Expandable Intervertebral Interbody Implant

Abstract

To provide expandable fusion devices, systems, instruments, and methods thereof. An expandable fusion implant may include: an upper endplate and a lower endplate that are configured to engage adjacent vertebrae; an expansion gear configured to adjust the height of the upper endplate; a locking collar configured to attach to an inserter instrument at multiple orientations for a desired surgical approach; and an actuation ram configured to lock or unlock the locking collar or change the insertion orientation of the locking collar. The expandable fusion device is attachable to the inserter instrument to reorient the locking collar and expand the upper endplate.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application is a continuation-in-part of U.S. Patent Application No. 18 / 341,810, filed June 27, 2023, which is hereby incorporated by reference in its entirety for all purposes.

[0002] FIELD OF THE INVENTION The present disclosure relates to surgical devices, and in particular to expandable fixation devices that can be deployed inside an intervertebral disc space and then expanded in height to maintain disc spacing, restore spinal stability, and / or facilitate intervertebral fusion. [Background technology]

[0003] A common treatment for addressing pain associated with degenerated discs due to various factors, such as trauma or aging, is the use of an intervertebral fusion device to stabilize one or more adjacent vertebral bodies. Generally, to stabilize the adjacent vertebral bodies, the disc is first partially or completely removed. An intervertebral fusion device is then typically inserted between the adjacent vertebrae to maintain normal disc spacing and restore spinal stability, thereby facilitating intervertebral fusion.

[0004] Several fixation devices and methods exist for achieving intervertebral fusion. These may include solid bone implants, fixation devices that include cages or other implant mechanisms that may be packed with bone and / or bone growth inducers, and expandable implants. The implants are placed between adjacent vertebral bodies to fuse them together, thereby alleviating associated pain and restoring disc height.

[0005] Interbody devices have been used to provide support and stability in the anterior column of spinal vertebrae when treating a variety of spinal conditions, including degenerative disc disease and spinal stenosis with spondylolisthesis. Clinical treatment of spinal pathology with anterior interbody devices relies on accurate placement of the interbody device to restore normal anterior column alignment. Iatrogenic pathology can result from a lack of surgical access to the disc space, failure to accurately place the interbody over the hard cortical bone often found over the apophyseal rings of the vertebral bodies, and / or failure to accurately control and restore normal anatomic spinal alignment.

[0006] Therefore, there is a need for a fixation device that can be inserted into the disc space at a collapsed height and then axially expanded to restore lost disc space height, yet provides precise interbody placement, which can be inserted from multiple approaches to allow access to the spine without requiring an extensive set of implants with fixed, approach-specific insertion features. Summary of the Invention

[0007] To meet this and other needs, and with its objectives in mind, the present application provides devices, systems, instruments, and methods for placing and expanding implants. In particular, expandable fixation devices are provided that can be inserted from any approach that allows access to the spine. The expandable fixation devices may have the ability to adjust the orientation of attachment to the implant to accommodate various approaches, provide distinct orientation positions about the implant's central axis, and may have an internal auto-lock that automatically locks the device after insertion into the disc space, and / or may have the ability to expand in height when implanted to achieve a desired spacer height that provides a desired disc height.

[0008] According to one embodiment, the expandable implant includes upper and lower end plates configured to engage adjacent vertebrae, an actuation gear coupled to and engaged with the lower end plate configured to adjust the height of the upper end plate, an interface collar configured to be attached to an inserter instrument in multiple orientations for a desired surgical approach and including a plurality of angled protrusions, and an expansion and orientation lock configured to lock the orientation of the interface collar and lock the height of the upper end plate, the interface collar being retained within the lower end plate and including a tapered outer surface having a plurality of notches defined therein configured to interface with the plurality of angled protrusions in the interface collar.

[0009] The expandable implant may include one or more of the following features: The interface collar can freely rotate about the central axis of the implant when not engaged by an inserter instrument or when engaged in an open position. The interface collar may be a split ring having a gap between opposite sides of the split ring. The interface collar may include a pair of eyelets defining a pair of openings through the interface collar. The bottom endplate may include a plurality of snap-fit ​​posts arranged in pairs defining a space therebetween, and the lock may include a plurality of guide rail posts configured to fit into the spaces between the snap-fit ​​posts, thereby guiding movement of the lock. Upper portions of the guide rail posts may protrude upward from the lock and be configured to engage pockets on the underside of the actuation gear to constrain rotational movement of the actuation gear and prevent expansion and collapse of the implant. The lock may include a plurality of spring arms extending from a bottom surface of the lock, which, in a disengaged state, push the lock up and away from the bottom endplate. The actuation gear may include a disc having a plurality of teeth projecting radially outward therefrom and a threaded central opening configured to threadably mate with the upper endplate. The upper endplate may include an annulus with a bone-engaging surface and a downwardly-projecting cylinder configured to mate with the actuation gear. The downwardly-projecting cylinder of the upper endplate may include external threads and a vertical slot bisecting the external threads, and the lower endplate may include a post receivable in the vertical slot.

[0010] According to one embodiment, an implantable system includes an expandable implant and an inserter instrument. The expandable implant includes a superior endplate configured to engage a superior vertebra, an actuation gear configured to adjust the height of the superior endplate, an interface collar configured to rotate about a central axis of the implant for a desired surgical approach, an expansion and orientation lock configured to lock the orientation of the interface collar and the height of the superior endplate, and a inferior endplate configured to engage a inferior vertebra. The inserter instrument has a mounting assembly configured to engage the interface collar and an expansion assembly configured to expand the implant. The inserter instrument is attachable to the interface collar in open, half, and full positions to control the position of the interface collar and the expansion of the implant.

[0011] The implantable system may include one or more of the following features: The mounting assembly may include a mounting fork having a pair of prongs. The interface collar may include a pair of openings configured to receive the prongs of the mounting fork. In the open position, the inserter instrument is attached to the implant such that the mounting fork does not engage the interface collar, thereby allowing full rotation of the interface collar and the lock prevents expansion of the superior endplate. In the half position, the inserter instrument is attached to the implant such that the mounting fork engages the interface collar, thereby fixing the position of the interface collar and the lock prevents expansion of the superior endplate. In the full position, the inserter instrument is attached to the implant such that the mounting fork engages the interface collar, thereby fixing the position of the interface collar and the lock disengages from the actuation gear to allow expansion of the superior endplate.

[0012] According to another embodiment, a method of installing an expandable implant includes: (a) providing an expandable implant including a superior endplate configured to engage a superior vertebra, an actuation gear configured to adjust the height of the superior endplate, an interface collar configured to rotate about a central axis of the implant for a desired surgical approach, an expansion and orientation lock configured to lock the orientation of the interface collar and lock the height of the superior endplate, and an inferior endplate configured to engage a inferior vertebra; and (b) attaching an inserter instrument to the interface collar, the inserter instrument configured to allow full rotation of the interface collar and move the interface collar to an open position where the lock prevents expansion of the superior endplate, a half position where the lock locks the position of the interface collar and prevents expansion of the superior endplate, or a full position where the lock locks the position of the interface collar and the lock is disengaged from the actuation gear and allows expansion of the superior endplate. The inserter instrument may be attached to the interface collar to establish a desired trajectory, including a direct anterior, a direct lateral, or an unspecified oblique approach between a direct anterior and a direct lateral. The expandable implant may be positioned within the disc space in a collapsed position when the inserter instrument moves the interface collar to a half or full position and locks the position of the interface collar. When the inserter instrument moves the interface collar to the full position, the lock disengages from the actuation and the actuation gear can be rotated to adjust the height of the upper end plate.

[0013] According to one embodiment, the expandable implant includes upper and lower end plates configured to engage adjacent vertebrae, an expansion gear configured to adjust the height of the upper end plate and coupled to and engaging the lower end plate, a locking collar positioned between the expansion gear and the lower end plate and configured to attach to an inserter instrument in multiple orientations for a desired surgical approach, a spring received in a recess in the locking collar, and an actuation ram housed in the locking collar configured to lock, unlock, or change the insertion orientation of the locking collar.

[0014] The expandable implant may include one or more of the following features. In a first position, the locking collar may be locked relative to the inferior endplate and expansion gear, thereby completely locking the implant. In a second position, the locking collar may be allowed to spin freely around the inferior endplate for a desired surgical approach. In a third position, the locking collar may lock relative to the inferior endplate and translate away from the expansion gear, thereby allowing expansion of the superior endplate. The inferior endplate may include a ring of teeth configured to engage a corresponding mating surface of the locking collar. The spring may include an elongated tab having a curved central portion that deforms under pressure. The actuation ram may include a body having two enlarged ends with a narrowed middle portion. The spring may be located on opposite sides of the actuation ram. The expansion gear may include a disk having a plurality of teeth protruding radially outward from the disk and a threaded central opening configured to threadably engage with the superior endplate. The locking collar may include a pair of vertically protruding beams, each having an inwardly facing surface configured to engage the teeth of the expansion gear. The upper endplate may include an annulus with a bone-engaging surface and a downwardly protruding cylinder configured to mate with the expansion gear. The downwardly protruding cylinder of the upper endplate may include external threads and a vertical slot bisecting the external threads, and the lower endplate may include a post receivable in the vertical slot.

[0015] According to one embodiment, an implantable system includes an expandable implant and an inserter instrument. The expandable implant includes an upper endplate configured to engage a superior vertebra, an inferior endplate configured to engage a inferior vertebra, an expansion gear configured to adjust the height of the upper endplate, a locking collar configured to rotate around the inferior endplate for a desired surgical approach, a spring for biasing the locking collar toward or away from the inferior endplate and the expansion gear, and an actuation ram housed within the locking collar configured to lock, unlock, or change the insertion orientation of the locking collar. The inserter instrument has a mounting assembly configured to engage the locking collar and an expansion assembly configured to expand the implant. The inserter instrument is attachable to the locking collar in a first position to lock the implant, a second position to allow the locking collar to spin freely for a desired surgical approach, and a third position to allow expansion of the upper endplate.

[0016] The implantable system may include one or more of the following features. The locking collar may include an internally threaded central opening and a pair of unthreaded openings positioned on either side of the central opening. The actuation ram may be located within a pocket in the locking collar. The actuation ram may include a body having two enlarged ends and a narrowed intermediate portion. The enlarged ends may be aligned with the unthreaded openings, and the narrowed intermediate portion may be aligned with the central opening. The narrowed intermediate portion may define a notch partially aligned with the central threaded opening. The inserter instrument may include a central threaded shaft configured to engage with the central threaded opening and a pair of unthreaded shafts configured to engage with the pair of unthreaded openings. In a first position, the inserter instrument may be attached to the implant such that the inserter is not threaded into the locking collar and a spring biases the locking collar against the inferior endplate and expansion gear, thereby fully locking the implant. In a second position, the inserter instrument may be attached to the implant such that the inserter is threaded into the locking collar until it is in place and the unthreaded shaft presses against the actuation ram, releasing the locking collar from the inferior endplate, allowing the locking collar to spin freely for the desired surgical approach. In a third position, the inserter instrument may be attached to the implant such that the inserter is threaded fully into the locking collar and the unthreaded shaft presses against the actuation ram, overcoming the spring and causing the locking collar to release the expansion gear, allowing the superior endplate to expand.

[0017] According to another embodiment, a method for installing an expandable implant includes: (a) providing an expandable implant having an upper endplate, an lower endplate, an expansion gear configured to adjust the height of the upper endplate, a locking collar configured to rotate around the lower endplate for a desired surgical approach, a spring for biasing the locking collar toward or away from the lower endplate and the expansion gear, and an actuation ram housed within the locking collar configured to lock, unlock, or change the insertion orientation of the locking collar; (b) attaching an inserter instrument to the expandable implant; (c) controlling the position and orientation of the locking collar with the inserter instrument to determine a desired trajectory; (d) inserting the expandable implant in a collapsed position between adjacent vertebrae along the desired trajectory; and (e) expanding the expandable implant with the inserter instrument. In a disengaged state, the implant may be locked so that the locking collar and expansion gear are fully locked. The desired trajectory may be selected from a direct anterior, a direct lateral, or an unspecified oblique approach between a direct anterior and a direct lateral.

[0018] Also provided are kits containing various types and sizes of expandable fixation devices, rods, fasteners or anchors, k-wires, insertion tools, and other components for performing the procedure. [Brief explanation of the drawings]

[0019] A more complete understanding of the present invention and its attendant advantages and features will be more readily appreciated by reference to the following detailed description when considered in conjunction with the accompanying drawings. [Figure 1A] 1A-1C are inserter instruments attached to expandable implants for a direct anterior approach, an unspecified oblique approach, and a direct lateral approach, respectively, according to one embodiment. [Figure 1B]1A-1C are inserter instruments attached to expandable implants for a direct anterior approach, an unspecified oblique approach, and a direct lateral approach, respectively, according to one embodiment. [Figure 1C] 1A-1C are inserter instruments attached to expandable implants for a direct anterior approach, an unspecified oblique approach, and a direct lateral approach, respectively, according to one embodiment. [Figure 2] FIG. 1 is an exploded view of an expandable implant, according to one embodiment. [Figure 3A] 3A and 3B are front and left side views, respectively, of the expandable fixation device of FIG. 2 at a collapsed starting height. [Figure 3B] 3A and 3B are front and left side views, respectively, of the expandable fixation device of FIG. 2 at a collapsed starting height. [Figure 4A] 3A and 3B are front and left side views, respectively, of the expandable fixation device of FIG. 2 fully expanded in height. [Figure 4B] 3A and 3B are front and left side views, respectively, of the expandable fixation device of FIG. 2 fully expanded in height. [Figure 5] FIG. 3 is a top view of the expandable fixation device of FIG. 2. [Figure 6A] 1A and 1B are top and cross-sectional views, respectively, of an inserter instrument attached to an expandable implant, according to one embodiment. [Figure 6B] 1A and 1B are top and cross-sectional views, respectively, of an inserter instrument attached to an expandable implant, according to one embodiment. [Figure 6C] 1A and 1B are top and cross-sectional views, respectively, of an inserter instrument attached to an expandable implant, according to one embodiment. [Figure 7] FIG. 10 is a partial top view (left) and partial cross-sectional view (right) of the inserter instrument in a neutral open position with the implant but not engaged with the interface collar. [Figure 8A]1A-1C are partial top view (left) and partial cross-sectional view (right) and side cross-sectional view, respectively, of the inserter instrument in a semi-locked position with the implant locking the implantation track but not unlocking the expansion gear. [Figure 8B] 1A-1C are partial top view (left) and partial cross-sectional view (right) and side cross-sectional view, respectively, of the inserter instrument in a semi-locked position with the implant locking the implantation track but not unlocking the expansion gear. [Figure 9A] Partial top view (left) and partial cross-sectional view (right) and side cross-sectional view, respectively, of the inserter instrument positioned in a fully locked position with the implant to lock the implant trajectory and unlocking the expansion gear to allow expansion or contraction of the implant. [Figure 9B] Partial top view (left) and partial cross-sectional view (right) and side cross-sectional view, respectively, of the inserter instrument positioned in a fully locked position with the implant to lock the implant trajectory and unlocking the expansion gear to allow expansion or contraction of the implant. [Figure 10] FIG. 1 is an exploded view of an expandable implant, according to one embodiment. [Figure 11A] 11A and 11B are front and left side views, respectively, of the expandable fixation device of FIG. 10 at a collapsed starting height. [Figure 11B] 11A and 11B are front and left side views, respectively, of the expandable fixation device of FIG. 10 at a collapsed starting height. [Figure 12A] 11A and 11B are front and left side views, respectively, of the expandable fixation device of FIG. 10 fully expanded in height. [Figure 12B] 11A and 11B are front and left side views, respectively, of the expandable fixation device of FIG. 10 fully expanded in height. [Figure 13] FIG. 11 is a top view of the expandable fixation device of FIG. 10. [Figure 14A] 1A-1C are partial top (left) and partial cross-sectional (right) views, respectively, of the inserter instrument engaged with the implant in a first position in which the expansion mechanism is fully locked by the collar. [Figure 14B] 1A-1C are partial top (left) and partial cross-sectional (right) views, respectively, of the inserter instrument engaged with the implant in a first position in which the expansion mechanism is fully locked by the collar. [Figure 15A] 1A-1C are partial top (left) and partial cross-sectional (right) views, respectively, of the inserter instrument engaged with the implant in a second position that allows the collar to be freely rotated to select an insertion orientation. [Figure 15B] 1A-1C are partial top (left) and partial cross-sectional (right) views, respectively, of the inserter instrument engaged with the implant in a second position that allows the collar to be freely rotated to select an insertion orientation. [Figure 16A] A partial top view (left) and partial cross-sectional view (right) and side cross-sectional view, respectively, of the inserter instrument engaged with the implant in a third position where the collar cannot rotate and the expansion gear can expand or contract the implant. [Figure 16B] A partial top view (left) and partial cross-sectional view (right) and side cross-sectional view, respectively, of the inserter instrument engaged with the implant in a third position where the collar cannot rotate and the expansion gear can expand or contract the implant. DETAILED DESCRIPTION OF THE INVENTION

[0020] To restore height loss within the disc space and provide precise interbody placement, expandable implants may have: (1) the ability to adjust the orientation of the implant attachment to accommodate various surgical approaches; (2) an internal automatic lock that provides distinct orientation positions around the implant's central axis and automatically locks the device after insertion into the disc space; and (3) the ability to expand in height when implanted to achieve a desired spacer height that provides a desired disc height. Accordingly, embodiments of the present application are generally directed to devices, systems, instruments, and methods for installing and expanding interbody implants. The terms implant, interbody, interbody implant, fixation device, spacer, and expandable device may be used interchangeably herein. While described with reference to interbody implants, it will be understood that the implants may also be used as partial body resection spacers, positioned between non-adjacent vertebral bodies, or used in trauma or other suitable surgical applications.

[0021] The expandable interbody spacer may be inserted from any approach that allows access to the spine. The expandable spacer is inserted into the disc space at a collapsed height and then axially expanded to restore lost height within the disc space. The expandable interbody spacer may be configured to maximize the volume within and around the device for implant material. Alternatively, the spacer may be used as a corpectomy spacer disposed between non-adjacent vertebral bodies. The spacer may be provided in a variety of footprints and geometries with superior and inferior geometries that, when implanted, contact the bony surfaces of the vertebral bodies between which the spacer is implanted. The superior and inferior geometries may be provided angled to accommodate a wide range of anatomical geometries and to match or restore lordosis, for example, when used in the lumbar spine.

[0022] Referring now to the drawings, wherein like reference numerals refer to like elements, FIGS. 1A-1C illustrate an expandable interbody fusion device or implant 10 and installation method, according to one embodiment. The expandable device 10 is configured to be inserted between two adjacent vertebrae 2. The expandable implant 10 is attached to an inserter instrument 12 to deploy the device 10 within the intervertebral disc space (the upper vertebra is omitted from FIGS. 1A-1C for clarity). The inserter 12 may be suitable for use during a minimally invasive surgical (MIS) procedure, for example, such that the inserter 12 and attached implant 10 may be positioned through a guide tube or cannula to access and guide the implant 10 within the intervertebral disc space. The expandable implant 10 is inserted between the vertebral bodies 4 of the vertebrae 2 and inserted into the intervertebral disc space in a collapsed position.

[0023] The implant 10 is configured to adjust the orientation of the attachment of the inserter 12 relative to the implant 10 to accommodate various surgical approaches to the spine. The ability to adjust the implant 10's implant orientation accommodates various approach angles and trajectories to the spine. The surgical approach angles and trajectories may include direct anterior, direct lateral, oblique, and subdivisions between direct anterior and direct lateral. FIG. 1A illustrates placement of the implant 10 via a direct anterior approach to the spine from the front of the body. When operating on the lumbar spine, this surgical technique is sometimes referred to as an anterior lumbar interbody fusion (ALIF). FIG. 1B illustrates placement of the implant 10 via an unspecified oblique approach (e.g., an angle between direct anterior and direct lateral). FIG. 1C illustrates placement of the implant 10 via a direct lateral approach to the spine from the side of the body. When operating on the lumbar spine, this surgical technique is sometimes referred to as a lateral lumbar interbody fusion (LLIF). It will be appreciated that the surgeon may determine the best surgical approach and placement of the expandable implant 10 before or during the surgical procedure.

[0024] Once inserted into the disc space through the desired surgical approach, the implant 10 is then expanded in height to an expanded position to precisely restore normal spinal alignment and distribute loads across the vertebral end plates 6. With an adjustable attachment interface, the implant 10 may be oriented or angled to better contact the natural end plate curvature of the vertebral bodies 4 above and below the disc space in which the device 10 is implanted. This may be particularly beneficial in cases of highly complex deformities where the vertebral bodies 4 may be rotated relative to two or more dimensional planes, thus requiring atypical surgical access approaches to the level the surgeon desires to treat.

[0025] Referring now to FIG. 2 , an exploded view of an expandable implant 10 is shown, according to one embodiment. The implant 10 includes an upper endplate 20 for engaging the superior vertebral body 4, an inferior endplate 22 for engaging the inferior vertebral body 4, an expansion or actuation gear 24 for adjusting the height of the upper endplate 20, an orientation and interface collar 26 configured to attach the inserter 12 to the implant 10 at various orientations or angles for a desired surgical approach angle or trajectory, and an expansion and orientation lock 28 configured to lock the orientation of the interface collar 26 and / or automatically lock the height of the implant. The endplates 20, 22, actuation gear 24, interface collar 26, and lock 28 are aligned along a central longitudinal axis 30. The implant 10 can define a large central graft-retaining opening or window 32 configured to receive bone graft or other suitable bone growth-promoting material. As best seen in FIG. 5 , the central graft window 32 can be generally cylindrical in shape with its central axis aligned with the central longitudinal axis 30.

[0026] The upper or superior endplate 20 includes an annulus 34 having a downwardly protruding cylinder 36 configured to mate with the actuation gear 24. The annulus 34 may be a ring or circle that surrounds a portion of the central graft window 32. The annulus 34 has a thickness between an upper bone-engaging surface 38 and a bottom, or inferior, surface 40 of the annulus 34. As best seen in FIGS. 3A-3B and 4A-4B, the annulus 34 may be angled and / or the thickness between the upper and lower surfaces 38, 40 of the annulus 34 may be varied to accommodate a wide range of anatomical contours and to match or restore lordosis when used in the lumbar spine.

[0027] The annulus 34 includes an upper bone-engaging surface 38 configured to engage the superior vertebral body 4. The upper bone-engaging surface 38 may be contoured to mimic the shape of the vertebral endplate 6. The upper bone-engaging surface 38 may include a plurality of teeth, protrusions, or other friction-enhancing surfaces configured to engage bone. In one embodiment, the upper endplate 20 includes an aggregate-like, ejection-resistant pattern or texture on its upper surface geometry for contacting the bone surface, which can be angled to match or restore lordosis when used in the lumbar spine. The bone-contacting surface 38 may further include a porous or porous structure to allow for additional bone ingrowth into the spacer. The upper endplate 20 may be 3D printed, for example, to increase the potential for bone growth. It will be understood that the bone-engaging surface 38 may be modified to include one or more surface treatments, coatings, textures, or other features to enhance fixation.

[0028] The cylinder 36 extends from the bottom, or lower surface 40, of the annular body 34. The protruding cylinder 36 defines one or more external threads 42 configured to mate with corresponding threads 50 inside the actuation gear 24. The external threads 42 may include a helical thread profile machined into the outer surface of the cylinder 36. The external threads 42 may have any suitable attributes, including diameter, winding direction, thread form, thread angle, lead(s), pitch, etc. The threads 42 may extend along the entire length of the cylinder 36 or a suitable portion thereof. When the cylinder 36 is telescopically received into / from the actuation gear 24, the upper end plate 20 is configured to increase or decrease in height, thereby adjusting the overall height of the implant 10. The slot 44 may extend the entire length or a portion of the length of the threads 42 and extend into the central graft window 32. The slot 44 may be vertically oriented and in fluid communication with the central graft window 32. The slot 44 may be angled from directly anterior to allow access from various approach angles. The slot 44 may act as a backfill window and counter torque for expansion and collapse of the spacer.

[0029] The expansion gear or actuation gear 24 is configured to expand and collapse the implant 10. The actuation gear 24 has a central through opening 48 that is sized and dimensioned to telescopically receive the protruding cylinder 36 of the upper endplate 20. The central opening 48 has a central axis that is coaxial with the central longitudinal axis 30 of the implant 10. The central opening 48 defines one or more internal threads 50 cut into its inner diameter that are configured to engage the external threads 42 of the upper endplate 20. The threaded engagement between the cylinder 36 and the threaded opening 48 allows the actuation gear 24 to adjust the height of the upper endplate 20 when rotated.

[0030] The outer periphery of the actuation gear 24 includes a plurality of cogs or teeth 52. In one embodiment, the actuation gear 24 may be a spur gear or straight gear having straight teeth 52 projecting radially from a cylinder or disc. The edges of each tooth 52 may be straight and aligned parallel to the axis of rotation. While a particular arrangement of the teeth 52 is shown, it is envisioned that the number, position, thickness, diameter, pitch, and configuration of the teeth may be varied or selected by one skilled in the art. When engaged by the inserter instrument 12, the actuation gear 24 may be rotated about the axis 30 to move the upper endplate 20 up or down, thereby adjusting the height of the implant 10.

[0031] The teeth 52 may extend between an upper surface 54 and an opposite lower surface 56 of the actuation gear 24. The upper surface 54 of the actuation gear 24 may be configured to contact the bottom surface 40 of the annulus 34 of the upper end plate 20 when the upper end plate 20 is fully collapsed (as shown in FIGS. 3A-3B). The lower surface 56 of the actuation gear 24 is configured to always contact or be adjacent to the upper surface 78 of the collar 26. The upper and lower surfaces 54, 56 of the actuation gear 24 may be generally flat and smooth.

[0032] The actuation gear 24 includes a snap-fit ​​lip 58 that protrudes downwardly and is configured to be retained by the bottom endplate 22. As best seen in FIG. 8B , the snap-fit ​​lip 58 may include a circular rim 60 defined by a circular groove above the rim 60. The circular rim 60 protrudes radially outward to engage the bottom endplate 22. The bottom portion or surface of the rim 60 may be angled or rounded to aid in the snap-fit ​​engagement. The underside 56 of the actuation gear 24 defines a plurality of pockets 62 configured to retain portions of the locks 28. The locks 28 are configured to engage with the pockets 62 in the underside 56 of the actuation gear 24 to restrain rotational movement of the expansion gear 24 and prevent both expansion and collapse of the implant 10.

[0033] The orientation and interface collar 26 is configured to engage the inserter 12 for implantation. When not engaged by the inserter 12, the collar 26 is free to rotate about the axis 30. When engaged by the inserter 12 in a particular position, the collar 26 is locked in place relative to the inserter 12 for implantation for a desired approach or trajectory. The interface collar 26 includes a split ring body 66 having a gap 68 between opposite sides of the split ring 66. The interface collar 26 defines one or more openings 70 through an outer surface 72 of the outer diameter configured to engage the inserter 12 for implantation. The outer surface 72 may be generally smooth, except for a pair of protruding oval eyelets 71 on either side of the gap 68. Each opening 70 may be defined through a respective eyelet 71.

[0034] The inner surface 74 of the interface collar 26 includes a plurality of angled protrusions 76. The angled protrusions 76 may include a series of alternating protrusions and grooves configured to engage corresponding mating surfaces 94 on the lock 28. The angled protrusions 76 may define sides or ramps configured to translate the lock 28 vertically along the axis 30. The angled protrusions 76 may extend a distance from the upper surface 78 toward the lower surface 80, stopping short of the lower surface 80 to allow for a smooth area below the protrusions 76. In one embodiment, a first series of angled protrusions 76 extends a distance along the inner surface 74 from the first opening 70, and a second series of angled protrusions 76 extends a distance along the inner surface 74 from the second opening 70, with a smooth area along the inner surface 74 between the two series of protrusions 76. While a particular arrangement of angled protrusions is shown, it is envisioned that the number, location, and configuration of surfaces may be varied or selected by one skilled in the art.

[0035] A rotatable interface collar 26 is located between the actuation gear 24 and the bottom endplate 22. The interface collar 26 may be retained within the bottom endplate 22 by overlapping lips 82, 120 on the collar 26 and the bottom endplate 22. The lip 82 on the interface collar 26 may include a downwardly protruding lip that continues along the inner surface 74 to the body of the split ring 66. It will be appreciated that the interface collar 26 may be retained within the bottom endplate 22 using any suitable mechanism that allows rotational movement of the collar 26 about the axis 30 when the collar 26 is not secured by the inserter 12.

[0036] When not engaged by the inserter 12, the interface collar 26 is free to rotate 360° about the central axis 30 of the implant core. The collar 26 can be engaged by the inserter 12 in multiple positions. In a first position, the angled protrusion 76 of the collar 26 engages the lock 28 to prevent the collar 26 from rotating, thereby locking the orientation of the implant 10 relative to the inserter 12 for implantation. In a second position, the collar 26 disengages the lock 28 from the actuation gear 24, thereby allowing the implant 10 to expand or collapse and preventing rotation and reorientation of the collar 26.

[0037] The expansion and orientation lock 28 is configured to lock the orientation of the interface collar 26 and / or automatically lock the height of the implant 10. The outer diameter 92 of the lock 28 is tapered by shallow angled notches 94 that interact with and engage with the mating protrusions 72 on the interface collar 26. The lock 28 includes a ring-like body 86 that is angled or tapered from a top edge 88 to a bottom edge 90. The body 86 gradually increases in diameter around its circumference from the top edge 88 to the bottom edge 90, forming an outer cone-like shape. Thus, the top edge 88 has a smaller diameter than the bottom edge 90. The outer diameter of the lock 28 includes a plurality of shallow notches 94. The shallow notches 92 may be generally rectangular in shape extending perpendicularly from the top edge 88 to the bottom edge 90. The notches 92 may have equal widths, may be evenly spaced around the circumference of the lock 28, or may be otherwise configured to mate with corresponding protrusions 72 in the interface collar 26. The inner surface 96 of the lock 28 may be smooth.

[0038] The lock 28 has one or more guide rail posts 98 that engage the bottom end plate 22, acting as a counter-torque means, so that the lock 28 can only move linearly up and down along the axis 30. Each guide rail post 98 may include a vertical rail that protrudes radially inward. For example, four guide rail posts 98 may be equally spaced around the inner surface 94 of the lock 28. It will be understood that any suitable number and configuration of guide rail posts may be used to guide the movement of the lock 28. The upper portions of the guide rail posts 98 protrude upward and are configured to engage with the pockets 62 on the underside of the actuation gear 24 to constrain rotational movement of the actuation gear 24 and prevent expansion and collapse of the implant 10. The lock 28 may include one or more spring arms 102 extending from the bottom surface 90 of the lock 28 and each terminating in a free end. The spring arms 102 may include curved beams or structures that bend downward with a convex profile on the underside. A spring arm 102 may be positioned below each guide rail post 98. Each spring arm 102 may be machined into the lock 28 such that in the disengaged state of the implant, the spring arm 102 pushes the lock 28 up and away from the bottom endplate 22.

[0039] The inferior endplate 22 includes an annulus 106 configured to receive the expansion and orientation lock 28, the interface collar 26, and the actuation gear 24. Similar to the superior endplate 20, the annulus 106 may be a ring or circle that surrounds a portion of the central implant window 32. The annulus 106 has a thickness between a lower bone-engaging surface 108 and an upper edge 110 of the annulus 34. As best seen in FIGS. 3A-3B and 4A-4B, the annulus 106 may be angled and / or the thickness between the superior and inferior surfaces 108, 110 of the annulus 106 may be varied to accommodate a wide range of anatomical contours and to match or restore lordosis when used in the lumbar spine.

[0040] The lower bone-engaging surface 108 of the lower endplate 22 is configured to engage the inferior vertebral body 4. The lower bone-engaging surface 108 may be contoured to mimic the shape of the vertebral endplate 6. Similar to the upper bone-engaging surface 38, the lower bone-engaging surface 108 may include a plurality of teeth, protrusions, or other friction-enhancing surfaces configured to engage bone. In one embodiment, the bottom endplate 22 includes a bone-like ejection-resistant pattern or texture on its lower surface geometry for contact with the bone surface, which can be angled to match or restore lordosis when used in the lumbar spine. The lower bone-engaging surface 108 may further include a porous or porous structure to allow additional bone ingrowth into the spacer. The lower endplate 22 may be 3D printed, for example, to increase the potential for bone growth. It will be understood that the bone-engaging surface 108 may be modified to include one or more surface treatments, coatings, textures, ejection-resistant structures or geometries, or other features to enhance fixation.

[0041] Assembly, counter-torque, and interface features for the lock 28 are machined into the upper portion of the lower endplate 22. The expansion and orientation lock 28 resides nested within a pocket and groove 112 machined in the bottom endplate 22. The lower endplate 22 has an inner wall 114 defined by a portion of the central graft window 32. A plurality of snap-fit ​​posts 116 extend perpendicularly from the inner wall 114. The snap-fit ​​posts 116 are arranged in pairs with spaces 118 therebetween configured to receive respective guide rail posts 98 of the lock 28. In the illustrated embodiment, four pairs of snap-fit ​​posts 116 are evenly spaced around the inner wall 114, defining four respective spaces 118 for corresponding guide rail posts 98. The guide rail posts 98 engage with the spaces 118 between the snap-fit ​​posts 116 to guide linear movement of the lock 28 up and down along the axis 30. Although a particular number and configuration of posts 98, 116 are shown, it will be understood that another suitable arrangement may be selected to guide the lock 28.

[0042] After the lock 28 is positioned within the inferior endplate 22, the interface collar 26 is disposed within the inferior endplate 22 such that the collar 26 surrounds and engages the lock 28. The interface collar 26 may be retained within the inferior endplate 22 by overlapping lips 82, 120 on the collar 26 and the bottom endplate 22. The collar 26 may be sized and dimensioned such that the outer surface 72 of the orientation collar 26 is generally flush with the outer periphery of the annular body 106 of the inferior endplate 22.

[0043] The actuation gear 24 may then be positioned on top of the orientation collar 26 and secured to the bottom end plate 22. The lower surface 56 of the actuation gear 24 abuts the upper surface 78 of the interface collar 26. The actuation gear 24 may be sized and dimensioned so that the outer diameter of the gear 24 is generally flush with the outer surface 72 of the interface collar 26 and the outer periphery of the annulus 34 of the top end plate 20. The lower surface 56 of the actuation gear 24 rests on top of a snap-fit ​​post 116 in the bottom end plate 22. The actuation gear 24 is retained within the bottom end plate 22 via the snap-fit ​​lip 60. Each free end of the snap-fit ​​post 116 defines a protruding portion or finger 122 configured to fit into a groove defining the circular rim 60 of the actuation gear 24. The snap-fit ​​post 116 may be configured to bend or flex slightly as the fingers 122 are inserted, thereby securely connecting the actuation gear 24 to the lower endplate 22 .

[0044] The upper endplate 20 is threadedly engaged with the actuation gear 24. Posts 124 may protrude perpendicularly from the lower endplate 22 and are sized and configured to fit within the slots 44 in the cylinder 36 of the upper endplate 20. When in the fully collapsed position, the slots 44 and posts 124 may act as a counter-torque means for expanding and collapsing the spacer. When the implant 10 is fully collapsed, as shown in FIGS. 3A-3B, the bottom surface 40 of the annulus 34 of the upper endplate 20 may contact and abut the top surface 54 of the actuation gear 24. When the implant 10 is expanded, as shown in FIGS. 4A-4B, the annulus 34 of the upper endplate 20 lifts off the actuation gear 24 and the bottom surface 40 of the annulus 34 is spaced apart from the actuation gear 24.

[0045] The devices described herein or their components may be fabricated from a number of biocompatible materials, including, but not limited to, titanium, titanium alloys, non-titanium metal alloys, stainless steel, polymeric materials, plastics, plastic composites, polyetheretherketone (PEEK), ceramics, and elastomeric materials. The devices or their components may be fabricated by machining, additive methods such as three-dimensional (3D) printing, and / or subtractive methods.

[0046] 6A-9B, the implant 10 can be inserted into the intervertebral disc space using the inserter 12 through an agnostic approach. In other words, the surgeon can determine the trajectory or approach to the spine before or during the procedure and adjust the orientation of the implant 10 during the procedure to accommodate the desired surgical approach. The implant 10 is configured to be inserted from multiple approaches, eliminating the need for an extensive set of implants with fixed, approach-specific insertion features. The ability of the implant 10 to be inserted from multiple approaches and trajectories can significantly reduce the number of implants required in a set list for a given procedure. The versatility of the implant 10 also provides the surgeon with more options and greater control during the procedure, thereby resulting in better patient outcomes.

[0047] 6A-6C show an inserter instrument 12 attached to an implant 10, according to one embodiment. The inserter 12 controls the position of the interface collar 26, the position of the lock 28, and the expanded height of the superior endplate 20 when properly attached. The inserter 12 extends along the central longitudinal axis of the tool from a proximal end 130 to a distal end 132. The proximal end 130 includes an attachment interface for connecting a handle (not shown) configured for manipulation by a user. The distal end 132 is configured to attach to the interface collar 26 of the implant 10. The inserter 12 includes an outer body 134 in the form of a hollow outer tube or cannula defining a central channel configured to receive an expansion assembly including an expansion drive shaft 136 configured to expand the implant 10 and an attachment assembly including a distal attachment fork 140 configured to engage the interface collar 26 at different locations.

[0048] The expansion assembly may include an expansion drive shaft 136, which is a cylindrical shaft extending through the outer body 134 and attached to a drive gear 138 configured to engage the actuation gear 24 of the implant 10. The proximal end 130 of the expansion drive shaft 136 is connectable to a handle (not shown) to permit rotation of the drive shaft 136. When the inserter 12 is engaged with the orientation collar 26 in the full position, rotating the expansion drive shaft 136 rotates the drive gear 138, which engages the actuation gear 24 to permit expansion or contraction of the superior endplate 20, thereby permitting adjustment of the height of the implant 10.

[0049] The mounting assembly may include a mounting fork 140, which includes a central body or base 142 with a pair of distal prongs 144 extending therefrom. The prongs 144 may be straight or curved and may be spaced to match the spacing of the mounting locations 70 along the interface collar 26. The prongs 144 may be configured to be slightly curved or bent to engage the interface collar 26 at different locations. The free end 146 of each prong 144 may be inserted into a respective opening 70 and may be contoured or shaped to engage with both sides of the opening 70. A sleeve 148 may be configured to draw the prongs 144 together or apart. An outer control knob 150 and an inner half nut 152 may be used to manipulate the prongs 144. For example, the control knob 150 may be rotated to translate the sleeve 148, drawing the prongs 144 together or spreading the prongs 144 apart. It will be appreciated that any suitable mechanism may be used to control the movement of the mounting fork 140 and prongs 144 .

[0050] FIG. 7 shows the inserter 12 attached to the implant 10 so that the mounting fork 140 does not engage the interface collar 26, thereby providing a neutral or open position. When the collar 26 is not engaged by the inserter 12, the collar 26 is free to rotate 360° about the central axis 30 of the implant core. The angled protrusion 76 of the interface collar 26 is not received in the shallow notch 94 of the lock 28. The open position occurs when the control knob 150 is twisted to position the mounting fork 138 so that the prongs 144 of the fork 140 do not engage the attachment points 70 on the interface collar 26. FIG. 7 shows the prongs 144 in the neutral position within the openings 70 of the interface collar 26, allowing the interface collar 26 to be fully rotated to the desired insertion orientation.

[0051] When the collar 26 is engaged by the inserter 12, the angled protrusion 76 of the collar 26 engages with the shallow angled notch 94 on the lock 28. The collar 26 may be engaged by the inserter 12 in two different positions: a half position and a full position. FIGS. 8A-8B show the inserter 12 attached to the implant 10 in the half position. In the half position, the attachment fork 140 engages the interface collar 26, and the prongs 144 are positioned within the openings 70 of the interface collar 26 such that the prongs 144 move away from each other. When engaged by the inserter 12 in the half position, the protrusions 76 of the interface collar 26 mate with the notches 94 on the lock 28, preventing the collar 26 from rotating, which in turn defines the orientation of the implant 10 relative to the inserter 12 for implantation. The half position occurs when the control knob 150 is twisted to bring the mounting fork 140 into a position where the prongs 144 of the fork 140 engage the angled interaction features on the interface collar 26 with the lock 28. In the half position, the orientation of the interface collar 26 is firmly defined but does not unlock the expansion mechanism.

[0052] 9A-9B show the inserter 12 attached to the implant 10 in the full position. When engaged by the inserter 12 in the full position, the ramp feature on the interface collar 26 presses into and over the lock 28, disengaging the rail post 98 from the underside of the gear 24 and allowing the implant 10 to expand or collapse and be embedded or removed. The full position also prevents rotation and reorientation of the collar 26. In the full position, the prongs 144 of the mounting fork 140 may be pulled toward each other to grip the interface collar 26 so that the ends of the split ring 66 approach each other, thereby engaging the interface collar 26 with the lock 28. The full position occurs when the control knob 150 is twisted to bring the mounting fork 140 into a position where the prongs 144 of the fork 140 engage the interaction feature 76 on the interface collar 26 with the lock 28. In this manner, the orientation of the interface collar 26 is firmly defined, and the angled interaction feature 76 of the interface collar 26 urges the lock 28 downward, away from the expansion gear 24. The upper end of the guide rail post 98 on the lock 28 disengages from the pocket 62 in the underside 56 of the actuation gear 24, thereby unlocking the implant 10.

[0053] Once in the full position, the upper endplate 20 can be raised or lowered. For example, rotating the expansion drive shaft 136 on the inserter 12 causes the spacer 10 to expand or contract. The drive gear 138 engages the actuation gear 24, thereby allowing the height of the implant 10 to be adjusted. Conversely, in the half or open position, rotating the expansion drive shaft 136 on the inserter 12 does not expand or contract the spacer 10 because the lock 28 is coupled to the expansion gear 24, thereby preventing this movement. Furthermore, when the inserter 12 is removed from the implant 10, the lock 28 automatically re-engages with the actuation gear 24 such that the spring 102 urges the lock 28 upward and the upper end of the guide rail post 98 re-enters the pocket 62 on the underside 56 of the actuation gear 24, thereby re-locking the implant 10 and preventing further expansion or contraction of the implant 10.

[0054] 10-16B, an expandable interbody fusion device or implant 210 is shown, according to one embodiment. The expandable implant 210 is similar to implant 10, except that the locking mechanism and its interaction with the inserter instrument 212 is modified, thereby allowing for three operating positions. In a disengaged or first engaged position with the inserter 212, the implant 210 is locked and prevented from expanding. In a second engaged position with the inserter 212, the implant 210 can be reoriented to select a desired implantation trajectory. In a third engaged position with the inserter 212, the implant 210 can be expanded.

[0055] Similar to implant 10, implant 210 is configured to adjust the orientation of attachment of inserter 212 relative to implant 210 to accommodate various surgical approaches to the spine. The ability to adjust the implant orientation of implant 210 accommodates various approach angles and trajectories to the spine. Surgical approach angles and trajectories may include direct anterior, direct lateral, oblique, and fine increments between direct anterior and direct lateral. It will be appreciated that the surgeon may determine the best surgical approach and placement of expandable implant 210 before or during the surgical procedure.

[0056] 11A-11B show the assembled 0° implant 210 at an initial starting height in a collapsed position. Once inserted into the disc space through the desired surgical approach, the implant 210 is then expanded in height to an expanded position to precisely restore normal spinal alignment and distribute load across the vertebral end plates 6. FIGS. 12A-12B show the assembled 0° implant 210 fully expanded. The adjustable attachment interface allows the implant 210 to be oriented or angled to better contact the natural endplate curvature of the vertebral bodies 4 above and below the disc space in which the device 210 is implanted. This can be particularly beneficial in cases of highly complex deformities where the vertebral bodies 4 may be rotated relative to two or more dimensional planes, thus requiring atypical surgical access approaches to the level the surgeon desires to treat.

[0057] 10 , an exploded view of the expandable implant 210 is shown in greater detail. The implant 210 includes an upper endplate 220 for engaging the upper vertebral body 4, an lower endplate 222 for engaging the lower vertebral body 4, an expansion or actuation gear 224 for adjusting the height of the upper endplate 220, an interface or locking collar 226 configured to attach the inserter instrument 212 to the implant 210 at various orientations or angles for a desired surgical approach angle or trajectory, an actuation ram 228 housed within the locking collar 226 and configured to lock, unlock, or change the insertion orientation of the collar 226, and a spring 230 fitted within the locking collar 226 and configured to urge the locking collar 226 against the bottom endplate 222 and expansion gear 224 in a locked position. The upper and lower endplates 220, 222, and actuation gear 224 are aligned along a central longitudinal axis 30. The locking collar 226 slides and moves about the central longitudinal axis 30 depending on the position of engagement with the spring 230 and the inserter 212. The implant 210 may define a large central graft-retaining opening or window 232 configured to receive a bone graft or other suitable bone growth promoting material therethrough.

[0058] The upper or superior endplate 220 includes an annulus 234 having a downwardly protruding cylinder 236 configured to mate with the actuation gear 224. The annulus 234 may be a ring that surrounds a portion of the central graft window 232. The annulus 234 has a thickness between an upper bone-engaging surface 238 and a bottom, or inferior, surface 240 of the annulus 234. The upper bone-engaging surface 238 is configured to engage the superior vertebral body 4. The annulus 234 may be circular, oval, elliptical, or another suitable shape for engaging the adjacent vertebral endplate 6. The upper bone-engaging surface 238 may be contoured to mimic the shape of the vertebral endplate 6 or may be provided with various footprints and geometries configured to contact the bone surfaces of the adjacent vertebral bodies. The upper bone-engaging surface 238 may include a plurality of teeth, protrusions, or other friction-enhancing surfaces configured to engage bone. In one embodiment, the superior endplate 220 includes a bone-like, ejection-resistant pattern or texture on its upper surface geometry for contacting a bone surface that can be angled to conform to or restore lordosis when used in the lumbar spine. The bone-contacting surface 238 may further include a porous or porous structure to allow for additional bone ingrowth into the spacer. The superior endplate 220 may be 3D printed, for example, to enhance the potential for bone ingrowth. It will be appreciated that the bone-engaging surface 238 may be modified to include one or more surface treatments, coatings, textures, or other features to enhance fixation.

[0059] The cylinder 236 extends from the bottom, or lower surface 240, of the annular body 234. The protruding cylinder 236 defines one or more external threads 242 configured to mate with corresponding threads 250 on the interior of the expansion gear 224. The external threads 242 may include a helical thread profile machined into the exterior surface of the downwardly protruding cylinder 236. The external threads 242 may have any suitable attributes, including diameter, winding direction, thread form, thread angle, lead(s), pitch, etc. The threads 242 may extend along the entire length of the cylinder 236 or an appropriate portion thereof. When the cylinder 236 is telescopically received within / from the expansion gear 224, the upper end plate 220 is configured to increase or decrease in height, thereby adjusting the overall height of the implant 210. The slot 244 may extend the entire length or a portion of the length of the threads 242 and into the central graft window 232. The slot 244 may be vertically oriented and in fluid communication with the central graft window 232. The slot 244 may be positioned at an angle, for example, about 45°, from directly anterior to allow access from various approach angles. The slot 244 may act as a backfill window and counter torque for expansion and collapse of the spacer.

[0060] The expansion gear or actuation gear 224 is configured to expand and collapse the implant 210. The expansion gear 224 has a central through opening 248 that is sized and dimensioned to telescopically receive the protruding cylinder 236 of the upper endplate 220. The central opening 248 has a central axis that is coaxial with the central longitudinal axis 30 of the implant 210. The central opening 248 defines one or more internal threads 250 cut into its inner diameter that are configured to engage with the external threads 242 of the upper endplate 220. The threaded engagement between the cylinder 236 and the threaded opening 248 allows the actuation gear 224 to adjust the height of the upper endplate 220 when rotated.

[0061] The outer periphery of the expansion gear 224 includes a plurality of cogs or teeth 252. In one embodiment, the expansion gear 224 may be a spur gear or straight gear having straight teeth 252 projecting radially from a cylinder or disc. The edges of each tooth 252 may be straight and aligned parallel to the axis of rotation. While a particular arrangement of the teeth 252 is shown, it is contemplated that the number, position, thickness, diameter, pitch, and configuration of the teeth may be varied or selected by one skilled in the art. When engaged by the inserter instrument 212, the expansion gear 224 may be rotated about the axis 30 to move the upper endplate 220 up or down, thereby adjusting the height of the implant 210.

[0062] The teeth 252 may extend between an upper surface 254 and an opposite lower surface 256 of the actuation gear 224. The upper surface 254 of the expansion gear 224 may be configured to contact the bottom surface 240 of the annular body 234 of the upper end plate 220 when the upper end plate 220 is fully collapsed (as shown in FIGS. 11A-11B). The lower surface 256 of the expansion gear 224 is configured to contact or be adjacent to the upper surface 274 of the collar 226. The upper and lower surfaces 254, 256 of the expansion gear 224 may be generally flat and smooth.

[0063] Expansion gear 224 includes a lip 258 that projects downwardly and is configured to be retained by bottom end plate 222. Lip 258 may include a circular rim 260 defined by a circular groove 262 above rim 260. Circular rim 260 projects radially outward to engage bottom end plate 222. A bottom portion or surface of rim 260 may be angled or rounded to facilitate a snap-fit ​​type engagement.

[0064] The orientation and locking collar 226 is configured to engage the inserter 212 in different states to manipulate the implant 210. When engaged by the inserter 212 in a first position, the collar 226 is locked relative to the bottom endplate 222 and expansion gear 224, thereby fully locking the implant 210. When engaged by the inserter 212 in a second position, the slidable collar 226 is translated away from the bottom endplate 222 so that the locking collar 226 is free to spin about the central axis 30 to a desired position for implantation in a desired approach or trajectory. When engaged by the inserter 212 in a third position, the collar 226 is locked relative to the bottom endplate 222 and translated away from the expansion gear 224 to allow expansion of the top endplate 220.

[0065] The locking collar 226 includes a loop or ring-shaped body 266 defining a central through opening 268 sized and dimensioned to receive a portion of the lower endplate 222 and the actuation gear 224. The ring-shaped body 266 has an outer surface 270 and an inner surface 272 with a thickness between an upper surface 274 that contacts the lower surface 256 of the expansion gear 224 and a lower surface 276 that contacts the upper surface 312 of the bottom endplate 222. Although the interface collar 226 is free to rotate around the lower endplate 222 (when in the second position), the interface collar 226 has a proximal portion 275 that always engages the inserter instrument 212 and an opposite distal portion 277. As best seen in FIG. 13 , the proximal portion 275 of the locking collar 226 may protrude radially beyond the endplates 220, 222. The proximal portion 275 may have, for example, a convex shape with a flat proximal face and rounded sides, which is sized and dimensioned to fit within a corresponding recess in the inserter instrument 212. The protruding proximal portion 275 of the collar 226 can aid in aligning the implant 210 with the inserter instrument 212.

[0066] The proximal portion 275 of the interface collar 226 defines one or more openings 278, 280 through the outer surface 270 of the ring-shaped body 266, which openings are configured to mate with the inserter instrument 212 for implantation. For example, the central opening 278 may be internally threaded to mate with the threaded shaft 340 of the inserter instrument 212, and a pair of unthreaded openings 280 may be positioned on either side of the central opening 278 to receive the unthreaded shaft 338 of the inserter instrument 212.

[0067] The interface and locking collar 226 includes one or more vertically protruding beams 282 extending from the top surface 274 of the ring-shaped body 266. The vertical beams 282 may be located at the proximal portion 275 of the collar 226. For example, a pair of vertical beams 282 may be positioned on either side of the instrument openings 278, 280. As best seen in FIG. 11A , in the collapsed position, the top of each vertical beam 282 may be adjacent to or in contact with the bottom surface 240 of the upper end plate 220. The inward-facing surface 284 of each beam 282 may be configured to engage with the teeth 252 of the expansion gear 224 when in the locked position. The inward-facing surface 284 may have a V-shaped notch or other suitable shape to mate with a corresponding tooth 252 on the expansion gear 224. When the locking collar 226 presses against the expansion gear 224, the inward facing surface 284 of the beam 282 prevents the expansion gear 224 from rotating, thereby preventing the upper end plate 220 from expanding.

[0068] The interface and locking collar 226 houses the actuation ram 228 and the spring 230. The locking collar 226 defines a pocket 286 sized and dimensioned to receive the actuation ram 228. The pocket 286 is defined in the proximal portion 275 of the ring 266 from the bottom surface 276 along the inner surface 272 of the ring 266. The pocket 286 is in fluid communication with the instrument openings 278, 280 such that the actuation ram 228 is accessible to the instrument 212. The interface and locking collar 226 defines a recess 288 sized and dimensioned to receive the spring 230. The spring recess 288 may include a semicircular cutout that mimics the curvature of the ring 266. The spring recess 288 is defined in the ring 266 from the top surface 274 along the inner surface 272 of the ring 266. The spring recess 286 may be located in the distal portion 277 of the collar 226 opposite the actuation ram 228 and instrument openings 278, 280.

[0069] The inner surface 272 of the locking collar 226 may include one or more mating surfaces 290 configured to engage with the teeth 324 of the bottom endplate 222 in the locked configuration. The mating surfaces 290 may be located on the proximal and distal portions 275, 277 such that the proximal portion 275 engages the bottom endplate 222 when the collar 226 is slid distally and the distal portion 275 engages the bottom endplate 222 when the collar 226 is slid proximally. For example, the inner proximal and distal mating surfaces 290 of the collar 226 may include one or more protrusions, edges, serrations, teeth, etc. configured to mate with a corresponding ring of teeth 324 along the top of the bottom endplate 222. The number, location, and configuration of the mating surfaces 290 may be selected by one of ordinary skill in the art.

[0070] The actuation ram 228 is an intermediate component that operates within a groove cut into the pocket 286 and the locking collar 226. When the inserter 212 engages the locking collar 226, the inserter 212 also engages the actuation ram 228, which causes the ram 228 to safely press against the bottom endplate 222. This allows the implant 210 to be locked, unlocked, or reoriented for insertion depending on how the inserter 212 and locking collar 226 are engaged.

[0071] The actuation ram 228 may include a body having two enlarged ends 292 with a narrowed intermediate portion 294. The enlarged ends 292 may be generally wider than the central portion 294 of the actuation ram 228. The actuation ram 228 is disposed within the pocket 286 of the collar 226. The enlarged ends 292 are configured to align with the unthreaded opening 280 such that the enlarged ends 292 of the actuation ram 228 may be engaged by the unthreaded shaft 338 of the instrument 212. The narrowed intermediate portion 294 defines a notch 296 configured to partially align with the central threaded opening 278 that receives the threaded shaft 340 of the instrument 212. The notch 296 may define a square or rectangular shape with rounded corners, a square shape, or another suitable shape. A rear surface 298 of the actuation ram 228 is configured to contact the bottom end plate 222 to move the locking collar 226 into or out of contact with the bottom end plate 222 and the expansion gear 224. The rear surface 298 of the actuation ram 228 may be concave to mate with the rounded body of the bottom end plate 222.

[0072] The spring 230 includes an elongated tab extending between opposing ends 302. The spring 230 may bend, bend, or deform under force and then return to its original shape when the force is removed. For example, the spring 230 may include a curved or arched central portion 304 that is flexible and deformable under pressure. The ends 304 of the spring 230 fit within the ends of the spring recesses 288 of the locking collar 226. In its relaxed state and first inserter position (shown in FIG. 14A ), the curved central portion 304 protrudes from the recesses 288 such that the spring 230 presses the collar 226 against the bottom end plate 222 and the expansion gear 224. In the second inserter position (shown in FIG. 15A ), the curved central portion 304 still protrudes from the recess 288, but the locking collar 226 is pressed away from the teeth 324 of the bottom endplate 222 so that the locking collar 226 is free to spin around the implant 210. In the third inserter position (shown in FIG. 16A ), when enough force is applied to overcome the resistance of the spring, excessive force is applied to the spring 230, causing the curved central portion 304 to invert or flip beyond its equilibrium and fully seat within the spring recess 288 in the locking collar 226. When this force is removed, the spring 230 returns to its relaxed state (shown in FIG. 14A ).

[0073] The bottom or inferior endplate 222 includes an annulus 308, which may be a ring that surrounds a portion of the central graft window 232. The annulus 308 has a thickness between a lower bone-engaging surface 310 and an upper surface 312 of the annulus 308. The annulus 308 may be angled and / or the thickness between the upper surface 310 and the lower surface 312 of the annulus 308 may be varied to accommodate a wide range of anatomical contours and to match or restore lordosis when used in the lumbar spine.

[0074] The lower bone-engaging surface 310 of the lower endplate 222 is configured to engage the inferior vertebral body 4. The lower bone-engaging surface 310 may be contoured to mimic the shape of the vertebral endplate 6 or may be provided with various footprints and geometries configured to contact the bone surfaces of adjacent vertebral bodies. Similar to the upper bone-engaging surface 238, the lower bone-engaging surface 310 may include a plurality of teeth, protrusions, or other friction-enhancing surfaces configured to engage bone. In one embodiment, the bottom endplate 222 includes a bone-like ejection-resistant pattern or texture on its lower surface geometry for contacting the bone surface, which can be angled to match or restore lordosis when used in the lumbar spine. The lower bone-engaging surface 310 may further include a porous or porous structure to allow additional bone ingrowth into the spacer. The lower endplate 222 may be 3D printed, for example, to enhance the potential for bone ingrowth. It will be appreciated that the bone-engaging surface 310 may be modified to include one or more surface treatments, coatings, textures, ejection-resistant structures or geometries, or other features to enhance fixation.

[0075] Assembly, counter-torque, and interface features for the locking collar 226 and expansion gear 224 are machined into the upper portion of the lower endplate 222. The locking collar 226 is nested between the actuation gear 224 and the bottom endplate 222. The bottom 276 of the locking collar 226 is adjacent to or in contact with the upper surface 312 of the annulus 308. The lower endplate 222 has an inner wall 314 defined by a portion of the central graft window 232 and an outer wall 316. A plurality of slits 318 extend perpendicularly between the inner wall 314 and the outer wall 316. As best seen in FIG. 14B , the inner wall 314 defines a recess 320 configured to mate with the circular rim 260 and protruding portions or fingers 322 configured to fit into the grooves 262 of the expansion gear 224. The fingers 322 may be configured to bend or flex slightly as the fingers 322 are inserted into the grooves 262 , thereby firmly connecting the expansion gear 224 to the lower end plate 222 .

[0076] A ring of teeth 324 may be provided on the bottom endplate 222 to engage with the locking collar 226 at a specific location. The ring of teeth 324 may be located between the outer wall 314 and the top surface 312 of the annular body 308. The ring of teeth 324 may include straight teeth projecting radially from the outer wall 314. The edges of each tooth 324 may be straight and aligned parallel to the axis of rotation. The apex of each tooth 324 may be truncated, and the space between each tooth 324 may be rounded or semicircular, for example. While a specific arrangement of the teeth 324 is shown, it is contemplated that the number, location, thickness, diameter, pitch, and configuration of the teeth may be varied or selected by one skilled in the art. When the mating teeth 290 on the locking collar 226 engage the teeth 324, the locking collar 226 is locked relative to the bottom endplate 222. Once disengaged from teeth 324, locking collar 226 is free to rotate toward the desired implant orientation.

[0077] The inferior endplate 222 may include posts 326 that may be sized and dimensioned to fit within the slots 244 in the cylinder 236 of the superior endplate 220. The posts 326 may protrude vertically from the superior surface 312 of the inferior endplate 222. The posts 326 may include horizontal beams 328 having opposite ends that fit into corresponding grooves in the cylinder 236 of the superior endplate 220. The inward-facing surface 330 may be curved to mimic the shape of the central graft window 232. When the expansion gear 224 is rotated to expand the superior endplate 220, the slots 244 and posts 326 act as a counter-torque means for expanding and collapsing the superior endplate 220.

[0078] 14A-16B, the implant 210 can be inserted into the intervertebral disc space using an inserter 212 through an agnostic approach. In other words, the surgeon can determine the trajectory or approach to the spine before or during the procedure and adjust the orientation of the implant 210 during the procedure to accommodate the desired surgical approach. Surgical approach angles and trajectories may include direct anterior, direct lateral, oblique, and selected positions between direct anterior and direct lateral. In some cases, the implant 210 can help resolve insufficient anterior-posterior distance in the intervertebral disc space during insertion and placement of a medial-lateral wide-footprint spacer from an anterior-to-psoas approach. Additionally, the implant 210 can be inserted from multiple approaches without requiring an extensive set of implants with fixed, approach-specific insertion features. The ability to be inserted from multiple approaches and trajectories significantly reduces the number of implants required in a set for a given procedure. Additionally, the versatility of implant 210 provides surgeons with more options and greater control during the procedure, thereby resulting in better patient outcomes.

[0079] The inserter 212 controls the position and orientation of the interface collar 226 and the expanded height of the superior endplate 220 when properly attached. The inserter 212 includes a distal end 332 configured to attach to the interface collar 226 of the implant 210. The inserter 212 may include an outer body 334 in the form of a hollow outer tube or cannula, which may include an expansion assembly and an attachment assembly. The attachment assembly may include a distal attachment interface 336 sized to receive the proximal portion 275 of the locking collar 226, a pair of unthreaded shafts 338 configured to engage with the unthreaded openings 280, and a central threaded shaft 340 configured to engage with the threaded opening 278 of the locking collar 226.

[0080] 14A-14B show the inserter instrument 212 attached to the implant 210 in a first position. In the first position, or disengaged state, the implant 210 is locked such that the collar 226 and expansion gear 224 are fully locked. The unthreaded shaft 338 may be received within the opening 280, but the shaft 338 does not apply force against the actuation ram 228. In this position, the inserter 212 is not threaded into the locking collar 226. A protruding interface feature on the inserter 212 may contact or guide the inserter 212 into the correct alignment for threading into the locking collar 226. A mating, coupling, and / or interference feature on the proximal portion 275 of the locking collar 226 engages a similar complementary interface surface on the bottom endplate 222, with the spring 230 pulling / pushing against the locking collar 226 and bottom endplate 222.

[0081] In the first position, the locking collar 226 locks against the bottom endplate 222 and the expansion gear 224. A spring 230 on the locking collar 226 simultaneously presses the locking collar 226 against the bottom endplate 222 and the expansion gear 224. The spring 230 biases the locking collar 226 distally, away from the inserter 212. In this first position, the mating surfaces 290 on the locking collar 226 engage the teeth 324 on the bottom endplate 222, thereby acting as a counter torque and preventing the locking collar 226 from rotating. The contact surfaces 284 on the beam 282 also interfere with the teeth 252 on the expansion gear 224, thereby interfering with the rotational movement of the expansion gear 224 and preventing both expansion and collapse of the implant 210.

[0082] 15A-15B show the inserter instrument 212 attached to the implant 210 in a second position. In the second position, the locking collar 226 can only be moved by rotating it about the inferior endplate 222 when the inserter 212 is properly attached. In this position, the locking collar 226 can be rotated to the desired insertion orientation, but the expansion gear 224 remains locked. The unthreaded shaft 338 and the threaded shaft 340 can be received in the openings 278, 280 such that the shafts 338, 340 apply a force to the actuation ram 228 that moves the locking collar 226 toward the instrument 212. In the second position, the inserter 212 is threaded into the locking collar 226 to a predetermined position, but not completely threaded onto the collar 226.

[0083] The protruding interface features of the inserter 212 are configured to contact the implant 210 and help control the orientation of the implant 210 relative to the inserter 212 for implantation. The actuation ram 228 presses against a central element of the bottom endplate 222 such that the locking collar 226 is pulled and translated by the threaded engagement 340 of the inserter 212, moving any mating, coupling, and / or interference features away from the bottom endplate 222 and expansion gear 224. When engaged with the inserter 212 in the second position, the locking collar 226 is pressed away from the interface teeth 324 on the bottom endplate 222 and is held in this position by the spring 230. The locking collar 226 is free to spin around the implant 210 to apply the desired inserter-implant orientation for implantation.

[0084] 16A-16B show the inserter instrument 212 attached to the implant 210 in a third position. In the third position, the locking collar 226 is locked relative to the bottom endplate 222, but the expansion gear 226 is released and free to rotate to expand the top endplate 220. An unthreaded shaft 338 and a threaded shaft 340 can be received in the openings 278, 280 such that the shafts 338, 340 apply a force to the actuation ram 228 that moves the locking collar 226 fully into the instrument 212. When the inserter 212 is fully threaded into the locking collar 226 such that the actuation ram 228 presses against the central element of the bottom endplate 222, the locking collar 226 is pulled and translated by the threaded engagement of the inserter 212, and the mating, coupling, and / or interference feature on the distal portion 277 of the locking collar 226 is drawn into a similar complementary interface surface 324 on the bottom endplate 222. In the third position, the inserter 212 can drive the expansion or contraction of the implant 210 by actuating the expansion gear 224.

[0085] When engaged with the inserter 212 in this third position, the actuation ram 228 is fully pressed against the bottom endplate 222, and the locking collar 226 is pulled tight against the bottom endplate 222, completely overcoming the spring 230. The spring 230 flips into the spring recess 288 in the locking collar 226. The patterned mating surface 290 of the locking collar 226 engages with the teeth 324 on the bottom endplate to fix the orientation of the inserter 212 relative to the implant 210 and prepare the implant 210 for surgical insertion. In the third position, the combined interface geometries of the bottom endplate 222, actuation ram 228, and locking collar 226 firmly orient the implant 210 relative to the inserter 212, allowing it to be implanted in a defined orientation. The third position also unlocks the expansion gear 226 by pulling the locking collar 226 proximally toward the inserter 212 and away from the expansion gear 224, thereby disengaging the interface feature 284 on the top of the locking collar 226. In this state, the implant 210 can be expanded or contracted as the expansion gear 224 is articulated by the inserter 212.

[0086] In one embodiment, robotic and / or navigational guidance may be used to assist in orienting and placing the implant 10, 210 along one or more agnostic approaches. Details of surgical robotic and / or navigational systems can be found, for example, in U.S. Patent Nos. 10,675,094 and 9,782,229, the entireties of which are incorporated herein by reference for all purposes. The implant 10 may be implanted using one or more of the following steps: (1) determining the optimal implant position and positioning to optimize bone contact and desired correction; (2) using a robotic system and / or navigation system to determine potential trajectories that will enable optimal implant position and results; (3) optionally docking a cannula onto the disc space through an appropriate trajectory, including direct anterior, direct lateral, or an unspecified oblique approach between anterior and lateral; (4) inserting the expandable interbody 10 into the disc space in a collapsed position through the given trajectory; and (5) expanding the height of the expandable interbody 10 to accurately restore disc height and spinal alignment (e.g., lordosis).

[0087] The implants and systems described herein may include one or more of the following advantages: (1) the ability to adjust the orientation of the attachment to the implant to accommodate various approaches; (2) an internal auto-lock that provides distinct orientation positions around the central axis of the implant and automatically locks the device after insertion into the disc space; and (3) the ability to expand in height when implanted to achieve a desired spacer height that provides a desired disc height.

[0088] The ability to adjust the implantation orientation of the spacer relative to the sagittal angle of the spacer accommodates a variety of approach angles and trajectories, including, but not limited to, direct anterior, direct lateral, oblique, and fine increments between direct anterior and direct lateral. The spacer has a retained interface collar that allows for free rotation around the device's central axis. By pivoting / rotating around the central axis, the device can be oriented to better engage the natural endplate curvature of the vertebral bodies above and below the disc space in which it is implanted. This can be particularly beneficial in cases of highly complex deformities where the vertebral bodies may be rotated relative to two or more dimensional planes, thus requiring atypical surgical access approaches to the level the surgeon desires to treat.

[0089] The auto-lock with distinct orientation positions serves the dual function of both automatically locking the implant to prevent expansion and collapse of the implant and separately orienting the implant on the inserter for implantation. The auto-lock feature reduces the steps required during surgery to successfully implant the device, potentially reducing the cognitive load on the surgeon and creating a safer overall procedure because the surgeon cannot forget the step of locking the implant. The distinct orientations that the lock provides allow the surgeon to adapt to the approach that best suits the patient's anatomy.

[0090] Unlike static spacers, which only provide height restoration at discrete intervals, expandable implants are inserted into the disc space at a collapsed height and then expand axially to restore lost height within the disc space. The ability to expand in height upon implantation allows the surgeon to restore collapsed disc height at any height between the implant's starting height and its fully expanded height. Additionally, expandable interbody spacers maximize the volume within and around the device for implanted material.

[0091] It should further be understood that various changes in the details, materials, and arrangements of parts described and illustrated to explain the nature of the invention may be made by those skilled in the art without departing from the scope of the invention as expressed in the claims. Those skilled in the art will appreciate that the embodiments discussed above are non-limiting. It will also be understood that one or more features of one embodiment may be incorporated, in part or in whole, into one or more other embodiments described herein.

Claims

1. 1. An expandable implant comprising: superior and inferior end plates configured to engage adjacent vertebrae; an expansion gear configured to adjust the height of the upper end plate, the expansion gear being coupled to the lower end plate and engaged with the upper end plate; a locking collar positioned between the expansion gear and the inferior endplate and configured to attach to an inserter instrument in multiple orientations for a desired surgical approach; a spring received in a recess in the locking collar; an actuation ram housed within the locking collar configured to lock, unlock, or change the insertion orientation of the locking collar.

2. 2. The expandable implant of claim 1, wherein in a first position, the locking collar is locked relative to the inferior endplate and the expansion gear to completely lock the implant, in a second position, the locking collar is allowed to spin freely around the inferior endplate for the desired surgical approach, and in a third position, the locking collar is locked relative to the inferior endplate and translated away from the expansion gear to allow expansion of the superior endplate.

3. The expandable implant of claim 1 , wherein the inferior endplate includes a ring of teeth configured to engage a corresponding mating surface of the locking collar.

4. The expandable implant of claim 1 , wherein the spring is an elongated tab having a curved central portion that deforms under force.

5. The expandable implant of claim 1 , wherein the actuation ram includes a body having two enlarged ends with a narrowed intermediate portion.

6. The expandable implant of claim 1 , wherein the spring is located on an opposite side of the actuation ram.

7. 2. The expandable implant of claim 1, wherein the expansion gear includes a disk having a plurality of teeth protruding radially outward from the disk and a threaded central opening configured to threadably engage with the upper end plate.

8. 8. The expandable implant of claim 7, wherein the locking collar includes a pair of vertically protruding beams, each having an inwardly facing surface configured to engage the teeth of the expansion gear.

9. 2. The expandable implant of claim 1, wherein the upper end plate includes an annular body having a bone-engaging surface and a downwardly projecting cylinder configured to mate with the expansion gear, the downwardly projecting cylinder of the upper end plate including an external thread and a vertical slot bisecting the external thread, and the lower end plate includes a post receivable within the vertical slot.

10. an expandable implant including an upper endplate configured to engage a superior vertebra, an inferior endplate configured to engage a inferior vertebra, an expansion gear configured to adjust the height of the upper endplate, a locking collar configured to rotate around the inferior endplate for a desired surgical approach, a spring for biasing the locking collar toward or away from the inferior endplate and the expansion gear, and an actuation ram housed within the locking collar configured to lock, unlock, or change the insertion orientation of the locking collar; an inserter instrument having a mounting assembly configured to engage the locking collar and an expansion assembly configured to expand the implant, the inserter instrument being attachable to the locking collar in a first position to fully lock the implant, a second position to allow the locking collar to spin freely for the desired surgical approach, and a third position to allow expansion of the superior endplate.

11. 11. The implantable system of claim 10, wherein the locking collar includes an internally threaded central opening and a pair of unthreaded openings positioned on either side of the central opening.

12. 12. The implantable system of claim 11, wherein the actuation ram is positioned within a pocket of the locking collar, the actuation ram including a body having two enlarged ends and a narrowed intermediate portion, the enlarged ends aligned with the unthreaded opening and the narrowed intermediate portion aligned with the central opening.

13. The implantable system of claim 12 , wherein the narrowed intermediate portion defines a notch partially aligned with the central threaded opening.

14. 13. The implantable system of claim 12, wherein the inserter instrument includes a central threaded shaft configured to engage the central threaded opening and a pair of unthreaded shafts configured to engage the pair of unthreaded openings.

15. 15. The implantable system of claim 14, wherein in the first position, the inserter instrument is attached to the implant such that the inserter is not threaded onto the locking collar and the spring biases the locking collar against the inferior endplate and the expansion gear, thereby completely locking the implant.

16. 15. The implantable system of claim 14, wherein in the second position, the inserter instrument is attached to the implant such that the inserter is threaded into the locking collar to a predetermined position, the unthreaded shaft pushes the actuation ram, and the locking collar is released from the inferior endplate, thereby allowing the locking collar to spin freely for the desired surgical approach.

17. 15. The implantable system of claim 14, wherein in the third position, the inserter instrument is attached to the implant such that the inserter is fully threaded into the locking collar, the unthreaded shaft pushes against the actuation ram, overcoming the spring and causing the locking collar to release the expansion gear, thereby allowing expansion of the superior endplate.

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