Coronal plane laterally expandable implant

Abstract

Expandable interbody fusion implants, systems, and methods for coronal correction are provided.SOLUTION: The implant may include top and bottom end plates configured to engage adjacent vertebrae, a dual actuator assembly including a rotatable drive screw actuator and a rotatable actuator nut concentric with the drive screw actuator, and a driving ramp disposed along a shaft of the drive screw actuator and engaged with the top and bottom end plates via complementary ramp surfaces. When inserted into the intervertebral disc space, the implant has an ipsilateral side and a contralateral side, and rotation of the drive screw actuator and / or the actuator nut causes movement of one or more of the driving ramps, thereby causing independent expansion of the height of the contralateral side and / or the ipsilateral side of the implant to correct the coronal plane deformity.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates generally to devices and methods for promoting interbody fusion, and more particularly to an expandable fixation device that can be inserted between adjacent vertebrae for disc height restoration and coronal correction. [Background technology]

[0002] A common procedure for addressing pain associated with degenerated intervertebral discs due to various factors (e.g., trauma or aging) is the use of an interbody fusion device to fuse one or more adjacent vertebral bodies. Generally, to fuse the adjacent vertebral bodies, the disc is first partially or completely removed. An interbody fusion device is then inserted between the adjacent vertebrae to maintain normal disc spacing and restore spinal stability, thereby facilitating interbody fusion.

[0003] Patients with thoracic and lumbar spinal deformities may experience spinal wedging or scoliosis, which causes unwanted curvature in the coronal plane in addition to nerve root or spinal cord compression that causes pain. To address this, static implants with a coronal taper may be used, but they lack the precise adjustment needed for patients with coronal imbalance. Expandable implants may be expanded in height, but do not provide asymmetric coronal expansion to address coronal correction and wedging. Therefore, there is a need for a fixation device that can be placed inside the disc space with minimal height, with coronal adjustment to correct coronal deformities, and expanded in height. Summary of the Invention

[0004] To meet this and other needs, devices, systems, and methods are provided for performing interbody fusion, coronal correction, and spinal stabilization. Specifically, expandable coronal implants for, for example, lateral or anterior approach spinal surgery can be used to treat a variety of patient conditions. Expandable coronal implants are configured for height expansion to restore disc height and for asymmetric coronal expansion to address wedged vertebrae and for coronal correction. The implants can be configured for contralateral or ipsilateral coronal angulation to address asymmetries and misalignments in the coronal (frontal) plane. By angling the implant ipsilaterally or contralaterally, corrective forces can be applied directly to the curvature, thereby realigning the spine and improving biomechanical balance and stability.

[0005] According to one embodiment, an expandable coronal implant includes top and bottom end plates configured to engage adjacent vertebrae, a dual actuator assembly including a rotatable drive screw actuator having a shaft and a rotatable actuator nut concentric with the drive screw actuator, and a plurality of drive ramps including an anterior ramp, a medial ramp, and a posterior ramp disposed along the shaft of the drive screw actuator and engaging the top and bottom end plates via complementary ramp surfaces. When inserted into an intervertebral disc space, the implant has an ipsilateral and contralateral side, and rotation of the drive screw actuator and / or the actuator nut causes movement of one or more of the drive ramps, thereby causing independent expansion of the contralateral and / or ipsilateral height of the implant to correct a coronal deformity.

[0006] The expandable implant may include one or more of the following features: The dual actuator assembly may be laterally offset relative to a central longitudinal axis of the implant, and the anterior, middle, and posterior beveled sections may define a throughbore along the offset axis for receiving the shaft of the drive screw actuator. The posterior beveled section may define a female beveled groove forming a male triangular region with an apex pointing anteriorly to the implant, the middle beveled section may define a female beveled groove forming a male triangular region with an apex pointing posteriorly to the implant, and the anterior beveled section may define a female beveled groove forming a male triangular region with an apex pointing anteriorly to the implant. The shaft of the drive screw actuator may include a first threaded section, a second threaded section, a first unthreaded section separating the first threaded section from the second threaded section, and a second unthreaded section toward the distal end of the shaft. The rear ramp portion may be disposed on an actuator nut disposed on a first threaded portion of the drive screw actuator, the middle ramp portion may be disposed on a second threaded portion of the drive screw actuator, and the front ramp portion may be disposed on a second, non-threaded portion of the drive screw actuator. The actuator nut may include a cylindrical body having an enlarged head defining an instrument recess and a neck portion with a reduced diameter defining internal threads that engage with the first threaded portion of the shaft of the drive screw actuator. The actuator nut may be secured to the rear ramp portion with a first retaining clip that fits into an annular groove along the outside of the actuator nut and a corresponding inner annular groove along the inside of the rear ramp portion. The actuator nut may be further secured to the rear ramp portion with a second retaining clip that fits under the first retaining clip around the head of the actuator nut and rests within an internal annular groove along the inside of the rear ramp portion.

[0007] According to one embodiment, an expandable coronal implant includes top and bottom end plates configured to engage adjacent vertebrae, the top and bottom end plates angled to provide an initial reverse taper configured to match the angle of the intervertebral disc space upon insertion; a dual actuator assembly including a rotatable drive screw actuator having a shaft and a rotatable actuator nut concentric with the drive screw actuator; and a plurality of drive ramps, including an anterior ramp, a middle ramp, and a posterior ramp, disposed along the shaft of the drive screw actuator and engaging the top and bottom end plates via complementary ramp surfaces. After insertion into the disc space, the implant is expanded by rotating the drive screw actuator and / or the actuator nut to cause movement of one or more of the drive ramps, thereby expanding the end plates to provide an angle opposite to the neutral position or the initial reverse taper and correcting the coronal deformity. The implant may have an ipsilateral and a contralateral side within the disc space, and the initial reverse taper may have an asymmetric taper such that the contralateral side is greater in height than the ipsilateral side. The implant may be expandable to tilt the top and bottom end plates at an angle opposite to the initial reverse taper so that the ipsilateral side is taller than the contralateral side to correct the coronal deformity. The implant may be expandable so that the top and bottom end plates are parallel to each other in a neutral position.

[0008] According to one embodiment, a method for correcting a coronal plane deformity may include one or more of the following steps, in any suitable order: (a) inserting an implant into a disc space of a spine having a coronal plane deformity through a lateral approach, the implant including top and bottom end plates, a dual actuator assembly including a rotatable drive screw actuator having a shaft and a rotatable actuator nut concentric with the drive screw actuator, and a plurality of drive ramps, including an anterior ramp, a middle ramp, and a posterior ramp, disposed along the shaft of the drive screw actuator and engaging the top and bottom end plates via complementary ramp surfaces; (b) expanding the implant to a height to restore the disc space; and (c) independently adjusting the heights of the contralateral and ipsilateral sides of the implant to provide the desired coronal plane angle. The drive screw actuator and the actuator nut may be rotated simultaneously to translate both the posterior ramp and the middle ramp, thereby translating the top and bottom end plates in parallel. Only the actuator nut may be rotated so that the posterior slope is translated anteriorly, increasing the ipsilateral side of the implant. Only the drive screw actuator may be rotated so that the intermediate slope is pulled posteriorly, increasing the contralateral side of the implant. The implant may include an initial reverse taper to match the slope of the disc space upon insertion. After insertion, the top and bottom end plates may be tilted to a neutral position to achieve optimal spinal alignment, or the top and bottom end plates may be tilted to angle the top and bottom end plates opposite the initial reverse taper, thereby providing an adjusted angular position for optimal correction. The method may also include correcting any compensatory curvature above the coronal plane deformity since such compensation is no longer necessary.

[0009] According to yet another embodiment, a kit may include multiple implants of different sizes and configurations. The kit may further include one or more devices suitable for installing and / or removing the implants and systems described herein, such as an insertion device or driver, one or more removal devices, and other tools and devices that may be suitable for surgical procedures. [Brief explanation of the drawings]

[0010] The present embodiments will become more fully understood from the detailed description and the accompanying drawings, wherein: [Figure 1] 1 shows a lumbar spine with an implant inserted laterally for height expansion and coronal tilt. [Figure 2A] 1 illustrates a coronal targeting approach, a sweeping approach, and a double expansion approach to correct a coronal spinal deformity, respectively. [Figure 2B] 1 illustrates a coronal targeting approach, a sweeping approach, and a double expansion approach to correct a coronal spinal deformity, respectively. [Figure 2C] 1 illustrates a coronal targeting approach, a sweeping approach, and a double expansion approach to correct a coronal spinal deformity, respectively. [Figure 3] 1 illustrates an expandable coronal implant with dual expansion according to one embodiment. [Figure 4A] 4 shows an exploded view of the expandable coronal implant of FIG. 3. [Figure 4B] 4 shows an exploded view of the expandable coronal implant of FIG. 3. [Figure 5A] 10A-10C show perspective views of a posterior driving ramp, a central driving ramp, and an anterior driving ramp for an expandable coronal implant, respectively. [Figure 5B] 10A-10C show perspective views of a posterior driving ramp, a central driving ramp, and an anterior driving ramp for an expandable coronal implant, respectively. [Figure 5C] 10A-10C show perspective views of a posterior driving ramp, a central driving ramp, and an anterior driving ramp for an expandable coronal implant, respectively. [Figure 6A] 10A and 10B show perspective views of an actuator nut and an actuator screw, respectively, for an expandable coronal implant. [Figure 6B] 10A and 10B show perspective views of an actuator nut and an actuator screw, respectively, for an expandable coronal implant. [Figure 7A] 10A-10C show cross-sectional views of expandable coronal implants with parallel, contralateral, and ipsilateral angular biases, respectively. [Figure 7B] 10A-10C show cross-sectional views of expandable coronal implants with parallel, contralateral, and ipsilateral angular biases, respectively. [Figure 7C] 10A-10C show cross-sectional views of expandable coronal implants with parallel, contralateral, and ipsilateral angular biases, respectively. [Figure 8A] 13 illustrates an alternative embodiment for endplate angulation using a pin in slot configuration. [Figure 8B] 13 illustrates an alternative embodiment for endplate angulation using a pin in slot configuration. [Figure 9A] 10 shows an alternative expandable coronal implant with two internal screws for independently lifting the proximal or distal sides of the implant. [Figure 9B] 10 shows an alternative expandable coronal implant with two internal screws for independently lifting the proximal or distal sides of the implant. [Figure 10A] 13 illustrates a coronal targeted expandable implant according to another embodiment. [Figure 10B] 13 illustrates a coronal targeted expandable implant according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of the present disclosure are generally directed to devices, systems, and methods for interbody fusion, coronal correction, and spinal stabilization. Specifically, expandable coronal implants are configured to expand in height for disc height restoration and to expand to a given coronal angle for coronal correction and wedging. The expandable coronal implants can be implanted laterally or anteriorly and expanded to a given coronal angle and height using, for example, an insertion instrument. The expandable implants can provide contralateral or ipsilateral coronal angulation. Contralateral angulation involves adjusting the implant on the side opposite the direction of the deformity. For example, if the spine is curving to the left, the implant can be angled to the right to offset this deviation. In contrast, ipsilateral angulation adjusts the implant on the same side as the deformity. This can similarly involve angulating the implant to correct the deformity or making adjustments to support structural integrity and relieve pressure on the spinal column. The ability to adjust the angulation on both sides of the spine provides the surgeon with greater flexibility to tailor treatment to the specific characteristics of the coronal spinal deformity.

[0012] Spinal fusion is typically used to eliminate pain caused by movement or deformation of degenerated disc material. Successful fusion results in the fusion device being permanently secured within the intervertebral disc space. Expandable fusion devices may be positioned between adjacent vertebral bodies in a contracted position. In this case, expandable coronal fusion implants are configured to expand in height with asymmetric coronal expansion to address coronal curvatures. The implant's adjustable angulation allows for customized interventions, regardless of whether the curvature is due to scoliosis, kyphosis, or other conditions. The implant engages the end plates of adjacent vertebral bodies and, in its installed position, maintains the desired disc spacing, adjusts the coronal angulation, and restores spinal stability, thereby correcting coronal deformities and facilitating interbody fusion.

[0013] Minimally invasive surgery (MIS) can be used to preserve muscle anatomy by causing disruption only where necessary. Benefits of MIS surgical approaches include reduced postoperative pain and improved patient recovery time. In one embodiment, the expandable fixation device can be configured to be placed within a surgical target site through an endoscopic tube. By way of example, the surgical site may be the intervertebral disc space located between two adjacent vertebrae. The implant may be placed laterally to allow for contralateral and ipsilateral angulation for correction of coronal deformity. With precise angulation adjustment, the implant allows for focused, targeted correction, which may reduce the need for additional interventions, leading to a faster recovery and fewer complications. While particularly suitable for use in lateral fusion procedures, those skilled in the art will readily appreciate that the implant can be used in any number of suitable orthopedic approaches and procedures, including, but not limited to, anterior, posterior, transforaminal, anterolateral, or posterolateral approaches to the lumbar, cervical, or thoracic spine, as well as any non-spinal application, such as the treatment of fractures and the like.

[0014] Components of all devices disclosed herein may be fabricated from any suitable material, including metals (e.g., titanium), metal alloys (e.g., stainless steel, cobalt-chromium, and titanium alloys), ceramics, plastics, plastic composites, or polymeric materials (e.g., polyetheretherketone (PEEK), polyphenylene sulfone (PPSU), polysulfone (PSU), polycarbonate (PC), polyetherimide (PEI), polypropylene (PP), polyacetal, or mixtures or copolymers thereof), and / or combinations thereof. In some embodiments, devices may include radiolucent and / or radiopaque materials. Components may also be machined and / or fabricated using any suitable techniques (e.g., 3D printing).

[0015] Referring now to the drawings, wherein like reference numerals may refer to like elements, FIG. 1 illustrates a portion of the lumbar spine, e.g., lumbar vertebrae L1-L5 and sacrum S1. The left side shows lumbar vertebra 2A with lumbar imbalance and deformity causing the spine to have an extreme curvature (e.g., a curve to the left), while the right side shows lumbar vertebra 2B that has been corrected using an implant 10 inserted between two vertebrae and adjusted with a coronal tilt. As shown, the implant 10 can be placed laterally at the apex of the spinal curve or another appropriate spinal level. In this example, the ipsilateral height of the implant is increased to impart a coronal tilt to straighten the spine. Using the implant 10, the coronal angle can be manipulated with a height extension to correct the deformity at the apex of the concave curve. Additionally, any compensatory curvature above the deformity may be corrected since compensation is no longer necessary.

[0016] Referring now to FIGS. 2A-2C, several different approaches can be used to correct deformities using an implant 10 having expandable top and bottom end plates 12 and 14 with ipsilateral (e.g., posterior) and contralateral (e.g., anterior) sides 16 and 18, respectively. As shown in FIG. 2A, a coronal-targeted approach provides coronal tilt and subsequent height expansion of the implant 10 to correct the deformity. The implant 10A is placed in a collapsed state, coronal tilt is introduced, for example, on the ipsilateral side 16 of the implant 10A, and the end plates 12, 14 are then expanded in height. As described in more detail below, FIGS. 10A-10B show an example of a coronal-targeted implant 500. In FIG. 2B, the implant 10B can be configured to expand asymmetrically in height on the ipsilateral 16 and contralateral 18 sides of the disc space, generating an increased coronal angle throughout the expansion range. Implant 10B is placed in a collapsed state, coronal tilt is introduced on both the ipsilateral 16 and contralateral 18 sides together, and the endplates 12, 14 are expanded in height, thereby increasing the coronal angle throughout the range of expansion. The mechanism may expand asymmetrically in either direction relative to the convexity of the spinal deformity and the approach direction, thereby providing a sweeping approach. In FIG. 2C, implant 10C may be independently controlled using a dual expansion mechanism that allows independent ipsilateral and contralateral height expansion. Implant 10C is placed in a collapsed state, and the endplates 12, 14 are expanded in height, and coronal tilt is introduced independently on the ipsilateral 16 and / or contralateral 18 sides to the final desired coronal angle. As described in more detail below, Figures 3-7C show an independently controlled dual expansion implant 100 with two concentric actuators, Figures 8A and 8B show examples of dual expansion implants 300, 300A with pin-and-slot actuators, and Figures 9A and 9B show a dual expansion implant 400 with a pin-and-tilt configuration with two separate internal threads. It will be understood that any suitable mechanism for height and coronal angle adjustment can be used for dual expansion to thereby provide the desired coronal correction.

[0017] The top and bottom end plates 12, 14 may be initially aligned parallel using a coronal or reverse taper. In one embodiment, the top and / or bottom end plates 12, 14 of the implant 10 may be angled to provide an initial reverse taper configured to match the angle of the intervertebral disc space upon insertion. After insertion, one or both of the end plates 12, 14 can be expanded to tilt the end plates 12, 14 to a neutral position or to angle the end plates 12, 14 opposite the initial reverse taper, thereby providing a tailored angular position for optimal coronal correction. The top and bottom end plates 12, 14 may be designed with a reverse taper intended to match or accommodate a sloped or uneven disc space found in spinal deformities such as scoliosis. For example, the initial reverse taper may have an asymmetric taper such that one side (e.g., the contralateral side 18) is intentionally higher than the other (e.g., the ipsilateral side 16), or vice versa. The reverse taper may help accommodate an angled disc space more naturally and make the implant 10 easier to insert. After insertion, the implant 10 may be expanded to tilt the top and bottom end plates 12, 14 to a neutral position (e.g., parallel) or at an angle opposite to the initial reverse taper. For example, the ipsilateral side 16 may be expanded in height to a greater extent than the contralateral side 18 to correct a coronal deformity (or vice versa, depending on the slope of the initial reverse taper). By asymmetrically expanding the implant 10 in a direction opposite to the initial installation, the vertebral end plates can shift to provide an angle opposite to the initial tilt, thereby correcting coronal imbalance and helping to achieve better spinal alignment.

[0018] With further reference to FIGS. 3-7C, the expandable coronal implant 100 can include an independently controlled dual expansion mechanism, which allows for independent ipsilateral and contralateral height expansion. FIG. 3 shows the expandable fusion implant 100 partially expanded at a near-side coronal angle. The expandable implant 100 includes a top end plate 102 and a bottom end plate 104 configured to engage adjacent vertebrae. The implant 100 extends along a central longitudinal axis between a posterior end 106 (or ipsilateral) configured to connect with an insertion instrument and an anterior end 108 (or contralateral) configured to be inserted first into the disc space. References to the posterior end 106 and the anterior end 108 are described with respect to the orientation of placement into the disc space, with it being understood that the anterior portion 108 (e.g., contralateral) of the expandable fusion implant 100 is placed into the disc space first, followed by the posterior portion 106 (e.g., ipsilateral) of the expandable fusion implant 100. These and other directional terms may be used herein for purposes of explanation and do not limit the orientation in which the device may be used.

[0019] 4A-4B, an exploded view of an expandable coronal implant 100 is shown. The expandable implant 100 includes an upper or top end plate 102, a lower or bottom end plate 104, and a plurality of internal drive ramps 110, 112, 114 that are actuated by dual actuators 116, 118 to expand the top and bottom end plates 102, 104. The internal drive ramps include a posterior ramp 110, a middle ramp 112, and an anterior ramp 114 that engage the upper and lower end plates 102, 104 to expand the implant 100. The dual actuator assembly includes a central drive screw actuator 116 and an actuator nut 118, which control the drive ramps 110, 112, 114 by independently rotating one or both of them. By rotating one of the actuator 116 and actuator nut 118 while holding the other in place, either the ipsilateral side 106 or contralateral side 108 of the implant 100 can be raised to a desired coronal angle. This angle may correspond to the inclination of the vertebral endplates or can be used to correct the deformity after height correction has been achieved.

[0020] The top end plate 102 is described in further detail herein, and that description applies equally to the bottom end plate 104, which may include similar features (e.g., mirror image) as the top end plate 102. The end plates 102, 104 may include a leading end 120, an opposing trailing end 122, and a pair of sidewalls 124 connecting the leading end 120 to the trailing end 122. The end plates 102, 104 may form a generally quadrilateral shape, such as a rectangle with the long sidewalls 124, or any other suitable shape. The leading end 120 may include a smooth, tapered nose to facilitate insertion into the disc space. The end plates 102, 104 include an inner surface 126 and an opposing outer surface 128 configured to contact the adjacent vertebrae. The outer surface 128 may include a plurality of teeth or other friction-increasing elements, such as ridges, roughness, keels, gripping or trapping projections, configured to retain the implant 100 within the disc space. The end plates 102, 104 may define one or more windows 130 extending between the outer surface 126 and the inner surface 128. The windows 130 may be configured to receive bone graft or similar bone growth inducing material that may be introduced into and / or around the device 100 to further enhance and promote bone growth.

[0021] The sidewall 124 defines a plurality of angled surfaces 132 configured to mate with corresponding drive ramps 110, 112, 114. The angled surfaces 132 may include angled surfaces, tracks, grooves, channels, or other mating regions configured to form a slidable interface between the drive ramps 110, 112, 114 and the end plates 102, 104. The angled surfaces 132 may be angled, beveled, sloped, or inclined to provide sliding engagement with the corresponding drive ramps 110, 112, 114. The angled surfaces 132 may define female channels or internal slots that form male protrusions or overhangs configured to be received in female counterparts of the drive ramps 110, 112, 114. In particular, a pair of rearmost angled surfaces 132A, which define inwardly facing slots with protrusions, are configured to engage the rear drive ramp 110. When approached from the rear end 106, the slope of the angled ramp 132A may be downward. A pair of central ramps 132B, which define an inwardly facing slot with a protrusion, are configured to engage with the central drive ramp 112. When approached from the rear end 106, the slope of the angled surface 132B may be upward. A pair of front-most ramps 132C, which define an inwardly facing slot with a male protrusion, are configured to engage with the front ramp 114. When approached from the rear end 106, the slope of the front-most angled surface 132C may be downward. The slope of each ramp 132 may be the same or different to achieve a desired rate and amount of expansion.

[0022] The bottom end plate 104 may be similar to (e.g., a mirror image of) the end plate 102. In this sense, the slope of the rearmost ramp 132A may be increasing as it is approached from the rear end 106. The slope of the central ramp 132B may be decreasing as it is approached from the rear end 106. The slope of the forwardmost ramp 132C may be increasing as it is approached from the rear end 106. While the ramps 132 are shown in a given configuration, it will be understood that the ramps may be sloped, beveled, curved, or otherwise configured in any manner to provide the desired type of expansion, the female / male configuration may be reversed, or other suitable ramp interactions, sliding features, or mating components may be used to provide expansion of the top and bottom end plates 102, 104.

[0023] The actuation mechanism may include multiple internal drive ramps 110, 112, 114 driven by dual actuators 116, 118 to expand the top and bottom end plates 102, 104. The dual actuators 116, 118 may be aligned along longitudinal axes that are laterally offset toward one sidewall 124 within the internal drive ramps 110, 112, 114. The offset axis may be parallel to one side of the central longitudinal axis of the implant 100 and laterally offset. The dual actuators 116, 118 may be concentric with one another along the offset axis. In a concentric configuration, each actuator 116, 118 may be independently controlled without interfering with the movement of the other, allowing for precise control of the internal drive ramps 110, 112, 114 and the corresponding expansion of the end plates 102, 104.

[0024] As best shown in FIG. 5A , the posterior drive ramp 110 can include a block-like body located toward the proximal or posterior end 106 of the implant 100. The posterior drive ramp 110 can include an upper surface 140 configured to mate with the top end plate 102 and a lower surface 142 configured to mate with the bottom end plate 104 when in the collapsed configuration. The posterior drive ramp 110 includes a forward-facing surface (anterior surface) 144 configured to interface with an insertion instrument, and an opposite rearward-facing surface (posterior surface) 146. The upper surface 140 and / or the lower surface 142 can define one or more channel grooves 141 between the anterior surface 144 and the posterior surface 146. For example, parallel grooves 141 can be used to facilitate linear translation of the posterior drive ramp 110.

[0025] Opposite sides of the rear drive ramp 110 each define a ramp surface 148 configured and dimensioned to interface with the corresponding rearmost ramp surfaces 132A of the top and bottom end plates 102, 104. The ramp surfaces 148 may be angled continuous surfaces having a given inclination angle that engage with the corresponding ramp surfaces 132A of the end plates 102, 104. For example, the ramp surfaces 148 may define female grooves or channels that form male protrusions that engage with the corresponding ramp surfaces 132A in the end plates 102, 104. For example, the male protrusions may include a triangular region 150 defined between two converging angled grooves. The triangular regions 150 may extend laterally from both sides of the drive ramp 110. On each side, approaching from the posterior end 106 of the implant 100, one upper angled groove 148 above the triangular region 150 may have a descending slope, while one lower angled groove 148 below the triangular region 150 may have an ascending slope, thereby forming the apex of the triangular region 150 that points toward the anterior portion 144 of the posterior drive ramp 110. The angled surfaces 148 of the posterior drive ramp 110 complement the angled surfaces 132A of the end plates 102, 104, for example, using a sliding dovetail configuration. It will be understood that the female / male configuration may be reversed or may include other suitable ramp interactions, sliding features, or mating components to provide vertical expansion. As the posterior drive ramp 110 is translated toward the anterior end 106 or posterior end 108 of the implant 100, the ramp surface 148 of the drive ramp 110 slides against the ramp surface 132A of the end plates 102, 104, thereby increasing or decreasing the height of the posterior end 106 (e.g., on the same side) of the implant 100.

[0026] The rear drive ramp 110 defines a first internal bore 152 between the front and rear faces 144, 146 of the drive ramp 110, the first internal bore 152 configured to receive the concentric actuators 116, 118. The axis of the bore 152 may be aligned with the laterally offset longitudinal axis of the dual-actuator drive assembly when assembled. The bore 152 may define a protruding internal rim 153 near the front face 144, which helps secure the actuator nut 118 within the bore 152. The rear drive ramp 110 may define a second internal bore 154 between the front and rear faces 144, 146 of the rear drive ramp 110, which may be configured, for example, for coupling to an insertion instrument and / or for receiving graft material. The second bore 154 may have a smaller diameter than the first bore 152. The second internal bore 154 may be parallel to and laterally offset from the opposite sidewall 124, facing the first internal bore 152. The rear drive ramp 110 may define one or more instrument recesses or depressions 156 configured to connect an instrument, such as an insertion instrument or implant inserter. For example, a pair of depressions 156 may be provided on opposite sides of the rear drive ramp 110 to aid in implantation and / or expansion.

[0027] As best shown in FIG. 5B , the intermediate ramp 112 may include a block-like body centrally located toward the distal or anterior end 108 of the implant 100. The intermediate ramp 112 may have a cross-shaped cross-section having an upper surface 160, a lower surface 162, a front surface 164, and a rear surface 166. The upper and lower surfaces 160, 162 may be flat or substantially planar, with a sharp corner connected to the front surface 164. The sides of the ramp 112 may include wings or protrusions that define a ramp surface 168 that complements the corresponding ramp surfaces 132B of the top and bottom end plates 102, 104. The ramp surface 168 may define a female groove or channel that forms a male protrusion, which engages with the corresponding ramp surface 132B in the end plates 102, 104. For example, the male protrusion may include a triangular region 170 defined between two converging angled grooves. On each side, approaching from the posterior end 106 of the implant 100, one upper angled groove 168 above the triangular region 170 may have an ascending slope, while one lower angled groove 168 below the triangular region 170 may have a descending slope, thereby forming the apex of the triangular region 170, pointing toward the posterior end 166 of the intermediate ramp 112. The ramped surfaces 168 of the intermediate drive ramp 112 complement the ramped surfaces 132B of the end plates 102, 104, for example, using a sliding dovetail configuration. It will be understood that the female / male configuration may be reversed or may include other suitable ramp interactions, sliding features, or mating components to provide vertical expansion. As the intermediate drive ramp 112 is translated, the ramp surface 168 of the drive ramp 112 slides against the ramp surfaces 132B of the end plates 102, 104, thereby increasing or decreasing the height of the leading end 108 of the implant 100.

[0028] The intermediate ramp 112 defines a throughbore 172 between the front face 164 and the rear face 166 of the drive ramp 112, the throughbore 172 being configured to receive the drive screw actuator 116 therethrough. The throughbore 172 may be internally threaded to interface with the threaded portion 212 of the drive screw actuator 116. The threaded throughbore 172 is laterally offset through the intermediate ramp 112 such that, when assembled, the axis of the threaded throughbore 172 is aligned with the laterally offset axis of the drive assembly.

[0029] As best shown in FIG. 5C , the anterior ramp 114 may include a blocky body located toward the distal or anterior end 108 of the implant 100. The anterior ramp 114 includes an upper surface 180, a lower surface 182, a front surface 184, and a rear surface 186. The upper and lower surfaces 180, 182 may be flat or substantially planar, with rounded corners connected to the front surface 184. The sides of the ramp 114 may include wings or protrusions that define an inclined surface 188 configured to mate with corresponding inclined surfaces 132C of the top and bottom end plates 102, 104. The inclined surface 188 may define a female groove or channel that forms a male protrusion, which engages with the corresponding inclined surfaces 132C in the end plates 102, 104. For example, the male protrusion may include a triangular region 190 defined between two converging angled grooves. On each side, approaching from the posterior end 106 of the implant 100, one upper angled groove 188 above the triangular region 190 may have a decreasing slope, while one lower angled groove 188 below the triangular region 190 may have an increasing slope, thereby forming the apex of the triangular region 190, pointing toward the anterior portion 184 of the anterior ramp 114. The angled surfaces 188 of the anterior ramp 114 complement the angled surfaces 132C of the end plates 102, 104, for example, using a sliding dovetail configuration. It will be understood that the female / male configuration may be reversed or may include other suitable ramp interactions, sliding features, or mating components to provide vertical expansion. As the posterior and / or intermediate ramps 110, 112 are translated, the ramp surface 188 of the anterior drive ramp 114 slides against the ramp surface 132C of the end plates 102, 104, thereby increasing or decreasing the height of the anterior end 108 of the implant 100 depending on the movement of the other ramps 110, 112.

[0030] The middle ramp 114 defines a bore 192 between the front face 184 and the rear face 186 of the drive ramp 114, the bore 192 configured to receive the drive screw actuator 116 therethrough. The bore 192 may be unthreaded to interface with the non-threaded portion 216 of the drive screw actuator 116. The non-threaded through bore 192 is laterally offset such that, when assembled, the axis of the non-threaded through bore 192 is aligned with the laterally offset axis of the dual actuator drive assembly. The bore 192 may define a circumferential or annular groove 194 configured to receive a locking ring 244, thereby securing the actuator screw 116 to the front drive ramp 114 while still allowing rotation of the actuator screw 116 relative to the front drive ramp 114.

[0031] As best shown in FIG. 6A , the central drive screw 116 may include a shaft 200 extending from a proximal end 202 to a distal end 204. The proximal end 202 may include an enlarged head 206 defining a drive recess 208 configured to be engaged by a drive instrument to rotate the actuator screw 116. The drive recess 208 may be a hexalobe, slot, cross, or other suitable shape that may engage with a tool or device having a corresponding tip. The shaft 200 includes a first threaded portion 210, a second threaded portion 212, a first non-threaded portion 214 between the threaded portions 210, 212, and a second non-threaded portion 216 toward the distal end 204. The first threaded portion 210 may include external threads configured to mate with an actuator nut 118 connected to the rear drive ramp 110. The second threaded portion 212 may have external threads configured to mate with the intermediate ramp 112. The first threaded portion 210 and the second threaded portion 212 may have different attributes including major diameter, thread turn, thread form, thread angle, lead, pitch, etc. For example, the second threaded portion 212 may have a reduced diameter relative to the first threaded portion 210, and the first threaded portion 210 may have a finer thread pitch or more lead than the second threaded portion 212. The second unthreaded portion 216 may have a reduced diameter relative to the remainder of the shaft 200. The second unthreaded portion 216 is configured to receive the front drive ramp 114. The second non-threaded portion 216 may define a circumferential or annular groove 218 near the distal end 204 that is configured to receive a retaining clip 246, thereby securing the drive screw 116 to the front drive ramp 114 while still allowing rotation of the drive screw 116 relative to the front drive ramp 114.

[0032] As best shown in FIG. 6 , the actuator nut 118 may include a cylindrical body 220 extending along a central axis A1 from a proximal end 222 to a distal end 224. The cylindrical body 220 may have an enlarged head 226 defining a second instrument recess 228 configured to be engaged by a second driving instrument to rotate the actuator nut 118. The instrument recess 228 may include a notched head or other suitable shape that may engage with a tool or device having a corresponding tip, thereby rotating the actuator nut 118. The actuator nut 118 may have a reduced diameter neck 230 that, when fitted within the bore 152 of the rear drive ramp 110, engages with the protruding inner rim 153 of the rear drive ramp 110. The enlarged head 226 may define a circumferential or annular groove 232 configured to receive a retaining clip 240, thereby securing the actuator nut 118 to the rear drive ramp 110 while still allowing rotation of the actuator nut 118 relative to the rear drive ramp 110. The actuator nut 118 defines a through bore 234 between the proximal end 222 and the distal end 224. The through bore 234 may be at least partially threaded to engage the threaded proximal portion 210 of the actuator screw 116. For example, the through bore 234 may be internally threaded along the neck portion 230 of the actuator nut 118.

[0033] To assemble the implant 100, the top end plate 102 and the bottom end plate 104 may be attached to a drive assembly including the dual actuators 116, 118 and the attached internal drive ramps 110, 112, 114. First, the dual actuators 116, 118 may be combined and mated to the rear drive ramp 110. The proximal end 202 of the actuator screw 116 may be placed through the distal end 224 of the through bore 234 of the actuator nut 118. The actuator nut 118 may be threaded onto the first threaded portion 210 of the actuator drive screw 116. The proximal end 202 of the actuator drive screw 116 with the attached actuator nut 118 may be placed through the bore 152 of the rear drive ramp 110. The assembly may be seated within the rear drive ramp 110 with the protruding inner rim 153 of the rear drive ramp 110 gripping the neck 230 of the actuator nut 118. The assembly may be secured to the rear drive ramp 110 via, for example, one or more securing or retaining clips 240, 242. The retaining clips 240, 242 may include C-shaped clips or partial rings with a central opening. A first retaining clip 240 may fit into an annular groove 232 along the outside of the actuator nut 118 and into a corresponding internal annular groove 158 in the bore 152 of the rear drive ramp 110. A second retaining clip 242 may fit beneath the first retaining clip 242 around the head 226 of the actuator nut 118. The second retaining clip 242 may also rest within the internal annular groove 158 in the bore 152 of the rear drive ramp 110. While C-shaped retaining clips are shown, it will be understood that any suitable mechanism may be used to secure the actuator assembly to the rear drive ramp 110 while still allowing independent rotation of both actuators 116, 118.

[0034] Next, other drive ramps 112, 114 can be added to the dual actuator assembly. The middle drive ramp 112 may be added to the actuator drive screw 116. The distal end 204 of the actuator screw 116 may be positioned through the proximal end 166 of the threaded bore 172 of the middle ramp 112. The middle ramp 112 may be threaded onto the second threaded portion 212 of the actuator drive screw 116. Next, the front drive ramp 114 may be added to the actuator drive screw 116. The distal end 204 of the actuator screw 116 may be positioned through the proximal end 186 of the unthreaded bore 192 of the front drive ramp 114. The front drive ramp 114 may be secured via, for example, one or more locking or retaining rings 244, 246. The first retaining ring 244 may include a complete ring having a central opening. The first retaining ring 244 may fit around the unthreaded portion 216 of the actuator screw 116 and within the annular groove 194 in the front drive ramp 114. The retaining ring 244 may also act as a friction ring to apply friction or may protect the actuator screw 116. The second retaining ring 246 may include a C-shaped clip or partial ring with a central opening. The second retaining ring 246 may be positioned adjacent the front face 184 of the front drive ramp 114 and fit within the groove 218 in the distal end 204 of the actuator screw 116, thereby securing the front drive ramp 114 to the actuator screw 116.

[0035] Finally, the top end plate 102 and the bottom end plate 104 may be assembled into a dual actuator drive assembly. The top end plate 102 and the bottom end plate 104 may be assembled to the rear drive ramp 110, the middle drive ramp 112, and the front drive ramp 114. In particular, the ramp surface 148 of the rear ramp 110 slidably mates with the rear ramp surface 132A of the top end plate 102 and the bottom end plate 104, the ramp surface 168 of the middle ramp 112 slidably mates with the middle ramp surface 132B of the top end plate 102 and the bottom end plate 104, and the ramp surface 188 of the front ramp 114 slidably mates with the front ramp surface 132C of the top end plate 102 and the bottom end plate 104.

[0036] As best shown in Figures 7A-7C, as one or more of the drive ramps 110, 112, 114 move, the ramp surfaces 148, 168, 188 push against the corresponding ramp surfaces 132 of the top and bottom end plates 102, 104. In this manner, the individual drive ramps 110, 112, 114 control the rate and angle of expansion of the upper and lower end plates 102, 104. Figure 7A shows an example of an implant 100 with parallel expansion of the end plates 102, 104. For example, when both the actuator drive screw 116 and the actuator nut 118 are rotated simultaneously, the posterior ramp 110 and the middle ramp 112 slide together in parallel, thereby causing the end plates 102, 104 to move in parallel. It will further be appreciated that when both actuators 116, 118 are rotated simultaneously at different speeds and / or in different directions, the implant 100 can expand in a coordinated but different manner at both ends 106, 108, allowing for customized fit and coronal correction.

[0037] FIG. 7B shows an example of an implant 100 with ipsilateral height expansion. When only the actuator nut 118 is rotated, the posterior ramp 110 can be translated anteriorly along the drive screw 116, increasing its posterior height and decreasing its anterior height. The actuator drive screw 116 can also be rotated to push the middle ramp toward the anterior ramp 114 and away from the posterior ramp 110, thereby creating the maximum amount of contralateral angle bias. FIG. 7C shows an example of an implant 100 with contralateral height expansion. When the actuator nut 118 remains stationary (and is positioned toward the posterior end 106) and only the actuator drive screw 116 is rotated, the middle ramp 112 can increase its anterior height and decrease its posterior height, thereby pulling it back toward the posterior ramp 110, creating the ipsilateral angle bias. Depending on the direction and amount of rotation of the actuators 116, 118, the posterior ramp 110 and intermediate ramp 112 are allowed to move along the length of the respective threaded portions 210, 212 of the drive screw 116, allowing for precise and controlled adjustment of height and coronal angle. It will be appreciated that the movement and resulting expansion of the drive ramps 110, 112, 114 can be manipulated by the concentric actuators 116, 118 with any suitable configuration and mechanism to obtain the desired expansion and angular bias for coronal correction.

[0038] In one embodiment, the end plates 102, 104 or the implant as a whole may have a reverse taper, and after insertion, the implant 100 may be adjusted to a neutral or opposite angle to correct coronal deformity. In this design, the end plates 102, 104 or the body of the implant 100 may be shaped with a reverse taper to match the inclination or angular orientation of the insertion site, for example, to allow easier insertion into the disc space. After insertion, the end plates 102, 104 may be tilted to or beyond neutral such that the taper is reversed to change the angle of the end plates 102, 104 relative to one another. In this manner, the implant 100 can be manipulated to shift from its initial oblique alignment to a more neutral or adjusted angular position to achieve optimal spinal alignment and stability.

[0039] During use, the implant 100 can enter the disc space in a collapsed orientation and then be expanded to achieve a desired height and coronal correction to the desired coronal angle. The implant 100 may be placed laterally or anteriorly, for example, using an insertion instrument to align the implant 100 with the ipsilateral and contralateral sides of the disc space. After placement, the height and angle of the implant may be adjusted by rotating one or both of the concentric actuators 116, 118 to achieve the desired alignment and coronal angle, thereby correcting the coronal deformity. Asymmetric coronal expansion provides independent height expansion on the ipsilateral and contralateral sides for a customized fit to the patient. Angular bias may be used to match the inclination of vertebral endplates and / or to correct spinal deformities such as wedged vertebrae or scoliosis, thereby correcting curvature in the coronal plane, realigning the spine, and restoring biomechanical balance to the spine.

[0040] 8A-8B, examples of expandable coronal implants 300, 300A with pin-and-slot actuators are shown. In these embodiments, mating ramps are replaced with pins that ride along angled slots on the sides of the implant to control implant expansion. The expandable implants 300, 300A are shown without a portion of the upper endplate 302 for clarity. In FIG. 8A, the expandable implant 300 includes an angled slot 314 to allow for unidirectional angulation. In FIG. 8B, an alternative expandable implant 300A includes a multi-angled slot 314 to allow for multiple stages of endplate angulation.

[0041] With further reference to FIG. 8A , the implant 300 includes a top end plate 302 and a bottom end plate 304 configured to engage adjacent vertebrae. The implant 300 extends along a central longitudinal axis between a posterior end 306 (or ipsilateral) configured to connect with an insertion instrument and an anterior end 308 (or contralateral) configured to be initially inserted into the intervertebral disc space. The implant 300 may define a frame 310 having, for example, a rectangular shape. A pair of rails 312 may extend along each side of the frame 310. Each rail 312 may define an angled slot 314. The angled slot 314 may have a given slope, for example, that increases or decreases along the length of the rail 312. The implant 300 includes a drive ramp 316 from which a pin 318 extends. The pin 318 may include a circular peg or dowel sized and dimensioned to fit within the angled slot 314. The rail 312 may be pinned to one end of the frame 310 using, for example, a hinge or pivot pin 320. The drive ramp 316 may be translated, for example, by a threaded drive screw (e.g., similar to implant 100) or other suitable mechanism. As the pin 318 moves within the angled slot 314, it pushes against the side of the slot 314, causing the endplates 302, 304 to move outward or change angulation. In this embodiment, the bottom endplate 304 expands to increase ipsilateral height. It will be understood that the slot 314 can be reconfigured for contralateral expansion. The position and angle of the slot 314 determine how the force applied by the pin 318 translates into movement of the endplates 302, 304, allowing for precise control over expansion.

[0042] In an alternative embodiment shown in FIG. 8B, each angled slot 314 is divided into two separate angled portions 322, 324 with different slope directions. The first angled slot portion 322 may include a descending slope, while the second angled slot portion 324 includes an ascending slope (or vice versa). The two angled portions 322, 324 meet midway, e.g., at a low point, to provide a transition between the two types of expansion. In this embodiment, the rails 312 may be secured to both ends of the frame 310 using, for example, pins 326 that move along respective vertical slots in the rails 312. The dual-slope configuration allows for adjustment in multiple directions depending on which portion of the slot 314 the pin 318 engages. By moving the pin 318 forward or backward within the slot 314, the pin 318 can engage with either the ascending or descending slope portion to create different angulations (e.g., ipsilateral or contralateral angulations) of the end plates 302, 304 of the implant 300A.

[0043] 9A-9B, an alternative embodiment of an expandable coronal implant 400 having two separate pin-in-slot actuators is shown. In this embodiment, the pins ride along angled surfaces but are controlled by two separate internal drive screws to control the expansion and angulation of the implant. With further reference to FIG. 9A, the implant 400 includes a top end plate 402 and a bottom end plate 404 configured to engage adjacent vertebrae. The implant 400 extends along a central longitudinal axis between a posterior end 406 (or ipsilateral) configured to connect with an insertion instrument and an anterior end 408 (or contralateral) configured to be initially inserted into the disc space. The implant 400 may include a pair of drive ramps 410, 412, each having one or more pins 418 extending therefrom. The pins 418 may include circular pegs or dowels sized and dimensioned to slide against the angled surfaces 420 along the top and bottom end plates 402 and 404 .

[0044] The ramp surfaces 420 along the top and bottom end plates 402, 404 may be divided into different regions with different ramp directions. Similar to the dual ramp slot 314, the first angled surface may include a descending ramp, while the second angled surface may include an ascending ramp (or vice versa). The two angled surfaces may meet in the middle, such as at a high point (e.g., in the case of the top end plate 402) or a low point (e.g., in the case of the bottom end plate 404), but each drive ramp 410 may follow only one side of the ramp surface. For example, for the ramp surface 420, the first drive ramp 410 may slide between a first region of descending ramp, and the second drive ramp 412 may slide in the opposite direction between a second region of ascending ramp (although each may independently slide up and down the ramp surface). It will be understood that the dual ramp and sliding configuration may be reconfigured or modified for desired extensions.

[0045] Each drive ramp 410, 412 may be independently actuated via a separate actuator drive screw 422, 424. Similar to the actuator drive screw 116, the screws 422, 424 may have threads that threadingly engage with the respective drive ramp 410, 412. As each actuator screw 422, 424 is rotated, the drive ramps 410, 412 are independently translated forward or backward, causing the pins 418 to move along the ramped surfaces 420 of the top and bottom end plates 402, 404. In this manner, each end 406, 408 of the implant 400 may be independently controlled with a different drive ramp 410, 412 engaging a different region of the ramped surface 420, allowing independent elevation of the proximal or distal side of the implant 400. By independently moving the drive ramps 410, 412 anteriorly or posteriorly along the ramp surface 420, the implant 400 can be expanded with the desired ipsilateral or contralateral angulation to correct coronal imbalance.

[0046] 10A-10B, an example of a coronal expandable implant 500 is shown that provides a coronal targeting approach when the implant 500 is placed laterally within the intervertebral disc space. The expandable implant 500 includes top and bottom end plates 502, 504, a posterior end 506 (or ipsilateral), and an anterior end 508 (or contralateral). The implant 500 may include a housing or body 510 disposed between the end plates 502, 504, a nose 512, and a single drive screw 514. The end plates 502, 504 may have two primary pairs of ramps that allow expansion: two posterior ramps that mate with the two ramps of the body 510 and two anterior ramps that mate with the ramps of the nose 512. The drive screw 514 provides a threaded mechanism for expanding and contracting the expandable fixation device 500. Further details of expandable implants can be found, for example, in U.S. Patent No. 11,191,650, which is incorporated herein by reference in its entirety for all purposes. When placed laterally within the disc space, the anterior end 508 of the implant 500 may be expanded to, for example, increase contralateral height, provide ipsilateral angular bias, and provide a coronal targeting approach.

[0047] Unlike static implants with a coronal taper, the implants described herein can be adjustable in coronal angulation and expansion height. The implants can be provided with a small footprint suitable for minimally invasive procedures, in which the implant is inserted in a collapsed configuration and then expanded to restore disc space, correct coronal deformity, and enhance spinal stability. The implants may be particularly suitable for MIS lateral implantation to restore disc height and address asymmetric coronal expansion. The implants may be configured for contralateral and / or ipsilateral coronal angulation, depending on the desired deformity and correction. The implants can provide the precise adjustments needed in surgery for patients with coronal imbalance and / or wedged vertebrae, thereby restoring disc space and providing coronal correction. In some cases, the implants can provide independently controlled dual expansion, allowing ipsilateral and contralateral independent height expansion to address asymmetry and misalignment, thereby achieving optimal spinal alignment and stabilization.

[0048] While the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention. Accordingly, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. For example, it is expressly intended that all of the elements of the various devices disclosed above can be combined or modified in any suitable configuration.

Claims

1. 1. An expandable coronal implant comprising: top and bottom end plates configured to engage adjacent vertebrae; a dual actuator assembly including a rotatable drive screw actuator having a shaft and a rotatable actuator nut concentric with the drive screw actuator; and a plurality of drive ramps, including a front ramp, a middle ramp, and a rear ramp, disposed along the shaft of the drive screw actuator and engaging the top end plate and the bottom end plate via complementary ramped surfaces; An expandable coronal implant, wherein when inserted into an intervertebral disc space, the implant has an ipsilateral and a contralateral side, and rotation of the drive screw actuator and / or the actuator nut causes movement of one or more of the drive ramps, thereby causing independent expansion of the contralateral and / or ipsilateral height of the implant to correct a coronal deformity.

2. 2. The expandable implant of claim 1, wherein the dual actuator assembly is laterally offset relative to a central longitudinal axis of the implant, and the anterior, intermediate, and posterior sloped portions define a through bore along the offset axis for receiving the shaft of the drive screw actuator.

3. 2. The expandable implant of claim 1, wherein the posterior sloped portion defines a female sloped groove forming a male triangular region with an apex pointing anteriorly to the implant, the intermediate sloped portion defines a female sloped groove forming a male triangular region with an apex pointing posteriorly to the implant, and the anterior sloped portion defines a female sloped groove forming a male triangular region with an apex pointing anteriorly to the implant.

4. 2. The expandable implant of claim 1, wherein the shaft of the drive screw actuator includes a first threaded portion, a second threaded portion, a first unthreaded portion separating the first threaded portion from the second threaded portion, and a second unthreaded portion toward a distal end of the shaft.

5. 5. The expandable implant of claim 4, wherein the rear ramp portion is disposed on the actuator nut that is disposed on the first threaded portion of the drive screw actuator, the middle ramp portion is disposed on the second threaded portion of the drive screw actuator, and the front ramp portion is disposed on the second non-threaded portion of the drive screw actuator.

6. 6. The expandable implant of claim 5, wherein the actuator nut includes a cylindrical body having an enlarged head defining an instrument recess and a neck portion with a reduced diameter defining internal threads that engage the first threaded portion of the shaft of the drive screw actuator.

7. 6. The expandable implant of claim 5, wherein the actuator nut is secured to the posterior ramp portion using a first retaining clip that fits into an annular groove along the outside of the actuator nut and a corresponding inner annular groove along the inside of the posterior ramp portion.

8. 8. The expandable implant of claim 7, wherein the actuator nut is secured to the posterior ramp portion with a second retaining clip that fits under the first retaining clip around the head of the actuator nut and rests within the internal annular groove along the inside of the posterior ramp portion.

9. 1. An expandable coronal implant comprising: top and bottom end plates configured to engage adjacent vertebrae, the top and bottom end plates being angled to provide an initial reverse taper configured to match the angle of the intervertebral disc space upon insertion; a dual actuator assembly including a rotatable drive screw actuator having a shaft and a rotatable actuator nut concentric with the drive screw actuator; and a plurality of drive ramps, including a front ramp, a middle ramp, and a rear ramp, disposed along the shaft of the drive screw actuator and engaging the top end plate and the bottom end plate via complementary ramped surfaces; After insertion into the disc space, the implant is expanded by rotating the drive screw actuator and / or the actuator nut to cause movement of one or more of the drive ramps, thereby expanding the end plates to provide an angle opposite to a neutral position or the initial reverse taper and correcting a coronal deformity.

10. 10. The expandable implant of claim 9, wherein the implant has an ipsilateral and a contralateral side within the disc space, and the initial reverse taper has an asymmetric taper such that the contralateral side is greater in height than the ipsilateral side.

11. 11. The expandable implant of claim 10, wherein the implant is expandable to tilt the top and bottom end plates at an angle opposite to the initial reverse taper so that the ipsilateral side is taller than the contralateral side to correct the coronal deformity.

12. 11. The expandable implant of claim 10, wherein the implant is expandable such that the top and bottom end plates are parallel to one another in the neutral position.

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