Expandable intervertebral interbody implants

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 on 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 more particularly to expandable fixation devices that can be deployed inside the disc space and then expanded in height to maintain the disc space, restore spinal stability, and / or facilitate spinal fusion.

Background Art

[0003] A common treatment for pain associated with discs degenerated by various factors such as trauma or aging is the use of spinal fusion devices to fix one or more adjacent vertebral bodies. Generally, to fix adjacent vertebral bodies, the disc is first partially or completely removed. Then, generally, a spinal fusion device is inserted between the adjacent vertebrae to maintain the normal disc space, restore spinal stability, and thereby facilitate spinal fusion.

[0004] There are several fixation devices and methods for achieving spinal fusion. These can include solid bone implants, fixation devices including cages or other implant mechanisms that can be packed with bone and / or bone growth - inducing substances, and expandable implants. The implants are placed between adjacent vertebral bodies to fix the vertebral bodies to each other, thereby reducing the associated pain and restoring disc height.

[0005] Intervertebral devices have been used to provide support and stability in the anterior column of spinal vertebrae when treating various spinal conditions, including degenerative disc disease and spinal stenosis with spondylolisthesis. Clinical treatment of spinal pathology using anterior vertebral interbody devices depends on the accurate placement of the interbody device to restore normal anterior column alignment. Iatrogenic pathology can result from failure to accurately place the interbody between the surgical access window into the disc space, the hard cortical bone often found on the end rings of the vertebral bodies, and / or failure to accurately control and restore normal anatomical spinal alignment.

[0006] Accordingly, there is a need for a fixation device that can be inserted into the disc space at a crush height and then axially expanded to restore disc space height loss, and further provide accurate placement between the vertebral bodies, which allows insertion from multiple approaches to enable access to the spine without the need for a wide range of implants having fixed-approach-specific insertion features. SUMMARY OF THE INVENTION

[0007] To meet this and other needs, and in view of that purpose, the present application provides devices, systems, instruments, and methods for installing and expanding an implant. In particular, an expandable fixation device is provided that can be inserted from any approach that enables access to the spine. The expandable fixation device may have the ability to adjust the orientation of attachment to the implant to accommodate various approaches, provide distinct orientation positions around the central axis of the implant, and have an internal automatic lock that automatically locks the device after insertion into the disc space, and / or 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, an expandable implant includes an upper end plate and a lower end plate configured to engage adjacent vertebrae, an actuating gear configured to adjust the height of the upper end plate, coupled to the lower end plate, and engaged with the upper end plate, an interface collar configured to be attached to an inserter instrument in a plurality of orientations for a desired surgical approach and including a plurality of angled protrusions, and an expansion and orientation lock including a tapered outer surface having a plurality of cuts defined therein configured to lock the orientation of the interface collar and lock the height of the upper end plate and to interface with the plurality of angled protrusions within the interface collar and retained within the lower end plate.

[0009] The expandable implant may include one or more of the following features. The interface collar can rotate freely about the central axis of the implant when not engaged by the inserter instrument or when engaged in the open position. The interface collar may be a split ring having a gap between both sides of the split ring. The interface collar may include a pair of eyelets that define a pair of openings through the interface collar. The lower end plate may include a plurality of snap-fit posts arranged in pairs that define a space therebetween, and the lock may include a plurality of guide rail posts configured to fit into the space between the snap-fit posts and thereby guide the movement of the lock. The upper portion of the guide rail post may project upward from the lock and be configured to engage a pocket below the operating gear to restrain the rotational movement of the operating gear and prevent expansion and crushing of the implant. The lock may include a plurality of spring arms extending from the bottom surface of the lock, and in the disengaged state, the spring arms push up the lock and away from the bottom end plate. The operating gear may include a disk having a plurality of teeth projecting radially outward from the disk and a threaded central opening configured to engage the upper end plate. The upper end plate may include an annular body with a bone-engaging surface and a downwardly projecting cylinder configured to mate with the operating gear. The downwardly projecting cylinder of the upper end plate may include an external thread and a vertical slot that bisects the external thread, and the lower end plate may include a support post that can be received within the vertical slot.

[0010] According to one embodiment, an implantable system includes an expandable implant and an inserter instrument. The expandable implant includes an upper end plate configured to engage an upper vertebra, an actuating gear configured to adjust the height of the upper end plate, an interface collar configured to rotate about the 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 upper end plate, and a lower end plate configured to engage a lower vertebra. The inserter instrument has an attachment 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 an open position, a half position, and a full position 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 attachment assembly may include an attachment fork having a pair of prongs. The interface collar may include a pair of openings configured to receive the prongs of the attachment fork. In the open position, the inserter instrument is attached to the implant such that the attachment fork does not engage the interface collar, thereby allowing full rotation of the interface collar and preventing expansion of the upper end plate by the lock. In the half position, the inserter instrument is attached to the implant such that the attachment fork engages the interface collar, thereby fixing the position of the interface collar and preventing expansion of the upper end plate by the lock. In the full position, the inserter instrument is attached to the implant such that the attachment fork engages the interface collar, thereby fixing the position of the interface collar and disengaging the lock from the actuating gear to allow expansion of the upper end plate.

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

[0013] According to one embodiment, an expandable implant includes an upper end plate and a lower end plate configured to engage adjacent vertebrae, an expansion gear configured to adjust the height of the upper end plate, coupled to the lower end plate, and engaging the upper end plate, a locking collar positioned between the expansion gear and the lower end plate and configured to be attached to an inserter instrument in a plurality of orientations for a desired surgical approach, a spring received in a recess of the locking collar, and an actuating ram received in the locking collar and 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 to the lower end plate and the expansion gear, thereby fully locking the implant. In a second position, the locking collar may be able to spin freely around the lower end plate for a desired surgical approach. In a third position, the locking collar may lock to the lower end plate and translate parallel away from the expansion gear, thereby enabling expansion of the upper end plate. The lower end plate may include a ring of teeth configured to engage a corresponding mating surface of the locking collar. The spring may include an elongate tab having a curved central portion that deforms under pressure. The actuating ram may include a body having two enlarged ends with a narrowed middle portion. The spring may be located on the opposite side of the actuating ram. The expansion gear may include a disk having a plurality of teeth projecting radially outward from the disk and a threaded central opening configured to threadably engage the upper end plate. The locking collar may include a pair of vertically projecting beams each having an inwardly facing surface configured to engage the teeth of the expansion gear. The upper end plate may include an annular body with 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 may include an external thread and a vertical slot bisecting the external thread, and the lower end plate may include a strut receivable within 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 end plate configured to engage an upper vertebra, a lower end plate configured to engage a lower vertebra, an expansion gear configured to adjust the height of the upper end plate, a locking collar configured to rotate around the lower end plate for a desired surgical approach, a spring for biasing the locking collar toward or away from the lower end plate and the expansion gear, and an actuating ram housed within the locking collar and configured to lock, unlock, or change the insertion orientation of the locking collar. The inserter instrument has an attachment 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 for locking the implant, a second position that allows the locking collar to spin freely for a desired surgical approach, and a third position that allows expansion of the upper end plate.

[0016] The implantable system may include one or more of the following features. The locking collar may include a central opening with internal threads and a pair of threadless openings positioned on either side of the central opening. The actuating ram may be positioned within a pocket of the locking collar. The actuating ram may include a body having two enlarged ends and a narrowed middle portion. The enlarged ends may be aligned with the threadless openings, and the narrowed middle portion may be aligned with the central opening. The narrowed middle portion may define a notch that is partially aligned with the centrally threaded opening. The inserter instrument may include a centrally threaded shaft configured to engage the centrally threaded opening and a pair of threadless shafts configured to engage the pair of threadless openings. In a first position, the inserter instrument may be attached to the implant such that the inserter is not screwed into the locking collar and the spring biases the locking collar against the lower end plate and the 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 screwed into the locking collar to a predetermined position, the threadless shaft presses the actuating ram, and the locking collar is released from the lower end plate, thereby allowing the locking collar to spin freely for a desired surgical approach. In a third position, the inserter instrument may be attached to the implant such that the inserter is fully screwed into the locking collar, the threadless shaft presses the actuating ram, overcomes the spring, and the locking collar releases the expansion gear, thereby allowing the upper end plate to expand.

[0017] According to another embodiment, a method of installing an expandable implant includes: (a) providing an expandable implant having an upper end plate, a lower end plate, an expansion gear configured to adjust the height of the upper end plate, a locking collar configured to rotate about the lower end plate for a desired surgical approach, a spring for biasing the locking collar toward or away from the lower end plate and the expansion gear, and an actuating ram housed within the locking collar and 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 by the inserter instrument to determine a desired trajectory; (d) inserting the expandable implant in a collapsed position along the desired trajectory between adjacent vertebrae; and (e) expanding the expandable implant by the inserter instrument. In a non-engaged state, the implant may be locked such that the locking collar and the expansion gear are fully locked. The desired trajectory may be selected from a direct anterior, a non-specified oblique approach between direct anterior and direct lateral, or a direct lateral approach.

[0018] Also provided is a kit including expandable fixation devices, rods, fasteners or anchors, k-wires, insertion tools, and other components of various types and sizes for performing the procedures.

Brief Description of the Drawings

[0019] A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.

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

[0021] An expandable intervertebral spacer may be inserted from any approach that allows access to the spine. The expandable spacer is inserted into the intervertebral disc space at a collapsed height and then axially expanded to restore height loss within the intervertebral disc space. The expandable intervertebral spacer may be configured to maximize the volume within and around the device for graft material. Alternatively, the spacer may be used as a vertebral body resection spacer disposed between non-adjacent vertebral bodies. The spacer may be provided in a variety of installation areas and outer shapes with upper and lower geometries that contact the bone surface of the vertebral bodies in which the spacer is embedded when implanted. The upper and lower geometries may be angled, for example, when used in the lumbar spine, to accommodate a wide range of anatomical shapes and to conform to or restore lordosis.

[0022] Referring now to the drawings, like reference numerals refer to like elements, and FIGS. 1A-1C illustrate an expandable intervertebral fixation device or implant 10 and method of installation 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 for deploying the device 10 into the disc space (the upper vertebra is omitted in FIGS. 1A-1C for clarity). The inserter 12 may be suitable for use during minimally invasive surgical (MIS) procedures, for example, such that the inserter 12 and attached implant 10 can be positioned through a guide tube or cannula to access the implant 10 and direct the implant 10 into the disc space. The expandable implant 10 is inserted between the vertebral bodies 4 of the vertebrae 2 and inserted into the disc space at the crush location.

[0023] The implant 10 is configured to adjust the orientation of the inserter 12 relative to the implant 10 to accommodate various surgical approaches to the spine. The ability to adjust the implant orientation of the implant 10 accommodates various approach angles and trajectories to the spine. The surgical approach angles and trajectories may include directly anterior, directly lateral, oblique, and subdivided increments between directly anterior and directly lateral. FIG. 1A shows the placement of the implant 10 by a directly anterior approach to the spine from the front of the body. When operating on the lumbar spine, this surgical technique may also be referred to as anterior lumbar interbody fusion (ALIF). FIG. 1B shows the placement of the implant 10 by an unspecified oblique approach (e.g., an angle between directly anterior and directly lateral). FIG. 1C shows the placement of the implant 10 by a directly lateral approach to the spine from the side of the body. When operating on the lumbar spine, this surgical technique may also be referred to as 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 surgery.

[0024] Once inserted into the disc space through the desired surgical approach, the implant 10 is then expanded in height to an expanded position so as to accurately restore normal spinal alignment and distribute load across the vertebral endplate 6. The adjustable attachment interface may orient or angle the implant 10 to better contact the natural endplate curvature of the vertebral bodies 4 above and below the disc space in which the device 10 is implanted. This can be particularly beneficial in cases of highly complex deformities where the vertebral bodies 4 can be rotated with respect to two or more planes of dimension and thus require an atypical surgical access approach to the level desired by the surgeon to treat.

[0025] Referring now to FIG. 2, a exploded view of an expandable implant 10 according to one embodiment is shown. The implant 10 includes an upper end plate 20 for engaging an upper vertebra 4, a lower end plate 22 for engaging a lower vertebra 4, an expansion or actuating gear 24 for adjusting the height of the upper end plate 20, an orientation and interface collar 26 configured to attach an 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 end plates 20, 22, the actuating gear 24, the interface collar 26, and the 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 a bone graft or other suitable bone growth promoting material. As best seen in FIG. 5, the central graft window 32 may be generally cylindrical with a central axis aligned with the central longitudinal axis 30.

[0026] The upper or upper end plate 20 includes an annular body 34 having a downwardly projecting cylinder 36 configured to mate with the actuating gear 24. The annular body 34 may be a ring or circular and surround a portion of the central graft window 32. The annular body 34 has a thickness between an upper bone engaging surface 38 and a bottom, or lower surface 40, of the annular body 34. As best seen in FIGS. 3A - 3B and FIGS. 4A - 4B, the annular body 34 may be angled and / or the thickness between the upper surface 38 and the lower surface 40 of the annular body 34 may vary to accommodate a wide range of anatomical profiles and to conform to or restore lordosis when used in the lumbar spine.

[0027] The annular body 34 includes an upper bone engagement surface 38 configured to engage the superior vertebral body 4. The upper bone engagement surface 38 may be contoured to mimic the shape of the vertebral endplate 6. The upper bone engagement 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 discharge resistance pattern or texture on the 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 contact surface 38 may further include porosity or a porous structure to allow additional ingrowth of bone into the spacer. The upper endplate 20 may be 3D printed, for example, to enhance the potential for bone growth. It will be understood that the bone engagement 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 of the annular body 34, i.e., the lower surface 40. The protruding cylinder 36 defines one or more external threads 42 configured to mate with corresponding threads 50 inside the actuating gear 24. The external threads 42 may include a helical thread profile machined on the outer surface of the cylinder 36. The external threads 42 may have any suitable attributes including diameter, winding direction, thread shape, 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 received telescopically within / from the actuating gear 24, the upper endplate 20 is configured to move up or down in height, thereby adjusting the overall height of the implant 10. The slot 44 may extend over the entire length or a partial length of the threads 42 and reach 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 positioned at an angle from directly in front to allow access from various approach angles. The slot 44 may act as a backfill window and reverse torque for spacer expansion and collapse.

[0029] The expansion gear or actuating gear 24 is configured to expand and crush the implant 10. The actuating gear 24 is sized and dimensioned to coaxially receive the protruding cylinder 36 of the upper end plate 20 and has a central through-opening 48. 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 and configured to engage the external threads 42 of the upper end plate 20. By the threaded engagement between the cylinder 36 and the threaded opening 48, the actuating gear 24 can adjust the height of the upper end plate 20 during rotation.

[0030] The outer periphery of the actuating gear 24 includes a plurality of cogs or teeth 52. In one embodiment, the actuating gear 24 may be a spur gear or straight-tooth gear having straight teeth 52 that project radially from a cylinder or disk. The edge of each tooth 52 may be linear and aligned parallel to the axis of rotation. Although a particular arrangement of the teeth 52 is shown, it is contemplated that the number, position, thickness, diameter, pitch, and configuration of the teeth may be varied or selected by one of ordinary skill in the art. When engaged by the inserter instrument 12, the actuating gear 24 can be rotated about the axis 30 to move the upper end plate 20 up and down, thereby adjusting the height of the implant 10.

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

[0032] The actuating gear 24 includes a snap - fit lip 58 that projects downward and is configured to be held by the bottom end plate 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 projects radially outward to engage the bottom end plate 22. The bottom portion or surface of the rim 60 may be angled or rounded to assist in the snap - fit engagement. The lower surface 56 of the actuating gear 24 defines a plurality of pockets 62 configured to hold a portion of the lock 28. The lock 28 is configured to engage the pockets 62 within the lower surface 56 on the underside of the actuating gear 24 to restrain the rotational movement of the actuating gear 24 and prevent both the expansion and the crushing 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 can rotate freely about the axis 30. When engaged by the inserter 12 at a particular position, the collar 26 is locked in a fixed position 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 both sides of the split ring 66. The interface collar 26 defines one or more openings 70 through the outer surface 72 of the outer diameter, which is configured to engage the inserter 12 for implantation. The outer surface 72 may generally be smooth except for a pair of protruding elliptical eyelets 71 on both sides of the gap 68. Each opening 70 may be defined through its 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 can define a side or inclined surface configured to vertically translate the lock 28 parallel along the shaft 30. The angled protrusions 76 may extend a distance from the upper surface 78 towards the lower surface 80, but stop short of the lower surface 80, allowing a smooth region 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, having a smooth region 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 the surfaces can be varied or selected by one of ordinary skill in the art.

[0035] The rotatable interface collar 26 is positioned between the actuating gear 24 and the bottom end plate 22. The interface collar 26 may be retained within the bottom end plate 22 by overlapping lips 82, 120 on the collar 26 and the bottom end plate 22. The lip 82 on the interface collar 26 may include a downwardly projecting lip that follows the body of the split ring 66 along the inner surface 74. It will be understood that the interface collar 26 may be retained within the bottom end plate 22 using any suitable mechanism that allows rotational movement of the collar 26 about the shaft 30 when the collar 26 is not fixed by the inserter 12.

[0036] When the interface collar 26 is not engaged by the inserter 12, it can rotate freely 360° around the central axis 30 of the implant core. The collar 26 can be engaged by the inserter 12 at a plurality of positions. In a first position, the angled protrusion 76 of the collar 26 engages with 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 actuating gear 24, thereby enabling expansion or compaction of the implant 10 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 a shallow angled cut 94 that interacts and engages with a mating protrusion 72 on the interface collar 26. The lock 28 includes an angled or tapered ring-like body 86 from an upper edge 88 to a bottom edge 90. The body 86 gradually increases in diameter along its circumference from the upper edge 88 to the bottom edge 90, forming an outer conical shape. Thus, the upper edge 88 has a smaller diameter than the bottom edge 90. The outer diameter of the lock 28 includes a plurality of shallow cuts 94. The shallow cut 92 may be of a generally rectangular shape extending vertically from the upper edge 88 towards the bottom edge 90. The cuts 92 may have equal widths, be equally spaced around the lock 28, or be otherwise configured to mate with corresponding protrusions 72 within the interface collar 26. The inner surface 96 of the lock 28 may be smooth.

[0038] Lock 28 has one or more guide rail posts 98, which engage with a bottom end plate 22 acting as reverse torque means such that the lock 28 can move linearly only vertically along the shaft 30. Each guide rail post 98 may include a vertical rail protruding radially inwards. 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 part of the guide rail post 98 protrudes upwards and is configured to engage with a pocket 62 below the actuating gear 24 to restrain the rotational movement of the actuating gear 24 and prevent expansion and crushing 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 at a free end. The spring arm 102 may include a curved beam or structure with a convex outer shape on the lower side and bent downwards. The 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 non-engaged state of the implant, the spring arm 102 pushes the lock 28 upwards and away from the bottom end plate 22.

[0039] The bottom end plate 22 includes an annular body 106 configured to receive the expansion and orientation lock 28, the interface collar 26, and the actuating gear 24. Similar to the upper end plate 20, the annular body 106 may be a ring or circular shape surrounding a portion of the central implant window 32. The annular body 106 has a thickness between a lower bone engagement surface 108 and an upper edge 110 of the annular body 34. As best seen in FIGS. 3A - 3B and FIGS. 4A - 4B, the annular body 106 may be angled and / or the thickness between the upper surface 108 and the lower surface 110 of the annular body 106 may vary to adapt to a wide range of anatomical profiles and to conform to or restore lordosis when used in the lumbar spine.

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

[0041] The assembly, reverse torque, and interface features for the lock 28 are machined into the upper portion of the lower end plate 22. The expansion and orientation lock 28 resides nested inside pockets and grooves 112 machined into the bottom end plate 22. The lower end plate 22 has an inner wall 114 defined by a portion of the central implant window 32. A plurality of snap-fit posts 116 extend vertically from the inner wall 114. The snap-fit posts 116 are arranged in pairs with a space 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 equally spaced around the inner wall 114, defining four respective spaces 118 for the corresponding guide rail posts 98. The guide rail posts 98 engage the space 118 between the snap-fit posts 116 to linearly guide the vertical movement of the lock 28 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 lower end plate 22, the interface collar 26 is disposed within the lower end plate 22 such that the collar 26 surrounds and engages the lock 28. The interface collar 26 may be retained within the lower end plate 22 by overlapping lips 82, 120 on the collar 26 and the bottom end plate 22. The collar 26 may be sized and dimensioned such that the outer surface 72 of the orientation collar 26 is substantially coplanar with the outer periphery of the annular body 106 of the lower end plate 22.

[0043] Next, the actuating gear 24 may be positioned on top of the orientation collar 26 and secured to the lower end plate 22. The lower surface 56 of the actuating gear 24 abuts the upper surface 78 of the interface collar 26. The actuating gear 24 may be sized and dimensioned such that the outer diameter of the gear 24 is substantially coplanar with the outer surfaces 72 of the interface collar 26 and the outer periphery of the annular body 34 of the upper end plate 20. The lower surface 56 of the actuating gear 24 is seated on top of the snap-fit post 116 within the bottom end plate 22. The actuating gear 24 is retained within the bottom end plate 22 via a snap-fit lip 60. Each of the free ends 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 actuating gear 24. The snap-fit post 116 may be configured to bend or flex slightly as the finger 122 is inserted, thereby securely connecting the actuating gear 24 to the lower end plate 22.

[0044] The upper end plate 20 is threaded onto the actuating gear 24. The strut 124 may project vertically from the lower end plate 22 and is sized and configured to fit within the slot 44 of the cylinder 36 of the upper end plate 20. When in the fully collapsed position, the slot 44 and the strut 124 may act as anti-torque means for spacer expansion and collapse. When the implant 10 is fully collapsed as shown in FIGS. 3A - 3B, the bottom surface 40 of the annular body 34 of the upper end plate 20 may contact and abut the upper surface 54 of the actuating gear 24. When the implant 10 is expanded as shown in FIGS. 4A - 4B, the annular body 34 of the upper end plate 20 lifts away from the actuating gear 24 and the bottom surface 40 of the annular body 34 is spaced from the actuating gear 24.

[0045] The devices or their components described in this specification may be manufactured 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 manufactured by machining, additive methods such as three-dimensional (3D) printing, and / or subtractive methods.

[0046] Referring now to FIGS. 6A-9B, the implant 10 can be inserted into the 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 can 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 without the need for an extensive set of implants having 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 within the set list for a given procedure. Further, the flexibility of the implant 10 provides the surgeon with more options and better control during the procedure, thereby leading to better patient outcomes.

[0047] Figures 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 extended height of the upper end plate 20 when properly attached. The inserter 12 extends from a proximal end 130 to a distal end 132 along the central longitudinal axis of the tool. The proximal end 130 includes an attachment interface for connecting a handle (not shown) configured to be operated 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 that defines 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 positions.

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

[0049] The attachment assembly may include an attachment 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 apart to match the spacing of the attachment locations 70 along the interface collar 26. The prongs 144 may be configured to bend slightly or flex so as to engage the interface collar 26 at different positions. The free end 146 of each prong 144 may be inserted into the respective opening 70 and may be contoured or shaped to engage both sides of the opening 70. A sleeve 148 may be configured to draw the prongs 144 together or separately. An outer control knob 150 and an inner half nut 152 may be used to manipulate the prongs 144. For example, rotating the control knob 150 translates the sleeve 148 and can draw the prongs 144 together or spread the prongs 144 apart from each other. It will be understood that any suitable mechanism may be used to control the movement of the attachment fork 140 and the prongs 144.

[0050] FIG. 7 shows an inserter 12 attached to the implant 10 such that the attachment 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 within the shallow notch 94 of the lock 28. The open position occurs when the control knob 150 is twisted such that the attachment fork 138 results in a position where 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 a neutral position within the opening 70 of the interface collar 26, thereby allowing the interface collar 26 to be rotated completely to the desired insertion orientation.

[0051] When the color 26 is engaged by the inserter 12, the angled protrusion 76 of the color 26 engages with the angled shallow notch 94 on the lock 28. The color 26 may be engaged by the inserter 12 in two different positions, namely the half position and the 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 color 26, and the prong 144 is positioned within the opening 70 of the interface color 26 such that the prongs 144 move away from each other. When engaged by the inserter 12 in the half position, the protrusion 76 of the interface color 26 couples with the notch 94 on the lock 28, preventing the color 26 from rotating, which then defines the orientation of the implant 10 with respect to the inserter 12 for implantation. The half position occurs when the control knob 150 is twisted such that the attachment fork 140 results in a position where the prongs 144 of the fork 140 engage the angled interaction feature on the interface color 26 with the lock 28. In the half position, the orientation of the interface color 26 is firmly defined, but the expansion mechanism is not unlocked.

[0052] Figures 9A - 9B show inserter 12 attached to implant 10 in the fully seated position. When engaged in the fully seated position by inserter 12, the inclined feature of interface collar 26 is pushed into and over lock 28, disengaging rail post 98 from under gear 24 and allowing for expansion or collapse of implant 10 and insertion or removal. The fully seated position also prevents rotation and reorientation of collar 26. In the fully seated position, prong 144 of attachment fork 144 may be drawn towards each other to grip interface collar 26 such that the ends of split ring 66 approach each other, thereby engaging interface collar 26 with lock 28. The fully seated position occurs when control knob 150 is turned such that attachment fork 140 provides a position where prong 144 of fork 140 engages interaction feature 76 on interface collar 26 with lock 28. In this way, the orientation of interface collar 26 is firmly defined and the inclined interaction feature 76 of interface collar 26 presses lock 28 downward and away from expansion gear 24. The upper end of guide rail post 98 on lock 28 is disengaged from pocket 62 in lower surface 56 of actuating gear 24, thereby unlocking implant 10.

[0053] Once in the fully seated position, upper end plate 20 can be raised or lowered. For example, rotating expansion drive shaft 136 of inserter 12 causes expansion or contraction of spacer 10. Drive gear 138 engages actuating gear 24, thereby allowing adjustment of the height of implant 10. Conversely, in the half or open position, rotating expansion drive shaft 136 on inserter 12 does not cause expansion or contraction of spacer 10 because lock 28 is engaged with expansion gear 24, thereby preventing this movement. Further, when inserter 12 is removed from implant 10, lock 28 automatically re - engages with actuating gear 24 such that spring 102 presses lock 28 upward and the upper end of guide rail post 98 re - enters pocket 62 in lower surface 56 of actuating gear 24, thereby re - locking implant 10 and preventing further expansion or contraction of implant 10.

[0054] Referring now to FIGS. 10 - 16B, an expandable intervertebral fixation device or implant 210 according to one embodiment is shown. The expandable implant 210 is similar to implant 10, except that the interaction with the locking mechanism and inserter instrument 212 is altered, thereby allowing three operating positions. In the disengaged state or first engagement position with the inserter 212, the implant 210 is locked and prevented from expanding. In the second engagement position with the inserter 212, the implant 210 can be reoriented for selection of a desired implantation trajectory. In the third engagement 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 the attachment of the inserter 212 to the implant 210 to accommodate various surgical approaches to the spine. The ability to adjust the implantation 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 subdivided increments between direct anterior and direct lateral. It will be understood that the surgeon may determine the best surgical approach and placement of the expandable implant 210 prior to or during the surgery.

[0056] Figures 11A - 11B show the assembled 0° implant 210 at the initial starting height at the crush position. When inserted into the disc space through the desired surgical approach, the implant 210 is then expanded in height to the expanded position so as to accurately restore normal spinal alignment and distribute load across the vertebral endplate 6. Figures 12A - 12B show the fully expanded assembled 0° implant 210. With the adjustable attachment interface, the implant 210 can 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 body 4 can be rotated with respect to two or more dimensional planes and thus requires an atypical surgical access approach to the level the surgeon desires to treat.

[0057] Referring now to FIG. 10, an exploded view of the expandable implant 210 is shown in more detail. The implant 210 includes an upper endplate 220 for engaging the upper vertebral body 4, a lower endplate 222 for engaging the lower vertebral body 4, an expansion gear or actuating 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 the desired surgical approach angle or trajectory, an actuating 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 press the locking collar 226 against the bottom endplate 222 and the expansion gear 224 in a locked position. The upper endplate 220, the lower endplate 222, and the actuating gear 224 are aligned along the central longitudinal axis 30. The locking collar 226 slides and moves about the central longitudinal axis 30 depending on the engagement position with the spring 230 and the inserter 212. The implant 210 may define a large central graft - holding opening or window 232 and is configured to receive a bone graft or other suitable bone - growth promoting material therethrough.

[0058] The upper or top endplate 220 includes an annular body 234 having a downwardly projecting cylinder 236 configured to mate with the drive gear 224. The annular body 234 may be a ring that surrounds a portion of the central graft window 232. The annular body 234 has a thickness between an upper bone engagement surface 238 and the bottom, i.e., lower surface 240, of the annular body 234. The upper bone engagement surface 238 is configured to engage the superior vertebral body 4. The annular body 234 may be circular, oval, elliptical, or any other suitable shape for engaging the adjacent vertebral endplates 6. The upper bone engagement surface 238 may be contoured to mimic the shape of the vertebral endplate 6 and may be provided with various footprint areas and outer profiles configured to contact the bone surface of the adjacent vertebral bodies. The upper bone engagement surface 238 may include a plurality of teeth, protrusions, or other friction enhancing surfaces configured to engage the bone. In one embodiment, the top endplate 220 includes an aggregate-like drainage resistance pattern or texture on the 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 contact surface 238 may further include porosity or a porous structure to allow for additional ingrowth of bone into the spacer. The top endplate 220 may be 3D printed, for example, to enhance the potential for bone growth. It will be understood that the bone engagement 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 of the annular body 234, i.e., the lower surface 240. The protruding cylinder 236 defines one or more external threads 242 configured to engage corresponding threads 250 inside the expansion gear 224. The external threads 242 may include a helical thread profile machined on the outer surface of the downward protruding cylinder 236. The external threads 242 may have any suitable attributes including diameter, winding direction, thread shape, thread angle, lead(s), pitch, etc. The threads 242 may extend along the entire length of the cylinder 236 or a suitable portion thereof. When the cylinder 236 is received telescopically within the expansion gear 224 / from the actuating gear 24, the upper end plate 220 is configured to move up or down in height, thereby adjusting the overall height of the implant 210. The slot 244 may extend over the entire length or a partial length of the threads 242 and reach into the central implant window 232. The slot 244 may be vertically oriented and in fluid communication with the central implant window 232. The slot 244 may be positioned at an angle, e.g., about 45°, directly forward, to allow access from various approach angles. The slot 244 may act as a backfill window and anti-torque for spacer expansion and collapse.

[0060] The expansion gear or actuating gear 224 is configured to expand and collapse the implant 210. The expansion gear 224 has a central through opening 248 sized and dimensioned to receive the protruding cylinder 236 of the upper end plate 220. The central opening 248 has a central axis 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 and configured to engage the external threads 242 of the upper end plate 220. By the screw engagement between the cylinder 236 and the threaded opening 248, the actuating gear 224 can adjust the height of the upper end plate 220 during rotation.

[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-tooth gear having straight teeth 252 that project radially from a cylinder or disk. The edge of each tooth 252 may be linear and aligned parallel to the axis of rotation. Although 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 changed or selected by those 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 end plate 220 up and down, thereby adjusting the height of the implant 210.

[0062] The teeth 252 may extend between the upper surface 254 and the lower surface 256 on the side opposite the upper surface 254 of the actuating 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 crushed (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 surface 254 and the lower surface 256 of the expansion gear 224 may be generally flat and smooth.

[0063] The expansion gear 224 includes a lip 258 that is configured to project downward and be retained by the bottom end plate 222. The lip 258 may include a circular rim 260 defined by a circular groove 262 above the rim 260. The circular rim 260 projects radially outward to engage the bottom end plate 222. The bottom portion or surface of the rim 260 may be angled or rounded to assist in a snap-fit type of engagement.

[0064] The orientation and locking collar 226 are configured to engage with the inserter 212 in different states for operating the implant 210. When engaged by the inserter 212 in the first position, the collar 226 is locked relative to the bottom end plate 222 and the expansion gear 224, thereby fully locking the implant 210. When engaged by the inserter 212 in the second position, the slidable collar 226 translates away from the bottom end plate 222 so that the locking collar 226 can freely spin around the central axis 30 to a desired position for implantation in a desired approach or trajectory. When engaged by the inserter 212 in the third position, the collar 226 is locked relative to the bottom end plate 22 and translates away from the expansion gear 224 to allow expansion of the upper end plate 220.

[0065] The locking collar 226 includes a loop or ring-shaped body 266 that defines a central through-opening 268 sized and dimensioned to receive a portion of the lower end plate 222 and the actuating gear 224. The ring-shaped body 266 has an outer surface 270 and an inner surface 272 having 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 end plate 222. The interface collar 226 rotates freely around the bottom end plate 222 (when in the second position), but the interface collar 226 always has a proximal portion 275 that engages with 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 project radially beyond the end plates 220, 222. The proximal portion 275 may have, for example, a convex shape having a flat proximal surface and a rounded side surface, which is sized and dimensioned to fit within a corresponding recess of the inserter instrument 212. The projecting proximal portion 275 of the collar 226 can assist 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 that pass through the outer surface 270 of the ring-shaped body 266, and these openings are configured to engage with the inserter instrument 212 for embedding. For example, the central opening 278 may be internally threaded to engage with the threaded shaft 340 of the inserter instrument 212, and the pair of unthreaded openings 280 may be positioned on both sides 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 projecting beams 282 that extend from the upper surface 274 of the ring-shaped body 266. The vertical beams 282 may be located in the proximal portion 275 of the collar 226. For example, a pair of vertical beams 282 may be positioned on both sides of the instrument openings 278, 280. As best seen in FIG. 11A, at the crimping position, the upper portion of each vertical beam 282 may be close to or in contact with the bottom surface 240 of the upper end plate 220. The inward 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 surface 284 may have a V-shaped notch or other suitable shape to mate with the corresponding teeth 252 on the expansion gear 224. When the locking collar 226 presses against the expansion gear 224, the inward 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 actuating ram 228 and spring 230. The locking collar 226 is sized and dimensioned to define a pocket 286 for receiving the actuating ram 228. The pocket 286 is defined within the proximal portion 275 of the ring 266 along the inner surface 272 of the ring 266 from the bottom surface 276. The pocket 286 is in fluid communication with the instrument openings 278, 280 such that the actuating ram 228 is accessible to the instrument 212. The interface and locking collar 226 is sized and dimensioned to define a recess 288 for receiving the spring 230. The spring recess 288 may include a semi-circular cutout that mimics the curvature of the ring 266. The spring recess 288 is defined within the ring 266 along the inner surface 272 of the ring 266 from the top surface 274. The spring recess 286 may be located within the distal portion 277 of the collar 226 opposite the actuating ram 228 and the 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 the teeth 324 of the bottom end plate 222 in the locked configuration. The mating surfaces 290 may be located on the proximal portion 275 and the distal portion 277 such that when the collar 226 is slid distally, the proximal portion 275 engages the bottom end plate 222, and when the collar 226 is slid proximally, the distal portion 275 engages the bottom end plate 222. For example, the proximal and distal mating surfaces 290 on the inside of the collar 226 may include one or more protrusions, edges, serrations, teeth, etc. configured to mate with corresponding rings of the teeth 324 along the upper portion of the bottom end plate 222. The number, location, and configuration of the mating surfaces 290 may be selected by one of ordinary skill in the art.

[0070] The actuating ram 228 is an intermediate component that operates within a pocket 286 and a groove cut into the locking collar 226. When the inserter 212 engages the locking collar 226, the inserter 212 also engages the actuating ram 228, thereby causing the ram 228 to safely press against the bottom end plate 222. Depending on how the inserter 212 and the locking collar 226 are engaged, the implant 210 can be locked, unlocked, or have its orientation for insertion changed.

[0071] The actuating ram 228 can 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 actuating ram 228. The actuating ram 228 is disposed inside the pocket 286 of the collar 226. The enlarged ends 292 are configured to be aligned with the threadless openings 280 such that the enlarged ends 292 of the actuating ram 228 can be engaged by the threadless shaft 338 of the instrument 212. The narrowed intermediate portion 294 defines a notch 296 configured to be partially aligned with a central threaded opening 278 that receives the threaded shaft 340 of the instrument 212. The notch 296 can define a square or rectangular, quadrilateral, or another suitable shape having rounded corners. The back surface 298 of the actuating ram 228 is configured to contact the bottom end plate 222 and move the locking collar 226 into contact with, or out of contact with, the bottom end plate 222 and the expansion gear 224. The back surface 298 of the actuating ram 228 may be concave to engage the rounded body of the lower end plate 222.

[0072] Spring 230 includes an elongated tab that extends between opposing ends 302. Spring 230 may be bent, flexed, or deformed under force and then return to its original shape when the force is removed. For example, spring 230 may include a curved or arched central portion 304 that is flexible and deformable under pressure. The ends 230 of spring 230 fit within the ends of spring recess 288 of locking collar 226. In its relaxed state and in a first inserter position (shown in FIG. 14A), the curved central portion 304 projects out of recess 288 such that spring 230 presses collar 226 against base plate 222 and drive gear 224. In a second inserter position (shown in FIG. 15A), the curved central portion 304 still projects out of recess 288, but locking collar 226 is pressed away from teeth 324 of base plate 222 such that locking collar 226 can freely spin around implant 210. In a third inserter position (shown in FIG. 16A), when sufficient force is applied to overcome the resistance of the spring, an excessive force is applied to spring 230 such that the curved central portion 304 flips or inverts beyond its equilibrium and fully seats within spring recess 288 in locking collar 226. When this force is removed, spring 230 returns to its relaxed state (shown in FIG. 14A).

[0073] Base plate or lower end plate 222 includes an annular body 308 that may be a ring surrounding a portion of central implant window 232. Annular body 308 has a thickness between a lower bone engagement surface 310 and an upper surface 312 of annular body 308. Annular body 308 may be angled and / or the thickness between upper surface 310 and lower surface 312 of annular body 308 may vary to accommodate a wide range of anatomical profiles and to conform to or restore lordosis when used in the lumbar spine.

[0074] The lower bone engagement surface 310 of the lower end plate 222 is configured to engage the inferior vertebra 4. The lower bone engagement surface 310 may be contoured to mimic the shape of the vertebral end plate 6 and may be provided with various footprint areas and outer shapes configured to contact the bone surface of adjacent vertebrae. Similar to the upper bone engagement surface 238, the lower bone engagement surface 310 may include a plurality of teeth, protrusions, or other friction enhancing surfaces configured to engage bone. In one embodiment, the bottom end plate 222 includes an aggregate-like drainage resistance pattern or texture on the lower surface geometry for contacting a bone surface that can be angled to conform to or restore lordosis when used in the lumbar spine. The lower bone engagement surface 310 may further include porosity or a porous structure to allow additional ingrowth of bone into the spacer. The lower end plate 222 may be 3D printed, for example, to enhance the potential for bone growth. It will be understood that the bone engagement surface 310 may be modified to include one or more surface treatments, coatings, textures, drainage resistance structures or geometries, or other features to enhance fixation.

[0075] The assembly, reverse torque, and interface features for the locking collar 226 and the expansion gear 224 are machined into the upper portion of the lower end plate 222. The locking collar 226 is nested between the actuating gear 224 and the bottom end plate 222. The bottom 276 of the locking collar 226 is proximate to or in contact with the upper surface 312 of the annular body 308. The lower end plate 222 has an inner wall 314 and an outer wall 316 defined by a portion of the central implant window 232. A plurality of slits 318 extend vertically 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 a protruding portion or finger 322 configured to fit into the groove 262 of the expansion gear 224. The finger 322 may be configured to bend or flex slightly as the finger 322 is inserted into the groove 262, thereby connecting the expansion gear 224 firmly to the lower end plate 222.

[0076] The ring of teeth 324 may be provided on the bottom end plate 222 so as to engage with the locking collar 226 at a specific position. The ring of teeth 324 may be located between the outer wall 314 and the upper surface 312 of the annular body 308. The ring of teeth 324 may include straight teeth protruding radially from the outer wall 314. The edge of each tooth 324 may be linear and aligned parallel to the axis of rotation. The apex of each tooth 324 may be chamfered, and the space between each tooth 324 may be, for example, rounded or semi-circular. Although a specific arrangement of the teeth 324 is shown, it is contemplated that the number, position, thickness, diameter, pitch, and configuration of the teeth may be changed or selected by those skilled in the art. When the mating teeth 290 on the locking collar 226 engage with the teeth 324, the locking collar 226 is locked relative to the bottom end plate 222. When disengaged from the teeth 324, the locking collar 226 rotates freely towards the desired implanted orientation.

[0077] The lower end plate 222 may include struts 326 that can be sized and dimensioned to fit within the slots 244 of the cylinder 236 of the upper end plate 220. The struts 326 can project perpendicularly from the upper surface 312 of the lower end plate 222. The struts 326 can include horizontal beams 328 having opposing ends that fit into corresponding grooves within the cylinder 236 of the upper end plate 220. The inward-facing surface 330 may be curved so as to mimic the shape of the central graft window 232. When the expansion gear 224 is rotated to expand the upper end plate 220, the slots 244 and the struts 326 act as anti-torque means when expanding and crushing the upper end plate 220.

[0078] Referring now to FIGS. 14A - 16B, the implant 210 can be inserted into the disc space using the 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 can adjust the orientation of the implant 210 during the procedure to accommodate the desired surgical approach. The surgical approach angles and trajectories may include directly anterior, directly lateral, oblique, and selected positions between directly anterior and directly lateral. In some cases, the implant 210 can help resolve insufficient anterior - posterior distance in the disc space during insertion and placement of a medial - to - lateral wide - footprint spacer from an anterior - to - psoas approach. Additionally, the implant 210 can be inserted from multiple approaches without requiring a wide 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 within a set for a given procedure. Also, the flexibility of the implant 210 provides the surgeon with more options and better control during the procedure, thereby leading to better patient outcomes.

[0079] The inserter 212 controls the position and orientation of the interface collar 226 and the extended height of the upper end plate 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 that 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 non - threaded shafts 338 configured to engage the non - threaded opening 280, and a central threaded shaft 340 configured to engage the threaded opening 278 of the locking collar 226.

[0080] Figures 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 the expansion gear 224 are fully locked. The non - threaded shaft 338 can be received within the opening 280, but the shaft 338 does not apply a force to the actuating ram 228. In this position, the inserter 212 is not screwed into the locking collar 226. The protruding interface shape of the inserter 212 can contact the inserter 212 or guide it to the correct alignment position for screwing the inserter 212 into the locking collar 226. The mating, coupling, and / or interference shape of the proximal portion 275 of the locking collar 226 engages the similar complementary interface surface of the bottom end plate 222 when the spring 230 pulls / pushes against the locking collar 226 and the bottom end plate 222.

[0081] In the first position, the locking collar 226 locks against the bottom end plate 222 and the expansion gear 224. The spring 230 of the locking collar 226 simultaneously presses the locking collar 226 against the bottom end plate 222 and the expansion gear 224. The spring 230 biases the locking collar 226 in the distal direction away from the inserter 212. In this first position, the mating surface 290 of the locking collar 226 engages the teeth 324 of the bottom end plate 222, thereby acting as a reverse torque to prevent the locking collar 226 from rotating. The contact surface 284 on the beam 282 also interferes with the teeth 252 on the expansion gear 224, thereby interfering with the rotational movement of the expansion gear 224 and preventing both the expansion and the crushing of the implant 210.

[0082] Figures 15A-15B show the inserter instrument 212 attached to the implant 210 at the second position. At the second position, the locking collar 226 can only move by rotating around the lower end plate 222 when the inserter 212 is properly attached. At this position, the locking collar 226 can be rotated to the desired insertion orientation, but the expansion gear 224 remains locked. The non-threaded shaft 338 and the threaded shaft 340 can be received within the openings 278, 280 such that the shafts 338, 340 apply a force to the actuating ram 228 that moves the locking collar 226 towards the instrument 212. At the second position, the inserter 212 is screwed into the locking collar 226 up to a predetermined position, but is not fully screwed into the collar 226.

[0083] The protruding interface shape of the inserter 212 is configured to contact the implant 210 and serves to control the orientation of the implant 210 relative to the inserter 212 for implantation. The actuating ram 228 presses on the central element of the lower end plate 222 such that the locking collar 226 is pulled and translated by the screw engagement 340 of the inserter 212, moving all mating, coupling, and / or interference shapes away from the bottom end plate 222 and the expansion gear 224. When engaged with the inserter 212 at the second position, the locking collar 226 is pressed away from the interface teeth 324 on the bottom end plate 222 and held in this position by the spring 230. The locking collar 226 can freely spin around the implant 210 to apply the desired inserter-implant orientation for implantation.

[0084] Figures 16A - 16B show the inserter instrument 212 attached to the implant 210 at the third position. At the third position, the locking collar 226 is locked against the bottom end plate 222, while the expansion gear 226 is released and free to expand the upper end plate 220 by rotation. The non - threaded shaft 338 and the threaded shaft 340 can be received within the openings 278, 280 such that the shafts 338, 340 apply a force to the actuating ram 228 to fully move the locking collar 226 towards the instrument 212. When the inserter 212 is fully screwed into the locking collar 226 such that the actuating ram 228 presses against the central element of the bottom end plate 222, the locking collar 226 is pulled and translated by the screw engagement of the inserter 212, and the mating, coupling, and / or interference shapes on the distal portion 277 of the locking collar 226 are drawn towards the similar complementary interface surface 324 on the bottom end plate 222. At 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 actuating ram 228 is fully pressed against the bottom end plate 222, the locking collar 226 is strongly pulled against the bottom end plate 222, overcoming the spring 230 completely. The spring 230 flips into the spring recess 288 within the locking collar 226. The mating surface 290 having the pattern of the locking collar 226 engages with the teeth 324 on the bottom end plate 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 shape of the bottom end plate 222, the actuating ram 228, and the locking collar 226 properly orients the implant 210 relative to the inserter 212 and allows it to be implanted in a defined orientation. Also, the third position unlocks the expansion gear 226 by disengaging the upper interface shape 284 of the locking collar 226 by pulling the locking collar 226 proximally towards the inserter 212 and away from the expansion gear 224. In this state, the implant 210 can be expanded or contracted when the expansion gear 224 is articulated by the inserter 212.

[0086] In one embodiment, a robot and / or navigation guidance may be used to assist in orienting and placing the implants 10, 210 along one or more agnostic approaches. Details of the surgical robot system and / or navigation system can be found, for example, in U.S. Patent No. 10,675,094 and U.S. Patent No. 9,782,229, the entire disclosures of which are incorporated herein by reference for all purposes. The implant 10 may be implanted using one or more of: (1) determining the optimal implant position and positioning to optimize contact with bone and the desired correction; (2) using the robot system and / or navigation system to determine potential trajectories that enable the optimal implant position and outcome; (3) optionally, docking a cannula onto the disc space through an appropriate trajectory, including a non-specified oblique approach directly anterior, directly lateral, or between anterior and lateral; (4) inserting the expandable interbody 10 into the disc space at the crush position through a given trajectory; and (5) expanding the expandable interbody 10 height 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 advantages of: (1) the ability to adjust the attachment orientation to the implant to accommodate various approaches; (2) an internal automatic 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 the desired spacer height that provides the desired disc height.

[0088] The ability to adjust the implant orientation of the spacer with respect to the sagittal angle of the spacer accommodates various approach angles and trajectories, including, but not limited to, directly anterior, directly lateral, oblique, and subdivided increments between directly anterior and directly lateral. The spacer has a retained interface collar that can rotate freely about the central axis of the device. By pivoting / rotating about the central axis, the device can be oriented to better engage the natural endplate curvature of the vertebral bodies above and below the intervertebral disc space in which the device is implanted. This can be particularly beneficial in cases of highly complex deformities where the vertebral bodies can be rotated with respect to two or more dimensional planes and thus require an atypical surgical access approach to the level the surgeon desires to treat.

[0089] An automatic lock with discrete orientation positions provides two functions: automatically locking the implant to prevent expansion and collapse of the implant and separately orienting the implant on the inserter for implantation. The automatic lock function 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 to lock the implant. The discrete orientations provided by the lock allow the surgeon to adapt to the approach that best fits the patient's anatomy.

[0090] Unlike static spacers that only provide height restoration at discrete intervals, an expandable implant is inserted into the intervertebral disc space at the collapsed height and then expanded axially to restore the height loss within the intervertebral disc space. The ability to expand in height when implanted allows the surgeon to restore the collapsed intervertebral disc height at any height from the starting height of the implant to the fully expanded height. Additionally, the expandable intervertebral body spacer maximizes the volume within and around the device for graft material.

[0091] Furthermore, it is to be understood that various changes in the details, materials, and arrangements of the parts described and illustrated for purposes of explaining the nature of the present invention may be made by those skilled in the art without departing from the scope of the invention as set forth in the claims. Those skilled in the art will understand that the embodiments discussed above are non-limiting. It will also be understood that one or more features of one embodiment may be incorporated partially or fully into one or more other embodiments described herein.

Claims

**Claim 1** An expandable implant, comprising an upper end plate and a lower end plate 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 lower end plate and configured to be attached to an inserter instrument in a plurality of orientations for a desired surgical approach, a spring received in a recess of the locking collar, and an actuating ram received within the locking collar and configured to lock, unlock, or change the insertion orientation of the locking collar. **Claim 2** In a first position, the locking collar is locked with respect to the lower end plate and the expansion gear to fully lock the implant. In a second position, the locking collar is free to spin around the lower end plate for the desired surgical approach. In a third position, the locking collar is locked with respect to the lower end plate and translated parallel away from the expansion gear to enable expansion of the upper end plate. The expandable implant according to claim 1. **Claim 3** The expandable implant according to claim 1, wherein the lower end plate includes a toothed ring configured to engage a corresponding mating surface of the locking collar. **Claim 4** The expandable implant according to claim 1, wherein the spring is an elongated tab having a curved central portion that deforms under force. **Claim 5** The expandable implant according to claim 1, wherein the actuating ram includes a body having two enlarged ends with a narrowed middle portion. **Claim 6** The expandable implant according to claim 1, wherein the spring is located on the opposite side of the actuating ram. **Claim 7** The expandable implant according to 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 engage with the upper end plate. **Claim 8** The expandable implant according to 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. **Claim 9** The upper end plate includes an annular body having a bone engagement surface and a downwardly projecting cylinder configured to mate with the expansion gear. The downwardly projecting cylinder of the upper end plate includes an external thread and a vertical slot bisecting the external thread. The lower end plate includes a strut receivable within the vertical slot. The expandable implant according to claim 1.

10. An expandable implant comprising: an upper end plate configured to engage an upper vertebra; a lower end plate configured to engage a lower vertebra; an expansion gear configured to adjust the height of the upper end plate; a locking collar configured to rotate about the lower end plate for a desired surgical approach; a spring for biasing the locking collar toward or away from the lower end plate and the expansion gear; and an actuating ram received within the locking collar and configured to lock, unlock, or change the insertion orientation of the locking collar. An inserter instrument having an attachment 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 for fully locking the implant, a second position allowing the locking collar to freely spin for the desired surgical approach, and a third position allowing expansion of the upper end plate. An implantable system.

11. The implantable system according to claim 10, wherein the locking collar includes a centrally opened aperture with an internal thread and a pair of unthreaded apertures positioned on both sides of the centrally opened aperture.

12. The actuating ram is located within a pocket of the locking collar. The actuating ram includes a body having two enlarged ends and a narrowed middle portion. The enlarged ends are aligned with the unthreaded apertures, and the narrowed middle portion is aligned with the centrally opened aperture. The implantable system according to claim 11.

13. The implantable system according to claim 12, wherein the narrowed middle portion defines a notch partially aligned with a centrally threaded aperture.

14. The inserter instrument includes a centrally threaded shaft configured to engage the centrally threaded opening and a pair of non-threaded shafts configured to engage the pair of non-threaded openings, the implantable system of claim 12.

15. In the first position, the inserter instrument is attached to the implant such that the inserter is not screwed into the locking collar and the spring biases the locking collar against the lower end plate and the expansion gear, thereby fully locking the implant, the implantable system of claim 14.

16. In the second position, the inserter instrument is attached to the implant such that the inserter is screwed into the locking collar to a predetermined position, the non-threaded shaft pushes the actuating ram, and the locking collar is released from the lower end plate, thereby enabling the locking collar to spin freely for the desired surgical approach, the implantable system of claim 14.

17. In the third position, the inserter instrument is attached to the implant such that the inserter is fully screwed into the locking collar, the non-threaded shaft pushes the actuating ram, overcomes the spring, and the locking collar releases the expansion gear, thereby enabling the upper end plate to expand, the implantable system of claim 14.

18. A method of installing an expandable implant, providing an expandable implant having an upper end plate, a lower end plate, an expansion gear configured to adjust the height of the upper end plate, a locking collar configured to rotate around the lower end plate for a desired surgical approach, a spring for biasing the locking collar toward or away from the lower end plate and the expansion gear, and an actuating ram housed within the locking collar and configured to lock, unlock, or change the insertion orientation of the locking collar; attaching an inserter instrument to the expandable implant; controlling the position and orientation of the locking collar by the inserter instrument to determine a desired trajectory. Inserting the expandable implant at the crush site along the desired trajectory between adjacent vertebrae; Expanding the expandable implant with the inserter instrument, a method comprising. **Claim 19** The method of claim 18, wherein in the disengaged state, the implant is locked such that the locking collar and the expansion gear are fully locked. **Claim 20** The method of claim 18, wherein the desired trajectory is selected from a direct anterior, direct lateral, or unspecified oblique approach between direct anterior and direct lateral.

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