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

There are a number of fusion devices and methodologies for accomplishing the intervertebral fusion. These may include solid bone implants, fusion devices which include a cage or other implant mechanism, which may be packed with bone and/or bone growth inducing substances, and expandable implants (<CIT>, <CIT>, <CIT> and <CIT> disclose examples thereof). The implants may be installed between adjacent vertebral bodies in order to fuse the vertebral bodies together, thereby alleviating the associated pain and providing disc height restoration.

Interbody devices have been used to provide support and stability in the anterior column of the spinal vertebrae when treating a variety of spinal conditions, including degenerative disc disease and spinal stenosis with spondylolisthesis. Clinical treatment of spinal pathologies with anterior vertebral body interbody devices relies on precise placement of the interbody device to restore normal anterior column alignment. Iatrogenic pathologies may result from the surgical access window to the disc space, failure to precisely place the interbody on hard cortical bone often found on the apophyseal ring of the vertebral body, and/or failure to precisely control and restore normal anatomical spinal alignment.

As such, there exists a need for a fusion device capable of being inserted into the intervertebral disc space at a collapsed height and then expand axially to restore height loss in the disc space and further provides precise placement of the interbody, which may be inserted from multiple approaches to allow access to the spine without the need for an extensive set of implants with fixed approach-specific insertion features.

To meet this and other needs, and in view of its purposes, the present application provides devices, systems, instruments, and methods (not claimed) for installing and expanding an implant. In particular, an expandable fusion device is provided, which can be inserted from any approach which allows access to the spine. The expandable fusion device may have the ability to adjust the orientation of attachment to the implant to accommodate various approaches, an internal automatic lock that both provides discrete orientation positions about the central axis of the implant and automatically locks the device after insertion into the disc space, and/or has the ability to expand in height when implanted to achieve a desired spacer height which in turn provides a desired disc height.

According to one embodiment, an expandable implant includes an upper endplate and a lower endplate configured to engage adjacent vertebrae, an actuation gear configured to adjust a height of the upper endplate, the actuation gear is coupled to the lower endplate and engaged with the upper endplate, an interface collar configured to attach to an inserter instrument at multiple orientations for a desired surgical approach, the interface collar includes 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 endplate, the lock is retained in the lower endplate, the lock includes a tapered outer surface with a plurality of cuts defined therein configured to interface with the plurality of angled protrusions in the interface collar.

The expandable implant may include one or more of the following features. The interface collar may be free to rotate about a center axis of the implant when not engaged by the inserter instrument or engaged in the open position. The interface collar may be a split ring with 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 lower 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. The tops of the guide rail posts may protrude upward from the lock and are configured to interface with pockets on an underside of the actuation gear in order to bind rotational movement of the actuation gear and prevent expanding and collapsing of the implant. The lock may include a plurality of spring arms extending from a bottom surface of the lock, wherein in an unengaged state, the spring arms press the lock up and away from the bottom endplate. The actuation gear may include a disk with a plurality of teeth projecting radially outward therefrom and a threaded central opening configured to threadedly mate with the upper endplate. The upper endplate may include an annular body with a bone-engaging surface and an inferiorly protruding cylinder configured to mate with the actuation gear. The inferiorly protruding cylinder of the upper endplate may include exterior threads and a vertical slot bisecting the exterior threads, and the lower endplate may include a pillar receivable in the vertical slot.

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 actuation gear configured to adjust a height of the upper endplate, an interface collar configured to rotate about a center 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 endplate, and a lower endplate configured to engage an inferior 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 a location of the interface collar and expansion of the implant.

The implantable system may include one or more of the following features. The attachment assembly may include an attachment fork with 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 is not engaged with the interface collar, thereby allowing full rotation of the interface collar and the lock prevents expansion of the upper endplate. In the half position, the inserter instrument is attached to the implant such that the attachment fork is engaged with the interface collar, thereby securing the location of the interface collar and the lock prevents expansion of the upper endplate. In the full position, the inserter instrument is attached to the implant such that the attachment fork is engaged with the interface collar, thereby securing the location of the interface collar and the lock disengages from the actuation gear allowing for expansion of the upper endplate.

According to another embodiment, a method (not claimed) of installing an expandable implant includes: (a) providing an expandable implant comprising an upper endplate configured to engage a superior vertebra, an actuation gear configured to adjust a height of the upper endplate, an interface collar configured to rotate about a center 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 endplate, and a lower endplate configured to engage an inferior vertebra; and (b) attaching an inserter instrument to the interface collar, wherein the inserter instrument is configured to move the interface collar to an open position allowing for full rotation of the interface collar and the lock prevents expansion of the upper endplate, a half position locking a location of the interface collar and the lock prevents expansion of the upper endplate, or a full position locking a location of the interface collar and the lock disengages from the actuation gear allowing for expansion of the upper endplate. The inserter instrument may be attached to the interface collar to establish a desired trajectory including direct anterior, direct lateral, or a non-specified oblique approach between direct anterior and direct lateral. When the inserter instrument moves the interface collar to the half or full position, locking the location of the interface collar, the expandable implant may be positioned into a disc space in a collapsed position. When the inserter instrument moves the interface collar to the full position, the lock disengages from the actuation, and the actuation gear may be rotated to adjust the height of the upper endplate.

Also provided are kits including expandable fusion devices of varying types and sizes, rods, fasteners or anchors, k-wires, insertion tools, and other components for performing the procedure.

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, wherein:.

In order to restore height loss in the disc space and provide precise placement of the interbody, the expandable implant may have the ability to: (<NUM>) adjust the orientation of attachment to the implant to accommodate various surgical approaches; (<NUM>) an internal automatic lock that both provides discrete orientation positions about the central axis of the implant and automatically locks the device after insertion into the disc space; and (<NUM>) the ability to expand in height when implanted to achieve a desired spacer height which in turn provides a desired disc height. Accordingly, embodiments of the present application are generally directed to devices, systems, instruments, and methods (not claimed) for installing and expanding the interbody implant. The present invention relates to a device as claimed hereafter. Preferred embodiments of the invention are set forth in the dependent claims. The terms implant, interbody, interbody implant, fusion device, spacer, and expandable device may be used interchangeably herein. Although described with reference to an interbody implant, it will be appreciated that the implant may also be used as a corpectomy spacer and placed between non-adjacent vertebral bodies or may be used in trauma or other suitable surgical applications.

Referring now to <FIG>, an expandable interbody fusion device or implant <NUM> and methods (not claimed) of installation are shown according to one embodiment. The expandable device <NUM> is configured to be inserted between two adjacent vertebrae <NUM>. The expandable implant <NUM> is attached to an inserter instrument <NUM> to deploy the device <NUM> into the disc space (the upper vertebra is omitted for clarity in <FIG>). The inserter <NUM> may be suitable for use during a minimally invasive surgical (MIS) procedure, for example, such that the inserter <NUM> and attached implant <NUM> may be positioned through a guide tube or cannula to access and guide the implant <NUM> into the disc space. The expandable implant <NUM> is inserted between the vertebral bodies <NUM> of the vertebrae <NUM> and into the disc space in a collapsed position.

The implant <NUM> is configured to adjust the orientation of attachment of the inserter <NUM> relative to the implant <NUM> to accommodate various surgical approaches to the spine. The ability to adjust the implantation orientation of the implant <NUM> accommodates a variety of approach angles and trajectories to the spine. The surgical approach angles and trajectories may include direct anterior, direct lateral, oblique, and subdivided increments in-between direct anterior and direct lateral. <FIG> shows placement of implant <NUM> through a direct anterior approach to the spine from the front of the body. When operating on the lumbar spine, this surgical technique may also be called an anterior lumbar interbody fusion (ALIF). <FIG> shows placement of implant <NUM> through a non-specified oblique approach (e.g., at an angle between direct anterior and direct lateral). <FIG> shows placement of implant <NUM> through a direct lateral approach to the spine from a side of the body. When operating on the lumbar spine, this surgical technique may also be called 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 <NUM> before or during the surgery.

Once inserted into the disc space through the desired surgical approach, the implant <NUM> is then expanded in height to an expanded position to precisely restore normal spinal alignment and distribute the load across the vertebral endplates <NUM>. Due to the adjustable attachment interface, the implant <NUM> may be oriented or angled to better contact the natural endplate curvature of the vertebral bodies <NUM> above and below the disc space in which the device <NUM> is being implanted. This may be especially beneficial in high-complexity deformity cases where vertebral bodies <NUM> may be rotated relative to more than one dimensional plane, thus requiring a non-typical surgical access approach to the level the surgeon desires to treat.

Turning now to <FIG>, an exploded view of expandable implant <NUM> is shown according to one embodiment. The implant <NUM> includes an upper endplate <NUM> for engaging a superior vertebral body <NUM>, a lower endplate <NUM> for engaging an inferior vertebral body <NUM>, an expansion or actuation gear <NUM> for adjusting the height of the upper endplate <NUM>, an orientation and interface collar <NUM> configured to attach the inserter <NUM> to the implant <NUM> at various orientations or angles for the desired surgical approach angle or trajectory, and an expansion and orientation lock <NUM> configured to lock the orientation of the interface collar <NUM> and/or automatically lock the height of the implant. The endplates <NUM>, <NUM>, actuation gear <NUM>, interface collar <NUM>, and lock <NUM> are aligned along central longitudinal axis <NUM>. The implant <NUM> may define a large central graft retaining opening or window <NUM> configured to receive bone graft or other suitable bone growth enhancing material. As best seen in <FIG>, the central graft window <NUM> may be generally cylindrical in shape with a central axis aligned with central longitudinal axis <NUM>.

The top or upper endplate <NUM> includes an annular body <NUM> with an inferiorly protruding cylinder <NUM> configured to mate with the actuation gear <NUM>. The annular body <NUM> may be a ring or circle surrounding a portion of the central graft window <NUM>. The annular body <NUM> has a thickness between an upper bone-engaging surface <NUM> and a bottom or lower surface <NUM> of annular body <NUM>. As best seen in <FIG> and <FIG>, the annular body <NUM> may be angled and/or the thickness between the upper and lower surfaces <NUM>, <NUM> of the annular body <NUM> may vary to accommodate wide ranging anatomical profiles and to match or restore lordosis when used in the lumbar spine.

The annular body <NUM> includes upper bone-engaging surface <NUM> configured to engage a superior vertebral body <NUM>. The upper bone-engaging surface <NUM> may be contoured to mimic the shape of the vertebral endplate <NUM>. The upper bone-engaging surface <NUM> may include a plurality of teeth, protrusions, or other friction enhancing surfaces configured to engage bone. In one embodiment, the upper endplate <NUM> includes aggregate-like expulsion resistant patterns or textures on the superior surface geometry for contacting bony surfaces that can be angled to match or restore lordosis when used in the lumbar spine. The bony-contacting surface <NUM> may further include a porosity or porous structure to allow for additional ingrowth of bone into the spacer. The upper endplate <NUM> may be 3D printed, for example, to enhance boney on-growth potential. It will be appreciated that the bone-engaging surface <NUM> may be modified to include one or more surface treatments, coatings, textures, or other features to enhance fusion.

Cylinder <NUM> extends from the bottom or lower surface <NUM> of annular body <NUM>. The protruding cylinder <NUM> defines one or more exterior threads <NUM> configured to mate with corresponding threads <NUM> inside the actuation gear <NUM>. The exterior threads <NUM> may include a helical thread profile machined into the outer surface of the cylinder <NUM>. The exterior threads <NUM> may have any suitable attributes including diameters, handedness, thread form, thread angle, lead(s), pitch, etc. The threads <NUM> may extend along the entire length of cylinder <NUM> or a suitable portion thereof. As the cylinder <NUM> is telescopingly received in/from the actuation gear <NUM>, the upper endplate <NUM> is configured to raise or lower in height, thereby adjusting the overall height of the implant <NUM>. A slot <NUM> may run the full length or partial length of the threads <NUM> and reaches into the central graft window <NUM>. The slot <NUM> may be vertically oriented and in fluid communication with the central graft window <NUM>. The slot <NUM> may be located at an angle from direct anterior to allow for access from various approach angles. The slot <NUM> may act as a backfill window and a counter-torque for expansion and collapsing of the spacer.

The expansion gear or actuation gear <NUM> is configured to expand and collapse the implant <NUM>. The actuation gear <NUM> has a central through opening <NUM> sized and dimensioned to receive the protruding cylinder <NUM> of the upper endplate <NUM> in a telescoping manner. The central opening <NUM> has a center axis coaxial with the central longitudinal axis <NUM> of the implant <NUM>. The central opening <NUM> defines one or more inner threads <NUM> cut into its inner diameter configured to interface with the exterior threads <NUM> of the upper endplate <NUM>. The threaded engagement between the cylinder <NUM> and threaded opening <NUM> permit the actuation gear <NUM> to adjust the height of upper endplate <NUM> when rotated.

An outer perimeter of the actuation gear <NUM> includes a plurality of cogs or teeth <NUM>. In one embodiment, the actuation gear <NUM> may be a spur gear or straight-cut gear with straight teeth <NUM> projecting radially from the cylinder or disk. The edge of each tooth <NUM> may be straight and aligned parallel to the axis of rotation. Although a specific arrangement of teeth <NUM> is shown, it is envisioned that the number, location, thickness, diameters, pitch, and configuration of the teeth may be modified or selected by one skilled in the art. When engaged by inserter instrument <NUM>, the actuation gear <NUM> may be rotated about axis <NUM> to move upper endplate <NUM> up or down, thereby adjusting the height of the implant <NUM>.

The teeth <NUM> may extend between an upper face <NUM> and an opposite lower face <NUM> of actuation gear <NUM>. The upper face <NUM> of the actuation gear <NUM> may be configured to contact the bottom surface <NUM> of annular body <NUM> of the upper endplate <NUM> when the upper endplate <NUM> is fully collapsed (as shown in <FIG>). The lower face <NUM> of the actuation gear <NUM> is configured to contact or be adjacent to the upper surface <NUM> of collar <NUM> at all times. The upper and lower surfaces <NUM>, <NUM> of the actuation gear <NUM> may be generally planar and smooth.

The actuation gear <NUM> includes a snap-fit lip <NUM>, which protrudes inferiorly and is configured to be retained by the bottom endplate <NUM>. As best seen in <FIG>, the snap-fit lip <NUM> may include a circular rim <NUM> defined by a circular groove superior to rim <NUM>. The circular rim <NUM> protrudes radially outward to engage with the bottom endplate <NUM>. A bottom portion or surface of the rim <NUM> may be angled or rounded to help with the snap-fit engagement. The lower surface <NUM> of the actuation gear <NUM> defines a plurality of pockets <NUM> configured to retain a portion of lock <NUM>. The lock <NUM> is configured to interface with pockets <NUM> in the lower face <NUM> on the underside of the actuation gear <NUM> in order to bind the rotational movement of the expansion gear <NUM> and prevent both expansion and collapsing of the implant <NUM>.

The orientation and interface collar <NUM> is configured to interface with the inserter <NUM> for implantation. When not engaged by the inserter <NUM>, the collar <NUM> is permitted to freely rotate about axis <NUM>. When engaged by the inserter <NUM> in certain positions, the collar <NUM> is locked into position relative to the inserter <NUM> for implantation for a desired approach or trajectory. The interface collar <NUM> includes a split ring body <NUM> with a gap <NUM> between opposite sides of the split ring <NUM>. The interface collar <NUM> defines one or more openings <NUM> through the outer face <NUM> of the outer diameter which are configured to interface with the inserter <NUM> for implantation. The outer face <NUM> may be generally smooth except for a pair of protruding oblong eyelets <NUM> on opposite sides of the gap <NUM>. Each opening <NUM> may be defined through the respective eyelet <NUM>.

The inner surface <NUM> of the interface collar <NUM> includes a plurality of angled protrusions <NUM>. The angled protrusions <NUM> may include a series of alternating protrusions and grooves configured to interface with corresponding mating surfaces <NUM> on the lock <NUM>. The angled protrusions <NUM> may define flanks or ramped surfaces configured to translate the lock <NUM> vertically along axis <NUM>. The angled protrusions <NUM> may extend from an upper face <NUM> a distance toward lower face <NUM> while stopping short of the lower face <NUM> allowing a smooth area below protrusions <NUM>. In one embodiment, a first series of angled protrusions <NUM> extend a distance along inner surface <NUM> from first opening <NUM> and a second series of angled protrusions <NUM> extend a distance along inner surface <NUM> from the second opening <NUM> with a smooth area along inner surface <NUM> between the two series of protrusions <NUM>. Although a specific arrangement of angled protrusions is shown, it is envisioned that the number, location, and configuration of surfaces may be modified or selected by one skilled in the art.

The rotatable interface collar <NUM> is located between the actuation gear <NUM> and the bottom endplate <NUM>. The interface collar <NUM> may be retained in the bottom endplate <NUM> by overlapping lips <NUM>, <NUM> on the collar <NUM> and the bottom endplate <NUM>. The lip <NUM> on interface collar <NUM> may include a downward projecting lip following the body of the split ring <NUM> along the interior surface <NUM>. It will be appreciated that the interface collar <NUM> may be retained in the bottom endplate <NUM> using any suitable mechanism that permits rotational movement of collar <NUM> about axis <NUM> when the collar <NUM> is not secured by the inserter <NUM>.

The interface collar <NUM>, when not engaged by the inserter <NUM>, is permitted to freely rotate <NUM>° around the central axis <NUM> of the implant core. The collar <NUM> may be engaged by inserter <NUM> in multiple positions. In a first position, the angled protrusions <NUM> of the collar <NUM> interface with the lock <NUM> to prevent the collar <NUM> from rotating, which locks the orientation of the implant <NUM> relative to the inserter <NUM> for implantation. In a second position, the collar <NUM> causes the lock <NUM> to disengage from the actuation gear <NUM>, thereby allowing for expansion or collapsing of the implant <NUM> and also prevents rotation and reorientation of the collar <NUM>.

The expansion and orientation lock <NUM> is configured to lock the orientation of the interface collar <NUM> and/or automatically lock the height of the implant <NUM>. The outer diameter <NUM> of lock <NUM> is tapered with angled shallowed cuts <NUM>, which interact and interface with mating protrusions <NUM> on the interface collar <NUM>. The lock <NUM> includes a ring-like body <NUM> angled or tapered from a top edge <NUM> to bottom edge <NUM>. The body <NUM> gradually increases in diameter along its circumference from top edge <NUM> to lower edge <NUM> forming an outer cone-like shape. Thus, the top edge <NUM> has a smaller diameter than bottom edge <NUM>. The outer diameter of the lock <NUM> includes a plurality of shallow cuts <NUM>. The shallow cuts <NUM> may be generally rectangular in shape extending vertically from upper edge <NUM> toward bottom edge <NUM>. The cuts <NUM> may have equal widths and may be equally spaced about the perimeter of the lock <NUM> or may be otherwise configured to mate with corresponding protrusions <NUM> in the interface collar <NUM>. The inner surface <NUM> of the lock <NUM> may be smooth.

The lock <NUM> has one or more guide rail posts <NUM> that interface with the bottom endplate <NUM> acting as counter-torque measure so that the lock <NUM> is permitted to only move in a linear fashion up and down along axis <NUM>. Each guide rail post <NUM> may include a vertical rail protruding radially inwardly. For example, four guide rails posts <NUM> may be spaced equally about the inner surface <NUM> of the lock <NUM>. It will be appreciated that any suitable number and configuration of guide rail posts may be used to guide the movement of the lock <NUM>. The tops of the guide rail posts <NUM> protrude upward and are configured to interface with the pockets <NUM> on the underside of the actuation gear <NUM> in order to bind the rotational movement of the actuation gear <NUM> and prevent expanding and collapsing of the implant <NUM>. The lock <NUM> may include one or more spring arms <NUM> extending from the bottom surface <NUM> of the lock <NUM> with each terminating at a free end. The spring arms <NUM> may include a curved beam or structure that bends downward with a convex lower profile. A spring arm <NUM> may be positioned beneath each guide rail post <NUM>. Each spring arm <NUM> may be machined into the lock <NUM> such that in the implant's unengaged state, the spring arms <NUM> press the lock <NUM> up and away from the bottom endplate <NUM>.

The lower endplate <NUM> includes an annular body <NUM> configured to receive the expansion and orientation lock <NUM>, the interface collar <NUM>, and the actuation gear <NUM>. Similar to upper endplate <NUM>, the annular body <NUM> may be a ring or circle surrounding a portion of central graft window <NUM>. The annular body <NUM> has a thickness between a lower bone-engaging surface <NUM> and an upper edge <NUM> of annular body <NUM>. As best seen in <FIG> and <FIG>, the annular body <NUM> may be angled and/or the thickness between the upper and lower surfaces <NUM>, <NUM> of the annular body <NUM> may vary to accommodate wide ranging anatomical profiles and to match or restore lordosis when used in the lumbar spine.

The lower bone-engaging surface <NUM> of lower endplate <NUM> is configured to engage an inferior vertebral body <NUM>. The lower bone-engaging surface <NUM> may be contoured to mimic the shape of the vertebral endplate <NUM>. Similar to upper bone-engaging surface <NUM>, lower bone-engaging surface <NUM> may include a plurality of teeth, protrusions, or other friction enhancing surfaces configured to engage bone. In one embodiment, the bottom endplate <NUM> includes aggregate-like expulsion resistant patterns or textures on the inferior surface geometry for contacting bony surfaces that can be angled to match or restore lordosis when used in the lumbar spine. The lower bone-engaging surface <NUM> may further include a porosity or porous structure to allow for additional ingrowth of bone into the spacer. The lower endplate <NUM> may be 3D printed, for example, to enhance boney on-growth potential. It will be appreciated that the bone-engaging surface <NUM> may be modified to include one or more surface treatments, coatings, textures, expulsion resistant structures or geometries, or other features to enhance fusion.

Assembly, counter-torque, and interfacing features for the lock <NUM> are machined into an upper portion of the lower endplate <NUM>. The expansion and orientation lock <NUM> lives nested inside of pockets and grooves <NUM> machined into the bottom endplate <NUM>. The lower endplate <NUM> has an inner wall <NUM> define by a portion of central graft window <NUM>. A plurality of snap-fit posts <NUM> extend vertically from the inner wall <NUM>. The snap-fit posts <NUM> are arranged in pairs with a space <NUM> therebetween configured to receive respective guide rail posts <NUM> of the lock <NUM>. In the embodiment shown, four pairs of snap-fit posts <NUM> are spaced equally around the inner wall <NUM> defining four respective spaces <NUM> for corresponding guide rail posts <NUM>. The guide rail posts <NUM> interface with the spaces <NUM> between the snap-fit posts <NUM> to guide movement of the lock <NUM> in a linear fashion up and down along axis <NUM>. Although a certain number and configuration of posts <NUM>, <NUM> are shown, it will be appreciated that another suitable arrangement may be selected to guide lock <NUM>.

After the lock <NUM> is positioned into lower endplate <NUM>, the interface collar <NUM> is placed into lower endplate <NUM> such that the collar <NUM> surrounds and engages lock <NUM>. The interface collar <NUM> may be retained in the lower endplate <NUM> by overlapping lips <NUM>, <NUM> on the collar <NUM> and bottom endplate <NUM>. The collar <NUM> may be sized and dimensioned such that the outer face <NUM> of the orientation collar <NUM> is generally flush with the outer circumference of the annular body <NUM> of the lower endplate <NUM>.

The actuation gear <NUM> may then be positioned on top of the orientation collar <NUM> and secured to the lower endplate <NUM>. The lower face <NUM> of the actuation gear <NUM> abuts the upper face <NUM> of the interface collar <NUM>. The actuation gear <NUM> may be sized and dimensioned such that the outer diameter of the gear <NUM> is generally flush with the outer face <NUM> of the interface collar <NUM> and the outer circumference of the annular body <NUM> of the upper endplate <NUM>. The lower face <NUM> of actuation gear <NUM> rests on top of the snap-fit posts <NUM> in the bottom endplate <NUM>. The actuation gear <NUM> is retained in the bottom endplate <NUM> via snap-fit lip <NUM>. Each of the free ends of snap-fit posts <NUM> define an overhang or finger <NUM> configured to fit in the groove defining circular rim <NUM> of actuation gear <NUM>. The snap-fit posts <NUM> may be configured to flex or bend slightly as the fingers <NUM> are inserted, thereby securely connecting the actuation gear <NUM> to the lower endplate <NUM>.

The upper endplate <NUM> is threadedly engaged with actuation gear <NUM>. A pillar <NUM> may protrude vertically from lower endplate <NUM>, which is sized and configured to fit within slot <NUM> in the cylinder <NUM> of the upper endplate <NUM>. When in the fully collapsed position, the slot <NUM> and pillar <NUM> may act as a counter-torque measure for expansion and collapsing of the spacer. When the implant <NUM> is fully collapsed as shown in <FIG>, the bottom surface <NUM> of the annular body <NUM> of the upper endplate <NUM> may contact and abut the upper face <NUM> of the actuation gear <NUM>. When the implant <NUM> is expanded as shown in <FIG>, the annular body <NUM> of the upper endplate <NUM> lifts off the actuation gear <NUM> and the bottom surface <NUM> of the annular body <NUM> is spaced apart from the actuation gear <NUM>.

The devices described herein or components thereof may be manufactured from a number of biocompatible materials including, but not limited to, titanium, titanium alloys, non-titanium metallic alloys, stainless steel, polymeric materials, plastics, plastic composites, polyetheretherketone (PEEK), ceramics, and elastic materials. The devices or components thereof may be manufactured by machining, additive processes such as <NUM>-dimensional (3D) printing, and/or subtractive processes.

Turning now to <FIG>, implant <NUM> is insertable into the disc space with inserter <NUM> through an agnostic approach. In other words, the surgeon is able to determine the trajectory or approach to the spine before or during the procedure and is able to adjust the orientation of the implant <NUM> during the procedure to accommodate the desired surgical approach. The implant <NUM> is configured to be inserted from multiple approaches without the need for an extensive set of implants with fixed approach-specific insertion features. The ability of implant <NUM> to be inserted from multiple approaches and trajectories can significantly reduce the number of necessary implants in the set list for a given procedure. The flexibility of implant <NUM> also provides the surgeon with more choices and greater control during the procedure, thereby resulting in better patient outcomes.

<FIG> show inserter instrument <NUM> attached to implant <NUM> according to one embodiment. The inserter <NUM> controls the position of the interface collar <NUM>, the position of the lock <NUM>, and the expanded height of the top endplate <NUM> when properly attached. The inserter <NUM> extends from a proximal end <NUM> to a distal end <NUM> along a central longitudinal tool axis. The proximal end <NUM> includes an attachment interface for connecting a handle (not shown) configured to be manipulated by a user. The distal end <NUM> is configured to attach to the interface collar <NUM> of the implant <NUM>. The inserter <NUM> includes a main outer body <NUM> 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 <NUM> configured to expand the implant <NUM> and an attachment assembly including a distal attachment fork <NUM> configured to engage the interface collar <NUM> in different positions.

The expansion assembly may include expansion drive shaft <NUM>, which is a cylindrical shaft extending through outer body <NUM>, attached to a drive gear <NUM> configured to engage with the actuation gear <NUM> of the implant <NUM>. The proximal end <NUM> of expansion drive shaft <NUM> is connectable to a handle (not shown) to allow for rotation of the drive shaft <NUM>. When the inserter <NUM> is engaged with the orientation collar <NUM> in a full position, turning the expansion drive shaft <NUM> rotates drive gear <NUM>, which interfaces with actuation gear <NUM> to allow for expansion or contraction of the upper endplate <NUM>, thereby allowing for adjustment of the height of the implant <NUM>.

The attachment assembly may include attachment fork <NUM>, which includes a central body or base <NUM> with a pair of distal prongs <NUM> extending therefrom. The prongs <NUM> may be straight or curved and may be spaced apart to match the spacing of the attachment locations <NUM> along the interface collar <NUM>. The prongs <NUM> may be configured to flex or bend slightly to engage the interface collar <NUM> in different positions. The free end <NUM> of each prong <NUM> may be inserted into respective opening <NUM> and may be contoured or shaped to engage with opposite sides of the opening <NUM>. A sleeve <NUM> may be configured to draw the prongs <NUM> together or apart. An outer control knob <NUM> and inner half nut <NUM> may be used to manipulate the prongs <NUM>. For example, the control knob <NUM> may be rotated to translate sleeve <NUM> to draw prongs <NUM> together or allow prongs <NUM> to spread apart from one another. It will be appreciated that any suitable mechanism may be used to control movement of the attachment fork <NUM> and prongs <NUM>.

<FIG> shows the inserter <NUM> attached to implant <NUM> such that the attachment fork <NUM> is not engaged with the interface collar <NUM>, thereby providing a neutral or open position. When the collar <NUM> is not engaged by the inserter <NUM>, the collar <NUM> is permitted to freely rotate <NUM>° around the central axis <NUM> of the implant core. The angled protrusions <NUM> of the interface collar <NUM> are not received in the shallow cuts <NUM> of the lock <NUM>. The open position occurs when the control knob <NUM> is twisted such that the attachment fork <NUM> results in a position where the prongs <NUM> of the fork <NUM> are not engaged with the attachment points <NUM> on the interface collar <NUM>. <FIG> shows the prong <NUM> in a neutral position in opening <NUM> of the interface collar <NUM>, thereby allowing for full rotation of the interface collar <NUM> to the desired insertion orientation.

When the collar <NUM> is engaged by the inserter <NUM>, the angled protrusions <NUM> of the collar <NUM> interface with the angled shallow cuts <NUM> on the lock <NUM>. The collar <NUM> may be engaged by the inserter <NUM> in two different positions: half position and full position. <FIG> show the inserter <NUM> attached to implant <NUM> at the half position. In the half position, the attachment fork <NUM> is engaged with the interface collar <NUM>, and the prong <NUM> is located in opening <NUM> of the interface collar <NUM> such that the prongs <NUM> move away from one another. When engaged at the half position by inserter <NUM>, the protrusions <NUM> of interface collar <NUM> bind with the cuts <NUM> on the lock <NUM> and prevent the collar <NUM> from rotating, which in turn defines the orientation of the implant <NUM> relative to the inserter <NUM> for implantation. The half position occurs when the control knob <NUM> is twisted such that the attachment fork <NUM> results in a position where the prongs <NUM> of the fork <NUM> are forcing the ramped interacting features on the interface collar <NUM> to engage with the lock <NUM>. In the half position, the orientation of the interface collar <NUM> is rigidly defined, while not unlocking the expansion mechanism.

<FIG> show the inserter <NUM> attached to implant <NUM> at the full position. When engaged in the full position by the inserter <NUM>, the ramped features of the interface collar <NUM> push into and down on the lock <NUM> disengaging the rail posts <NUM> from the underside of the gear <NUM> allowing for expansion or collapsing of the implant <NUM>, as well as implantation or removal. The full position also prevents rotation and reorientation of the collar <NUM>. In the full position, the prongs <NUM> of the attachment fork <NUM> may be drawn toward one another to grip the interface collar <NUM> such that the ends of split ring <NUM> approach one another, thereby causing the interface collar <NUM> to engage the lock <NUM>. The full position occurs when the control knob <NUM> is twisted such that the attachment fork <NUM> results in a position where the prongs <NUM> of the fork <NUM> are forcing the interacting features <NUM> on the interface collar <NUM> to engage with the lock <NUM>. In this manner, the orientation of the interface collar <NUM> is rigidly defined and the ramped interacting features <NUM> of the interface collar <NUM> push the lock <NUM> downward and away from the expansion gear <NUM>. The upper ends of guide rail posts <NUM> on the lock <NUM> disengage from the pockets <NUM> in lower surface <NUM> of the actuation gear <NUM>, thereby unlocking the implant <NUM>.

Once in the full position, the upper endplate <NUM> may be raised or lowered. For example, turning the expansion drive shaft <NUM> of the inserter <NUM> causes expansion or contraction of the spacer <NUM>. The drive gear <NUM> engages the actuation gear <NUM>, thereby permitting adjustment of the height of the implant <NUM>. Conversely, in the half or open positions, turning the expansion drive shaft <NUM> on the inserter <NUM> will not cause the spacer <NUM> to expand or contract as the lock <NUM> will be binding with the expansion gear <NUM>, thereby preventing this movement. Furthermore, once the inserter <NUM> is removed from the implant <NUM>, the lock <NUM> automatically reengages with the actuation gear <NUM> such that the springs <NUM> push the lock <NUM> upwards and the upper ends of guide rail posts <NUM> re-enter the pockets <NUM> in lower surface <NUM> of the actuation gear <NUM>, thereby re-locking the implant <NUM> and preventing any further expansion or contraction of the implant <NUM>.

In one embodiment, robotic and/or navigation guidance may be used to assist in orienting and installing the implant <NUM> along one or more of the agnostic approaches. Details of surgical robotic and/or navigation systems can be found, for example, in <CIT> and <CIT>, which are incorporated by reference herein in their entireties for all purposes. The implant <NUM> may be implanted with one or more of the following steps: (<NUM>) determining optimal implant location and positioning to optimize contacted bone and desired correction; (<NUM>) employing robotic and/or navigational systems to determine the potential trajectories to allow for optimal implant location and outcome; (<NUM>) optionally docking a cannula on the disc space through a suitable trajectory including direct anterior, direct lateral, or a non-specified oblique approach between anterior and lateral; (<NUM>) inserting the expandable interbody <NUM> into the disc space in a collapsed position through the given trajectory; and (<NUM>) expanding the expandable interbody <NUM> in height to precisely restore disc height and spinal alignment (e.g., lordosis).

The implant and systems described herein may include one or more of the following advantages: (<NUM>) the ability to adjust the orientation of attachment to the implant to accommodate various approaches; (<NUM>) an internal automatic lock that both provides discrete orientation positions about the central axis of the implant and automatically locks the device after insertion into the disc space; and (<NUM>) the ability to expand in height when implanted to achieve a desired spacer height which in turn provides a desired disc height.

The ability to adjust the implantation orientation of the spacer relative to the spacer's sagittal angle accommodates a variety of approach angles and trajectories which include, but are not limited to, direct anterior, direct lateral, oblique, and subdivided increments in-between direct anterior and direct lateral. The spacer has a retained interfacing collar which can freely rotate about the device's central axis. By pivoting/rotating about the central axis, the device can be oriented to better interface with the natural endplate curvature of the vertebral bodies above and below the disc space in which the device is being implanted. This may be especially beneficial in high-complexity deformity cases where vertebral bodies may be rotated relative to more than one dimensional plane, thus requiring a non-typical surgical access approach to the level the surgeon desires to treat.

The automatic lock with discrete orientation positions provides two functions of both automatically locking the implant preventing expansion and collapsing of the implant, and discretely orienting the implant on the inserter for implantation. The automatic lock function reduces the steps intraoperatively needed to successfully implant the device potentially reducing cognitive load on the surgeon. The discrete orientations the lock provides allow the surgeon to adapt to the approach that best fits the patient's anatomy.

Unlike static spacers that only provide height restoration at discrete intervals, the expandable implant is inserted into the intervertebral disc space at a collapsed height and then expand axially to restore height loss in the disc space. The ability to expand in height when implanted allows for the surgeon to restore collapsed disc height at any height from the implant starting height up to and including the fully expanded height. In addition, the expandable interbody spacer maximizes volume within and around the device for graft material.

Claim 1:
An expandable implant (<NUM>) comprising:
- an upper endplate (<NUM>) and a lower endplate (<NUM>) configured to engage adjacent vertebrae (<NUM>);
- an actuation gear (<NUM>) configured to adjust a height of the upper endplate (<NUM>), the actuation gear (<NUM>) is coupled to the lower endplate (<NUM>) and engaged with the upper endplate (<NUM>);
- an interface collar (<NUM>) configured to attach to an inserter instrument (<NUM>) at multiple orientations for a desired surgical approach, the interface collar (<NUM>) includes a plurality of angled protrusions (<NUM>); and
- an expansion and orientation lock (<NUM>) configured to lock the orientation of the interface collar (<NUM>) and lock the height of the upper endplate (<NUM>), wherein the lock (<NUM>) is retained in the lower endplate (<NUM>), the lock (<NUM>) includes a tapered outer surface with a plurality of cuts (<NUM>) defined therein configured to interface with the plurality of angled protrusions (<NUM>) in the interface collar (<NUM>).