Patent Description:
A spinal column can require correction of spinal deformities and abnormalities resulting from trauma or degenerative issues. Various methods of correcting issues with the spinal column can include fusing adjacent vertebrae together with a spacer and/or a rod system to immobilize the degenerated portion of the spine. Such procedures can be beneficial in patients having diseased or degenerated disc material between the vertebrae. For example, intervertebral implants can be positioned between adjacent vertebrae to fuse the vertebrae together, after disk material located therebetween is removed. In order to facilitate insertion between the adjacent vertebrae, the implants can be configured to expand. As such, the implant can be collapsed to have a smaller height for insertion and after being positioned into the target anatomy can be expanded to a taller height to provide the desired spacing. It can, however, be difficult to expand the implant to the desired level due to, for example, resistance from the anatomy.

Examples of expandable intervertebral spacer implants are described in Pub. No. <CIT>; Pub. No. <CIT>; Pub. No. <CIT>; Pub. No. <CIT>; <CIT>; <CIT>and <CIT>.

The present inventors have recognized, among other things, that a problem to be solved can include the lack of variability in lordotic expansion for traditional expandable intervertebral spacers. In particular, the present inventors have recognized that many typical expandable implants utilize only a single mechanism to expand the implant. As such, each of these implants typically include tradeoffs between providing bone support, expansion height, mechanical advantage, and lordotic expansion angles. For example, most expandable intervertebral implants utilize a single actuation mechanism that limits the variability in achievable angles of lordotic expansion (e.g., greater height expansion for distal (or anterior) side of implant versus proximal (or posterior) side). The current inventors recognize that providing a surgeon with the ability to adjust the amount of expansion as well as the amount of lordotic angle provides greater intraoperative flexibility to achieve desire spinal correction.

The present subject matter can help provide a solution to these problems, such as by providing an interbody implant that is configured to expand using two different expansion mechanisms. The two different expansion mechanisms (anterior and posterior) can be configured to be deployed independently through separate adjustment mechanisms. For example, a first (anterior) expansion mechanism adjusts the expansion height of the anterior portion of the implant, while a second (posterior) expansion mechanism adjusts the posterior expansion height. In examples, the expansion mechanisms can be configured to work cooperatively, e.g., at the same time, and then exclusively, e.g., one at a time. In other examples, the expansion mechanisms can be configured to operate sequentially, e.g., one and then the other. In an example, the expansion (or adjustment) mechanisms operate independently, so it is a function of the implant instrument to allow for concurrent and also independent operation of the expansion mechanisms.

The invention provides an expandable interbody implant as claimed in claim <NUM>. In an example, an intervertebral implant can comprise a first cage (end plate), a second cage (end plate), a central frame, a distal (anterior) wedge, a distal (anterior) adjustment mechanism, a proximal (posterior) wedge, and a proximal (posterior) adjustment mechanism. In this example, the adjustment mechanisms include a threaded screw rotationally coupled to the central frame. In some examples, the distal adjustment mechanism can include a distal screw threadably engaged with a thread bore in the central frame. In certain examples, the proximal screw can be free to rotate with a proximal bore in the central frame, but is translationally fixed relative to the frame.

Also described is, a method of inserting (not claimed) an intervertebral implant can comprise inserting the intervertebral implant into anatomy of a patient, the intervertebral implant comprising a first (superior) end plate and a second (inferior) end plate coupled to opposing sides of a central frame housing the first (distal) and second (proximal) adjustment mechanisms. The method can continue with expansion of the implant by operating the first expansion mechanism to expand the distal height of the implant and by operating the second adjustment mechanism to expand the proximal height of the implant.

Additional examples of variations in the adjustment mechanisms, end plates, and central frame are discussed in detail below.

As eluded to in the drawing descriptions and further detailed below, many of the illustrated example structures can be utilized across different embodiments, as would be understood by a person of ordinary skill in the art.

The expandable intervertebral implant discussed in detail below includes differentiated proximal (posterior) and distal (anterior) expansion with wedges actuated by screw-based adjustment mechanisms. The embodiments discussed below include a central frame, upper (superior) and lower (inferior) end plates, and proximal and distal adjustment mechanisms. The proximal and distal adjustment mechanisms involve threaded screws coupled in some manner to the central frame. In some examples, the distal screw is threadably engaged with a threaded bore in a distal portion of the central frame. In certain examples, the distal screw includes two threaded portions one threadably engaged with the threaded bore in the central frame and the second threadably engaged with the distal wedge. In these examples, articulation of the distal screw results in linear translation of the distal wedge, which enables height adjustment of the distal ends of the end plates. The height adjustment is enabled through interaction between the distal wedge and ramped surfaces on the interior sides of the end plates (e.g., on the inferior side of the superior end plate and on the superior side of the inferior end plate). The screw-based adjustment mechanisms allow for infinitely variable adjustment of proximal and distal height within the overall adjustment range. The overall adjustment range is dictated by the wedge size and ramped surfaces on the end plates. In some examples, distal expansion is extended through crossed (interleaved) arrangement between ramped surfaces of the opposing end plates, which allows the expended height to exceed the height of the wedge alone.

In some examples, the proximal adjustment screw is cylindrical to allow passage of the adjustment instrument to articulate the distal adjustment screw. The cylindrical structure of the proximal adjustment screw also enables post-packing of bone graft materials into the central frame and end plates. Both the central frame and the end plate can include large lateral and vertical openings to enable passage of bone graft material into the adjacent disc space.

The following discussion of the drawings provides detailed explanation of the various different expansion mechanisms, end plate structures, central frame structures, and assembly techniques for the expandable interbody implants. A person of ordinary skill in the art will understand that many of the different structures described below can be combined in manner not specifically discussed, but within the understanding of the present inventors.

<FIG> illustrate an example expandable interbody implant across three distinct states of expansion-closed (collapsed), distal (anterior) expansion, and distal and proximal (posterior) expansion. In this example, the expandable interbody implant <NUM> ("the implant <NUM>") includes a lower (inferior) endplate <NUM>, an upper (superior) endplate <NUM>, a central frame <NUM>, a distal (anterior) wedge <NUM>, a distal (anterior) screw <NUM>, a proximal (posterior) screw <NUM>, and a proximal (posterior) wedge <NUM>. Additional components of this example of the implant <NUM> as discussed below in reference to the different state of expansion figures.

<FIG> are perspective and cross-sectional views of implant <NUM> with the independently adjustable expansion mechanisms in a closed state, according to an example embodiment. In this example, both the proximal and distal expansion mechanism are in a closed state (or implant state). The implant <NUM> is designed for implantation in a closed or collapsed state to minimize soft tissue disruption and ease implantation. In this example, the distal expansion mechanism includes the distal screw <NUM> coupled to the distal wedge <NUM> with assembly pins <NUM>. In some embodiments, assembly pins <NUM> are elastic pins that allow the distal screw <NUM> to rotate relative to the distal wedge <NUM>, but prevent relative translation between the distal screw <NUM> and the distal wedge <NUM>. The implant holder interface <NUM> on the proximal end of the central frame <NUM> is also illustrated. The implant holder interface <NUM> provides a t-shape slot for engaging the implant instrument allows for manipulation of the implant during the implant procedure.

<FIG> also illustrates a lower endplate pin <NUM> within an endplate guide slot <NUM> in the central frame <NUM>. The lower endplate pin <NUM> retains the lower endplate <NUM> within the guide slot <NUM>, which allows for vertical expansion of the lower endplate <NUM> relative to the central frame <NUM>.

<FIG> is a cross-sectional illustrating depicting various internal structures of the example implant <NUM>. Starting with the distal expansion mechanism, <FIG> illustrates the distal wedge <NUM> including opposing angled surfaces <NUM> that engage with a distal lower angled surface <NUM> on the superior surface of the lower endplate <NUM> and a distal upper angled surface <NUM> on the inferior surface of the upper endplate <NUM>. Interaction of these angled surfaces enables expansion of the distal end of the implant <NUM>. The angulation of these angled surfaces also dictates the amount of expansion and expansion force the implant <NUM> can exert and adjacent vertebral bodies during implantation. The distal expansion mechanism further includes the distal screw <NUM> with threads <NUM> engaging a threaded portion <NUM> of the central frame <NUM>. The distal screw <NUM> also includes a drive socket <NUM> that can receive an expansion driver portion of an implant instrument. Rotation of the expansion driver when engaged with the drive socket <NUM> results in linear translation of the distal wedge <NUM>, which in turn causes vertical separation of the distal ends of the lower endplate <NUM> and the upper endplate <NUM>.

In this example, the proximal expansion mechanism includes proximal wedge <NUM> with opposing angled surfaces <NUM> that engage with a lower angled surface <NUM> extending from an superior surface of the lower endplate <NUM> and an upper angled surface <NUM> extending from an inferior surface of the upper endplate <NUM> (elements <NUM> and <NUM> also referred to as endplate angled surfaces). The proximal wedge <NUM> also includes a threaded bore <NUM> that engages with threads <NUM> on the proximal screw <NUM>. In this example, the proximal screw <NUM> is translationally fixed relative to the central frame <NUM>. The proximal screw <NUM> further includes a drive socket <NUM> to receive a proximal expansion driver portion of an implant instrument.

<FIG> are perspective and cross-sectional views of the implant <NUM> with independently adjustable expansion mechanisms with distal expansion only, according to an example embodiment. In this example, the distal expansion mechanism is fully expanded separating the distal ends of the lower endplate <NUM> and the upper endplate <NUM> to the fullest extent of the design. As shown, the distal wedge <NUM> is advanced distally between the lower endplate <NUM> and the upper endplate <NUM> engaging the angled surfaces <NUM>, <NUM> on the respective endplates. The distal screw <NUM> has also translated distally within the distal threaded bore (e.g., threaded portion <NUM>) in the central frame <NUM>. <FIG> illustrates overexpansion slots <NUM> and <NUM> on the lower endplate <NUM> and upper endplate <NUM> respectively. The overexpansion grooves <NUM>, <NUM> operate to prevent the distal wedge <NUM> from pushing to far distally and dislodging from the endplates. As illustrated below <FIG>, the distal wedge <NUM> includes overexpansion pegs <NUM> extending from each outer corner of the wedge.

<FIG> are perspective and cross-sectional views of the implant <NUM> with independently adjustable expansion mechanisms with distal and proximal expansion, according to an example embodiment. In this example, the proximal expansion mechanism (e.g., proximal screw <NUM> and proximal wedge <NUM>) are engaged to expand the proximal ends of the lower endplate <NUM> and upper endplate <NUM> to the furthest extent of the design. Similar to the distal expansion mechanism, the proximal wedge <NUM> is captured within proximal overexpansion grooves <NUM> and <NUM> in the lower endplate <NUM> and upper endplate <NUM> respectively.

<FIG> is an exploded view of the expandable interbody implant <NUM> with independently adjustable expansion mechanisms, according to an example embodiment. In this example, all the individual components of the implant <NUM> are illustrated. In this example, the lower endplate <NUM> includes a lower endplate pin <NUM> that extends through the guide slot <NUM> in the central frame <NUM>. The distal overexpansion groove <NUM> of the lower endplate <NUM> is also shown. The upper endplate <NUM> also includes a distal overexpansion groove <NUM> as well as a proximal overexpansion groove <NUM>. The upper endplate <NUM> further includes an upper endplate pin <NUM> that engages with vertical guide groove <NUM> to restrict movement of the proximal end of upper endplate in a vertical direction.

In this example, the central frame <NUM> includes proximal screw assembly pin(s) <NUM>, proximal wedge locking pin(s) <NUM>, guide slot <NUM>, proximal wedge horizonal guide slot <NUM>, and vertical guide groove <NUM>. The proximal screw assembly pin(s) <NUM> extend vertically into a periphery of the proximal screw bore to capture the proximal screw <NUM> within the central frame <NUM>. In this example, the proximal screw assembly pin(s) <NUM> retain the proximal screw <NUM> in translation relative to the central frame <NUM>, while allowing the proximal screw <NUM> to rotate. In this example, there are two proximal screw assembly pins <NUM>, one illustrated above the central frame <NUM> and the other below the central frame <NUM>. The proximal screw assembly pins <NUM> are received through apertures in opposing sides of the central frame <NUM> into pin grooves <NUM> that are partially exposed to the bore that the proximal screw extends into in the proximal portion of the central frame <NUM>. Proximal screw assembly pins <NUM> can flex within the pin grooves <NUM> to allow rotation of the proximal screw <NUM>. The proximal wedge locking pins <NUM> extend through opposing lateral sides of the central frame <NUM> to capture the proximal wedge <NUM>. The locking pins <NUM> engage a guidance groove <NUM> on the lateral sides of the proximal wedge <NUM>. In this example, the guidance groove <NUM> on the proximal wedge <NUM> is also adapted to engage a corresponding proximal wedge horizonal guide slot <NUM> milled (or otherwise formed) in the lateral sides of the central frame <NUM>.

In this example, the distal wedge <NUM> includes structures such as overexpansion pegs <NUM> and pin holes <NUM>. The pin holes <NUM> receive assembly pins <NUM> to capture the distal screw <NUM> within the distal wedge <NUM>. The assembly pins <NUM> can be elastic pins that allow for the distal screw <NUM> to rotation within the distal wedge <NUM>, but prevent relative translation between the distal screw <NUM> and the distal wedge <NUM>. The proximal wedge <NUM> includes overexpansion pegs <NUM> and guidance groove <NUM>, as discussed above. Finally, the proximal screw <NUM> includes flats <NUM>, which operate in coordination with proximal screw assembly pins <NUM> to lock the proximal screw <NUM> into the central frame <NUM>.

<FIG> are various assembly drawings of the implant <NUM> with independently adjustable expansion mechanisms, according to an example embodiment. In this example, the implant <NUM> is assembly by tilting the endplates (lower endplate <NUM> and upper endplate <NUM>) into the central frame <NUM>. As shown in <FIG>, the lower endplate <NUM> is angled to insert the lower endplate pin <NUM> into guide slot <NUM> and then the lower endplate pin <NUM> is slid into vertical guide groove <NUM>. The upper endplate <NUM> is assembled in a similar fashion. The upper endplate pin <NUM> is tilted into an opposing guide slot <NUM> and upper endplate pin <NUM> is slid into another vertical guide groove <NUM>.

<FIG> is a cross-sectional view illustrating end plate retention structures built into expansion wedges, such as the proximal wedge <NUM>. In this example, the proximal wedge <NUM> includes overexpansion pegs <NUM> extending from all four outer corners. The overexpansion pegs <NUM> extend into proximal overexpansion grooves <NUM> on the lower endplate <NUM>, and proximal overexpansion grooves <NUM> on the upper endplate <NUM>. The cross-sectional view also illustrates the interaction between proximal wedge horizonal guide slot <NUM> and guidance groove <NUM>.

<FIG> are cross-sectional drawings of expansion mechanism retention pins, operable within any of the example embodiments. In these examples, assembly pins <NUM> and <NUM> are illustrated. <FIG> is a cross-sectional view illustrating how proximal screw assembly pins <NUM> extend vertically into a proximal portion of the central frame <NUM> to capture proximal screw <NUM> vie interaction with flats <NUM>. <FIG> is a cross-sectional view illustrating how distal wedge assembly pins <NUM> capture the distal end of the distal screw <NUM> within the distal wedge <NUM>. The distal wedge <NUM> includes pin holes <NUM> to receive assembly pins <NUM>, which engage flats <NUM> on the distal end of the distal screw <NUM>.

<FIG> are various drawings of three different configurations for implant <NUM> that all illustrating bone graft openings, illustrated structures are operable within any of the example embodiments. Each pair of drawings illustrates a full implant and central frame combination. <FIG> illustrate an external central frame where the majority of the body of the central frame <NUM> surrounds the endplates and expansion mechanisms. <FIG> illustrate a first internal frame design where the majority of the central frame <NUM> is within the endplates. In this example, the proximal end of the central frame <NUM> surrounds the proximal end of the endplates (e.g., lower endplate <NUM> and upper endplate <NUM>). <FIG> illustrate a second internal frame design where the majority of the central frame <NUM> is internal to the endplates (when the implant is assembled). The central frame <NUM> illustrated in <FIG> includes a superior/inferior support structure <NUM> instead of the vertical bone graft openings <NUM> shown in <FIG>. These examples also illustrate various positions for lateral bone graft openings <NUM>, <NUM> and vertical bone graft openings <NUM>, <NUM>.

<FIG> are perspective drawings of implant <NUM> using an outer-inner central frame structure, according to an example embodiment. This example illustrates another example of an outer-inner frame structure (primarily internal central frame <NUM>), similar to those discussed above in reference to <FIG>. The implant <NUM> in these figures also includes lateral bone graft openings <NUM>, <NUM> and vertical bone graft openings <NUM>, <NUM>.

<FIG> are perspective drawings of implant <NUM> using an inner central frame structure, according to an example embodiment. In this example, the central frame <NUM> is completely internal to the endplates, as shown in <FIG>. This example also includes lateral bone graft openings <NUM> and vertical bone graft openings <NUM>.

<FIG> are perspective drawings of implant <NUM> using an outer central frame structure, according to an example embodiment. In this example, the central frame <NUM> is completely external to the endplates as shown in <FIG>. This example also includes lateral bone graft openings <NUM> and vertical bone graft openings <NUM>.

<FIG> are various drawings illustrating different configurations for the distal end portion of the endplates, which are operable with any of the example embodiments. <FIG> illustrates an implant <NUM> with a lower endplate <NUM> and an upper endplate <NUM> that have no crossing or interleaved portion. <FIG> illustrates an implant <NUM> with a lower endplate <NUM> and an upper endplate <NUM> with crossed portions <NUM>, <NUM>. In this example, the lower endplate <NUM> includes a center crossed portion <NUM> that can be interleaved with crossed portions <NUM> extending inferiorly from the upper endplate <NUM>. The crossed portions <NUM>, <NUM> are shown in a closed (collapsed) state in <FIG> illustrates an alternative configuration for crossed portions <NUM>, <NUM> where the crossed portions <NUM> form two recesses in the lower endplate <NUM> and the crossed portions <NUM> form protrusions extending inferiorly from the upper endplate <NUM>. <FIG> illustrates the crossed portions <NUM>, <NUM> from <FIG> in a closed state. In all of these examples, the cross portions <NUM>, <NUM> form a part of ramped surfaces on the endplates or are immediately adjacent to ramped portions. The crossed portions <NUM>, <NUM> allow for the ramped surfaces to be larger on each endplate and enable more vertical expansion of the distal portion of the endplates. <FIG> illustrate additional example configurations for the crossed portions <NUM>, <NUM>.

<FIG> are various drawings illustrating an alternative proximal end plate configuration operable with any of the example embodiments. In this example, the proximal portion of each endplate (e.g., lower endplate <NUM> and upper endplate <NUM>) also includes crossed portions, such as crossed portions <NUM>, <NUM>. In this example, the lower endplate <NUM> includes distal crossed portion <NUM> and proximal crossed portion <NUM>, which enable the endplates to collapse into a smaller form factor in the closed state. The upper endplate includes distal crossed portion <NUM> and proximal crossed portion <NUM>.

The implant <NUM> in this example uses an external central frame, central frame <NUM> and the endplates are secured on the proximal end with proximal endplate assembly pins <NUM>. In this example, the proximal endplate assembly pins <NUM> extend through a proximal portion of central frame <NUM> to engage endplate expansion guides <NUM>, <NUM>. In this example, the proximal endplate assembly pins <NUM> are press fit into corresponding holes in the central frame <NUM>. As illustrated in <FIG>, the proximal endplate assembly pins <NUM> engage the endplate expansion guides <NUM>, <NUM>, which are located at least partially within the crossed portions <NUM>, <NUM> respectively.

<FIG> are various drawings illustrating an example distal screw arrangement operable within any of the example embodiments. In this example, the distal expansion mechanism (e.g., distal wedge <NUM> and distal screw <NUM>) includes a first threaded portion <NUM> and a second threaded portion <NUM>. The first threaded portion <NUM> engages with threaded portion <NUM> on the central frame <NUM>, while the second threaded portion <NUM> engages with threaded portion <NUM> on the distal wedge <NUM>. The two different threaded portions doubles the speed of expansion as rotation of the distal screw <NUM> translates the distal screw <NUM> with respect to the central frame <NUM> (via threaded portions <NUM> and <NUM>) and also translates the distal wedge with respect to the distal screw (via threaded portions <NUM> and <NUM>). A comparison of <FIG> (closed state) and <FIG> (expanded state) demonstrates the linear movement of both the distal wedge <NUM> and the distal screw <NUM>.

<FIG> also illustrate an alternative arrangement for the proximal expansion mechanism (e.g., proximal screw <NUM> and proximal wedge <NUM>). In this example, the proximal wedge <NUM> includes angled surfaces <NUM> that interact with endplate angled surfaces <NUM>, <NUM> on the lower endplate <NUM> and upper endplate <NUM> respectively. The proximal wedge <NUM> is translationally fixed to the proximal end of the proximal screw <NUM>, and the proximal screw <NUM> translates upon rotation relative to the central frame <NUM> via threaded portions <NUM>, <NUM>. The proximal wedge <NUM> engages the proximal screw <NUM> at planar edges <NUM>, <NUM>. Planar edge <NUM> is formed on the proximal end of the proximal screw <NUM> and abuts planar edge <NUM> formed by the proximal end of the proximal wedge <NUM>.

<FIG> are various drawings illustrating an example proximal expansion mechanism operable within any of the example embodiments. In this example, the proximal expansion mechanism includes a proximal wedge <NUM> with angled slots <NUM> that proximal endplate assembly pins <NUM> ride in (engage) to create the expansion forces upon translation of the proximal wedge <NUM>. The proximal endplate assembly pins <NUM> extend through endplate guide slots <NUM> and into angled slots <NUM>. The endplate guide slot <NUM> are vertical to guide expansion of the endplates caused by translation of the proximal wedge <NUM> with angled slots <NUM>.

<FIG> are various drawings illustrating another example distal expansion mechanism operable within any of the example embodiments (also included in <FIG>). In this example, the distal expansion mechanism includes two threaded distal screws 6a, 6b. The inner distal screw 6b is secured to the distal wedge <NUM> on the distal end and threads into the outer distal screw 6a. The outer distal screw 6a includes an inner threaded bore to receive the inner distal screw 6a and outer threads that thread into a distal portion of the central frame <NUM>. Upon rotation of the outer distal screw 6a, the outer distal screw translates due to interaction between the outer threaded surface and the central frame <NUM>. Simultaneously, when the outer distal screw 6a rotates the inner distal screw 6b also translates with respect to the outer distal screw 6a causing expansion speed to double (over the standard single distal screw <NUM>).

<FIG> are various drawings illustrating a double wedge distal expansion mechanism operative within any of the example embodiments. In this example, the distal expansion mechanism uses a dual wedge design, which are split into a lower distal wedge 5a and an upper distal wedge 5b. The dual wedges each include a vertical groove <NUM>, <NUM> that cooperates with wedge retainer <NUM> to couple the wedges to distal screw <NUM>. Rotation of distal screw <NUM> causes the lower wedge 5a and upper wedge 5b to advance distally and separate through interaction with structures on the central frame <NUM>. The dual action of the split wedge design amplifies the amount of expansion achieved by the distal expansion mechanism.

<FIG> also illustrate a proximal expansion mechanism where the proximal wedge <NUM> bears against lateral faces of the endplates (lower endplate <NUM> and upper endplate <NUM>) to create expansion between the endplates.

<FIG> are various drawings illustrating an example distal expansion mechanism operable within any of the example embodiments. In this example, the distal wedge <NUM> includes a extended frame portion <NUM> that translates within frame slot <NUM>. The interaction of these sturctures (<NUM>/<NUM>) prevents any rotation of the distal wedge <NUM>, but allows for translation of distal wedge <NUM> within the central frame <NUM>.

<FIG> are various drawings illustrating an example assembly technique for the expandable interbody implant according to various example embodiments. In this example, the endplates, lower endplate <NUM> and upper endplate <NUM>, can be inserted vertically into the central frame <NUM>. The lower endplate pins <NUM> (not shown), <NUM> can slide directly into vertical guide grooves <NUM> from below, and similarly the upper endplate pins <NUM> (not shown), <NUM> can slide directly into vertical guides grooves <NUM> from above. The proximal screw <NUM> is inserted from the proximal end after the distal screw <NUM> is first inserted and threaded into the central frame <NUM>. The distal screw <NUM> is captured by assembly pins <NUM> within the distal wedge <NUM>.

<FIG> are various drawings illustrating a proximal wedge integrated into a central frame according to an example embodiment. In this example, the central frame <NUM> and the proximal wedge <NUM> are formed into a single structure (frame wedge <NUM>). The frame wedge <NUM> includes angled surfaces <NUM> which interact with endplate angled surfaces <NUM>, <NUM>. Accordingly, in this example, actuation of the proximal screw <NUM> will advance both the frame wedge <NUM> (proximal wedge <NUM> integral with central frame <NUM>) and the distal wedge <NUM>. Actuation of the proximal screw <NUM> results in simultaneous expansion of both the proximal ends and distal ends of the lower endplate <NUM> and upper endplate <NUM>. Expansion is parallel if the proximal wedge <NUM> and the distal wedge <NUM> as well as the corresponding ramped surfaces have the same inclination. In this example, the implant <NUM> also includes a separate distal screw <NUM> that can further advance the distal wedge <NUM>. Actuation of the distal screw <NUM> results in inducing a lordotic angle to the expansion of implant <NUM>. The endplates are retained in this example by a proximal outer fame <NUM>, which forms the proximal end of implant <NUM> and wraps around a portion of the lateral sides. The endplates are retained by the proximal endplate assembly pins <NUM>, which translate vertically within the endplate guide slots <NUM>.

<FIG> are various drawings illustrating an elastic tab mechanism to limit rotation of the proximal screw <NUM>, according to an example embodiment. In this example, the proximal screw <NUM> includes an elastic tab mechanism having opposing elastic locking tabs <NUM> and tab gaps <NUM>. The elastic locking tabs <NUM> interact with locking recesses <NUM> formed in the bore receiving the proximal screw <NUM> within the central frame <NUM>. The tab gaps <NUM> allow the elastic locking tabs <NUM> to flex, and snap into locking recesses <NUM> upon rotation of proximal screw <NUM>.

<FIG> are cross-sectional views illustrating uses of elastic pins to limit rotation of the proximal screw, according to various example embodiments. In this example, the elastic longitudinal pin <NUM> is inserted into the end of the distal screw <NUM> and interacts with pin housing <NUM> which allows for elastic flexion of elastic longitudinal pin <NUM> upon rotation of distal screw <NUM>. The elastic longitudinal pin <NUM> interacts with assembly pins <NUM> to prevent unwanted rotation of distal screw <NUM>, but allow rotation with the driver portion of the implant instrument.

This example also includes elastic ring <NUM>, which assists in retaining the proximal screw <NUM> after assembly into the central frame <NUM>. The elastic ring <NUM> maintains the proximal screw <NUM> in position after assembly.

<FIG> are various drawings illustrating cylindrical polymer (PEEK) elements to limit rotation of a proximal screw, according to an example embodiment. The PEEK ring <NUM> is assembled with a light press fit on the proximal screw <NUM> and within a recess in the central frame <NUM>. The PEEK ring <NUM> functions to avoid unintended rotation of the proximal screw <NUM> by friction. Similarly, the PEEK ring <NUM> is assembled with a light press fit on the distal screw <NUM> and within a recess in the distal wedge <NUM>. The PEEK ring <NUM> also functions to avoid unintended rotation of the distal screw <NUM> by friction.

Interbody implant <NUM> of the present disclosure can be configured for use in various spinal correction procedures. Intervertebral implants of the present disclosure can be used with different insertion approaches and for various levels of the spine. Specifically, the illustrated example can be used as a Transforaminal Lumbar Interbody Fusion (TLIF) device or a Posterior Lumbar Interbody Fusion (PLIF) device. However, the features and benefits of the present disclosure can additionally be configured for use as an anatomic Anterior Cervical Interbody Fusion (ACIF) device or a lordotic Anterior Cervical Interbody Fusion (ACIF) device.

TLIF devices can be configured for insertion in between vertebrae from a posterior side of the spinal column. More specifically, a TLIF device of the present disclosure can be configured for insertion into a spinal column between a spinous process and an adjacent transverse process. A TLIF device of the present disclosure can be configured, e.g., with different thicknesses, sizes, widths, lengths to accommodate usage at different levels in the spinal column or in different sized patients. A TLIF device of the present application can be rotated on a superior-inferior axis in a transverse plane while being inserted to the position TLIF device to extend across the spinal column. An insertion device can be coupled to implant holder interface <NUM> can be pushed through tissue into the spinal column such that superior and inferior surfaces of the upper endplate <NUM> and lower endplate <NUM>, respectively, align with an inferior surface of a superior vertebra and a superior surface of an inferior vertebra.

PLIF devices can be configured for insertion in between vertebrae from a posterior side of the spinal column. More specifically, a PLIF device of the present disclosure can be configured for insertion into a spinal column between a spinous process and an adjacent transverse process. A PLIF device of the present disclosure can be configured, e.g., with different thicknesses, sizes, widths, lengths to accommodate usage at different levels in the spinal column or in different sized patients. A PLIF device of the present disclosure can inserted straight into the spinal column on one side of the spinal cord. In examples, a second PLIF device can be inserted straight into the spinal column on the opposite side of the spinal column. An insertion device can be coupled to implant holder interface <NUM> can be pushed through tissue into the spinal column such that superior and inferior surfaces the upper endplate <NUM> and lower endplate <NUM>, respectively, align with an inferior surface of a superior vertebra and a superior surface of an inferior vertebra.

The systems, devices and methods discussed in the present application can be useful in implanting expandable interbody implants, such as those that can be used in spinal correction procedures involving lateral, transverse, anterior or posterior insertion of a spacer between adjacent vertebrae. The interbody implant can have first and second bodies that can be coupled to each other at a pivoting coupling. The angle between the lower endplate <NUM> and the upper endplate <NUM> can be adjusted to push adjacent anatomy into a desired orientation, such as a desired angle therebetween. The lower endplate <NUM> and the upper endplate <NUM> can be moved into the desired angle using two expansion mechanisms that can provide different actuation qualities, such as expansion strength or force, expansion height and mechanical leverage. Thus, the two expansion mechanisms can be arranged in conjunction with an actuation mechanism to sequentially operate to pivot the lower endplate <NUM> and the upper endplate <NUM> relative to each other to overcome resistance from the anatomy and position the anatomy in the desired orientation. The first expansion mechanism can be configured to adjust a distal portion of the implant. The second expansion mechanism can be configured to adjust a proximal portion of the implant to create a desire lordotic correction.

However, the present inventor also contemplates examples in which only those elements shown or described are provided. Moreover, the present inventor also contemplates examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

Claim 1:
An expandable interbody implant (<NUM>) comprising:
a central frame (<NUM>) including an anterior (distal) threaded bore (<NUM>) and a posterior (proximal) bore;
a superior (upper) end plate (<NUM>) movably coupled along a posterior portion of the central frame (<NUM>);
an inferior (lower) end plate (<NUM>) movably coupled along the posterior portion of the central frame (<NUM>) opposite the superior end plate (<NUM>);
an anterior adjustment mechanism including an anterior wedge (<NUM>) rotationally coupled to an anterior screw (<NUM>) movable within the anterior threaded bore; and
a posterior adjustment mechanism including a posterior wedge (<NUM>) coupled to a posterior screw (<NUM>) movable within the posterior bore (<NUM>),
wherein the rotation of the anterior screw (<NUM>) advances the anterior screw (<NUM>) within the threaded anterior bore (<NUM>) resulting in linear advancement of the anterior wedge (<NUM>) against anterior ramped surfaces of the superior end plate (<NUM>) and inferior end plate (<NUM>).