded configuration, wherein the second distance is greater than the first distance. Those skilled in the art may appreciate that, in use, the height of the vertebral fusion device  600  can be adjusted to accommodate an individual patient&#39;s anatomy. Additionally, the device  600  may be inserted into an intervertebral space in the collapsed configuration, which may entail less trauma to surrounding tissue due to its smaller size. 
     Embodiments herein are also directed to methods of installing the vertebral fusion device  600 . Methods can include providing the device  600  in the collapsed configuration, for example, as illustrated in  FIG. 12D . In some embodiments, this step can include providing (e.g., inserting) the device  600  between two adjacent vertebrae (e.g., between the L4 and L5 vertebrae). In some embodiments, the device  600  can be inserted using an inserter, such as a straight inserter or an angled inserter. In these embodiments, the methods of installation can include coupling the inserter with the device  600 , for example, threading a threaded member of the inserter into the second bore  690 ,  696  of the first and/or second ramps  606 ,  608 . In some embodiments, the device  600  may be inserted along a lateral approach, for example, when a straight inserter is used. In other embodiments, the device  600  can be inserted along an anterolateral and/or oblique approach, for example, when an angled inserter is used. In these embodiments, the device  600  can be subsequently pivoted into a lateral orientation while in the intervertebral space. In some embodiments, the device  600  may be inserted using minimally invasive methods. In some embodiments, the intervertebral space may be prepared beforehand, for example, by performing a discectomy to remove some or all of the intervertebral disc. 
     Methods herein can also include expanding the device  600 , for example, by transitioning the device  600  from the collapsed configuration to the expanded configuration. To expand the device  600 , the second ramped body  608  may be moved towards the first ramped body  606 , or vice versa. As the first and second ramps  606 ,  608  translate towards each other, the respective mating features of the first and second ramps  606 ,  608  may push against corresponding mating features on the first and second endplates  602 ,  604 , thereby pushing the first and second endplates  602 ,  604  apart and increasing the height of the device  600 . 
     In some embodiments, the step of expanding the device  600  can include actuating the actuator  702 . This step can include applying a rotational force to the threaded member  704  to threadably engage the first ramped body  606 . The rotational force can be added directly (e.g., manually) and/or indirectly (e.g., through a driver or other tool). In some embodiments, as the threaded member  704  is rotated in a first direction, the threaded member  704  may pull the first ramped body  606  towards the second ramped body  608 . As the first ramped body  606  moves towards the second ramped body  608 , the mating features on the first ramped body  606  may engage the mating features on the first and/or second endplates  602 ,  604 , thereby pushing (e.g., wedging) the first and second endplates  602 ,  604  apart. In other embodiments, as the threaded member  704  is rotated in a second direction, the threaded member  704  may push the first ramped body  606  away from the second ramped body  608 . Those skilled in the art may appreciate that the device  600  may be reversibly expandable. Accordingly, some embodiments can include reducing the height of the device  600 , for example, by bringing the first and second endplates  602 ,  604  together. 
     In some embodiments, the device  600  can include a locking member configured to lock the device  600  in a desired configuration (e.g., at a desired height). In other embodiments, after the device  600  is expanded, bone growth material may be introduced into the cavity  692  through a channel  691 , as illustrated in  FIG. 12F . The channel  691  may pass through the first and/or second endplates  602 ,  604  from the outer surface  614 ,  638  to the cavity  692 . In some embodiments, the channel  691  may be located on the second side  620 ,  636  of the first and/or second endplates  602 ,  604 . Advantageously, the channel  691  may be positioned at a location (e.g., on the second side  620  and/or  636 ) configured to enable direct access by a surgeon in situ. In embodiments that include movable extension portions  648 ,  660 , methods herein can also include the step of adjusting a position of one or both extension portions  648 ,  660  relative to at least one of the body portions of the first and second endplates  602 ,  604 . In some embodiments, this step may be accomplished by translating (e.g., sliding) one or both extension portions  648 ,  660  along the respective body portions of the first and second endplates  602 ,  604 . For example, this step can include sliding a tongue member of at least one of the first and second extension portions  648 ,  660  within a groove member of at least one of the respective body portions of the first and/or second endplates  602 ,  604 . In other embodiments, the first and/or second extension portions  648 ,  660  may be pivoted and/or articulated relative to the respective body portions of the first and/or second endplates  602 ,  604 . Some embodiments can also include locking the position of at least one of the first and second extension portions  648 ,  660  relative to the respective body portions of the first and/or second endplates  602 ,  604 . 
     Methods herein can also include the step of inserting fastener  651  into bore  650  and/or inserting fastener  663  into bore  662 . This step can include inserting fastener  651  along an axis (e.g., axis  652 ) that is configured to intersect the longitudinal axis  626  and/or the vertical, longitudinal plane  658 . This step can also include inserting fastener  663  along an axis (e.g., axis  668 ) that is configured to intersect the longitudinal axis  670  and/or the vertical, longitudinal plane  658 . In some embodiments, this step can include inserting fastener  651  and/or fastener  663  along an anterolateral and/or oblique trajectory. In other embodiments, this step can include inserting fastener  651  into a superior vertebra and inserting fastener  663  into an inferior vertebra. As described herein, those skilled in the art may appreciate that this trajectory may advantageously avoid certain anatomical structures, such as the psoas major, lumbar plexus, and/or iliac crest. Accordingly, in some embodiments, device  600  may be inserted laterally between lumbar vertebrae and subsequently coupled to the vertebrae with minimal interference. After the fasteners  651  and/or  663  have been inserted, they may be secured by retention member  656  and/or  666 . The retention members  656 ,  666  may be disposed within the receptacles  654 ,  664 . The retention members  656 ,  666  may be configured to rotate until a portion of the retention members  656 ,  666  overlaps the bore  650 ,  662  and prevents the fasteners  651 ,  663  from backing out. Those skilled in the art may appreciate that in some embodiments, the fasteners  651 ,  663  may be inserted prior to expansion of the device  600 . 
     Turning now to  FIGS. 13A-E , an alternative embodiment of a vertebral fusion device is illustrated. Unless otherwise described herein, vertebral fusion device  800  can include some or all of the features of the vertebral fusion devices described in U.S. patent application Ser. No. 14/449,428, entitled “VARIABLE LORDOSIS SPACER AND RELATED METHODS OF USE,” filed Aug. 1, 2014, U.S. Patent Publication No. 2014/0163683, entitled “EXPANDABLE VERTEBRAL IMPLANT,” published Jun. 12, 2014, and U.S. Patent Publication No. 2013/0023993, entitled “EXPANDABLE FUSION DEVICE AND METHOD OF INSTALLATION THEREOF,” published Jan. 23, 2013. Vertebral fusion device  800  can include a first (e.g., upper and/or superior) endplate  802 , a second (e.g., lower and/or inferior) endplate  804 , a first engagement, angled or ramped body  806 , and a second engagement, angled surface or ramped body  808 . As illustrated in  FIG. 13D , the device  800  can also include a first side  801  and a second side  803 . As described further herein, vertebral fusion device  800  can include an adjustable height and/or lordotic angle. In some embodiments, one or both of the first and second sides  801 ,  803  may be configured to pivotably expand about a pivot point P. The vertebral fusion device  800  may be wedge-shaped along a latitudinal axis, such as seen from the front view shown in  FIG. 13D . For example, the device  800  may have a height that increases from the first side  801  to the second side  803 . In some embodiments, the first and/or second ramped bodies  806 ,  808  may be wedge-shaped. 
     As illustrated in  FIG. 13A , first endplate  802  can include a body portion that can include a first (e.g., leading and/or distal) end  810 , a second (e.g., trailing and/or proximal) end  812 , a first (e.g., posterior) side  818 , and a second (e.g., anterior) side  820 . The first endplate  802  can extend from the first side  801  to the second side  803  of the device  800 . The body portion of the first endplate  802  can also include an outer surface  814 , an inner surface  816 , an upper surface  822 , and a lower surface  828 . The upper surface  822  can include a plurality of protrusions (e.g., bumps, teeth, and/or peaks) configured to engage a vertebral body. The upper surface  822  can be generally planar, concave, and/or convex. As described further herein, the first endplate  802  can include one or more mating features. In some embodiments, the mating feature(s) may be located on the inner surface  816 . The first side  818  may include at least one mating feature  823 , and the second side  820  may include at least one mating feature  824 . In yet other embodiments, the first and/or second sides  818 ,  820  can each include a mating feature at the first end  810 , a mating feature at an intermediate portion, and/or a mating feature at the second end  812 . 
     As illustrated in  FIG. 13A , the first endplate  802  can also include a first extension portion  848 . The first extension portion  848  can extend from the second end  812  of the body portion of the first endplate  802 . The first extension portion  848  can have a height that is greater than a height of the body portion of the first endplate  802 . For example, the first extension portion  848  may extend beyond the upper surface  822 . In some embodiments, the first extension portion  848  may be coupled (e.g., attached, joined, and/or connected) to the body portion of the first endplate  802 . In some embodiments, the first extension portion  848  may be moveably (e.g., articulably and/or jointedly) coupled to the body portion of the first endplate  802 , for example, as described herein with respect to vertebral fusion device  50 . For example, the body portion of the first endplate  802  and the extension portion  848  may together form a dovetail joint. In some embodiments, the first extension portion  848  and the body portion of the first endplate  802  may each include a different material (e.g., a metal and/or a polymer). In other embodiments, the first extension portion  848  and the body portion of the first endplate  802  may form a unitary body. The first extension portion  848  can include a bore  850  passing therethrough. The bore  850  can be configured to receive a fastener therein. The first extension portion  848  can also include a receptacle  854 . The receptacle  854  may at least partially overlap the bore  850 . The receptacle  854  may be configured to receive a retention member  856  therein. 
     As illustrated in  FIG. 13B , the bore  850  can include an axis  852 . In some embodiments, axis  852  may be generally parallel to a longitudinal axis (e.g., midline) and/or a vertical, longitudinal plane  858  of the assembled device  800 . In other embodiments, axis  852  may be skewed relative to the vertical, longitudinal plane  858 . In yet other embodiments, axis  852  may be configured to intersect the vertical, longitudinal plane  858 . In some embodiments, the axis  852 , bore  850 , and/or first extension portion  848  may be horizontally offset from the longitudinal midline and/or vertical, longitudinal plane  858 . In some embodiments, the axis  852 , bore  850 , and/or first extension portion  848  may be horizontally offset towards the second side  820 . In other embodiments, the axis  852 , bore  850 , and/or first extension portion  848  may be horizontally offset towards the first side  818 . In some embodiments, the axis  852  can intersect the plane  858  by an angle in the range of from about 0° to about 90°. In other embodiments, the axis  852  can intersect the plane  858  by an angle in the range of from about 5° to about 45°. In yet other embodiments, the axis  852  can intersect the plane  858  by an angle in the range of from about 20° to about 30°. 
     Second endplate  804  can include some or all of the same features as the first endplate  802 . In some embodiments, the first and second endplates  802 ,  804  may be symmetrical with respect to each other. As illustrated in  FIG. 12A , second endplate  804  can include a body portion that can include a first (e.g., leading and/or distal) end  830 , a second (e.g., trailing and/or proximal) end  832 , a first (e.g., posterior) side  834 , and a second (e.g., anterior) side  836 . The second endplate  804  can extend from the first side  801  to the second side  803  of the device  800 . As illustrated in  FIG. 13A , the body portion of the second endplate  804  can also include an outer surface  838 , an inner surface  840  (illustrated in  FIG. 13D ), an upper surface  842 , and a lower surface  844 . The lower surface  844  can include a plurality of protrusions (e.g., bumps, teeth, and/or peaks) configured to engage a vertebral body. The lower surface  844  can be generally planar, concave, and/or convex. As described further herein, the second endplate  804  can include one or more mating features. In some embodiments, the mating feature(s) may be located on the inner surface  840 . The first side  834  may include at least one mating feature  845 , and the second side  820  may include at least one mating feature  846 . In yet other embodiments, the first and/or second sides  834 ,  836  can each include a mating feature at the first end  830 , a mating feature at an intermediate portion, and/or a mating feature at the second end  832 . 
     As illustrated in  FIG. 13A , the second endplate  804  can also include a second extension portion  860 . The second extension portion  860  can extend from the second end  832  of the body portion of the second endplate  804 . The second extension portion  860  can have a height that is greater than a height of the body portion of the second endplate  804 . For example, the second extension portion  860  may extend beyond the lower surface  844 . In some embodiments, the second extension portion  860  may be coupled (e.g., attached, joined, and/or connected) to the body portion of the second endplate  804 . In some embodiments, the second extension portion  860  may be articulably and/or jointedly coupled to the body portion of the second endplate  804 , for example, as described herein with respect to vertebral fusion device  50 . For example, the body portion of the second endplate  804  and the second extension portion  860  may together form a dovetail joint. In some embodiments, the second extension portion  860  and the body portion of the second endplate  804  may each include a different material (e.g., a metal and/or a polymer). In other embodiments, the second extension portion  860  and the body portion of the second endplate  804  may form a unitary body. The second extension portion  860  can include a bore  862  passing therethrough. The bore  862  can be configured to receive a fastener therein. The second extension portion  860  can also include a receptacle  864 . The receptacle  864  may at least partially overlap the bore  862 . The receptacle  864  may be configured to receive a retention member  866  therein. 
     As illustrated in  FIG. 13B , the bore  862  can include an axis  868 . In some embodiments, axis  868  may be generally parallel to a longitudinal axis (e.g., midline) and/or the vertical, longitudinal plane  858 . In other embodiments, axis  868  may be skewed relative to the vertical, longitudinal plane  858 . In yet other embodiments, axis  868  may be configured to intersect the vertical, longitudinal plane  858 . In some embodiments, the axis  868 , bore  862 , and/or second extension portion  860  may be horizontally offset from the longitudinal midline and/or vertical, longitudinal plane  858 . In some embodiments, the axis  868 , bore  862 , and/or second extension portion  860  may be horizontally offset towards the second side  836 . In other embodiments, the axis  868 , bore  862 , and/or second extension portion  860  may be horizontally offset towards the first side  834 . In some embodiments, the axis  868  can intersect the plane  858  by an angle in the range of from about 0° to about 90°. In other embodiments, the axis  868  can intersect the plane  858  by an angle in the range of from about 5° to about 45°. In yet other embodiments, the axis  868  can intersect the plane  858  by an angle in the range of from about 20° to about 30°. 
     Mating feature  823  may be generally similar to mating feature  824 , except that mating feature  824  may have different (e.g., larger) dimensions than mating feature  823 . In some embodiments, mating features  823 ,  824  of the first endplate  802  may be inclined (e.g., may extend from lower surface  828  towards upper surface  822 ) along longitudinal axis  826  (illustrated in  FIG. 13C ) in a direction from the second end  812  towards the first end  810 . In some embodiments, mating features  823 ,  824  may be angled, e.g., towards the first end  810 . In other embodiments, mating features  823 ,  824  may be inclined along the longitudinal axis  826  in a direction from the first end  810  towards the second end  812 . Mating feature  845  may be generally similar to mating feature  846 , except that mating feature  846  may have different (e.g., larger) dimensions than mating feature  845 . In some embodiments, mating features  845 ,  846  of the second endplate  804  may be declined (e.g., may extend from upper surface  842  towards lower surface  844 ) along longitudinal axis  826  in a direction from the second end  832  towards the first end  830 . In some embodiments, mating features  845 ,  846  may be angled, e.g., towards the first end  830 . In other embodiments, mating features  845 ,  846  may be declined along the longitudinal axis  826  from the first end  830  towards the second end  832 . Those skilled in the art may appreciate that mating features  823 ,  824  of the first endplate  802  may be symmetrical to (e.g., mirror images of) mating features  845 ,  846  of the second endplate  804 . 
     As described further herein, the first and/or second endplates  802 ,  804  may be configured to engage (e.g., mate with) the first ramped body  806 . As illustrated in  FIG. 13A , the first ramped body  806  can include a first (e.g., leading and/or distal) end  872 , a second (e.g., trailing and/or proximal) end  874 , a first (e.g., posterior) side portion  876 , and a second (e.g., anterior) side portion  878 . The first ramped body  806  can also include a third (e.g., superior) end  880  and a fourth (e.g., inferior) end  882 . The first ramped body  806  may extend from the first side  801  to the second side  803  of the device  800 . The first ramped body  806  can include a plurality of mating features configured to engage the mating features on the first and/or second endplates  802 ,  804 . As illustrated in  FIGS. 13A and 13E , the third end  880  can include one or more mating features  883  on the first side  876  and one or more mating features  884  on the second side  878 . The fourth end  882  can include one or more mating features  885  on the first side  876  and one or more mating features  886  on the second side  878 . Those skilled in the art may appreciate that mating features  884 ,  886  may extend in generally opposite vertical directions. Additionally, mating features  883 ,  885  may extend in generally opposite vertical directions. In some embodiments, the first side portion  876  can include at least two mating elements  883  and at least two mating elements  885 . In other embodiments, the second side portion  878  can include at least two mating elements  884  and at least two mating elements  886 . In some embodiments, the first end  872  of the first ramped body  806  can include mating features  883 ,  884 ,  885 , and  886 . 
     Each of the mating features of the first ramped body  806  may be configured (e.g., shaped) to mate with a corresponding mating feature on the first and/or second endplates  802 ,  804 . The mating features  883 ,  884  may be configured to engage the mating features  823 ,  824  of the first endplate  802 . The mating features  885 ,  886  may be configured to engage the mating features  845 ,  846  of the second endplate  804 . Mating features  884 ,  886  may have substantially similar inclinations, when in an assembled configuration, as their corresponding mating features  824 ,  846 . In some embodiments, each mating feature  884  is inclined towards the first end  872  of the first ramped body  806 , and each mating feature  886  is declined towards the first end  872  of the first ramped body  806 . In other embodiments, mating feature  884  and mating feature  886  may diverge from each other along a longitudinal axis from a position relatively adjacent to the second end  874  to a position relatively adjacent to the first end  872 . In yet other embodiments, the mating features  884 ,  886  may be angled, e.g., towards the first end  872 . In still other embodiments, one or more mating features  884  may be inclined towards the second end  874  of the first ramped body  806  and/or one or more mating features  886  may be declined towards the second end  874  of the first ramped body  806 . In some embodiments, one or more mating features  884 ,  886  can include a protrusion (e.g., a tongue, rail, and/or shoulder). In some embodiments, the protrusion can be integrally formed with the body of the first ramped body  806 , or can be a separate component. For example, in some embodiments, a series of external pins can create a protrusion in the form of a rail. In other embodiments, one or more mating features  884 ,  886  can include a recess (e.g., a groove, track, and/or channel). In some embodiments, for example, as illustrated in  FIGS. 13A and 13E , the mating features  884 ,  886  can alternate longitudinally along the second side  878 . Each mating feature  884  on the first ramped body  806  can be generally the same. Each mating feature  886  may be generally the same. In some embodiments, at least one mating feature  884  and/or  886  may include different properties as compared to the other mating features  884 ,  886 . Mating feature(s)  883  may be similar to mating feature(s)  884 , except that mating feature(s)  884  may have different (e.g., larger) dimensions than mating feature(s)  883 . Mating feature(s)  885  may be similar to mating feature(s)  886 , except that mating feature(s)  886  may have different (e.g., larger) dimensions than mating feature(s)  885 . In some embodiments, the mating features  883 ,  885  can alternate longitudinally along the first side  876 . In other embodiments, the mating features  883 ,  884  can alternate transversely along the third end  880  of the first and/or second sides  876 ,  878 . In yet other embodiments, the mating features  885 ,  886  can alternate transversely along the fourth end  882  of the first and/or second sides  876 ,  878 . In some embodiments, each mating feature  883  may be generally the same. In other embodiments, each mating feature  885  may be generally the same. In yet other embodiments, at least one of the mating features  883 ,  885  may include different properties as compared to the other mating features  883 ,  885 . 
     The mating features  823 ,  824  on the first endplate  802  may be configured to form a slidable joint with a corresponding mating feature  883 ,  884  on the first ramped body  806 . The mating features  845 ,  846  on the second endplate  804  may be configured to form a slidable joint with a corresponding mating feature  885 ,  886  on the first ramped body  806 . Accordingly, the first ramped body  806  may be configured to slideably engage the first and/or second endplates  802 ,  804 . The slideable joint may advantageously enable the vertebral fusion device  800  to transition reversibly between expanded and contracted configurations. The slidable joint may include, for example, a tabled splice joint, a dovetail joint, a tongue and groove joint, or another suitable joint. In some embodiments, one or more mating features on the first and/or second endplates  802 ,  804  can include a recess (e.g., a groove, track, and/or channel), and one or more mating features on the first ramped body  806  can include a protrusion (e.g., a tongue, rail, and/or shoulder) configured to slide within the groove. In other embodiments, one or more mating features on the first and/or second endplates  802 ,  804  can include a protrusion and one or more mating features on the first ramped body  806  can include a recess. 
     The mating features  883 ,  884 ,  885 ,  886  on the first ramped body  806  may be curved in order to impart curvature to the first and second sides  801 ,  803  of the device  800 . Advantageously, one or more of the curvatures of the mating features  883 ,  884 ,  885 ,  886  can be in the form of a helix, which results in the first endplate  802  and the second endplate  804  moving not just parallel away from one another, but also at an angle (as shown in  FIG. 13D ). The mating features of the first ramped body  806  may have a radius of curvature about the pivot point P. Furthermore, as the mating features of the first ramped body  806  may be complementary to corresponding mating features on the first and second endplates  802 ,  804 , the mating features on the first and/or second endplates  802 ,  804  may also be curved (e.g., may include a radius of curvature about the pivot point P). 
     As illustrated in  FIG. 13A , the second end  874  of the first ramped body  806  can include a first threaded bore  888  passing longitudinally therethrough. The first threaded bore  888  may be configured to receive (e.g., threadably engage) a threaded member  904  of an actuator  902 . As illustrated in  FIG. 13A , the threaded member  904  of the actuator  902  can include a proximal end having a tool-engaging recess  910 . The actuator  902  can also include a washer  906  and/or one or more snap rings  908 ,  909 . The second end  874  of the first ramped body  806  can also include a second bore  890  passing longitudinally therethrough. In some embodiments, the second bore  890  may be threaded. The second bore  890  may be configured to engage an inserter. In other embodiments, the second bore  890  can advantageously be configured for use as an access port to enable bone growth material to be delivered into a cavity of the device  800 . The second bore  890  may be laterally displaced from the first threaded bore  888 . In some embodiments, the first threaded bore  888  may be located adjacent to the second side  878  of the first ramped body  806  and the second bore  890  may be located adjacent to the first side  876 , or vice versa. In other embodiments, the first threaded bore  888  may be anteriorly offset relative to the second bore  890 , or vice versa. In some embodiments, the second bore  890  can be located adjacent to the second side  878  and/or anteriorly offset relative to the first threaded bore  888 . In these embodiments, the device  800  may be advantageously configured to engage an inserter at an angle offset from the plane  858 , thereby enabling a user to position the device  800  in a direct lateral orientation, e.g., in a patient&#39;s lumbar spine, while reducing interaction with the psoas muscle. 
     The first threaded bore  888  and/or the second bore  890  can include an axis that is horizontally offset from the vertical, longitudinal plane  858 . In some embodiments, the axis (e.g., of the first threaded bore  888  and/or the second bore  890 ) can be horizontally offset towards the second side  878 . In some embodiments, the axis (e.g., of the first threaded bore  888  and/or the second bore  890 ) can be parallel or skewed relative to the vertical, longitudinal plane  858 . In other embodiments, the axis of the first threaded bore  888  and/or the second bore  890  can intersect the plane  858  to form an angle. In some embodiments, the angle can be in the range of from about 0° to about 90°. In other embodiments, the angle can be in the range of from about 5° to about 45°. In yet other embodiments, the angle can be in the range of from about 20° to about 30°. 
     When in an assembled configuration, the second ramped body  808  can be disposed adjacent to the first ramped body  806 . The second ramped body  808  can extend from the first side  801  to the second side  803  of the device  800 . Second ramped body  808  can include one or more mating features configured to engage corresponding mating features  823 ,  824 ,  845 ,  846  on the first and/or second endplates  802 ,  804 . The mating features on the second ramped body  808  can include some or all of the same features as the mating features  883 ,  884 ,  885 ,  886  of the first ramped body  806 . For example, the mating features on the second ramped body  808  can be curved in order to impart curvature to the first and second sides  801 ,  803  of the device  800 . As illustrated in  FIG. 13A , the second ramped body  808  can include a first bore  894 . The first bore  894  can be configured to be coaxial with the first threaded bore  888  of the first ramped body  806  when in an assembled configuration. The first bore  894  may be configured to receive the head portion of the actuator  902  therein. In use, the head portion may be configured to rotate within the first bore  894 . The second ramped body  808  can also include a second bore  896 . The first and/or second bores  894 ,  896  may be threaded. In some embodiments, the second bore  896  can be configured to engage an inserter. The second bore  896  can be configured to be coaxial with the second bore  890  of the first ramped body  806  when in an assembled configuration. The second bore  896  can be laterally displaced from the first bore  894 . In some embodiments, the first bore  894  may be located adjacent to a second side  898  of the second ramped body  808  and the second bore  896  may be located adjacent to a first side  897 , as illustrated in  FIG. 13A . In other embodiments, the first bore  894  may be located adjacent to the first side  897  and the second bore  896  may be located adjacent to the second side  898 . In other embodiments, the first bore  894  may be anteriorly offset relative to the second bore  896 , or vice versa. In some embodiments, the second bore  896  can be located adjacent to the second side  898  and/or anteriorly offset relative to the first bore  894 . In these embodiments, the device  800  may be advantageously configured to engage an inserter at an angle offset from the plane  858 , thereby enabling a user to position the device  800  in a direct lateral orientation, e.g., in a patient&#39;s lumbar spine, while reducing interaction with the psoas muscle. 
     The first threaded bore  894  and/or the second bore  896  can include an axis that is horizontally offset from the vertical, longitudinal plane  858 . In some embodiments, the axis of the first bore  894  and/or the second bore  896  can be horizontally offset towards the second side  898 . In some embodiments, the axis of the first bore  894  and/or the second bore  896  can be parallel and/or skewed relative to the plane  858 . In other embodiments, the axis of the first bore  894  and/or the second bore  896  can intersect the plane  858  to form an angle. In some embodiments, the angle can be in the range of from about 0° to about 90°. In other embodiments, the angle can be in the range of from about 0° to about 45°. In yet other embodiments, the angle can be in the range of from about 20° to about 30°. 
     The vertebral fusion device  800  can advantageously include an adjustable height and/or lordotic angle. In some embodiments, the device  800  may be expandable. The vertebral fusion device  800  may advantageously be configured to reversibly transition between a collapsed configuration and an expanded configuration. In the collapsed configuration, for example, as illustrated in  FIGS. 13B-C , the vertebral fusion device  800  can include a first height (e.g., as measured from the upper surface  822  of the first endplate  802  to the lower surface  844  of the second endplate  804 ). In some embodiments, the device  800  (e.g., first and second endplates  802 ,  804 ) may define a first angle when in the collapsed configuration. In other embodiments, the first and second endplates  802 ,  804  may be generally parallel when in the collapsed configuration. In some embodiments, the first endplate  802  and the second endplate  804  can begin at an angle, and can be expanded to a greater angle. 
     In the expanded configuration, for example, as illustrated in  FIGS. 13D-E , the vertebral fusion device  800  can include a second height that is greater than the first height. In some embodiments, the second height can be from about 25% to about 200% greater than the first height. In other embodiments, the second height can be from about 100% to about 150% greater than the first height. In some embodiments, the first height can be in the range of from about 5 mm to about 10 mm, and/or the second height can be in the range of from about 15 mm to about 20 mm. In some embodiments, the change in height can be caused by movement of the first and second endplates  802 ,  804  towards and/or away from each other. In these embodiments, the first and second endplates  802 ,  804  can be separated by a first distance when in the collapsed configuration and a second distance when in the expanded configuration, wherein the second distance is greater than the first distance. Those skilled in the art may appreciate that, in use, the height of the vertebral fusion device  800  can be adjusted to accommodate an individual patient&#39;s anatomy. Additionally, the device  800  may be inserted into an intervertebral space in the collapsed configuration, which may entail less trauma to surrounding tissue due to its smaller size. 
     In other embodiments, at least one of the first and second endplates  802 ,  804  may be configured to pivot about pivot point P, illustrated in  FIG. 13D . In these embodiments, the change in height can be caused by pivoting the first and/or second endplates  802 ,  804  about pivot point P. In these embodiments, the first and second endplates  802 ,  804  be oriented at a first angle when in the collapsed configuration. The first and/or second endplates  802 ,  804  can pivot apart about the pivot point P to expand the device  800  and orient the first and second endplates  802 ,  804  at a second angle. In some embodiments, the first (e.g., collapsed) angle can be in the range of from about 5° to about 20°. For example, the first angle may be about 10.4°. In other embodiments, the second (e.g., expanded) angle can be in the range of from about 10° to about 40°. For example, the second angle may be about 22.5°. Those skilled in the art may appreciate that in some embodiments, the device  800  can be expanded by both the linear and pivotal movement of the first and/or second endplates  802 ,  804  away from each other. 
     Embodiments herein are also directed to methods of installing the vertebral fusion device  800 . Methods can include providing the device  800  in the collapsed configuration, for example, as illustrated in  FIGS. 13B-C . In some embodiments, this step can include providing (e.g., inserting and/or positioning) the device  800  between two adjacent vertebrae (e.g., between the L4 and L5 vertebrae). In some embodiments, the device  800  can be inserted using an inserter, such as a straight inserter or an angled inserter. In these embodiments, the methods of installation can include coupling the inserter with the device  800 , for example, threading a threaded member of the inserter into the second bore  890 ,  896  of the first and/or second ramped bodies  806 ,  808 . In some embodiments, the device  800  may be inserted along a lateral approach, for example, when a straight inserter is used. In other embodiments, the device  800  can be inserted along an anterolateral and/or oblique approach, for example, when an angled inserter is used. In these embodiments, the device  800  can be subsequently pivoted into a lateral orientation while in the intervertebral space. In some embodiments, the device  800  may be inserted using minimally invasive methods. In some embodiments, the intervertebral space may be prepared beforehand, for example, by performing a discectomy to remove some or all of the intervertebral disc. 
     Methods herein can also include expanding the device  800 , for example, by transitioning the device  800  from the collapsed configuration to the expanded configuration. This step can include pivotably expanding at least one of the first and second sides  801 ,  803  of the device  800 . In some embodiments, the first and second sides  801 ,  803  may be pivotably expanded at a same angular rate of change about the pivot point P. To expand the device  800 , at least one of the first and second ramped bodies  806 ,  808  may be translated relative to at least one of the first and second endplates  802 ,  804 . For example, the second ramped body  808  may be moved (e.g., translated) towards the first ramped body  806 , or vice versa. The mating features of the first and/or second ramped bodies  806 ,  808  may engage the mating features of the first and/or second endplates  802 ,  804 . As the first and second ramped bodies  806 ,  808  translate towards each other, the respective mating features of the first and second ramped bodies  806 ,  808  may push against corresponding mating features on the first and second endplates  802 ,  804 , thereby pushing (e.g., pivoting) the first and second endplates  802 ,  804  apart and increasing the height and/or angle of the device  800 . The device  800  can be expanded until it defines a second angle with respect to the pivot point P, wherein the second angle is greater than the first angle. 
     In some embodiments, the step of expanding the device  800  can include actuating the actuator  902 . This step can include inserting the threaded member  904  into the first bore  894  of the second ramped body  808  and the first threaded bore  888  of the first ramped body  806 . This step can also include applying a rotational force to the threaded member  904  to threadably engage the first ramped body  806 . The rotational force can be added directly (e.g., manually) and/or indirectly (e.g., through a driver or other tool). In some embodiments, as the threaded member  904  is rotated in a first direction, the threaded member  904  may pull the first ramped body  806  towards the second ramped body  808 . As the first ramped body  806  moves towards the second ramped body  808 , the mating features on the first ramped body  806  may engage the mating features on the first and/or second endplates  802 ,  804 , thereby pushing (e.g., wedging and/or pivoting) the first and second endplates  802 ,  804  apart. In other embodiments, as the threaded member  904  is rotated in a second direction, the threaded member  904  may push the first ramped body  806  away from the second ramped body  808 . Those skilled in the art may appreciate that the device  800  may be reversibly expandable. Accordingly, some embodiments can include reducing the height and/or angle of the device  800 , for example, by bringing the first and second endplates  802 ,  804  together. 
     In some embodiments, the device  800  can include a locking member configured to lock the device  800  in a desired configuration (e.g., at a desired height and/or angle). In these embodiments, the methods can further include locking the device  800  in the expanded configuration. In other embodiments, after the device  800  is expanded, bone growth material may be introduced into a cavity within the device  800  through the second bores  890  and/or  896  of the first and second ramped bodies  806 ,  808 . In some embodiments, the first and/or second endplate  802 ,  804  can include a channel passing from an outer surface to an inner surface and configured to receive bone graft material therethrough. In embodiments that include movable extension portions  848 ,  860 , methods herein can also include the step of adjusting a position of one or both extension portions  848 ,  860  relative to at least one of the body portions of the first and second endplates  802 ,  804 . In some embodiments, this step may be accomplished by translating (e.g., sliding) one or both extension portions  848 ,  860  along the respective body portions of the first and second endplates  802 ,  804 . For example, this step can include sliding a tongue member of at least one of the first and second extension portions  848 ,  860  within a groove member of at least one of the respective body portions of the first and/or second endplates  802 ,  804 . In other embodiments, the first and/or second extension portions  848 ,  860  may be pivoted and/or articulated relative to the respective body portions of the first and/or second endplates  802 ,  804 . Some embodiments can also include locking the position of at least one of the first and second extension portions  848 ,  860  relative to the respective body portions of the first and/or second endplates  802 ,  804 . 
     Methods herein can also include the step of inserting a first fastener into bore  850  along first axis  852  and/or a second fastener into bore  862  along second axis  868 . In some embodiments, this step can include inserting the fastener(s) along an axis that is parallel and/or skewed relative to the vertical, longitudinal plane  858 . In other embodiments, this step can include inserting the fastener(s) along an axis that is configured to intersect the vertical, longitudinal plane  858 . In some embodiments, this step can include inserting the fastener(s) along an anterolateral and/or oblique trajectory. In other embodiments, this step can include inserting the first fastener into a superior vertebra and inserting the second fastener into an inferior vertebra. As described herein, those skilled in the art may appreciate that this trajectory may advantageously avoid certain anatomical structures, such as the psoas major, lumbar plexus, and/or iliac crest. Accordingly, in some embodiments, device  800  may be inserted laterally between lumbar vertebrae and subsequently coupled to the vertebrae with minimal interference. After the fasteners have been inserted, they may be secured by retention member  856  and/or  866 . The retention members  856 ,  866  may be disposed within the receptacles  854 ,  864 . The retention members  856 ,  866  may be configured to rotate until a portion of the retention members  856 ,  866  overlaps the bore  850 ,  862  and prevents the fasteners from backing out. Those skilled in the art may appreciate that in some embodiments, the first and/or second fasteners may be inserted prior to expansion of the device  800 . 
     In addition to advantageously providing fusion devices that allow a surgeon to navigate around the lumbar plexis and iliac crest, the present application provides instrumentation that can be used with the fusion devices to accomplish these advantages. In addition to providing instrumentation in the form of straight inserters that can deliver the fusion devices to one or more desired surgical sites, the present application also includes angled inserters that can deliver the fusion devices to one or more desired surgical sites. Advantageously, an angled inserter would allow for a fusion device to be inserted and expanded into a disc space in a direct lateral placement without disrupting the psoas muscle. 
       FIGS. 14A and 14B  illustrate perspective views of an inserter engaging a vertebral fusion device in accordance with some embodiments. In particular, the inserter  900  comprises an angled inserter capable of engaging a fusion device. In the present embodiment, the fusion device  600  is the same as that shown in  FIG. 12A , and includes a first endplate  602 , a second endplate  604 , a first ramped body  606  extending therebetween and a second ramped body  608  having a first extension portion  648  for receiving a fastener and a second extension portion  660  for receiving a fastener. As the inserter  900  is angled, it advantageously helps to avoid the psoas muscle while delivering the fusion device  600  to a desired location within a disc space. 
     As shown in  FIGS. 14A and 14B , the inserter  900  comprises an outer body or shaft  906  having a distal engagement portion  908  extending therefrom. The distal engagement portion  908  is configured to engage the fusion device  600  via its second ramped body  608 . The distal engagement portion  908  is angulated relative to the outer shaft  906 . In some embodiments, the distal engagement portion  908  is at an acute angle relative to the outer shaft  906 . In some embodiments, the distal engagement portion  908  is at an angle between 10 and 75 degrees relative to the outer shaft  906 . In other embodiments, the distal engagement portion  908  is at an angle between 10 and 45 degrees relative to the outer shaft  906 . 
       FIGS. 15A-D  illustrate different views of an angled inserter and particular components in accordance with some embodiments.  FIG. 15A  shows a side view of an inserter  900   a  comprising a proximal portion  902  and a distal portion  904 , with an outer shaft  906  extending between the proximal portion  902  and distal portion  904 . The distal portion  904  comprises a pair of engagement tips  912 ,  922 —one for the holding and retaining the fusion device  900  and the other for causing expansion of the fusion device  900 . The proximal portion  902  comprises an opening in fluid communication with a pair of lumens  910 ,  920  (shown in FIG.  15 B), one corresponding to engagement tip  912  and the other corresponding to engagement tip  922 . One or more drive shafts  950  are capable of extending through the lumens  910 ,  920  to engage and actuate the engagement tips  912 ,  922 , as will be discussed in more detail below. 
       FIGS. 15B and 15C  show cross-sectional views of a distal portion  904  of the angled inserter  900   a  of  FIG. 15A . From these views, one can see the interior of the distal portion  904  of the inserter  900   a . In  FIG. 15B , a drive shaft  950  extends through the inserter  900   a  to engage a first engagement tip  912 . In  FIG. 15C , the same drive shaft  950  extends through the inserter  900   a  to engage a second engagement tip  922 . 
     As shown in  FIG. 15B , the inserter  900   a  comprises an outer shaft  906  from which a distal engagement portion  908  extends therefrom. In some embodiments, the distal engagement portion  908  houses a pair of engagement tips. The first engagement tip  912  comprises an inserter engagement tip that is designed to engage and attach the fusion device  600  to the inserter  900   a . The second engagement tip  922  comprises an actuator engagement tip that is designed to engage the actuator  702  (shown in  FIG. 12A ), thereby causing desired expansion of the fusion device  600 . The outer shaft  906  houses a first lumen  910  in communication with the first engagement tip  912  and a second lumen  920  in communication with the second engagement tip  922 . A drive shaft  950  can be delivered through either lumen  910 ,  920  in order to engage the first engagement tip  912  or the second engagement tip  922 . In some embodiments, a single drive shaft  950  is provided. The single drive shaft  950  can be used to engage both the first engagement tip  912  and the second engagement tip  922 , one at a time. In other embodiments, two or more drive shafts  950  are provided. In addition to the first lumen  910  and the second lumen  920 , the inserter  900   a  can include an angled outlet  925  which leads directly to the distal engagement portion  908 . The angled outlet  925  advantageously allows a drive shaft  950  to enter at an angle directly into the distal engagement portion  908 , as shown in  FIG. 16E . 
     The first engagement tip  912  comprises an inserter engagement tip that is designed to engage and attach the fusion device  600  to the inserter  900   a . The first engagement tip  912  comprises a rotatable body  914  having a threaded distal end configured to engage the second bore  696  (shown in  FIG. 12D ). The second bore  696  can include corresponding threads that engage the threads of the first engagement tip  912  to retain the fusion device  600  to the inserter  900   a . The first engagement tip  912  further comprises a proximal end having two or more beveled or angled ends  916 ,  918  that are capable of being engaged with corresponding beveled or angled ends  952 ,  954  of the drive shaft  950 . In some embodiments, the interface between the angled ends of the first engagement tip  912  and the distal end of the drive shaft  950  serves as gears that allow the first engagement tip  912  to be rotated. Upon rotation, the first engagement tip  912  can be threaded into the threaded bore  696  of the fusion device  600 , thereby securing the inserter  900   a  to the fusion device  600 . As shown in  FIG. 15B , the first engagement tip  912  further comprises a spherical guide  917  at a proximal end thereof. Advantageously, the spherical guide  917  helps to maintain a proper distance of separation between the angled ends or gears formed between the first engagement tip  912  and the drive shaft  950 , thereby helping to ensure that the gears are capable of rotation. In some embodiments, the first engagement tip  912  can be retained in the distal engagement portion  908  by a retaining fastener  930 . 
     The second engagement tip  922  comprises an actuator engagement tip that is designed to engage the actuator  702  (shown in  FIG. 12A ). The second engagement tip  922  comprises a rotatable body  924  having a distal end in the form of a protrusion or nub that can rotate actuator  702 . The second engagement tip  922  further comprises a proximal end having two or more beveled or angled ends  926 ,  928  that are capable of being engaged with corresponding beveled or angled ends  952 ,  954  of the drive shaft  950 . In some embodiments, the interface between the angled ends of the second engagement tip  922  and the distal end of the drive shaft  950  serves as gears that allow the second engagement tip  922  to be rotated. Upon rotation, the second engagement tip  922  causes the actuator  702  to rotate, thereby causing expansion of the fusion device  600 . Rotation of the second engagement tip  922  in an opposite direction causes the actuator  702  to rotate oppositely, thereby causing a reduction of the height of the fusion device  600 . As shown in  FIG. 15B , the second engagement tip  922  further comprises a spherical guide  927  at a proximal end thereof. Advantageously, the spherical guide  927  helps to maintain a proper distance of separation between the angled ends or gears formed between the second engagement tip  922  and the drive shaft  950 , thereby helping to ensure that the gears are capable of rotation. In some embodiments, the second engagement tip  922  can be retained in the distal engagement portion  908  by a retaining fastener  930  (as shown in  FIG. 16B ). 
     The drive shaft  950  comprises a shaft body having one or more angled or beveled ends  952 ,  954 . In some embodiments, the drive shaft  950  is advantageously capable of engaging the first engagement tip  912  and the second engagement tip  922 , thereby reducing the need for multiple instruments or drive shafts. 
       FIG. 15D  shows a close-up cross-sectional view of a proximal portion  902  of the inserter  900   a . From this view, one can see how the drive shaft  950  is retained within the body of the inserter  900   a . As the drive shaft  950  is inserted through a lumen (e.g., first lumen  910 ), the drive shaft  950  is locked within the inserter  900   a  by a spring button  960  with a taper that snaps into place to lock the drive shaft  950  therein. As shown in  FIG. 15D , the drive shaft  950  comprises one or more recessed portions  953  that are engaged by one or more protruding portions  963  of the spring button  960 . This engagement prevents the drive shaft  950  from being pushed out of the inserter  900   a  while applying torque to the angled gears described above. To remove the drive shaft  950  from the inserter  900   a , the spring button  960  can be pressed downward, thereby disengaging the spring button  960  from the drive shaft  950 . 
       FIGS. 16A-E  illustrate different views of an alternative inserter and particular components in accordance with some embodiments.  FIG. 16A  shows a close-up cross-sectional view of an inserter  900   b  comprising similar features as the inserter  900   a  in  FIG. 15A , including an outer shaft  906  housing a first lumen  910  in fluid communication with a first engagement tip  912  and a second lumen  920  in fluid communication with a second engagement tip  922 . A drive shaft  950  is capable of extending through the first lumen and the second lumen to engage and actuate the engagement tips. The first engagement tip  912  is similar to the first engagement tip in  FIG. 15A  and includes a rotatable body  914  with a threaded distal tip for engaging threads of a second bore  696  (shown in  FIG. 12D ), a pair of angled or beveled surfaces  916 ,  918  for engaging angled or beveled surfaces of the drive shaft  950 , and a spherical guide  917 . The second engagement tip  922  is different from the second engagement tip in  FIG. 15A  and includes additional features, including a translating tip, as is discussed below. 
     The second engagement tip  922  comprises a rotatable body  924  having a distal end in the form of a protrusion or nub that can rotate actuator  702  to thereby change the height of the fusion device  600 . The second engagement tip  922  further comprises a proximal end having two or more beveled or angled ends  926 ,  928  that are capable of being engaged with corresponding beveled or angled ends  952 ,  954  of the drive shaft  950 . In addition to these features, the second engagement tip  922  further comprises a translating tip  925  that is spring-loaded into the second engagement tip  922  via spring  929 . The purpose of the translating tip  925  is to advantageously make the second engagement tip  922  in proper alignment with the actuator  702 . When the second engagement tip  922  is in proper alignment with the actuator  702 , the translating tip  925  will extend outwardly from the rotatable body  924  (as shown in  FIG. 16A ), thereby allowing torque to be applied via the translating tip  925  to the actuator  702  upon rotation of the second engagement tip  922 . When the second engagement tip  922  is not in proper alignment with the actuator  702 , the translating tip  925  will be retracted from view into the rotatable body  924  (as shown in  FIG. 16B ), thereby preventing torque from being applied via the translating tip  925  to the actuator  702  upon rotation of the second engagement tip  922 . In some embodiments, one or more retaining fasteners  930  can retain first engagement tip  912  or the second engagement tip  922  within the distal engagement portion  908  of the inserter  900   b.    
       FIGS. 16C and 16D  illustrate a close up view and a cross-sectional view, respectively, of a second engagement tip  922  in accordance with some embodiments. The second engagement tip  922  comprises a body  924  that receives the translating tip  922  therein. From the cross-sectional view in  FIG. 16D , one can see how the body  924  houses the spherical guide  927 , the spring  929  and the translating tip  925 , which are all in alignment along a longitudinal axis of the second engagement tip  922 . 
       FIG. 16E  illustrates a close up view of a distal portion of the inserter  900   b , whereby the drive shaft  950  extends through an angled outlet  925  formed in the body of the inserter  900   b . With the angled outlet  925 , the first engagement tip  912  can be approached from different directions by the drive shaft  950 , thereby providing a surgeon with greater versatility when engaging the first engagement tip  912 . In some embodiment, an angled outlet extends adjacent the second engagement tip  922  such that the second engagement tip  922  can also be approached from different directions by the drive shaft  950 . 
       FIG. 17  illustrates a cross-sectional view of an alternative inserter in accordance with some embodiments. The inserter  900   c  comprises similar features as the inserters  900   a ,  900   b  discussed above, including an angled distal engagement portion  908  extending from an outer shaft  906 . In contrast to the prior embodiments, the inserter  900   c  includes a single lumen  910  in fluid communication with an engagement tip  912 . Accordingly, the inserter  900   c  can work to hold an implant (e.g., fusion device  600 ) via the engagement tip  912 , but can be expanded in another means or via a different instrument. While the inserters  900   a ,  900   b ,  900   c  are shown with respect to fusion device  600 , one skilled in the art will appreciate that the instruments can be used on their own or with other devices or implants. 
       FIGS. 18-21  illustrate an exemplary embodiment of a vertebral fusion device  1000  consistent with the principles of the present disclosure. Vertebral fusion device  1000  may include some or all of the features of vertebral fusion devices contained herein including vertebral fusion devices  350 ,  600 , and  800  and devices described in U.S. patent application Ser. No. 14/449,428, entitled “VARIABLE LORDOSIS SPACER AND RELATED METHODS OF USE,” filed Aug. 1, 2014, U.S. Patent Publication No. 2014/0163683, entitled “EXPANDABLE VERTEBRAL IMPLANT,” published Jun. 12, 2014, and U.S. Patent Publication No. 2013/0023993, entitled “EXPANDABLE FUSION DEVICE AND METHOD OF INSTALLATION THEREOF,” published Jan. 23, 2013, all of which are hereby incorporated by reference herein in their entireties for all purposes. 
     Device  1000  may include endplates  1002  and  1004  and one or more anchors  1006 . Anchors  1006  may be used as fasteners in order to attach device  1000  to the patient in a manner similar as described previously with regard to  FIG. 7A . This may be an alternative to other fasteners described herein. Anchors may be used because in certain conditions where the angle at which a bone screw may be inserted could interfere with a patient&#39;s anatomy such as soft tissue or the iliac crest. Anchors may be used and, in particular curved anchors, as described in greater detail below to minimize damage to the patient during a procedure. 
     Device  1000  may be operative, when positioned between adjacent bones of a joint, such as for example vertebrae, to stabilize a joint formed between adjacent vertebrae. Device  1000  has a collapsed state or height or an expanded state or height as previously described herein. Device  1000  may be expanded in a non-parallel fashion as previously described. 
     Device  1000  may be inset into the intervertebral disc space at a collapsed height, and then expand axially (superior/inferior) to restore height loss in the disc space. Device  1000  provides distraction as well as achieves optimal separation of adjacent vertebrae, or disc height restoration. When inserted in a collapsed state, device  1000  may have a reduced height profile which reduces adverse impact to tissue adjacent to and within the joint space during insertion, while presenting the least visually blocking or physically obstructing profile. Device  1000  may be reduced in height after implantation, for example by inserting a tool through a minimal incision, to perform a therapeutic height adjustment. Device  1000  may also be reduced in height to a compressed configuration, to facilitate removal from the body. Device  1000  supports the cortical rim of adjacent vertebrae, and distributes forces across the vertebra, thereby maximizing vertebral endplate preservation. 
     Device  1000  includes two separable endplates  1002  and  1004 . A surface  1008  of an endplate  1002  and/or  1004  can be provided with teeth or other projections  1010  which can penetrate body tissue to reduce a likelihood of migration of device  1000  after implantation. Device  1000  is further secured with one or more fasteners, such as anchors  1006 , which pass through an adapter, such as socket or bore  1012  within device  1000 , and into body tissue of the patient. Two sockets  1012  may be provided for two anchors  1006 , although one or more than two fasteners and fastener adapters, may be provided. Anchors  1006  can be retained in connection with spacer  1000  by blocking fasteners  1014 . 
     As shown in  FIGS. 22A-C , anchors  1006  may be have a spherical head  1016 . The portion of anchor  1006  that is inserted may be curved and may be t-shaped with sharp edges to cut into the bone of the patient. Anchor  1006  may have serrated edges to aid insertion into the bone and may also aid in restriction expulsion of anchor  1006 . Anchor  1006  is depicted as being curved, however, anchor  1006  may be straight or helical and be consistent with the principles of the present disclosure. 
       FIGS. 23-26  illustrate vertebral device  1500 , which may be consistent with vertebral devices previously described herein. Device  1500  may have the same or similar components as previously described. Device  1500  may include endplates  1502  and  1504  and one or more anchors  1506  which may be consistent with previously described endplates and anchors. Anchors  1506  may be used as an alternative to bone screws in order to attach the spacer to the patient. Anchors may be used because in certain conditions the angle at which a bone screw may be inserted could interfere with a patient&#39;s anatomy such as soft tissue or the iliac crest. Anchors may be used and, in particular curved anchors, as described in greater detail below to minimize damage to the patient during a procedure. 
     Device  1500  may be inset into the intervertebral disc space at a collapsed height, and then expand axially (superior/inferior) to restore height loss in the disc space. Device  1500  may expand in a parallel fashion such that endplates  1502  and  1504  expand in parallel with respect to each other. Device  1500  provides distraction as well as achieves optimal separation of adjacent vertebrae, or disc height restoration. When inserted in a collapsed state, device  1500  may have a reduced height profile which reduces adverse impact to tissue adjacent to and within the joint space during insertion, while presenting the least visually blocking or physically obstructing profile. Device  1500  may be reduced in height after implantation, for example by inserting a tool through a minimal incision, to perform a therapeutic height adjustment. Device  1500  may also be reduced in height to a compressed configuration, to facilitate removal from the body. Device  1500  supports the cortical rim of adjacent vertebrae, and distributes forces across the vertebra, thereby maximizing vertebral endplate preservation. 
     Device  1500  includes two separable endplates  1502  and  1504 . A surface  1508  of an endplate  1502 ,  1504  can be provided with teeth or other projections  1510  which can penetrate body tissue to reduce a likelihood of migration of device  1500  after implantation. Device  1500  is further secured with one or more fasteners, such as anchors  1506 , which pass through an adapter, such as socket  1512  within device  1500 , and into body tissue of the patient. Two sockets  1512  may be provided for two anchors  1506 , although one or more than two fasteners and fastener adapters, may be provided. Anchors  1506  can be retained in connection with device  1500  by blocking fasteners  1514 . In some embodiments, the adapters or sockets can be integrated with the device. In other embodiments, a coupling member, such as a set screw, can be configured to couple the adapter to the device. In yet other embodiments, the adapters may not be engaged with the device. 
     In addition to the angled inserters shown in  FIGS. 14A-17 , additional angled inserters can be provided to deliver and expand a fusion device at a surgical site.  FIGS. 27-30  show different views of an alternative inserter in accordance with some embodiments. Like prior inserters, the alternative inserter  1600  is angled and capable of expanding a fusion device without removing the inserter from the fusion device. In addition, in contrast to prior inserters that may use an external drive shaft (e.g., drive shaft  950  in  FIGS. 16E and 17 ) to actuate an engagement tip to retain and secure a fusion device, the present inserter  1600  advantageously has a drive shaft (e.g., drive shaft  1650  as shown in  FIG. 30 ) that is integrated and built-in within the inserter  1600 , thereby reducing the need to remove and insert a drive shaft into the inserter. 
       FIG. 27  illustrates a top perspective view of an alternative inserter in accordance with some embodiments. The inserter  1600  comprises a proximal portion having one or more handles  1607 ,  1609  and a distal portion having a distal engagement portion  1608  for engaging an expandable fusion device  600  (or other cage, spacer or fusion device). An outer body, shaft, or housing  1606  extends between the proximal portion and the distal portion and houses one or more drive shafts  1650 ,  1660  (shown in  FIG. 30 ). In some embodiments, drive shaft  1650  is an integrated drive shaft that is configured to actuate an attachment mechanism in the form of a rotatable body  1614 , to thereby attach the inserter  1600  to the expandable fusion device  600 . One skilled in the art will appreciate that the inserter  1600  is capable of attachment to cages, spacer and fusion devices beyond just fusion device  600 , though it is used here as a representative example. In some embodiments, drive shaft  1660  is an integrated drive shaft that is configured to actuate an expansion mechanism in the form of a rotatable body  1624 , to thereby expand (or contract) the expandable fusion device  600 . Drive shaft  1660  is rotated via a torque driver  1609  with drive shaft  1611 , as will be discussed in more detail below. 
     With reference to  FIG. 27 , the inserter  1600  comprises a distal portion having a distal engagement portion  1608  that is configured to engage the expandable fusion device  600 . In some embodiments, the distal engagement portion  1608  comprises a forked end capable of being received in one or more recesses of the expandable fusion device  600 . In other embodiments, the distal engagement portion  1608  can be non-forked and can comprise pins or any other mechanism used for holding a fusion device  600  and providing torsional stability thereto. As shown in  FIG. 29 , a first engagement tip  1612  and a second engagement tip  1622  extend from the distal engagement portion  1608 , whereby the first engagement tip  1612  is used to secure the expandable fusion device  600  to the inserter  1600  while the second engagement tip  1622  is used to expand the expandable fusion device  600  while attached to the inserter  1600 . In the present embodiment, the inserter  1600  is attached to an expandable fusion device  600  (similar to as shown in  FIG. 12A ) including a first endplate  602  having a first extension portion  648 , a second endplate  604  having a second extension portion  660 , a first ramped body  606  and a second ramped body  608 . While the inserter  1600  is shown as attached specifically to expandable fusion device  600 , one skilled in the art will appreciate that any of expandable fusion devices described above can be used with the inserter  1600 . In addition, the inserter  1600  includes novel features that can be used with fusion devices not specifically described herein. 
     The outer housing  1606  of the inserter  1600  comprises a cylindrical body having a lumen or channel therethrough. In some embodiments, one or more drive shafts (e.g., drive shafts  1650 ,  1660 ,  1611  as shown in  FIG. 30 ) are received in the body of the outer housing  1606 . In some embodiments, the one or more drive shafts are capable of rotating and/or translating within the outer housing  1606 . In some embodiments, drive shaft  1650  is capable of rotation via a rotatable actuator in the form of a thumb wheel  1610 . In some embodiments, drive shaft  1660  is capable of rotation via rotation of a torque driver  1611 . In some embodiments, the outer housing  1606  advantageously comprises one or more windows that allow for visualization of the internal components. 
     The proximal portion of the inserter  1600  comprises a radially extending handle  1607  and a handle for a torque driver  1609 . In some embodiments, the radially extending handle  1607  is perpendicular to the longitudinal axis of the housing  1606  of the inserter  1600 . In some embodiments, the radially extending handle  1607  is removably detached from the inserter  1600  body. The radially extending handle  1607  can be coupled to one or more openings  1605  that are formed in a cuff, boss or flange of the inserter  1600 . By providing one or more openings  1605 , a surgeon advantageously has multiple location options for placing the radially extending handle  1607  to grip and stabilize the inserter  1600  during use. In some instances, a surgeon may want to place the radially extending handle  1607  through a particular opening  1605  to avoid interference with fluoroscopy x-rays. 
     The proximal portion of the inserter  1600  further comprises an opening for receiving a torque driver  1609 . The torque driver  1609  comprises a handle  1603  and a drive shaft  1611  (shown in  FIG. 30 ) that extends from the handle. Rotation of the torque driver  1609  and its drive shaft  1611  causes rotation of an additional drive shaft  1660 , which in turn causes rotation of the second engagement tip  1622 , thereby causing expansion or contraction of the expandable fusion device  600 . In some embodiments, the drive shaft  1611  of the torque driver  1609  comprises a trilobe recess for matingly engaging a trilobe of the drive shaft  1660 . In some embodiments, the drive shaft  1660  can comprise a hex, spline or other non-trilobe feature capable of mating with the torque driver  1609 . 
       FIG. 28  illustrates a close-up view of a distal end of the inserter of  FIG. 27  engaging a vertebral fusion device. From this view, one can see how the distal engagement portion  1608  extends from the outer housing  1606  of the inserter  1600 . The distal engagement portion  1608  comprises a pair of tines or prongs that engage the expandable fusion device  600 . 
       FIG. 29  illustrates a close-up view of a distal end of the inserter of  FIG. 27  without the vertebral fusion device. As shown in the figure, a first engagement tip  1612  and a second engagement tip  1622  extend outwardly from the distal engagement portion  1608 . The first engagement tip  1612  comprises a threaded shaft  1612  for holding and retaining expandable fusion device  600 . The first engagement tip  1612  is capable of rotation via the drive shaft  1650 . The second engagement tip  1622  comprises a trilobe  1622  for rotating an actuator to thereby change the height of the expandable fusion device  600 . The second engagement tip  1622  is capable of rotation via the drive shaft  1660 , which itself rotates via the torque driver  1609 . 
       FIG. 30  illustrates a cross-sectional view of a distal end of the inserter of  FIG. 27  engaging a vertebral fusion device. The distal end of the inserter  1600  comprises a distal engagement portion  1608  from which the first engagement tip  1612  and the second engagement tip  1622  extend therefrom. As noted above, the first engagement tip  1612  comprises a rotatable body  1614  in the form of a threaded shaft. A spherical guide  1617  is received within the rotatable body  1614 . The upper surface of the rotatable body  1614  comprises angled or beveled surfaces that are configured to engage corresponding angled or beveled surfaces of a built-in drive shaft  1650 . Rotation of the drive shaft  1650  (e.g., via the thumbwheel  1610  shown in  FIG. 27 ) causes rotation of the first engagement tip  1612 , which thereby threadingly engages inner threads of the expandable fusion device  600 . 
     As noted above, the second engagement tip  1622  comprises a trilobular member that is capable of rotating an actuation member to expand or contract the fusion device  600 . The second engagement tip  1622  is similar to the second engagement tip  922  shown in  FIGS. 16C and 16D . The second engagement tip  1622  further comprises a translating tip  1625  that is spring-loaded into the second engagement tip  1622  via spring  1629 . The purpose of the translating tip  1625  is to advantageously make the second engagement tip  1622  in proper alignment with the actuator of the fusion device  600 . When the second engagement tip  1622  is in proper alignment with the actuator, the translating tip  1625  will extend outwardly from the rotatable body  1624 , thereby allowing torque to be applied via the translating tip  1625  to the actuator upon rotation of the second engagement tip  1622 . When the second engagement tip  1622  is not in proper alignment with the actuator, the translating tip  1625  will be retracted from view into the rotatable body  1624 , thereby preventing torque from being applied via the translating tip  1625  to the actuator upon rotation of the second engagement tip  1622 . In some embodiments. Like the second engagement tip  922 , the second engagement tip  1622  comprises a spherical guide  1627  adjacent to beveled or angled surfaces  1626 ,  1628 . The beveled or angled surfaces  1626 ,  1628  are capable of engagement with corresponding beveled or angled surfaces  1662 ,  1664  of the built-in drive shaft  1660 . Rotation of the drive shaft  1660  (e.g., via rotation of the torque driver  1603  shown in  FIG. 27 ), causes rotation of the second engagement tip  1622 , thereby causing expansion or contraction of the fusion device  600 . 
     After using the inserter  1600  to insert and expand a fusion device  600  in a disc space, the inserter  1600  can be removed. An angled funnel and plunger system can be provided to deliver graft material into the fusion device  600 . In other embodiments, the angled funnel and plunger system can be used to deliver bone filler (natural or synthetic), DBM, cement or any other desired material into the fusion device  600 . In the present embodiment, the angled funnel and plunger system abuts, but is not attached, to the fusion device  600 . In other embodiments, the angled funnel and plunger system is attached to the fusion device  600  via a mechanical connection. 
       FIG. 31  illustrates a side view of a funnel and plunger system in accordance with some embodiments. The system comprises an angled funnel  1710  and a plunger  1720  that extends through the angled funnel  1710 . In some embodiments, the distal portion of the funnel is configured to be at an angle of between 10 and 45 degrees, or approximately 25 degrees, relative to the longitudinal shaft of the funnel  1710 . Like the angled inserter, the angled funnel  1710  is advantageously capable of avoiding and maneuvering around the psoas, to thereby deliver graft material into the fusion device  600 . In some embodiments, after graft material is inserted into the angled funnel  1710 , the plunger  1720  can be inserted into the angled funnel  1710  to push the graft material into the fusion device  600 . 
       FIG. 32  illustrates a side view of the funnel of  FIG. 31 . The funnel  1710  comprises a proximal portion and a distal portion. The proximal portion comprises a cup or funnel shaped member  1710  for receiving graft material therein. A shaft  1711  extends from the proximal portion and transitions into a distal engagement portion  1708 . The distal engagement portion  1708  comprises an engagement tip  1712  and an adjacent opening  1720 . The engagement tip  1712  is capable of abutting or hooking into a trilobular actuator of the fusion device  600  to thereby steady the funnel  1710  relative to the fusion device  600 . In other embodiments, the engagement tip  1712  is capable of abutting, inserting or hooking into any portion of a fusion device to stabilize the fusion device such that it resists migration during bone graft delivery. The opening  1720  remains open and is capable of delivering graft material into the fusion device  600 . 
       FIG. 33  illustrates a perspective view of a distal end of the funnel of  FIG. 31 . From this view, one can see the engagement tip  1712  and the adjacent opening  1720 . In some embodiments, the engagement tip  1712  comprises a prong or peg. In other embodiments, the engagement tip  1712  can comprise a hook. The engagement tip  1712  of the funnel  1710  is advantageously configured to stabilize the funnel  1710  relative to the fusion device  600 , such that graft material can be delivered into the fusion device  600  via the adjacent opening  1720 . In the present embodiment, the graft material is backfilled into the fusion device  600 . However, in other embodiments, the graft material can be delivered to an anterior portion or side portions of a fusion device using the funnel and plunger system described herein. From this view, one can see how the distal end of the funnel  1710  comprises a flat surface  1717  that provides a flat foot print to provide a user with a tactile feel so that a user knows the funnel  1710  is properly seated against the fusion device  600 . 
       FIG. 34  illustrates a side view of the plunger of  FIG. 31 . The plunger  1720  comprises a handle  1722  and a shaft  1724  that extends distally from the handle. The plunger  1720  is configured to extend through the funnel  1710  to assist in pushing graft material out of the funnel  1710  and into the fusion device  600 . 
       FIG. 35  illustrates a cross-sectional view of the funnel and plunger system of  FIG. 31  engaging a vertebral fusion device in accordance with some embodiments. From this view, one can see the funnel  1710  with the plunger  1720  extending therethrough to expel graft material into the fusion device  600 . As shown in the figure, the graft material is delivered through the first bore hole  694  that is adjacent to the second bore hole  696 , which is configured to receive the actuator  702  therein. 
     The devices described herein can be used in combination with various other implants and tools used in spinal surgery. In some embodiments, the implants described herein can be accompanied with other stabilizing members, including plates, rods and pedicle screws. In addition, the devices can be used with prosthetic devices or other fusion based devices. 
     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 herein, the invention covers all combinations of all those embodiments.