Expandable footprint implant

Abstract

To provide expandable intervertebral fusion implants, system and methods.SOLUTION: The expandable intervertebral implant is capable of being installed inside an intervertebral disc space to maintain the intervertebral disc space and restore spinal stability, thereby facilitating an intervertebral fusion. The implant may include a central drive assembly configured to control left- and right-side assemblies. The expandable intervertebral implant may be configured to transition from a collapsed configuration having a first width and a first height to an expanded configuration having a second width and a second height.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure generally relates to devices and methods for facilitating spinal fixation, and more specifically to expandable fixation devices that can be inserted between adjacent vertebrae to facilitate the fixation process, as well as related systems and methods.

Background Art

[0002] A common technique for addressing pain associated with intervertebral discs degenerated by various factors (e.g., trauma or aging) is the use of an intervertebral fixation device to fix one or more adjacent vertebral bodies. Generally, to fix adjacent vertebral bodies, the intervertebral disc is first partially or completely removed. Then, an intervertebral fixation device is inserted between the adjacent vertebrae to maintain a normal intervertebral disc space, restore spinal stability, and thereby facilitate intervertebral fixation.

[0003] There are several fixation devices and methods for achieving intervertebral fixation. These may include solid bone implants, fixation devices that can be packed with bone and / or bone growth-inducing substances and a cage or other implant mechanism, and expandable implants. For example, a posterior implant can be implanted to provide restoration of intervertebral disc height. The implant is placed between adjacent vertebrae to fix the vertebral bodies to each other, thereby reducing the associated pain.

[0004] However, existing posterior implants have drawbacks including subsidence and sagittal balance problems. Therefore, there is a need for a fixation device that can be placed inside the intervertebral disc cavity with a minimal height and width, having an expandable footprint to address the subsidence problem and an adjustable lordosis to address the sagittal balance problem.

Summary of the Invention

[0005] To meet this and other needs, devices, systems, and methods for performing intervertebral fixation and spinal stabilization are provided. Specifically, for example, an expandable intervertebral implant for posterior spinal surgery can be used to treat various patient symptoms. The expandable implant is configured to increase the overall footprint size while also adjusting the lordosis and overall height after being inserted into the disc space. The expandable footprint or surface area at the site is configured to address the problem of subsidence, and the adjustable lordosis at the site is configured to address the problem of sagittal balance. The intervertebral implant can be combined with a posterior stabilization system, including, for example, pedicle screws and spinal rods, to further stabilize the spine.

[0006] According to one embodiment, an expandable intervertebral implant includes a central drive assembly and left and right assemblies. The central drive assembly includes a central drive screw positioned through a front plate, the central drive screw being threaded into a central actuator, the central actuator being coupled to a threaded sleeve, the threaded sleeve being positioned through a rear plate and threaded into a drive nut. Each of the left and right assemblies includes an upper end plate and a lower end plate, a side actuator, and a front ramp. The side actuator and the front ramp are slidably engaged with the upper and lower end plates. Rotation of the drive nut expands the width of the implant, and rotation of the drive screw expands the height of the implant.

[0007] The expandable intervertebral implant may include one or more of the following features. The drive nut may pull the threaded sleeve and the central actuator toward the rear plate and push the widths of the left and right portions outward. The drive screw may pull the front ramp toward the central actuator and then expand the heights of the upper end plate and the lower end plate. The central actuator may include a tubular body having an inner bore and a pair of opposed wings configured to mate with the side actuators. The rear plate may include a pair of female horizontal ramps defined on the upper and lower surfaces of the rear plate, and the side actuators may include a pair of male horizontal ramps configured to mate with the female horizontal ramps of the rear plate. The front plate may include a pair of female horizontal ramps defined on the upper and lower surfaces of the front plate, and the front ramp may include a pair of male horizontal ramps configured to mate with the female horizontal ramps of the front plate.

[0008] According to one embodiment, an expandable intervertebral implant includes a front plate having a central through bore, a central drive screw having an enlarged head and a threaded shaft positioned through the bore of the front plate, a central actuator having a tubular body with a through bore and a pair of opposed wings, wherein the threaded shaft of the central drive screw is threaded within one end of the bore of the central actuator, a rear plate having a central through bore, a threaded sleeve positioned through the bore of the rear plate and threaded to an opposite end of the bore of the central actuator, a drive nut threaded to the threaded sleeve, and left and right assemblies each including an upper end plate, a lower end plate, side actuators, and a front ramp. The side actuators and the front ramp are slidably engaged with the upper and lower end plates, the side actuators are slidably engaged with the rear plate and the central actuator, and the front ramp is slidably engaged with the front plate.

[0009] The expandable intervertebral implant may include one or more of the following features. The left and right assemblies may have a laterally contracted configuration having a first width and a laterally expanded configuration having a second width, and the left and right assemblies may have a vertically contracted configuration having a first height and a vertically expanded configuration having a second height. The wings on a pair of opposite sides may each define a female ramp configured to receive a corresponding male ramp from a side actuator. The wings on a pair of opposite sides may be angled distally toward the front plate. The rear plate may include a proximally projecting cylindrical ring. The cylindrical ring may define a threaded outer surface. The threaded sleeve may include a first proximally outer threaded section configured to mate with the inner threads of the bore of the drive nut and a second distally outer threaded section configured to mate with the inner threads of the bore of the central actuator. The central drive screw may be held within the front plate by a retaining ring. The drive nut may be held within the rear plate by a retaining sleeve.

[0010] According to another embodiment, an expandable intervertebral implant includes a central drive assembly and a side assembly. The central drive assembly includes a front plate aligned along a longitudinal central axis, a central drive screw, a central actuator, a threaded sleeve, a rear plate, and a drive nut. The central drive screw is held within the front plate. The central actuator is threaded with the central drive screw and the threaded sleeve. The threaded sleeve is held within the rear plate and is threaded with the drive nut. The side assembly includes an upper end plate and a lower end plate, a side actuator, and a front ramp. The side actuator and the front ramp are slidably engaged with the upper end plate and the lower end plate. The side actuator is slidably engaged with the rear plate and the central actuator, and the front ramp is slidably engaged with the front plate. When actuated, the drive nut controls the expansion of the width of the implant, and the drive screw controls the expansion of the height of the implant.

[0011] An expandable intervertebral implant may include one or more of the following features. A central drive screw may extend from a proximal end to a distal end, the distal end including an expansion head portion and the proximal end defining an instrument recess. A drive nut may define a central through-bore, and the proximal face of the drive nut may define an instrument recess different from the instrument recess of the central drive screw. The central drive screw may be positioned at the distal end of the implant, and the drive nut may be positioned at the proximal end of the implant. When actuated, the drive nut may pull proximally on a threaded sleeve and a central actuator, thereby causing an expansion in width. When actuated, the central drive screw may pull a front plate toward the central actuator and a front ramp toward a side actuator, thereby causing an expansion in height.

[0012] According to another embodiment, a method of assembling an expandable intervertebral implant may include one or more of the following steps, in any suitable order: (1) placing two front lamps onto a front plate by aligning mating lamps or sliders; (2) placing one side actuator onto a rear plate by aligning mating lamps or sliders; (3) placing a central actuator onto the side actuator and placing a second side actuator onto the rear plate and the central actuator by aligning the lamps or sliders; (4) assembling each of a left assembly and a right assembly by placing a lower end plate onto the side actuator and placing an upper end plate onto the side actuator; (5) placing the front lamp into the lower and upper end plates; (6) inserting a threaded sleeve through the rear plate into the central actuator; (7) placing a friction ring onto a drive nut; (8) threading the drive nut onto the threaded sleeve; (9) press-fitting a retaining sleeve into the rear plate to secure the drive nut; (10) placing the friction ring onto a central drive screw; (11) threading the central drive screw through the front plate into the central actuator; and (12) placing a retaining ring into the front plate to secure the central drive screw.

[0013] According to another embodiment, a spinal fixation system includes an expandable intervertebral implant, a bone fastener, and a spinal rod attachable to the bone fastener. The expandable intervertebral implant includes a central drive assembly, a left assembly, and a right assembly. The central drive assembly includes a front plate, a central drive screw, a central actuator, a threaded sleeve, a rear plate, and a drive nut. Each of the left assembly and the right assembly includes an upper end plate, a lower end plate, a side actuator, and a front lamp. Rotation of the drive nut is configured to expand the width of the implant, and rotation of the drive screw is configured to expand the height of the implant.

[0014] The spinal fixation system may include one or more of the following features. The expandable intervertebral implant may be configured to be installed through a transforaminal lumbar interbody fusion (TLIF) procedure. The bone fastener may include a threaded shaft and a tulip head. The bone fastener may be a multi-axis bone screw. The bone fastener may be a pedicle screw. A plurality of bone fasteners may be configured to be installed within the vertebra adjacent to the expandable intervertebral implant. The system may include a set of screws and rods configured to stabilize the spine.

[0015] According to another embodiment, the spinal fixation system includes an expandable intervertebral implant that includes a central drive assembly, a left assembly, a right assembly, and a posterior stabilization system. The central drive assembly includes a front plate having a central through-bore, a central drive screw having an enlarged head and a threaded shaft positioned through the bore of the front plate, and a central actuator having a tubular body with a through-bore and wings on opposite sides, wherein the threaded shaft of the central drive screw is threaded within one end of the bore of the central actuator; a rear plate having a central through-bore; a threaded sleeve positioned through the bore of the rear plate and threaded to an opposite end of the bore of the central actuator; and a drive nut threaded to the threaded sleeve. The left assembly and the right assembly each include an upper end plate, a lower end plate, a side actuator, and a front ramp.

[0016] The spinal fixation system may include one or more of the following features. The posterior stabilization system may include a plurality of bone fasteners including a threaded shaft and a tulip head. The plurality of bone fasteners may be configured to be inserted into the pedicles of adjacent vertebrae. The posterior stabilization system may include a spinal rod secured to the tulip heads of the bone fasteners to stabilize a portion of the spine. Actuation of the drive nut may be configured to expand the width of the intervertebral implant. Actuation of the central drive screw may be configured to expand the height of the intervertebral implant in situ.

[0017] According to yet another embodiment, a method of fixing the spine includes the following steps: (1) inserting an expandable intervertebral implant between vertebrae adjacent to the intervertebral disc space, the expandable implant comprising a central drive assembly, a left assembly, and a right assembly, the central drive assembly including a front plate, a central drive screw, a central actuator, a threaded sleeve, a rear plate, and a drive nut, and the left and right assemblies each including an upper end plate, a lower end plate, a side actuator, and a front ramp; (2) expanding the width and / or height of the implant; (3) fixing bone screws to the pedicles of adjacent vertebrae; and (4) connecting a spinal rod between the bone screws, which may be included in any suitable order. The method may further include expanding the width of the implant by rotating the drive nut and expanding the height of the implant by rotating the central drive screw. The implant may expand in width and increase its overall footprint size, thereby minimizing the possibility of the implant sinking. The implant may expand in the height direction in situ to adjust the anterior curve. Prior to inserting the expandable intervertebral implant into the intervertebral disc space, access the posterior aspect of the spine and perform a spinal facetectomy. A unilateral spinal facetectomy may be performed to enable visualization and removal of the intervertebral disc. A first set of bone screws may be fixed to the pedicles of the vertebrae, a first spinal rod may be connected between them, a second set of bone screws may be fixed to the opposing pedicles of the vertebrae, and a second spinal rod may be connected between them.

[0018] According to yet another embodiment, the kit may include a plurality of implants of different sizes and configurations. The kit may further include one or more devices suitable for the installation and / or removal of 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 surgery.

Brief Description of the Drawings

[0019] This embodiment will be more fully understood from the detailed description and the accompanying drawings.

Figure 1A

Figure 1B

Figure 1C

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10A

Figure 10B

Figure 10C

Figure 11A

Figure 11B

Figure 12A

Figure 12B

Figure 13A

Figure 13B

Figure 14

[0020] Embodiments of the present disclosure generally aim at devices, systems, and methods for intervertebral fixation and spinal stabilization. In particular, the expandable implant is configured to increase the overall footprint size after insertion into the intervertebral disc space, while also adjusting lordosis and overall height. The expandable implant may include one or more side assemblies configured to expand in width and height. By doing so, the expansion addresses sagittal balance correction and subsidence issues. The intervertebral implant may be combined with a posterior stabilization system, including, for example, pedicle screws and spinal rods, to further stabilize the spine.

[0021] Spinal arthrodesis is typically used to eliminate pain caused by movement of degenerated disc material. When successful, the fixation device is permanently secured within the intervertebral disc space. The expandable fixation device may be positioned between adjacent vertebral bodies in a collapsed position. The expandable fixation device is configured to expand in width and subsequently in height. The fixation device engages the end plates of adjacent vertebral bodies and, in the installed position, maintains the desired intervertebral disc space, restores spinal stability, and thereby facilitates intervertebral fixation.

[0022] Minimally invasive surgery (MIS) can be used to preserve the anatomical structure of muscle by causing disruption only where necessary. The advantages of the MIS surgical approach are that it can reduce postoperative pain and improve the patient's recovery time. In one embodiment, the expandable fixation device can be configured to be disposed within a surgical target site through an endoscopic tube. By way of example, the surgical site may be an intervertebral disc space located between two adjacent vertebrae. It is particularly suitable for use in transforaminal lumbar interbody fusion (TLIF), although the implant can be used in any number of suitable orthopedic approaches and procedures, including, but not limited to, anterior, posterior, lateral, anterolateral, or posterolateral approaches to the lumbar, cervical, or thoracic spine, and any non-spinal applications such as the treatment of fractures. This will be readily appreciated by those skilled in the art.

[0023] The components of all devices disclosed herein can be manufactured 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, the device may include radiopaque and / or radiolucent materials. The components can also be machined and / or manufactured using any suitable technique (e.g., 3D printing).

[0024] Referring now to the drawings, like reference numerals refer to like elements, and FIGS. 1A-1C illustrate an expandable fixation device or implant 10 according to one embodiment. The expandable fixation device 10 is configured to expand in width to increase the overall footprint of the device 10 and expand in height to correct disc height restoration, lordosis, and / or sagittal balance, and may include a left side assembly 12 and a right side assembly 14. The implant 10 may be suitable for transforaminal lumbar interbody fusion (TLIF) via a posterior approach or other suitable surgical technique.

[0025] The expandable fixation device 10 extends along a central longitudinal axis A between a front end and a rear end of the device 10. FIG. 1A shows the expandable fixation device 10 in a fully collapsed configuration in which the left side 12 and the right side 14 are collapsed in both width and height. FIG. 1B shows the expandable fixation device 10 in an expanded configuration in which the width of the left side 12 and the right side 14 is expanded. FIG. 1C shows the expandable fixation device in a fully expanded configuration in which the width and height of the left side 12 and the right side 14 are expanded. It should be understood that references to the front end and the rear end and to the left side 12 and the right side 14 are made with respect to the direction of placement into the disc space in which the front of the expandable fixation device 10 is first placed into the disc space and subsequently the rear of the expandable fixation device 10 is placed. Terms indicating these and other directions may be used herein for purposes of explanation and are not intended to limit the orientation in which the device may be used.

[0026] Focusing on the exploded view of FIG. 2, the implant 10 includes a first half or left portion 12, a second half or right portion 14, and a central drive assembly 16. The left portion assembly 12 and the right portion assembly 14 may each include an upper end plate 20 and a lower end plate 22, a front lamp 24, and a side actuator 26. The central drive assembly 16 includes a central drive screw 30 aligned along a central longitudinal axis A, a front plate 32, a central actuator 34, a rear plate 36, a centrally threaded sleeve 38, and a central drive nut 40. The left portion 12 and the right portion 14 are expanded in width by the central drive nut 40. The upper end plate 20 and the lower end plate 22 are expanded in height by the central drive screw 30.

[0027] Specifically, the left portion 12 and the right portion 14 are controllable by a central drive nut 40 attached to the centrally threaded sleeve 38 and the central actuator 34. The drive nut 40 uses lamps or sliders 70, 102, 132, 154, 156, 170 to pull the threaded sleeve 38 and the central actuator 34 toward the rear plate 36 and press the left portion 12 and the right portion 14 outward. When the widths of the left portion 12 and the right portion 14 are fully expanded, the front plate 32 becomes controllable by the central drive screw 30. The central drive screw 30 pulls the front plate 20 toward the central actuator 34 while also pulling the front lamp 24 toward the side actuator 26. The side assemblies 12, 14 each have an upper end plate 20 and a lower end plate 22, a front lamp 24, and a side actuator 26. The front lamp 24 is actuated while the drive screw 30 is rotated. This pulls the front lamp 24 toward the side actuator 26, and then the upper end plate 20 and the bottom end plate 22 expand vertically as lamps 142, 160, 168 engage the front lamp 24 and the side actuator 26.

[0028] As best seen in FIG. 3, the central drive screw 30 extends from a proximal end 44 to a distal end 46. The distal end 46 can be seen to have an enlarged head portion 48 configured to be received within a bore 62 defined through the front plate 32. The enlarged head 48 can include a wide cylindrical head having a smooth outer surface at the distal end of the central drive screw 30. The proximal end 44 of the drive screw 30 can define an instrument recess 50 configured to receive an instrument, such as a driver, for rotating or actuating the drive screw 30. The instrument recess 50 can include a three-lobed, hexagonal, star-shaped, or other suitable recess configured to engage a driver instrument to apply torque to the drive screw 30. The drive screw 30 can include a shaft having an externally threaded portion 52 extending along its length. The external thread 52 can extend from the proximal end 44 to a position near the bottom of the enlarged head 48. The drive screw 30 is receivable through the bore 62 of the front plate 32 such that the enlarged head portion 48 of the drive screw 30 is receivable within the front plate 32. A selective friction ring 56, such as a polyetheretherketone (PEEK) ring, can be assembled onto the drive screw 30, for example, below the enlarged head 48, to increase friction or drag on the drive screw 30 during rotation.

[0029] The central drive screw 30 can be inserted into the front plate 32 and held within the front plate 32 using a retaining ring 58. The drive screw 30, when actuated, controls the height expansion of the implant 10. The retaining ring 58 includes a split ring having a plurality of internal and / or external teeth 60 or various reliefs, whereby the retaining ring 58 can be compressed to enter the bore 62 of the front plate 32 and engage an internal groove. The retaining ring 60 can include, for example, two slots configured to engage an instrument to assist in the insertion and removal of the retaining ring 58. When the retaining ring 58 is positioned around the drive screw 30 and within the bore 62 of the front plate 32, the teeth 58 are configured to engage the central drive screw 30, thereby locking the screw 30 in a predetermined position within the plate 32.

[0030] The front plate 32 defines a central hole 62 therethrough configured to receive the drive screw 30. The axis of the bore 62 is aligned along the central longitudinal axis A. The front plate 32 includes an upper or top surface 64 and an opposite lower or bottom surface 66 connected by side surfaces 68. The top surface 64 and the bottom surface 66 may include one or more sliders or ramps 70 configured to mate with corresponding ramps 170 on the front lamps 24 of the left and right portions 12 and 14. The slider or ramp 70 may include a horizontal ramp defining a female channel or groove configured to receive the mating male counterpart 170 of the front lamp 24. However, it will be appreciated that the female / male configuration may be reversed or may include other suitable ramp interactions, sliding features, or mating components to provide lateral expansion of the left portion 12 and the riding portion 14.

[0031] In one embodiment, the front plate 32 may include a first pair of horizontal ramps 70 defined in the upper portion 64 of the front plate 32 and a second pair of horizontal ramps 70 defined in the bottom portion 66 of the front plate 32. Each of the ramps 70 may be aligned along a separate horizontal plane. In this way, each ramp 70 has a constant depth along its length such that one of the female horizontal ramps has a greater depth than the other female horizontal ramp. For example, the first ramp 70 defined along the upper portion 64 of the front plate 32 may be positioned along one given horizontal plane that is lower or higher than the other ramp 70 defined along the upper portion 64 of the front plate 32. The horizontal ramps 70 may be angled or inclined such that one end of each ramp 70 begins at the side surface 68 of the front plate 32 and extends centrally in a direction toward the central actuator 34 as the ramps 70 progress toward each other. Although the horizontal ramps are described as providing horizontal or lateral expansion of the left and right assemblies 12 and 14, it will be appreciated that the horizontal ramps 70 may be graded, inclined, or otherwise configured off-axis to provide different trajectories or expansion types.

[0032] As best seen in FIG. 4, the drive nut 40 can be inserted into the rear plate 36 and held using a retaining sleeve 74. The drive nut 40 controls the width expansion of the implant 10 when actuated. The drive nut 40 can have a generally cylindrical body extending from a proximal end 76 to a distal end 78. The proximal face 76 can define one or more depressions or notches to form an instrument recess 80 configured to mate with an instrument, such as a driver, to rotate or actuate the drive nut 40. The instrument recess 80 can define a slotted, splined, three-lobed, hexagonal, star-shaped, other suitable recess, or a portion thereof, configured to engage a driver instrument to apply torque to the drive nut 40. Since the instrument recess 80 of the drive nut 40 can be of a different type than the instrument recess 50 of the drive screw 30, the user can easily understand which component is being actuated. In this way, the instrument recess 80 is configured to engage a driver instrument to apply torque to the drive nut 40, thereby driving the width expansion of the left assembly 12 and the right assembly 14.

[0033] The drive nut 40 defines a central through bore 82 so that another instrument can access the distal drive screw 30. The axis of the through bore 82 can be aligned along the central longitudinal axis A. The drive nut 40 is receivable within the bore 88 of the rear plate 36 such that the body of the drive nut 40 is receivable within the rear plate 36. A selective friction ring 84, such as a polyetheretherketone (PEEK) ring, can be assembled onto the drive nut 40, for example near the distal end 78, to increase friction or drag on the drive nut 40 during rotation. The retaining sleeve 74 is press-fitted into the rear plate 36, thereby securing the drive nut 40 to the rear plate 36. The retaining sleeve 74 can include a ring or band sized and dimensioned to fit around the drive nut 40 and within a projection 96 of the rear plate 36.

[0034] The rear plate 36 is configured to receive the drive nut 40 and the threaded sleeve 38 and defines a central bore 88 therethrough. The axis of the bore 88 is aligned along the central longitudinal axis A. The rear plate 36 includes an upper or top surface 90 and an opposite lower or bottom surface 92 connected by side surfaces 94. The protrusion 96 may define a substantially cylindrical ring having an externally threaded portion 98 that extends proximally and is configured to engage, for example, an implant insertion instrument. The threaded connection to the rear plate 36 provides a rigid connection to the insertion instrument. The top surface 90 and the bottom surface 92 may include one or more sliders or ramps 102 configured to mate with corresponding ramps 154 on the side actuators 26 of the left portion 12 and the right portion 14.

[0035] The rear plate 36 includes one or more sliders or ramps 102 configured to mate with corresponding ramps 154 on the actuators 26 of the left portion 12 and the right portion 14. For example, near the distal end of the rear plate 36, the rear plate 36 may include a pair of ramps 102 defined on each of the top surface 90 and the bottom surface 92 of the rear plate 36. Similar to the ramp 70, the ramp 102 may be a horizontal ramp aligned along one or more horizontal planes. For example, one of the pair of ramps 102 may be positioned lower or higher relative to the other ramp 102 along another given horizontal plane, below one given horizontal plane. In other words, each ramp 102 has a constant depth along its length such that one ramp 102 has a greater depth than the other ramp 102. The horizontal ramp 102 may be angled, diagonal, or inclined such that one end of the ramp 102 begins at the side surface 94 of the rear plate 36 and extends toward the center of the rear plate 36 as the ramps 102 progress toward each other. The horizontal ramp 102 may define a female channel or groove configured to receive the mating male counterpart 154 of the actuator 26. However, it will be appreciated that the female / male configuration may be reversed or may include other suitable ramp interactions, sliding features, or mating components to provide lateral expansion of the left portion 12 and the right portion 14.

[0036] The rear plate 36 may include one or more instrument recesses or slots 104, 106 configured to be engaged by an instrument such as an insertion instrument or to allow access to the implant 10. For example, each side surface 94 of the rear plate 36 may include a side recess or instrument slot 104 configured to receive a graft delivery device. For example, the side surfaces 94 on opposite sides of the rear plate 36 may include circular recesses 104 on two semi-opposite sides configured such that when the width and / or height is fully expanded, the graft delivery device can enter the central portion of the implant 10. To further promote and facilitate intervertebral fixation, a bone graft or similar bone growth-inducing material can be introduced inside and / or around the fixation device 10. Additionally, one or more recesses 106 may be positioned around the proximal surface of the rear plate 36. These circular recesses 106 may be aligned at the four corners of the plate 36. The four recesses 106 may assist in aligning an instrument such as an insertion instrument.

[0037] The drive nut 40 is screwed into the threaded sleeve 38. The threaded sleeve 38 is positioned through the bore 88 of the rear plate 36 and is screwed into the drive nut 40. The threaded sleeve 38 is a cylindrical sleeve or shaft sleeve that defines a central through-bore 114 between the proximal end 110 and the distal end 112 of the sleeve 38. The axis of the central bore 114 is aligned with the central longitudinal axis A. The outer surface of the sleeve 38 includes outer threaded sections 116, 118. The first proximal outer threaded section 116 is configured to mate with the internal threads of the bore 82 of the drive nut 40. The second distal outer threaded section 118 is configured to mate with the internal threads of the bore 124 of the central actuator 34. The threaded section 116 can include a helically wound thread form having any suitable lead, pitch, hand, angle, diameter, etc. The separate threaded sections 116, 118 can have the same or different thread types. The threaded sections 116, 118 can be separated by a threadless or smooth section 120. The proximal threaded section 116 can be longer than the distal threaded section 118 such that the threadless section 120 is positioned closer to the distal end 112 of the sleeve 38. For example, the length of the proximal threaded section 116 can be two times, three times, four times, or more than the length of the distal threaded section 118.

[0038] Referring now to FIG. 5, the fully assembled central drive assembly 16 is shown. The threaded sleeve 38 is attached to the central actuator 34. The central actuator 34 includes a tubular body having an inner bore 124 that extends from a proximal end 126 to a distal end 128. The inner bore 124 of the central actuator 34 is female threaded to enable threading engagement with the distal threaded section 118 of the threaded sleeve 38 and the threaded shaft 52 of the drive screw 30. The central actuator 34 includes a pair of opposed wings 130 that extend from the outer surface of the tubular body. Each wing 130 may terminate at a distal free end. The wings 130 may be angled such that the distal free ends of the wings 130 face toward the front plate 32. Each wing 130 may define one or more sliders or ramps 132 configured to mate with a corresponding surface of the side actuator 26. The ramps 132 may be angled, diagonal, chamfered, or inclined such that one end of the ramp 132 begins at the body of the central actuator 34 and extends to the free end of each respective wing 130. The ramps 132 may define a female channel or groove configured to receive a mating male counterpart 156 of the side actuator 26. The female ramps 132 may extend open-endedly along the proximal face of each wing 130. It will be appreciated that the female / male configuration and position may be reversed or otherwise modified to include other suitable ramp interactions, sliding features, or mating components to assist in providing the lateral expansion of the left side portion 12 and the right side portion 14.

[0039] When the central drive assembly 16 is assembled, the proximal end 110 of the threaded sleeve 38 is positioned through the bore 88 of the rear plate 36. The drive nut 40 is threaded onto the proximal threaded section 116 of the threaded sleeve 38. The distal threaded section 118 of the threaded sleeve 38 is threaded into the central actuator 34. When fully assembled, actuation of the drive nut 40 is configured to push and pull the threaded sleeve 38 and the central actuator 34 relative to the rear plate 36 to expand the implant 10 width. The drive screw 30 is positioned through the bore 62 of the front plate 32. The threaded shaft 52 of the drive screw 30 is threaded into the distal end 128 of the central actuator 34 attached to the threaded sleeve 38. When fully assembled, actuation of the drive screw 30 is configured to push and pull the front plate 32 and the front lamp 24 relative to the central actuator 34 and the side actuators 26 to expand the height of the implant 10.

[0040] Referring now to FIGS. 6 and 7, the left assembly 12 and the right assembly 14 are each assembled by disposing an upper end plate 20 and a lower end plate 22 over the side actuators 26 and the front lamp 24. The left sub-assembly 12 and the right sub-assembly 14 may each include upper and lower end plates 20 and 22 configured to expand away from each other to increase the vertical height of the expandable fixation device 10. The upper end plate 20 and the lower end plate 22 may be the same as each other or mirror images. Although the assembly 12 and the upper end plate 20 are described, the discussion herein applies equally to the assembly 14 and the lower end plate 22. The upper end plate 20 includes an upper or outer facing surface 136 configured to conform to the vertebral end plates of adjacent vertebral bodies when implanted within the intervertebral disc space. The outer surface 136 may include a plurality of teeth, ridges, roughened surfaces, keels, gripping or holding protrusions, or other friction-increasing elements configured to retain the device 10 within the intervertebral disc space. For example, the end plates 20, 22 may be 3D printed using a laminate formation to provide a natural roughened surface to promote bone growth, or machined and blasted to obtain a roughened surface.

[0041] The upper end plate 20 includes a lower or inner opposing surface 138 and one or more side walls 140 that define one or more sliders or lamps 142 configured to respectively mate with the actuator 26 and corresponding lamps 160, 168 on the front lamp 24. For example, the upper end plate 20 may define a pair of side walls 140 that form a gap or channel 144 therebetween. The channel 144 may generally be U-shaped, J-shaped, C-shaped, or another suitable configuration. At least three pairs of lamps 142 may be defined within the channel 144 of the end plate 20. The lamps 142 may be vertical lamps aligned along one or more vertical planes. In one embodiment, all three vertical lamps 142 may be aligned along the same plane. The vertical lamps 142 are vertically oriented, but may be angled, diagonal, or inclined to increase the vertical height of the end plates 20, 22.

[0042] In one embodiment, two pairs of vertical lamps 142 that mate with the side actuator 26 may be angled in one direction, and a third pair of vertical lamps 142 that mate with the front lamp 24 may be angled in the opposite direction. For example, the outermost vertical lamp 142 near the front lamp 24 may be inclined to face the front lamp 24 as it extends from the inner surface 138 towards the outer surface 136 along the side wall 140. Similarly, the innermost vertical lamp 142 near the side actuator 26, and the centrally located vertical lamp 142, may be inclined to face the side actuator 26 as they extend from the inner surface 138 towards the outer surface 136 along the side wall 140. The innermost vertical lamp 142 and the central vertical lamp 142 may be aligned parallel with the same inclination, or may have different inclinations.

[0043] The vertical ramp 142 may define female channels or grooves configured to receive the mating male counterparts 160, 168 of the side actuator 26 and the front ramp 24, respectively. It will be appreciated that the female / male configuration may be reversed or may include other suitable ramp interactions, sliding features, or mating components to provide vertical extensions of the left side portion 12 and the riding portion 14. The vertical ramp is described as providing vertical extensions of the left side assembly 12 and the right side assembly 14, but it will be appreciated that the vertical ramp 142 may be graded, tilted, or otherwise configured off-axis to provide different trajectories or types of extensions.

[0044] One or more openings 146 may extend vertically through the bodies of the end plates 20, 22. As shown in FIG. 1A, in the contracted position, the inclined portion 160 of the side actuator 26 may be received through the opening 146. Similarly, as shown in FIG. 1B, when the width is expanded, the ramp 160 of the side actuator 26 can be received through the opening 146 of the end plates 20, 22. As shown in FIG. 1C, in the vertical expansion position, the opening 146 is open and may be free to receive a bone graft or other suitable bone-forming material. One or more openings or slots 148 may extend horizontally through the side walls 140 of the end plates 20, 22. The slot 148 may be provided between the most distal and central vertical ramps 142 and near the inner surfaces 138 of the end plates 20, 22. As shown in FIG. 1A, in the contracted position, the slots 148 from the upper end plate 20 and the lower end plate 22 may be aligned such that the wings 130 of the central actuator 34 can be positioned through the opening 148. As shown in FIG. 1B, when the width expands, the side assemblies 12, 14 expand outwardly and away from each other, and the opening 148 or a portion thereof becomes empty.

[0045] Referring now to FIG. 8, the left and right partial assemblies 12 and 14 may each include first and second actuators 26 positioned between upper and lower end plates 20 and 22 of the left and right portions 12 and 14, respectively. The actuator 26 may include a body extending along a central axis A1 from a proximal end 150 to a distal end 152. The central axis A1 may be substantially parallel to the central longitudinal axis A. The proximal end 150 may define one or more horizontal sliders or ramps 154 configured to engage the horizontal ramp 102 of the rear plate 36. The side actuators 26 may define a pair of upper and lower horizontal ramps 154 facing inwardly towards each other. The horizontal ramp 154 may have a diagonal or inclined surface angled in a complementary manner to the ramp 102 of the rear plate 36. Specifically, the horizontal ramp 154 may define a male protrusion configured to enter the female counterpart 102 of the rear plate 36. The ramp 154 may define a limiter 176 for stopping the movement of the mating sliders or ramps 102, 154. For example, the limiter 176 may include a wide ramp surface, a protrusion or projection, a bevel or a dovetail configured to reduce or limit the relative movement between the ramps 102, 154, etc.

[0046] The distal end 152 of the side actuator 26 may include a ramp 156 configured to engage a corresponding ramp 132 on the wing 130 of the central actuator 34. The side actuator 26 may define upper and lower grooves 158 for forming a single distal-facing male ramp 156. The male ramp 156 may have a diagonal or inclined surface angled in a complementary manner to the female ramp 132 on the wing 130 of the central actuator 34. This slidable interface 132, 156 may be configured to assist in guiding the outward expansion of the widths of the first and second side assemblies 12 and 14.

[0047] The actuator 26 includes a plurality of ramps 160 configured to engage the end plates 20, 22. The actuator 26 may define a plurality of vertical ramps 160 configured to engage the vertical ramps 142 of the end plates 20, 22. The actuator 26 may define a first set of vertical ramps 160 that slope upwardly toward the proximal end 150 or downwardly toward the distal end 152, and a second set of vertical ramps 160 that slope upwardly toward the distal end 152 or downwardly toward the proximal end 150 of the actuator 26. Each set of ramps 160 may define a pair of male protrusions configured to enter the female counterparts 142 of the end plates 20, 22. The vertical ramps 160 may have diagonal or inclined surfaces angled in a complementary manner to the corresponding ramps 142 of the end plates 20, 22.

[0048] As shown in FIG. 9, the left portion 12 and the right portion 14 may each include a front ramp 24 configured to extend the distal or front ends of the upper end plate 20 and the lower end plate 22. The front ramp 24 may include a body extending from a proximal end 164 to a distal end 166. The proximal end 164 may define one or more vertical ramps 168 configured to engage the vertical ramps 142 of the end plates 20, 22. The front ramp 24 may define a first vertical ramp 168 that slopes downwardly toward the proximal end 164 and a second vertical ramp 168 that slopes upwardly toward the proximal end 164 of the front ramp 24. Each of the ramps 168 may define a pair of opposed male protrusions configured to enter the female counterparts 142 of the channels 144 of the end plates 20, 22. The vertical male ramps 168 may have diagonal or inclined surfaces angled in a complementary manner to the female ramps 142 of the end plates 20, 22.

[0049] The distal end 166 of the front lamp 24 may define one or more horizontal lamps 170 configured to engage with the horizontal lamp 70 of the front plate 32. The front lamp 32 may define a pair of upper and lower horizontal lamps 170 separated by a gap and facing inwardly towards each other. The horizontal lamp 170 may have a diagonal or inclined surface angled in a complementary manner to the lamp 70 of the front plate 32. Specifically, the horizontal lamp 170 may define a male protrusion configured to enter the female counterpart 70 of the front plate 32. Similar to the lamp 154, the lamp 170 may define a fitting slider or a limiter 176 for stopping the movement of the lamps 70, 170. For example, the limiter 176 may include a wide lamp surface, a protrusion or a projection, a bevel or a double tail, etc. configured to reduce or limit the relative movement between the lamps 70, 170.

[0050] Figures 10A-10C each show a side actuator 26 slidably engaged with a rear plate 36 in a retracted position and an extended position. The side actuator 26 slides on the rear plate 36 by aligning keying features that control the expansion. In Figure 10A, the actuator 26 engages the rear plate 36 and retracts over each other. The concave surface 162 at the top of the actuator 26 sized and dimensioned to receive the other actuator 26 allows the actuators 26 to be nested together, thereby providing a small footprint for insertion. It will be appreciated that corresponding concave surfaces 162 may be provided at the bottom of the opposite actuator 26 to provide a complementary fit. As best seen in Figure 10C, one horizontal ramp 102 is positioned deeper than the other horizontal ramp 102 to further facilitate this nested configuration of adjacent side actuators 26. The horizontal male ramp 154 of the side actuator 26 slidably mates with the horizontal female ramp 102 of the rear plate 36, thereby allowing lateral or horizontal movement of the left assembly 12 and the right assembly 14. The side actuator 26 may have features such as a limiter 176 that engages a mating rear plate 36 to limit the amount of translation while expanding in width. When the width is expanded laterally, the side actuator 26 slides outwardly and away from each other, thereby increasing the width of the implant 10. Figure 10B shows the side actuator 26 fully expanded in width relative to the rear plate 32.

[0051] The front lamp 24 and the front plate 32 utilize a sliding interface surface similar to that of the actuator side portion 26 and the rear plate 36. FIGS. 11A-11B show the front lamp 24 slidably engaged with the front plate 32 in the retracted position and the extended position, respectively. The front lamp 24 slides onto the front plate 32 by aligning keying features that control the expansion. In FIG. 11A, the front lamp 24 is engaged with the front plate 32 and is retracted over one another. The concave surface 172 at the top of one front lamp 24 sized and dimensioned to receive the other front lamp 24 allows the front lamps 24 to be nested together, thereby providing a small footprint for insertion. It will be appreciated that corresponding concave surfaces 172 may be provided at the bottom of the opposite front lamp 24 to provide a complementary fit. Similar to the rear plate 36, one horizontal lamp 70 may be positioned at a greater depth than the other horizontal lamp 70 to further facilitate this nested configuration of the front lamps 24. The horizontal lamp 170 of the front lamp 24 slidably mates with the horizontal lamp 70 of the front plate 32. The front lamp 24 may also have features such as a limiter 176 that engages the mating front plate 32 to limit the amount of translation while expanding in width. In FIG. 11B, the front lamp 24 has its width fully expanded. As the width is expanded, the front lamp 24 slides outwardly and away from one another, thereby increasing the overall width of the implant 10.

[0052] Figures 12A - 12B respectively show a rear view and a perspective view of the assembled implant 10 when the width is fully expanded. The user can access the central drive assembly 16 through the bore 88 of the rear plate 36. Specifically, the drive nut 40 and the drive screw 30 can be rotated independently or rotated to operate the implant 10. When the drive nut 40 is operated, the threaded sleeve 38 is drawn proximally, and the widths of the left side portion 12 and the right side portion 14 are expanded. When the width is expanded, the rear plate 36 defining the recess 104 aligns with the corresponding recess 174 on the side actuator 28, enabling access to the central portion of the implant 10. In this way, an implant delivery device can be used to enter the central open area inside the implant 10 and deliver graft material therein. When the drive screw 30 is operated, the heights of the left side portion 12 and the ride portion 14 are expanded.

[0053] Figures 13A - 13B show implant 10 having left assembly 12 (for clarity, a set of end plates 20, 22, side actuator 26, and front lamp 24 are hidden). Implant 10 can be fully contracted so as to be inserted into the intervertebral disc cavity, for example, through a posterior approach. Implant 10 can be attached to, for example, a multi-component instrument. A first width driving instrument can be used to engage recess 80 of drive nut 40 with a compatible driving feature. When drive nut 40 is rotated, the drive nut pulls proximally or translates the threaded sleeve 38, central actuator 34, and front plate 32. Then, drive nut 40 translates the side actuator 26 and front lamp 24 outwardly to expand the width. When central actuator 34 and rear plate 36 contact each other, drive nut 40 can no longer rotate. As shown in Figure 13A, full width expansion is achieved. A second height driving instrument can be used to engage recess 52 of drive screw 30 with a compatible driving feature. When drive screw 30 is rotated, drive screw 30 pulls proximally or translates the front plate 32 and front lamp 24. Then, front lamp 24 translates proximally towards side actuator 26 to translate end plates 20, 22 upwardly and downwardly from the axial plane. When front plate 32 and central actuator 34 contact each other, drive screw 30 can no longer rotate. As shown in Figure 13B, implant 10 has its width and height fully expanded. The amount of height expansion of left assembly 12 and right assembly 14 can be the same or different. In this way, implant 10 has its width expanded so that the footprint increases to assist in overall stability, and implant 10 has its anterior curvature and height adjusted to fit the patient accurately.

[0054] The implant 10 can have width expansion on both sides or one side. In one embodiment, the expandable fixation device or implant 10 can be configured such that only the width of one of the assemblies 12, 14 expands and the other remains stationary. Both the left portion 12 and the right portion 14 can expand in height. In this embodiment, the front and rear plates 32, 36 can each include only a single horizontal ramp on each of the upper and lower surfaces for engaging a single side actuator 26 and a front ramp 24, respectively. A single side that does not expand laterally outward can incorporate a front ramp feature into the front distal plate 32 and an actuator feature into the rear proximal plate 36.

[0055] The implant 10 can be assembled as follows. Place the two front ramps 24 on the front plate 32 by aligning the sliders or ramps 70, 170. Place one side actuator 26 on the rear plate 36 by aligning the sliders or ramps 102, 154. Place the central actuator 34 on the side actuator 26. Place the other side actuator 26 on the rear plate 36 and the central actuator 34 by aligning the sliders or ramps 132, 156. The left 12 and right 14 sides can each be assembled by placing the lower end plate 22 on the side actuator 26 and the upper end plate 20 on the side actuator 26. Place the front ramp 24 into both the lower end plate 20 and the upper end plate 22. Pass the threaded sleeve 38 through the rear plate 36 and insert it into the central actuator 34 and secure it. The friction ring 84 can be placed on the drive nut 40. Then, thread the drive nut 40 onto the threaded sleeve 38 until it bottoms out. Press-fit the retaining sleeve 74 into the rear plate 36, thereby fixing the drive nut 40. The friction ring 56 can be placed on the drive screw 30. Insert the drive screw 30 through the front plate 32 and thread it into the central actuator 34. The retaining ring 58 can be placed on the front plate 32, thereby fixing the drive screw 30.

[0056] Referring now to FIG. 14, a system 210 for intervertebral fixation according to one embodiment is shown. The system 210 may include an expandable implant 10, a plurality of bone fasteners 212, and a spinal rod 214 connecting the bone fasteners 212. The expandable fixation device 10 may be surgically implanted into the intervertebral disc space 202 between the upper vertebra 204 and the lower vertebra 206. The posterior aspect of the spine may be accessed, for example, through minimally invasive surgical techniques. In one embodiment, the implant 10 may be implanted using a transforaminal lumbar interbody fusion (TLIF) technique in which the facet joint may be removed to access the intervertebral disc space 202. The intervertebral disc or a portion thereof may be removed. The TLIF technique may include a unilateral facetectomy to allow visualization and removal of the intervertebral disc. The implant 10 may be positioned between the vertebrae 204, 206 to fix the spinal segment.

[0057] One or more levels of the intervertebral disc may be further stabilized by inserting bone fasteners 212, such as pedicle screws, into the upper and lower vertebrae 204, 206 of the implant 10 and connecting the spinal rod 214 to the fasteners 212. The bone fasteners 212 may include bone screws, anchors, clamps, etc. configured to engage bone. In the embodiment shown, the bone fastener 212 is a bone screw extending from a proximal end to a distal tip 216. The proximal end may include an enlarged head, such as a multi-axis bone screw, that is receivable within the modular tulip element 218. The tulip head 218 is configured to secure the spinal rod 214. Examples of bone fasteners and other implant and rod constructs are described in more detail, for example, in U.S. Patent No. 10,368,917, which is hereby incorporated by reference in its entirety for all purposes. The pedicle screws 212 may be used with spinal fusion to add further support and strength to the fusion while allowing recovery. The pedicle screws 212 may be placed above and below the vertebrae 204, 206 to be fixed. Although only a single rod 214 is shown, bilateral constructs may be used with a pair of rods 214 fixed laterally along each side of the spine.

[0058] Although 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 without departing from the spirit and scope of the invention. Accordingly, the present invention is intended to cover the modifications and variations of the present invention provided that they are within the scope of the appended claims and their equivalents. For example, it is expressly intended that all components of the various devices disclosed above can be combined or modified in any suitable configuration.

Claims

**Claim 1** An expandable intervertebral implant, a central drive assembly including a central drive screw positioned through a front plate, a central actuator threaded onto the central drive screw, and a threaded sleeve coupled to the central actuator, the threaded sleeve being positioned through a rear plate and threaded to a drive nut, and left and right assemblies each including an upper end plate, a lower end plate, a side actuator, and a front ramp, the side actuator and the front ramp being slidably engaged with the upper end plate and the lower end plate, wherein rotation of the drive nut expands the width of the expandable intervertebral implant and rotation of the central drive screw expands the height of the expandable intervertebral implant. **Claim 2** The expandable intervertebral implant of claim 1, wherein the drive nut pulls the threaded sleeve and the central actuator toward the rear plate and pushes the width of the left and right portions of the expandable intervertebral implant outward. **Claim 3** The expandable intervertebral implant of claim 1, wherein the central drive screw pulls the front ramp toward the central actuator, and the pulling expands the height of the upper end plate and the lower end plate. **Claim 4** The expandable intervertebral implant of claim 1, wherein the central actuator includes a tubular body having an inner bore and a pair of opposed wings configured to mate with the side actuator. **Claim 5** The expandable intervertebral implant of claim 1, wherein the rear plate includes a pair of female horizontal ramps defined on an upper surface and a bottom surface of the rear plate, and the side actuator includes a pair of male horizontal ramps configured to mate with the female horizontal ramps of the rear plate. **Claim 6** The expandable intervertebral implant of claim 1, wherein the front plate includes a pair of female horizontal ramps defined on an upper surface and a bottom surface of the front plate, and the front ramp includes a pair of male horizontal ramps configured to mate with the female horizontal ramps of the front plate. **Claim 7** An expandable intervertebral implant, A front plate having a central through-bore, A central drive screw having an enlarged head and a threaded shaft positioned through the central through-bore of the front plate, A central actuator having a tubular body with a through-bore and a pair of opposed wings, wherein the threaded shaft of the central drive screw is threaded within one end of the tubular body through the through-bore of the central actuator, A rear plate having a central through-bore, A threaded sleeve positioned through the central through-bore of the rear plate and threaded to an opposite end of the tubular body through the through-bore of the central actuator, A drive nut threaded to the threaded sleeve, A left assembly and a right assembly each including an upper end plate, a lower end plate, a side actuator, and a front lamp, wherein the side actuator and the front lamp are slidably engaged with the upper end plate and the lower end plate, the side actuator is slidably engaged with the rear plate and the central actuator, and the front lamp is slidably engaged with the front plate, an expandable intervertebral implant.

8. The left assembly and the right assembly have a laterally contracted configuration having a first width and a laterally expanded configuration having a second width, and the left assembly and the right assembly have a vertically contracted configuration having a first height and a vertically expanded configuration having a second height, the expandable intervertebral implant according to claim 7.

9. The pair of opposed wings each define a female lamp configured to receive a corresponding male lamp from the side actuator, the expandable intervertebral implant according to claim 7.

10. The pair of opposed wings are angled distally toward the front plate, the expandable intervertebral implant according to claim 7.

11. The rear plate includes a proximally projecting cylindrical ring, the cylindrical ring defining a threaded outer surface, the expandable intervertebral implant according to claim 7.

12. The threaded sleeve includes a first proximal outer threaded section configured to mate with an inner thread of a bore of the drive nut, and a second distal outer threaded section configured to mate with an inner thread of the tubular body through the through bore of the central actuator. The expandable intervertebral implant according to claim 7.

13. The expandable intervertebral implant according to claim 7, wherein the central drive screw is held within the front plate by a retaining ring.

14. The expandable intervertebral implant according to claim 7, wherein the drive nut is held within the rear plate by a retaining sleeve.

15. An expandable intervertebral implant, A central drive assembly including a front plate aligned along a longitudinal central axis, a central drive screw, a central actuator, a threaded sleeve, a rear plate, and a drive nut. The central drive screw is held within the front plate, the central actuator is threaded with the central drive screw and the threaded sleeve, the threaded sleeve is held by the rear plate and is threaded with the drive nut. A central drive assembly. A side assembly including an upper end plate and a lower end plate, a side actuator, and a front ramp. The side actuator and the front ramp are slidably engaged with the upper end plate and the lower end plate. The side actuator is slidably engaged with the rear plate and the central actuator. The front ramp is slidably engaged with the front plate. And a side assembly. An expandable intervertebral implant that, when actuated, controls the expansion of the width of the expandable intervertebral implant, and the central drive screw controls the expansion of the height of the expandable intervertebral implant.

16. The expandable intervertebral implant according to claim 15, wherein the central drive screw extends from a proximal end to a distal end, the distal end includes an enlarged head portion, and the proximal end defines an instrument recess.

17. The expandable intervertebral implant according to claim 16, wherein the drive nut defines a central through bore, and a proximal surface of the drive nut defines an instrument recess different from the instrument recess of the central drive screw.

18. The expandable intervertebral implant according to claim 15, wherein the central drive screw is positioned at a distal end of the expandable intervertebral implant, and the drive nut is positioned at a proximal end of the expandable intervertebral implant.

19. The expandable intervertebral implant according to claim 15, wherein when actuated, the drive nut pulls the threaded sleeve and the central actuator proximally, thereby causing an expansion in width.

20. The expandable intervertebral implant according to claim 15, wherein when actuated, the central drive screw pulls the front plate towards the central actuator and the front ramp towards the side actuator, thereby causing an expansion in height.

Images