Adjustable lordotic expandable implants and devices

Abstract

To facilitate the fixation process, we provide expandable fixation devices, instruments, and related systems and methods that can be inserted between adjacent vertebrae. [Solution] Expandable fixation device, system, instrument, and method thereof. The expandable fixation implant may include an upper end plate and a lower end plate configured to engage with an adjacent vertebra, and an actuator assembly for expanding the upper end plate and the lower end plate. The insertion and expansion instrument includes an external drive unit and an internal drive unit, which enable the surgeon to independently control parallel and lordotic expansion of the implant.

Description

Technical Field

[0001] The present disclosure generally relates to devices and methods for promoting intervertebral fixation, and more particularly to expandable fixation devices, instruments, and related systems and methods that can be inserted between adjacent vertebrae to facilitate the fixation process.

Background Art

[0002] A common procedure for addressing pain associated with intervertebral discs degenerated due to 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 the 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 including cages or other implant mechanisms that can be packed with bone and / or bone growth-inducing substances, and expandable implants. The expandable implant can be inserted into the intervertebral disc space at a minimum height and then expanded to restore the height loss within the intervertebral disc space.

[0004] However, existing expandable implants have drawbacks including excessive insertion, visual obstruction, and incomplete matching with the patient's lordosis due to discrete increments in the lordosis angle. Thus, there is a need for a fixation device that can provide elongation and achieve optimal height restoration and lordosis angle change independent of its expansion.

Summary of the Invention

[0005] To meet this and other needs, implants, systems, instruments, and methods for performing intervertebral fixation and spinal stabilization are provided. Specifically, for example, expandable intervertebral implants for anterior spinal surgery can be used to treat a variety of patient conditions. Expandable implants are inserted into the intervertebral disc space at a minimum height and are then expanded axially to restore height loss in the intervertebral disc space, achieve normal spinal alignment, and / or distribute the load across the vertebral end plates. The implant can provide extension and achieve optimal height restoration. The implant can also be varied in lordosis angle, independently of its expansion.

[0006] According to one embodiment, an expandable implant includes an upper end plate and a lower end plate configured to engage with an adjacent vertebra, and an actuator assembly for expanding the upper end plate and the lower end plate to independently control the anterior and posterior heights of the implant. The actuator assembly includes a movable forward actuator, a movable rear actuator, a stationary rear actuator positioned between the upper and lower end plates, and actuator screws that screw into a forward actuator nut located within the movable forward actuator and a rear actuator nut located within the stationary rear actuator. The actuator screws screw through the movable rear actuator, translating the rear actuator. The upper and lower end plates work in conjunction with the movable forward actuator, the movable rear actuator, and the stationary rear actuator in a complementary mating ramp that slidably engages with each other to allow expansion of the upper and lower end plates. The mating ramp includes a single-point contact ramp and a full-contact ramp. When the actuator screw and the front actuator nut are turned together, the movable rear actuator moves toward the stationary rear actuator, forcing the upper and lower end plates apart and resulting in parallel expansion. When only the front actuator nut is turned, the movable front actuator moves independently to increase the forward height, resulting in an increase in the forward curvature angle.

[0007] An expandable implant may include one or more of the following features: A single-point contact ramp may include a single contact point or contact edge along one ramp surface that contacts a corresponding ramp surface. A full-contact ramp may include constant continuous contact between ramp surfaces, thereby bearing most of the lifting force during expansion. A single-point contact ramp may be located near the side of the implant, and a full-contact ramp may be located between single-point contact ramps near the midline of the implant. The forward actuator may define a pair of pinholes configured to receive a limiting pin that holds a forward actuator nut within the forward actuator. The pinholes may define threadless vertical slots substantially perpendicular to the longitudinal axis of the implant. The limiting pin may include a solid body having an L-shaped notched end and an enlarged base at the opposite end. The limiting pin may restrict the movement of the forward actuator assembly by contacting the surfaces of the upper and lower end plates when the implant is at its maximum expansion or lordosis.

[0008] According to another embodiment, the insertion and expansion device may include an insertion subassembly, an outer drive subassembly, an expansion subassembly, and a torque limiting handle. The insertion subassembly is configured to be mounted directly to the implant. The insertion subassembly has an outer tube having a threaded rod and a non-threaded rod on opposing sides, and an insertion collar for receiving the outer tube, the threaded rod, and the non-threaded rod. The outer drive subassembly has an outer drive that is positionable through the outer tube, and a drive collar that is mounted to the outer tube. The expansion subassembly has an inner drive that is positionable through the outer drive, and a housing having a removable cap that includes an internal expansion mechanism configured to control both the inner and outer drive. The internal expansion mechanism includes an inner shaft configured to engage with the inner drive, an outer drive gear configured to engage with the outer drive, an input gear for transmitting torque to the inner shaft and / or the outer drive gear, and a switch assembly for switching between parallel expansion mode and lordotic expansion mode. The torque limiting handle is configured to transmit torque to the input gear.

[0009] The insertion and expansion device may include one or more of the following features: In parallel expansion mode, the expansion mechanism rotates the inner and outer drive units simultaneously; in lordotic expansion mode, only the outer drive unit rotates, while the inner drive unit remains stationary. The internal expansion mechanism may include a parallel expansion gear defining teeth, an anti-rotation gear defining teeth, and an inner shaft including a toothed member with forward-facing teeth configured to interlock with the teeth of the anti-rotation gear and backward-facing teeth configured to interlock with the teeth of the parallel expansion gear. The switch assembly may include a switch, a mounting plate attached to the housing, a switch casing positioned within the mounting plate and having an elongated slot, and a pin connecting the switch to the elongated slot in the switch casing. When the switch is switched, the switch casing moves to engage or disengage the parallel expansion gear and the anti-rotation gear with the toothed member of the inner shaft. The internal expansion mechanism may include a parallel gear shaft aligned parallel to the internal shaft, the parallel gear shaft including spur gears at each end, the input gear including a spur gear engaging with a spur gear at one end of the parallel gear shaft, and the external drive gear including a spur gear engaging with a spur gear at the other end of the parallel gear shaft, thereby transmitting motion from the input shaft through the parallel gear shaft to the external drive gear. A parallel expansion indicator may be positioned along the threaded portion of the internal shaft, and a lordotic expansion indicator may be positioned along the external drive gear. The housing may define a pair of windows for viewing the movement of each indicator, thereby indicating the amount of parallel expansion and / or lordotic expansion. The internal and external drive units may be spring-biased forward to maintain engagement with the implant. The drive collar may define four notches at 90-degree intervals, these notches configured to engage with pins on the outer tube of the insertion subassembly, thereby locking the implant into one of four possible offset orientations.The outer tube may include a proximal plate defining a pair of holes and a distal plate defining a pair of holes, each hole being for securing a threaded rod and a non-threaded rod to the outer tube, and the distal plate includes a distal surface configured to contact the implant when the distal ends of the threaded rod and the non-threaded rod engage with the implant.

[0010] According to another embodiment, a method of spinal fixation is (a) attaching an insertion and expansion device to an expandable intervertebral implant, the expandable intervertebral implant comprising an upper end plate and a lower end plate, an actuator assembly including a movable forward actuator, a movable rear actuator, and a stationary rear actuator positioned between the upper end plate and the lower end plate, and actuator screws that screw onto a forward actuator nut located in the movable forward actuator and a rear actuator nut located in the stationary rear actuator, and actuator screws that screw through the movable rear actuator to translate the movable rear actuator, the insertion and expansion device comprising an insertion subassembly having an outer tube having threaded rods and unthreaded rods on both sides thereof that engage with the movable forward actuator, an outer drive subassembly having an outer drive unit that can be positioned through the outer tube, and positioning through the outer drive unit The insertion and expansion device includes an expansion subassembly having a possible internal drive unit, a housing having a removable cap for housing an internal expansion mechanism configured to control both the internal and external drive units, and a torque limiting handle configured to transmit torque to the internal expansion mechanism, and may include: (b) inserting an expandable intervertebral implant into the intervertebral disc space between adjacent vertebrae; and (c) expanding the implant via an insertion and expansion device by engaging the external drive unit with an anterior actuator nut and the internal drive unit with an actuator screw, by either (1) rotating the internal and external drive units simultaneously to rotate the actuator screw and the anterior actuator nut together to expand the upper and lower end plates in parallel expansion, or (2) rotating only the external drive unit to rotate the anterior actuator nut to expand the upper and lower end plates in lordotic expansion. The internal and external drive units may rotate simultaneously in the same direction to rotate the actuator screw and the anterior actuator nut simultaneously. The method may also include inserting the bone anchor into the adjacent vertebra through the sockets of the upper and lower end plates, and rotating the blocking screws of the upper and lower end plates to cover the bone anchor and prevent it from retracting.

[0011] In yet another embodiment, the kit may include multiple expandable implants of different sizes and configurations, fasteners or anchors, k-wires, and other components for performing the procedure. The kit may further include one or more instruments suitable for placing and / or removing the implant, such as insertion devices or drive units, expansion devices, removal devices, and other tools and devices suitable for surgery. [Brief explanation of the drawing]

[0012] This embodiment will be better understood from the detailed description and accompanying drawings. [Figure 1A] This is a perspective view of an expandable implant in its fully retracted position, according to one embodiment. [Figure 1B] This is a perspective view of an expandable implant at its maximum expansion, according to one embodiment. [Figure 1C] This is a perspective view of an expandable implant at maximum lordosis according to one embodiment. [Figure 2A] This is a side view of an expandable implant in its fully retracted position, according to one embodiment. [Figure 2B] This is a side view of an expandable implant at its maximum expansion, according to one embodiment. [Figure 2C] This is a side view of an expandable implant at maximum lordosis according to one embodiment. [Figure 3A] This is a cross-sectional view of an expandable implant in its fully retracted position, according to one embodiment. [Figure 3B] This is a cross-sectional view of an expandable implant at its maximum expansion, according to one embodiment. [Figure 3C] This is a cross-sectional view of an expandable implant at maximum lordosis according to one embodiment. [Figure 4] This is an exploded view of an expandable implant according to one embodiment. [Figure 5A] This figure shows a single-point contact between ramps of an expandable implant according to one embodiment. [Figure 5B] Figure showing single-point contact between lamps of an expandable implant according to one embodiment. [Figure 6A] Front view of a fully contracted implant emphasizing the fully contacting lamp at the midline according to one embodiment. [Figure 6B] Front view of a fully expanded implant emphasizing the single-point contact lamp on the side at the midline according to one embodiment. [Figure 7A] Top view of an expandable implant according to one embodiment. [Figure 7B] Cross-sectional view of an expandable implant according to one embodiment. [Figure 8] Partial view of an expandable implant where the limiting pin contacts the end plate according to one embodiment. [Figure 9A] Side view of an insertion and expansion instrument according to one embodiment. [Figure 9B] Exploded view of an insertion and expansion instrument according to one embodiment. [Figure 9C] Exploded view of an insertion and expansion instrument according to one embodiment. [Figure 10] Exploded view of an insertion subassembly according to one embodiment. [Figure 11A] Assembly state diagram of the insertion subassembly. [Figure 11B] Enlarged view of the distal end of the insertion subassembly. [Figure 12A] Top view of the insertion subassembly. [Figure 12B] Cross-sectional view of the insertion subassembly. [Figure 13A] Side views of the insertion subassembly attached to the implant at the contracted and expanded positions. [Figure 13B] Side views of the insertion subassembly attached to the implant at the contracted and expanded positions. [Figure 13C] Side views of the insertion subassembly attached to the implant at the contracted and expanded positions. [Figure 14] This is an exploded view of an external drive unit subassembly according to one embodiment. [Figure 15A] This is an assembly diagram of the drive unit subassembly. [Figure 15B] This is a cross-sectional view of the drive unit subassembly. [Figure 16A] This is an enlarged cross-sectional view of a drive collar assembly according to one embodiment. [Figure 16B] This is an enlarged cross-sectional view of a drive collar assembly according to one embodiment. [Figure 16C] This is a perspective view of a drive collar assembly according to one embodiment. [Figure 17] This is an exploded view of an extended drive unit subassembly according to one embodiment. [Figure 18A] This is a side view of an extension drive subassembly according to one embodiment, which includes a removable cap and indicators for lordosis and forward extension. [Figure 18B] This is a side view of an extension drive subassembly according to one embodiment, which includes a removable cap and indicators for lordosis and forward extension. [Figure 18C] This is a side view of an extension drive subassembly according to one embodiment, which includes a removable cap and indicators for lordosis and forward extension. [Figure 19A] This is an enlarged assembly diagram of the housing portion and expansion mechanism of the expansion drive unit subassembly according to one embodiment. [Figure 19B] This is a cross-sectional view of the housing portion and expansion mechanism of an expansion drive unit subassembly according to one embodiment. [Figure 20A] This figure shows the relative movement of the inner and outer drive parts for parallel expansion according to one embodiment. [Figure 20B] This figure shows the relative movement of the inner and outer drive parts for lordosis according to one embodiment. [Modes for carrying out the invention]

[0013] Embodiments of this disclosure generally aim to provide devices, systems, instruments, and methods for intervertebral fixation and spinal stabilization. Specifically, expandable implants are configured to be inserted into the intervertebral disc space at a minimum height and then expanded axially to restore height loss, provide normal spinal alignment, and / or distribute the load across the vertebral end plates. The implants can provide extension and achieve optimal height restoration. The implants can also be varied in lordosis angle, independently of their height expansion.

[0014] Spinal fusion is typically used to eliminate pain caused by the movement of degenerated intervertebral disc material. If successful, the fusion device is permanently fixed within the intervertebral disc space. Expandable fusion devices may be positioned between adjacent vertebral bodies in their contracted position. Expandable fusion devices are configured to expand in height to restore height loss within the intervertebral disc space. The fusion device engages with the end plates of adjacent vertebral bodies, maintaining the desired intervertebral disc space in the placement position, restoring spinal stability, and thereby facilitating intervertebral fusion.

[0015] Minimally invasive surgery (MIS) can be used to preserve the anatomical structure of muscles by causing destruction only where necessary. The advantages of an MIS surgical approach are that it can reduce postoperative pain and improve patient recovery time. In one embodiment, an expandable fixation device can be configured to be positioned within the surgical target site via an endoscopic tube. For example, the surgical site may be the intervertebral disc space located between two adjacent vertebrae. While the implant is particularly well-suited for use in anterior lumbar interbody fusion (ALIF), it will be readily apparent to those skilled in the art that it can be used in any number of suitable orthopedic approaches and procedures, such as a direct lateral approach to coronal deformities. Other approaches may include, but are not limited to, posterior, lateral, anterolateral, posterolateral, or transforaminal approaches to the lumbar, cervical, or thoracic spine, as well as any non-spine applications such as the treatment of fractures. The terms implant, intervertebral, intervertebral implant, fixation device, spacer, and expandable device may be used interchangeably herein.

[0016] All components of the apparatus disclosed herein may be manufactured from any suitable material, including metals (e.g., titanium), metal alloys (e.g., stainless steel, cobalt-chromium alloys, and titanium alloys), ceramics, plastics, plastic composites, or polymer materials (e.g., polyether ether ketone (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 apparatus may include radiopaque and / or radiopaque materials. Components may also be machined and / or manufactured using any suitable technique (e.g., 3D printing).

[0017] Referring here to the drawings, similar reference numerals refer to similar elements, and Figures 1A to 8 show an expandable fixation device or implant 10 according to one embodiment. The expandable implant 10 extends along the central longitudinal axis A between the front end 12 and the rear end 14 of the device 10. The implant 10 includes an upper end plate 16 and a lower end plate 18 configured to engage with adjacent vertebrae, defining the height of the implant 10. The implant 10 includes an actuator assembly 20 configured to extend the upper end plate 16 and the lower end plate 18. The actuator assembly 20 includes a single actuator screw 22 that screws into a front actuator ramp 28 and a rear actuator ramp 30 to independently control the anterior and posterior heights of the implant 10.

[0018] The implant 10 may include three separate actuators 28, 30, and 32 positioned between the upper end plate 16 and the lower end plate 18, namely a movable forward actuator 28, a movable rear actuator 30, and a stationary rear actuator 32. One end of the actuator screw 22 is screwed into a forward actuator nut 24 located within the forward actuator 28, and the other end of the actuator screw 22 is screwed into a rear actuator nut 26 attached to the stationary rear actuator 32. The actuator screw 22 is screwed through the movable rear actuator 30, translating the rear actuator 30 along the central longitudinal axis A. When the actuator screw 22 and the forward actuator nut 24 are turned together, the movable rear actuator 30 moves toward the stationary rear actuator 32, forcing the upper end plate 16 and the lower end plate 18 apart and resulting in parallel expansion. When only the forward actuator nut 24 is turned, the movable forward actuator 28 moves independently to increase the forward height, resulting in an increase in the forward curvature angle.

[0019] The upper end plate 16 and the lower end plate 18 are interlocked with actuators 28, 30, and 32 via a plurality of mating ramps 36 and 38. Optimal mating ramps 36 and 38 may include angled, inclined, or sloped surfaces that are slidably interlocked with each other to allow expansion of the upper end plate 16 and the lower end plate 18. The mating ramps 36 and 38 allow for controlled sliding motion on complementary surfaces, thereby providing vertical displacement of the end plates 16 and 18. The mating ramps 36 and 38 may include single-point contact ramps 36 and full-contact ramps 38. The single-point contact ramps 36 and full-contact ramps 38 may be integrated into the same implant 10 to allow for precise adjustment of both the height and angle of the implant 10 according to specific surgical needs.

[0020] As best shown in Figures 5A and 5B, the single-point contact ramp 36 may have an inclined design in which a localized contact area, such as a single point, edge, or minimum surface area along one ramp surface, contacts the corresponding ramp surface for any given time during operation. The single-point contact ramp 36 may allow controlled sliding, articulated, or pivotal movement around the contact point. As the actuator(s) 28, 30, 32 move, the contact point may move along the corresponding ramp surface, effectively changing the angle or position of the end plates 16, 18 in a controlled manner. The single-point contact ramp 36 may allow fine adjustment of the height and / or angle of the end plates 16, 18 to achieve desired height extension and spinal correction.

[0021] The full-contact ramp 38 may have a tilted design in which the ramp surface maintains constant, continuous contact with the corresponding ramp surface throughout the entire operating process. The full-contact ramp 38 may bear the majority of the lifting force with a shorter moment arm distance of the actuator screw 22, reducing bending in the ramp and improving the overall lifting force. In other words, the full-contact ramp maintains maximum surface area contact between the ramp surfaces during operation, and the continuous contact distributes the force more evenly across the interlock, providing stable and uniform expansion of the end plates 16, 18. The full-contact ramp 38 may not have engagement tabs to improve manufacturability. Furthermore, the even distribution of force can reduce the risk of localized stress points and increase the overall stability of the spinal fixation.

[0022] The single-point contact ramps 36 and full-contact ramps 38 may be distributed throughout the implant 10 to achieve the desired adjustment and uniform lift during spinal orthodontic procedures. As best shown in Figure 6B, the single-point ramps 36 may be located along or near the lateral edge or side of the implant 10, while the full-contact ramps 38 may be located near or in contact with the centerline or central axis A of the implant 10. In other words, the full-contact ramps 38 may be positioned midway between the single-point ramps 36 on each side. The single-point ramps 36 may address specific angle corrections, while the full-contact ramps 38 ensure that the adjustment does not impair the overall stability of the implant 10. The full-contact ramps 38 may be located in contact with or near the centerline of the implant 10, thereby concentrating the lifting force in a location that may be most effective in supporting the structural integrity of the implant 10.

[0023] The implant 10 is configured to be inserted into the intervertebral disc space in a contracted configuration. Figure 1A shows the implant 10 in a fully contracted configuration. Once inserted into the intervertebral disc space, the implant 10 expands in height to an expanded configuration to precisely restore normal spinal alignment and distribute the load across the vertebral end plates. Figure 1B shows the implant 10 in a fully expanded configuration at maximum expansion. Figure 1C shows the implant 10 in an expanded configuration at maximum lordosis. It will be understood that the implant 10 can expand to any desired height between these two extreme states. The anterior and posterior heights are independently adjustable to the desired lordosis profile. In this way, the height is adjustable to restore the height loss of the intervertebral disc space and the lordosis angle. It should be understood that references to the anterior and posterior ends, as well as anterior and posterior heights, refer to the direction of placement within the intervertebral disc cavity, such that the anterior end of the expandable fixation device 10 is first placed in the intervertebral disc cavity, followed by the posterior end of the expandable fixation device 10, and then the height and / or lordosis of the end plates 16, 18 are expanded. These and other directional terms may be used herein for illustrative purposes only and do not limit the orientation in which the device may be used.

[0024] Each end plate 16, 18 may include a front or rear rail 40 and a rear or front rail 42 extending between opposing lateral rails 44, 46. Rails 40-46 define an inner surface 50 and an opposite outer surface 52. The inner surface 50 may be configured to engage with the respective actuators 28, 30, 32, and the outer surface 52 may be configured to contact the adjacent vertebra. The outer surface 52 of each end plate 16, 18 may include a number of teeth 54 or other friction-increasing elements, such as protrusions, rough surfaces, keels, gripping projections, or trapping projections, configured to hold the device 10 within the intervertebral disc cavity. The end plates 16, 18 may be 3D printed using additive manufacturing techniques. Thus, the outer surface 52 may be fabricated using teeth and / or surface textures that can better promote bone surface growth. Each end plate 16, 18 may define a vertical window or through passage 56, thereby defining a central graft chamber within the implant 10. The window or through-hole 56 allows graft material or other therapeutically beneficial material to be filled into or grow through the implant 10.

[0025] The implant 10 may be fixed to an adjacent vertebra using one or more anchors or fixing screws (not shown). For example, the anterior rail 42 may define at least one anchor socket 60 configured to receive an anchor or fixing screw and insert it into an adjacent vertebra. In the illustrated embodiment, three sockets 60, each receiving three anchors or screws, are provided on the upper end plate 16 and the lower end plate 18, with one socket 60 oriented upward into the superior vertebra and two sockets 60 oriented downward into the inferior vertebra. The sockets 60 may be surrounded by hemispherical recesses so that the anchor or screw can be angled into the adjacent vertebra. The bone screw holes 60 in the end plates 16, 18 may be compatible with both conventional lag screws and / or anchor fixation. In one embodiment, the bone screw may be a multi-axis screw, and the socket 60 may be molded in correspondence so that the multi-axis screw can be inserted into the implant 10 at an optimal angle. In another embodiment, the anchor may be a curved T-shaped shim anchor with a sharp edge for penetrating bone. Examples of bone screws and anchors are further described in U.S. Patent No. 11,554,023, which is incorporated herein by reference in its entirety for all purposes. Although a given configuration of socket 60 is shown, it will be understood that socket 60 can be prepared in any preferred number and configuration for fastening. Alternatively, a standalone device may be provided without socket 60.

[0026] A cam-type block screw 62 may be used to prevent the anchor or fixing screw from coming loose after insertion. The front rail 42 may define blocking screw holes 64 positioned next to each respective socket 60. The blocking screw holes 64 may be provided with female threads to receive each threaded blocking screw 62. In one embodiment, three block screws 62 are screwed into end plates 16, 18 to secure the anchor or fixing screw in each of the three sockets 60. The blocking screw 62 may have an expanding head with a drive recess and a threaded shaft. These blocking screws 62 allow one type of blocking screw to be used across all of the implant bone screw holes 60. When the blocking screw 62 is rotated and engaged, a portion of the expanding head covers each anchor or fixing screw, thereby preventing the installed anchor or fixing screw from moving.

[0027] The rails 40-46 and / or inner surfaces 50 of each end plate 16, 18 may define one or more ramps 70, 72, 74 configured to engage with their respective actuators 28, 30, 32, thereby separating the end plates 16, 18. For example, the end plates 16, 18 may define a rear ramp 70 along the rear rail 40, which engages with the rear actuators 30, 32. The end plates 16, 18 may define a front ramp 72 along the front rail 42 and a central ramp 74 along the lateral rails 44, 46, which engage with the front actuator 28. The ramps 70, 72, 74 may include ramp surfaces, angled surfaces, or inclined planes having a given gradient or angle of inclination. The ramps 70, 72, 74 may have substantially straight ramp surfaces, be curved, or be configured in any way suitable for slidable interlocking between components. Lamps 70, 72, and 74 may define male or female sliding lamps configured to mate with corresponding lamps 90, 112, and 132 on actuators 28, 30, and 32. In one embodiment, lamps 70, 72, and 74 on end plates 16 and 18 include female lamps with defined grooves or slots. The grooves or slots may be configured to receive an optimal portion of the lamps 90, 112, and 132 on actuators 28, 30, and 32.

[0028] In one embodiment, the rear ramp 70 includes both single-point contact ramps 70A and full-contact ramps 70B. The single-point contact ramps 70A may be located near each side of the rear rail 40. A pair of full-contact ramps 70B may be located in the center between the single-point contact ramps 70A. The full-contact ramps 70B may be separated by a channel or gap 76 that receives a portion of the rear actuator 32 when fully retracted. The front ramp 72 also includes both single-point contact ramps 72A and full-contact ramps 72B. The single-point contact ramps 72A may be located near each side of the front rail 42. A pair of full-contact ramps 72B may be located in the center between the single-point contact ramps 72A. Similarly, the central ramp 74 may include single-point contact ramps defined along the inner surfaces of each lateral rail 44, 46.

[0029] The fully contact ramps 72B may be separated by channels or gaps 78 that receive a portion of the forward actuator 28 when fully retracted. As best shown in Figure 6B, the gaps 78 between fully contact forward ramps 72B on the upper end plate 16 may be smaller than the gaps 78 between fully contact forward ramps 72B on the lower end plate 18. Similarly, the spacing between single-contact forward ramps 72A on the upper end plate 16 may be narrower than the spacing between single-contact forward ramps 72A on the lower end plate 18. It will be understood that the spacing between any of the ramps 70, 72, and 74 may be selected to allow for proper nesting of the upper end plate 16 and the lower end plate 18 in order to obtain optimal lifting strength or any other preferred parameter when the implant 10 is retracted. The implant 10 expands or retracts due to the translation of the forward actuators and / or rear actuators 28, 30, and 32, and the movement of the end plates 16, 18 sliding against the ramps 70, 72, and 74.

[0030] The actuator assembly 20 includes a movable forward actuator 28 positioned between the upper end plate 16 and the lower end plate 18, thereby providing forward extension to the implant 10. The movable forward actuator 28 includes a laterally extending body having an enlarged central portion 80. The forward actuator 28 extends from a first free end 82 to a second free end 84. The first end 82 and the second end 84 may define irregular cross-sectional shapes, such as polygons with cut faces and rounded corners. The first free end 82 and the second free end 84 are receivable between lateral rails 44, 46 toward the front ends 14 of the upper end plate 16 and the lower end plate 18, and the enlarged central portion 80 is positionable through the graft window 56 of the upper end plate 16 and the lower end plate 18 when in a retracted configuration. The enlarged central portion 80 defines a central threadless hole 86 having size and dimensions for receiving a forward actuator nut 24. The central axis of the hole 86 may be aligned with the central longitudinal axis of the plate 10.

[0031] Additional recesses or holes 88 may be provided through the forward actuator 28. For example, the forward actuator 28 may include two mounting holes 88 designed to work in conjunction with instruments for inserting and / or removing the implant (e.g., the threaded rod 224 and unthreaded rod 226 of instrument 200). The first threaded hole 88 may be located on one side of the central hole 86, and the second unthreaded hole 88 may be located on the opposite side of the central hole 86. The recesses or holes 88 may be used to mount instruments such as the insertion and / or expansion instrument 200. In addition, the implant 10 may have multiple forward openings for engaging with a bone funnel, for example, to backfill the implant in situ after expansion.

[0032] The movable forward actuator 28 includes one or more ramps 90 configured to engage with corresponding forward ramps 72, 74 on end plates 16, 18. In one embodiment, the ramps 90 may include male ramps having projections or protrusions having rails configured to engage with corresponding grooves or slots in the end plates 16, 18. In some embodiments, the projections or rails may include L-shaped tabs 92 that extend outward from the actuator 28 and then rotate 90 degrees to form an L-shape. In other embodiments, the projections or rails may include T-shaped tabs with stems that extend outward from the actuator 28 and then provide a vertically extending portion at the free end of a stem that forms the upper part of a T-shape. In some cases, the free ends of the tabs 92 may be oriented laterally outward and away from each other, or inward toward each other, or oriented in any preferred manner. The slots machined into the upper end plate 16 and the lower end plate 18 are linked to the ramp 90 on the front actuator 28, enabling parallel expansion and forward curvature expansion while preventing disassembly by pulling the end plates apart.

[0033] In one embodiment, the forward actuator 28 may define a first pair of male ramps 90 configured to mate with corresponding single-point contact forward ramps 72A along end plates 16, 18, adjacent to each end 82, 84 of the actuator 28. The single-point contact ramps 90 may be configured to interlock with the corresponding forward ramps 72A at a single contact point or position to facilitate pivoting or rotational motion. The specific position where the ramp 90 interacts with the corresponding ramp 72A may be the center of rotation or movement. Unlike broad surface contact between mating ramps, the ramps 90 may make targeted contact for interlocking with the corresponding ramps 72 at a defined point or edge. For example, the engaging surface of one ramp 72B, 90 may be pointed, angled, tapered, or curved, etc., to define a single contact point or contact edge with the flat or angled surface of the other. These ramps 90 may include tabs 92 for securing end plates 16, 18 along the side edges of the implant 10 to the front actuator 28.

[0034] The forward actuator 28 may define a second pair of male ramps 90 toward the centerline, configured to mate with corresponding full-contact ramps 72B on end plates 16, 18. The full-contact ramps 90 may be configured to interlock with the corresponding centerline ramps 72B with continuous constant contact between the ramps 72, 90, thereby providing a lifting force with a shorter moment arm distance for the actuator screw, reducing bending in the ramps and improving the overall lifting force. The centerline ramps 90 on the forward actuator 28 do not have engaging tabs to improve manufacturability, since engagement of the end plates is already achieved using tabs 92 at the side edges of the parts.

[0035] The front actuator 28 defines a pair of pin holes 94 on either side of a central hole 86 configured to receive each limiting pin 96, the limiting pins 96 holding the front actuator nut 24 within the front actuator 28 while also preventing over-expansion of the implant. The pin holes 94 may include a non-threaded vertical slot, which may be substantially perpendicular to the longitudinal implant axis A. The pin holes 94 may have a cross-section that is substantially oval, elliptical, oblong, or egg-shaped. The limiting pin 96 may include a solid body having an L-shaped or notched end 98 and an enlarged base at the opposite end 99. Part of the pin hole 94 may have an enlarged portion configured to receive the enlarged base end 99 of the limiting pin 96.

[0036] The limiting pin 96 holds the forward actuator nut 24 within the forward actuator 28 and also functions to prevent the implant 10 from over-expanding and disassembling. The limiting pin 96 restricts the movement of the forward actuator assembly by contacting the surfaces on the upper end plate 16 and the lower end plate 18 when the implant 10 is at its maximum forward expansion relative to a given amount of backward expansion. For example, the limiting pin 96 may allow a maximum end plate forward curve of 30 degrees at 0 mm of backward expansion and a forward curve of 12-14 degrees at maximum expansion. As best shown in the partial cross-sectional view of Figure 8, the limiting pin 96 may contact both end plates 16, 18 simultaneously to prevent rotation of the forward actuator 28 at maximum expansion or forward curve. In addition, the limiting pin 96 may contact both end plates simultaneously to ensure consistency at maximum expansion and to prevent damage to the implant 10 even if torque-out occurs at maximum expansion. The limiting pins 96 on the front actuator 28 and the end plates 16, 18, and the support surfaces are configured to be strong enough to withstand the maximum extension torque of the device.

[0037] The actuator assembly 20 includes a movable rear actuator 30 positioned between the upper end plate 16 and the lower end plate 18, thereby providing rearward extension to the implant 10. The movable rear actuator 30 includes a laterally extending body connecting a first free end 102 to a second free end 104, having a flat front surface 106 and a rounded or curved rear surface 108 on the opposite side. The first free end 102 and the second free end 104 are receivable between the upper end plate 16 and the lower end plate 18 toward the rear end 12 of the implant 10. The front surface 106 includes a circular projection 109 defining a central threaded cylindrical hole 110 configured to receive an actuator screw 22. The central axis of the hole 110 may be aligned with the central longitudinal axis A of the implant 10. As best shown in Figure 3A, in the retracted position, the recess defined within the circular projection 109 may be configured to receive a portion of the enlarged collar 156 of the front actuator nut 24.

[0038] The movable rear actuator 30 includes one or more ramps 112 configured to engage with corresponding ramps 70 on end plates 16, 18. The ramps 112 may extend from the rear surface 108 of the actuator 30. In some cases, similar to the ramp 90, the ramps 112 may include male ramps having projections or protrusions with rails configured to engage with corresponding grooves or slots in the end plates 16, 18. The projections or rails may include L-shaped tabs 114 similar to tabs 92, which extend outward from the actuator 30 and then rotate 90 degrees to form an L-shape. In some cases, the free ends of tabs 92 may face laterally outward and away from each other at each end of the actuator 30. Some of the ramps 112 may include single-point contact ramp interlocking units incorporated into each side of the movable rear actuator 30. For example, two male ramps 112 may be positioned upward to interlock with the upper end plate 16, and two male ramps 112 may be positioned downward to interlock with the lower end plate 18. The tabs 92 interlock with corresponding slots in the upper end plate 16 and the lower end plate 18 to prevent disassembly and allow independent expansion. In addition to the single-point contact ramps 112 toward the side edges, additional full-contact ramps may be included toward the centerline of the actuator 30 or between the side single-point contact ramps 112. The full-contact midline ramps 112 on the movable rear actuator 30 do not need to include engaging tabs to simplify the manufacturing process, and because the end plates 16, 18 are already secured by tabs 92 located on the sides of the actuator 30.

[0039] The actuator assembly 20 includes a stationary rear actuator 32 positioned between the upper end plate 16 and the lower end plate 18, thereby providing a rearward extension to the implant 10. The stationary rear actuator 32 includes a laterally extending body having a first free end 120 and a second free end 122 on either side. The first free end 120 and the second free end 122 are receivable between the rear rails 40 of the upper end plate 16 and the lower end plate 18, and the stationary rear actuator 32 defines the nose or front end 12 of the implant 10. The stationary rear actuator 32 includes a front surface 124 and an opposite rear surface 126. The central portion of the actuator 32 may define a central threadless hole 130 having a size and dimensions for receiving a rear actuator nut 26. The central axis of the hole 130 may be aligned with the central longitudinal axis A of the implant 10.

[0040] The stationary rear actuator 32 includes one or more ramps 132 configured to mate with corresponding rear ramps 70 on end plates 16, 18. The ramps 132 may be defined within the front surface 124 of the actuator 32 and / or extend from the front surface 124. Similar to the ramps 90, 112, the ramps 132 may include male ramps configured to mate with the rear ramps 70 along the rear rails 40 of the end plates 16, 18. The male ramps 132 may include projections or protrusions having L-shaped tabs 134 configured to engage with corresponding grooves or slots in the end plates 16, 18. The free end of the tab 134 may be oriented laterally outward from the midline of the actuator 32. The ramps 132 oriented toward the side edges may include single-point contact ramps, while the ramps 132 oriented toward the midline may include full-contact ramps. In this case, all of the ramps 132 may include engaging tabs 134. The full-contact ramp 132 near the midline may include a tab 134 to counteract the bending forces experienced during lordosis lifting. As the movable rear actuator 30 moves toward the stationary rear actuator 32, these rear actuators 30, 32 work in conjunction with the ramp surfaces 70 on the upper end plate 16 and the lower end plate 18, pushing the upper end plate 16 and the lower end plate 18 in both directions, thereby extending the rear height of the implant 10.

[0041] In this single-point contact ramp, the implant 10 uses the contact point on the engagement interlocking part itself as a pivot point for adjusting the lordosis angle. The point-contact engagement interlocking parts 90, 112, and 132 include sufficient angular clearance with the engaging slots to accommodate the angle changes of the end plates required for in-situ lordosis adjustment and assembly of the device. The implant 10 also includes a full-contact interlocking part to bear the majority of the lifting force, thereby reducing bending in the ramp and improving the overall lifting force.

[0042] The rear extension mechanism operates by using an actuator screw 22 to drive the movable rear actuator 30 toward or toward the stationary rear actuator 32. As best shown in Figure 3B, the movable rear actuator 30 translates toward the forward actuator 28 and toward the stationary rear actuator 32. As the two rear actuators 30, 32 move toward each other, these rear actuators 30, 32 work in conjunction with the ramp surfaces 70 on the upper end plate 16 and the lower end plate 18, pushing the upper end plate 16 and the lower end plate 18 in both directions and extending the rear height of the implant 10.

[0043] The actuator assembly 20 includes an actuator screw 22, a front actuator nut 24, and a rear actuator nut 26, all aligned along the central longitudinal axis A of the implant 10. The actuator screw 22 extends from the proximal end 140 to the distal end 142. The actuator screw 22 may include a shaft having a reduced diameter or stepped diameter near the distal end 142 relative to the rest of the shaft. The shaft includes multiple male threads or male thread portions 144 extending along its longitudinal direction. The threaded shaft 144 may have a given diameter, lateral orientation, thread morphology, thread angle, lead, pitch, etc., suitable for interlocking with the front actuator nut 24 (which controls the movement of the front actuator 28) and the movable rear actuator 30. The reduced diameter at the distal end 142 may also include a threaded portion 145 suitable for interlocking with the rear actuator nut 26. In this embodiment, a single type of thread profile may be used for both parallel expansion and lordotic expansion. Unlike systems that use up to three different sets of threads to engage for parallel expansion, this design achieves both parallel and lordotic expansion through the interaction of a single set of threads. This reduces the overall increase in lifting torque caused by thread friction or constraint.

[0044] The proximal end 140 of the shaft 22 may define an instrument recess 146 configured to receive an instrument, such as an internal drive unit 320, and rotate or actuate the actuator screw 22. The instrument recess 146 may include a trefoil, hexagon, star, or other preferred recess configured to engage with the drive unit instrument to apply torque to the actuator screw 22. In one embodiment, the instrument recess 146 has a Torx® shape optimized to maximize the allowable input torque to improve the lifting capacity of the implant. The proximal end 140 of the shaft is configured to screw onto a forward actuator nut 24 to translate the movable forward actuator 28. The threaded shaft 144 also screws onto a movable rear actuator 30 to translate the movable rear actuator 30 along the central longitudinal axis A.

[0045] The distal end 142 of the actuator screw 22 may have a reduced distal tip, for example, having a diameter smaller than the diameter of the threaded shaft 144. The distal tip 142 may be threaded and configured to screw into a posterior actuator nut 26 held within the stationary posterior actuator 32. For example, even in the fully extended state, as best shown in Figure 3B, the distal end 142 of the actuator screw 22 does not protrude beyond the posterior edge or anterior nose 12 of the implant 10. Posterior protrusion of the actuator screw was a concern for surgeons, resulting from the appearance of a threaded rod protruding near the posterior structures of the spine. Therefore, the expansion assembly 20 and operation for the implant 10 eliminate any possibility of posterior protrusion of the actuator screw 22.

[0046] The front actuator nut 24 has a body extending from a proximal end 150 to a distal end 152. As best shown in Figures 3A-3C, a central hole 154 extends through the body of the front actuator nut 24 from the proximal end 150 to the distal end 152. A portion of the hole 154 defines a female thread configured to engage screwably with the male thread 144 of the actuator screw 22. The proximal end 150 of the front actuator nut 24 defines a drive engagement recess, such as a series of notches and teeth (e.g., a castle nut drive mechanism), or another preferred recess configured to engage with a drive device, such as an external drive unit 280, to apply torque to the front actuator nut 24. The shape of the external drive unit castle nut drive mechanism can be optimized to maximize the allowable input torque. Increasing the torque limit allows for improved implant lifting ability. The drive recess for the front actuator nut 24 may preferably be different from the drive recess 146 for the actuator screw 22. The distal end 152 of the actuator nut 24 may have an enlarged collar 156. A forward drag ring 160, such as a PEEK washer or annular ring, may be nested with respect to the collar 156. The forward drag ring 160 may be trapped between the forward actuator nut 24 and the forward actuator 28 and provide frictional resistance against the reverse drive of the forward expansion mechanism, which would result in a loss of forward height of the implant. In contrast to adding static friction to prevent height loss of the implant, the PEEK drag ring 160 also functions as a thrust washer to reduce dynamic expansion friction when under load. The forward actuator nut 24 may be permanently trapped inside the forward actuator 28, for example, by a limiting pin 96 or another preferred mechanism.

[0047] The rear actuator nut 26 includes a body with a central cylindrical hole 170 defined through it. The hole 170 defines a female thread configured to screw-engage with the male thread 145 of the distal tip 142 of the actuator screw 22. The actuator screw 22 is captured inside the stationary rear actuator ramp 32 by screwing it into the rear actuator nut 26. The end of the rear actuator nut 26 may have an expanding collar 172 having notches or teeth to assist in assembly, for example. A rear drag ring 180 may seat beneath the collar 172. The rear drag ring 180, such as a PEEK washer or an annular ring, is captured between the rear actuator nut 26 and the stationary rear actuator ramp 32 to provide frictional resistance against reverse drive of the rear expansion mechanism, which would result in a loss of overall expansion height of the implant 10. In contrast to adding static friction to prevent loss of implant height, the PEEK drag ring 180 also functions as a thrust washer to reduce dynamic expansion friction when under load. To ensure that neither the front actuator 28 nor the rear actuator 32 loses height during use, drag rings 160 and 180 may be added between the actuator screw 22 and the stationary rear actuator 32, and between the front actuator 28 and the front actuator nut 24. The drag rings 160 and 180 also function as thrust washers to improve extension capability.

[0048] During operation, the implant 10 may operate in one of two modes. In the first mode, the actuator screw 22 and the front actuator nut 24 are rotated or turned together simultaneously. This causes the movable rear actuator 30 to move toward the stationary rear actuator 32, forcing the upper end plate 16 and the lower end plate 18 apart. This results in equal expansion of both end plates 16 and 18, as the ramp angle of the ramp 72 on the front ends of the end plates 16 and 18 matches the ramp angle of the ramp 70 on the rear ends of the end plates 16 and 18. For example, Figure 2B shows the end plates 16 and 18 expanded in parallel. In the second mode, the actuator screw 22 is held in place, and the front actuator nut 24 is rotated or turned independently. This causes the front actuator 28 to move independently, expanding or contracting only the front ends of each end plate, resulting in an increase in the forward curve angle. For example, Figure 2C shows the end plates 16 and 18 expanded with increased forward height.

[0049] This expansion mechanism simplifies the expansion drive unit because the actuator screw 22 and the front actuator nut 24 need to be rotated in the same direction for both lordosis and parallel expansion. In other designs, for example, if the actuator screw needs to be rotated clockwise for parallel expansion, the front actuator nut needs to be rotated counterclockwise for lordosis expansion, and components 22 and 24 rotate in opposite directions. This design required either a counterintuitive counterclockwise movement for implant expansion or a complex and expensive drive unit mechanism. Conversely, in this embodiment, the actuator screw 22 and the front actuator nut 24 rotate in the same direction for both lordosis and parallel expansion, thereby simplifying the operation.

[0050] The implant 10 allows for continuous expansion and extension over a specific range of the implant. This provides not only the ability to extend the vertebral body to a desired height, but also the ability to contract the device 10 for repositioning as needed. The implant 10 has the ability to converge the end plates 16, 18 to provide lordosis while maintaining a large window for placing bone grafts. By changing the lordosis angle, the implant 10 may be matched to the patient's natural lordosis, or it may be used to provide a specific lordosis at a therapeutic level(s).

[0051] Referring here to Figures 9A to 20B, an insertion and expansion device 200 according to one embodiment is shown. The device 200 is configured to insert an ALIF-adjustable lordosis implant 10 into the intervertebral disc space, for example, after a discectomy. The device 200 connects to the implant 10 in a zero-profile manner, allowing the surgeon to see the cage as it is inserted into the contracted intervertebral disc space. Once inserted, the device 200 allows the surgeon to independently control the parallel and lordosis expansion of the implant 10. The device 200 allows the surgeon to alternate between parallel and lordosis expansion by toggling a switch 358. Indicators 420 and 422 on the device 200 indicate posterior and lordosis expansion measurements. Quick connectors allow for rapid assembly and disassembly of various components without time-consuming or difficult assembly steps. The device 200 can be completely disassembled for cleaning without requiring additional tools.

[0052] As best shown in Figures 9A–9C, the instrument 200 may include four subassemblies aligned along the instrument's axis 210, namely, an insertion subassembly 202, an external drive subassembly 204, an expansion drive subassembly 206, and a torque limiting handle 208. The insertion subassembly 202 is configured to be mounted directly to the implant 10 and may be used alone to insert the implant 10 into the intervertebral disc cavity, or it may be mounted on the complete insertor assembly 200. The external drive subassembly 204 includes an external drive 280 configured to engage with a front actuator nut 24 and transmit torque from the expansion subassembly 206. The expansion subassembly 206 includes an internal drive 320 configured to engage with an actuator screw 22 and control the movement of the external drive 280 and the internal drive 320, thereby controlling implant expansion. The torque limiting handle 208 includes a handle grip and a mounting interlocking mechanism 214 for easy attachment and detachment to, for example, the expansion subassembly 206.

[0053] Referring here to Figures 10 to 13C, the insertion subassembly 202 is shown in more detail. The insertion subassembly 202 includes an outer tube 220, an insertion collar 222, a threaded rod 224, and a non-threaded rod 226. The outer tube 220 includes a hollow tube 230 having a proximal plate 232 and a distal plate 234 configured to secure the threaded rod 224 and the non-threaded rod 226. The outer tube 230 may include one or more openings 231, which may be in fluid communication with a longitudinal through-hole. The insertion collar 222 is receivable on the proximal portion 236 of the outer tube 230, which also connects to the outer drive subassembly 204. The proximal portion 236 of the outer tube 230 defines an annular groove 237, which forms part of the ball seal connection to the outer drive assembly 204. The proximal portion 236 may also include one or more pins 239 (e.g., a pair of opposing pins 239) which, in conjunction with the external drive assembly 204, lock the implant 10 into one of four 90-degree offset positions, based on the surgeon's preference. The key engagement portion 318 of the drive collar 282 allows for four 90° orientations, based on the surgeon's preference for the ergonomics and visualization of the handle. Easy attachment / detachment from the insertor body allows for quick and easy changes in orientation during surgery.

[0054] The proximal plate 232 may include an annular projection extending from the outer tube 230 and defining a pair of holes 238 through which these holes 238 are configured to receive the proximal portions of the respective threaded rods 224 and unthreaded rods 226. The proximal plate 232 may project or bulge in the area of ​​the holes 238 to accommodate the respective rods 224, 226. The distal plate 234 may include a laterally extending wing extending from the outer tube 230 and defining a pair of holes 240 through which these receive the distal portions of the respective rods 224, 226. The respective holes 238, 240 may be aligned with each other and provided parallel to each other to receive the corresponding threaded rods 224 and unthreaded rods 226. The threaded rod 224 and the unthreaded rod 226 extend between the proximal plate 232 and the distal plate 234 on both sides of the outer tube 220 and may be aligned parallel to each other. The distal plate 234 includes a distal surface 242 which may contact the rear end 14 of the implant 10 when the instrument 200 is fixed to the implant 10. The distal surface 242 may define one or more notches or reliefs 244, for example, to provide clearance for a blocking screw 62 on the implant 10.

[0055] The insertion collar 222 includes an annular or ring-shaped body having a through-opening 250 sized and sized to receive the proximal portion 236 of the outer tube 220. The insertion collar 222 defines a pair of holes 252, which are configured to receive the proximal portions of the threaded rod 224 and the unthreaded rod 226, respectively. These holes 250 also align with corresponding holes 238, 240 that penetrate the plates 232, 234. The insertion collar 222 may protrude or bulge on each side to accommodate the respective holes 252. The insertion collar 222 may fit onto the proximal portion 236 of the tube 220 and abut against the proximal plate 232.

[0056] The insertion assembly 202 is securely attached to the implant 10 via a threaded rod 224. A non-threaded rod 226 provides additional torsional stability. The threaded rod 224 may include an elongated non-threaded shaft 256 having a threaded distal tip 258. The threaded distal tip 258 may have a reduced diameter compared to the shaft 256. The threaded distal tip 258 is configured to engage with a threaded hole 88 in the anterior actuator 28 of the implant 10. The threaded rod 224 may include a recessed shoulder 260 at its proximal end to engage with a pin 268 in the insertion collar 222. The non-threaded rod 226 may include an elongated non-threaded shaft 264 having a non-threaded distal tip 266. The non-threaded distal tip 266 may have a reduced diameter compared to the shaft 264. The unthreaded distal tip 266 is configured to engage with an unthreaded hole 88 in the anterior actuator 28 of the implant 10. The threaded rod 224 and the unthreaded rod 226 are reconnected by the insertion collar 222. The threaded rod 224 is rotatable but is axially constrained within the insertion collar 222 via a pin 268 that engages with a shoulder 260 on the threaded rod 224. The unthreaded rod 226 may be welded directly to the insertion collar 222 or may be fixed to the insertion collar 222 by other means.

[0057] The insertion subassembly 202 may be spring-biased to ensure tight contact with the implant surface during insertion. This allows the insertion force to be directly transmitted to the end plates 16, 18 without restricting the articular movement of the implant 10, as would be the case if the implant 10 were screwed to the surface of the inserter. The insertion collar 222 may be spring-biased rearward with two corrugated springs 270 that pull the implant 10 against the surface 242 of the inserter 202 when installed. The spring force prevents the implant 10 from feeling loose on the inserter 202, but does not add resistance to implant expansion as would occur if the implant end plates 16, 18 were screwed to the surface 242 of the inserter 202. This design ensures tight contact with the inserter 202 without interfering with the expansion mechanism.

[0058] Referring here to Figures 14 to 16C, the outer drive unit subassembly 204 is shown in more detail. The outer drive unit subassembly 204 includes a spring-biased outer drive unit 280 and a drive collar 282 that attaches the insertion subassembly 202 to the extension subassembly 206. At one end of the drive collar 282, a spring-biased button 284 may be used to connect the drive collar 282 to the extension subassembly 206, and at the other end of the drive collar 282, a quick-connect ball seal 286 may be used to connect the drive collar 282 to the insertion subassembly 202.

[0059] The outer drive unit 280 includes a cannulated shaft or hollow tube 290, which allows the inner drive unit 320 to pass through the outer drive unit 280. The distal tip 292 may include a drive tip having drive teeth configured to engage with, for example, the front actuator nut 24. The distal drive tip 292 may be configured to engage with a drive unit engagement recess (e.g., a castle nut drive mechanism) in the proximal end 150 of the front actuator nut 24 to apply torque to the front actuator nut 24. The drive tip 292 may have a reduced diameter compared to the shaft 290. The tube 290 may include one or more openings 291, which may be in fluid communication with a longitudinal through-hole. The proximal end of the outer drive unit 280 includes an annular shoulder 294, which helps to hold the outer drive unit 280 within the drive collar 282. The outer drive unit 280 further defines an internal drive recess 296 (e.g., a hexagonal recess) at its most proximal end. The internal drive recess 296 may have a size and dimensions such as to transmit torque and to allow the outer drive unit 280 to slide axially along the corresponding external hexagonal drive unit 380 of the outer drive gear 352.

[0060] As best shown in Figures 16A to 16C, the drive collar 282 has a cylindrical body defining an internal chamber 302 for receiving the proximal end of the outer drive unit 280. The outer drive unit 280 may be spring-biased within the drive collar 282 via a spring 304. The spring 304 may be positioned around the proximal portion of the shaft 290 and proximal to the shoulder portion 294. The spring 304 may be fixed via a retaining ring 306. The outer drive unit 280 may be spring-biased forward to maintain engagement with the forward actuator nut 24 or other outer drive mechanisms on the implant 10. The spring-biased outer drive unit 280 may have sufficient travel so that if the drive teeth on the distal tip 292 are not aligned with the implant 10, the outer drive unit 280 retracts, and as the outer drive unit 280 rotates, it snaps forward into position. This eliminates the need to perfectly align the drive units 280 and 320 when installing the implant 10.

[0061] The spring-biased outer drive unit 280 includes a spring 304 and a retaining ring 306 to prevent disassembly. The outer drive unit 280 receives input torque from the extension subassembly 206 via an internal drive recess 296 (e.g., a hexagonal recess). The internal drive recess 296 may be long enough not only to transmit torque but also to allow the outer drive unit 280 to slide axially backward along the corresponding outer hexagonal drive unit 380 when the instrument 200 is attached to the implant 10.

[0062] The drive collar 282 houses a ball seal connection 286 to an insertion subassembly 202 on one side and a spring-biased button connection 284 to an expansion subassembly 206 on the other side. The rear of the drive collar 282 includes the spring-biased button 284 and an alignment recess 316 for alignment with the expansion drive housing 322. The drive collar 282 holds the spring-biased button 284 within the proximal cavity 308. The button 284 may include a ring-shaped or circular shape that closely conforms to the outer contour of the drive collar 282. The button 284 may define holes 310 configured to receive respective pins 312 that secure the button 284 to the drive collar 282 on both sides. The holes 310 may be elongated in the longitudinal direction to allow translation of the button 284. The cavity 308 within the drive collar 282 also houses a small spring 314 that maintains a constant force to push out the button 284 and keeps the outer drive assembly 204 locked into the extension drive assembly 206. The inner diameter of the button may be chamfered at the leading edge to allow for easy connection to the extension drive housing 322. The alignment recess 316 may include a semicircular notch or a recess of other preferred shape along the inner surface of the nearest edge of the drive collar 282.

[0063] The front portion of the drive collar 282 houses a ball seal 286. The ball seal 286 may include a smooth ring that allows for uniform force distribution to ensure a secure seal when the insertion subassembly 202 is mounted to the outer drive subassembly 204. When the proximal portion 236 of the insertion subassembly seats within the distal end of the drive collar 282, the ball seal 286 fits into a groove 237 within the proximal portion 236 of the outer tube 220. As best shown in Figure 16C, the drive collar 282 further defines four notches 318 on its most distal surface. The notches 318 are configured to work in conjunction with a pin 239 on the rear surface of the insertion subassembly 202. The four notches 318 may be evenly and symmetrically distributed around the cavity to provide a precise alignment function. The four notches 318 may be cut into the wall of the drive collar 282, extending radially outward at 90-degree intervals. Each notch 318 may have a uniform depth and width, and the notches 318 interact with the corresponding pins 239 on the proximal portion 236 of the outer tube 220 to lock the implant 10 into one of four possible offset orientations relative to the instrument 200.

[0064] Referring here to Figures 17 to 20B, the expansion subassembly 206 is shown in more detail. The expansion subassembly 206 includes an inner drive unit 320 and a housing 322 having a cap 324, the housing 322 including an internal expansion mechanism 326 configured to control both the inner drive unit 320 and the outer drive unit 280. The inner drive unit 320 includes an elongated shaft configured to extend through the outer drive unit 280. The inner drive unit 320 includes a distal drive tip 330 configured to engage with the actuator screw 22 of the implant 10. The distal drive tip 330 may be configured to fit into an instrument recess 146 (e.g., a hexagonal recess) of the proximal end 140 of the actuator screw 22 to apply torque to the actuator screw 22. The drive tip 330 may have a reduced diameter compared to the shaft 320. The proximal end 332 of the shaft 320 may also include a reduced diameter portion that fits into the end of the inner shaft 350. The inner drive unit 320 defines an elongated slot 334 for receiving a pin 336 to secure the inner drive unit 320 to the inner shaft 350. The inner drive unit 320 may be spring-biased to the inner shaft 350 via a spring 338.

[0065] The housing 322 of the expansion drive unit subassembly 206 may include an elongated support structure having a closed proximal end 340 and an open distal end 342 for receiving the proximal end 332 of the internal drive unit 320. The housing 322 may be perforated, for example, with circular holes 344 to reduce material weight while maintaining structural integrity. The housing 322 may be made from a lightweight material such as aluminum. The housing 322 defines an internal cavity having guides, mounting points, or strategic locations configured to house and secure components of the internal expansion mechanism 326. The housing 322 further defines one or more elongated windows 346 for observing the movement of one or more indicators 420, 422.

[0066] The housing 322 may be completely enclosed via a cap 324 that can be removed when the outer drive subassembly 204 is removed. The cap 324 may include a similar circular perforation 344. The removable cap 324 exposes the expansion mechanism 326 for cleaning. In exemplary embodiments, none of these small components can be disassembled without special tools to prevent loss during sterilization. This configuration can help prevent unnecessary disassembly and / or loss of parts in hospital sterilization. The cap 324 can also help prevent fingers or gloves from getting caught in the gear mechanism during use of the instrument.

[0067] The internal expansion mechanism 326 may include an inner shaft 350 configured to engage with an inner drive unit 320, an outer drive unit gear 352 configured to engage with an outer drive unit 280, an input gear 354 that transmits torque from the handle 208 to the inner shaft 350 and / or the outer drive unit gear 352, a parallel gear shaft 356 that transmits torque from the input gear 354 to the outer drive unit gear 352, and a switch assembly 358 that toggles between parallel expansion and forward expansion.

[0068] The inner shaft 350 includes a proximal end 360 that is interlocked with an input gear 354 and a distal end 362 that is interlocked with an inner drive unit 320. The proximal end 360 defines a drive recess 364 configured to receive a hexagonal drive 398 of the input gear 320. The distal end 362 defines a hole 366 configured to receive the proximal end 332 of the inner drive unit 320. The central portion of the inner shaft 350 may be threaded with male threads 368. The proximal end 360 includes a toothed member 370 having a rearward-facing tooth 372 configured to engage with a tooth 402 on a parallel expansion gear 404 and a forward-facing tooth 374 configured to engage with a tooth 412 on an anti-rotation gear 410.

[0069] The inner shaft 350 partially extends through the outer drive gear 352. The outer drive gear 352 includes an outer spur gear 378 that interlocks with a corresponding spur gear 426 on the parallel gear shaft 356, thereby transmitting torque from the parallel gear shaft 356 to the outer drive gear 352. The distal end of the outer drive gear 352 includes an outer drive unit, for example, an outer hexagonal drive unit 380, which interlocks with an internal drive recess 296 (e.g., a hexagonal recess) on the outer drive unit 280, thereby transmitting torque to the outer drive unit 280. The proximal end of the outer drive gear 352 may include one or more longitudinal slots 384, thereby providing access to the inner shaft 350. The outer drive gear 352 may be held by bushings 386 and retaining rings 388 positioned on either side of the spur gear 378.

[0070] The input gear 354 transmits torque from the handle 208 to the inner shaft 350 and / or the outer drive gear 352. The input gear 354 includes a proximal collar 390 that is flush with the end of the housing 322 and defines a drive recess 392 configured to receive a mounting interlock 214 of the torque limiting handle 208. The handle 208 can be fixed to the input gear 354 using a quick-connect ball seal 394 or other suitable quick-connect mechanism. The input gear 354 includes a spur gear 396 configured to interlock with a corresponding spur gear 424 on a parallel gear shaft 356, thereby transmitting torque to the outer drive gear 352. The distal end of the input gear 354 includes a shaft having an outer drive unit, for example, an outer hexagonal drive 398, configured to transmit torque to the inner shaft 350 when engaged. The shaft of the input gear 354 is configured to pass through a parallel expansion gear 400 having teeth 402 configured to interlock with the rearward teeth 372 of a toothed member 370. The parallel extension gear 400 may be biased via a spring 404. The parallel extension gear 400 slides along a hexagonal drive 398 on the input gear 354 and, when engaged, allows the input torque to be transmitted to the inner shaft 350. The input gear 354 rotates within a bushing 406 in the housing 322 and is assembled with a retaining ring 408, such as a C-clip or C-shaped ring.

[0071] The anti-rotation gear 410 is positioned on the opposite side of the toothed member 370 to prevent rotation of the inner shaft 350. The anti-rotation gear 410 has teeth 412 configured to engage with the forward teeth 374 of the toothed member 370. The anti-rotation gear 410 is spring-biased along the inner shaft 320 via a spring 414. As the anti-rotation gear 410 slides backward under spring bias from the housing 322, the teeth 412 engage with the forward teeth 374 of the inner shaft, further preventing rotation of the inner shaft 350.

[0072] The inner shaft 350 may support one or more indicators 420, 422. The indicators 420, 422 may include rings that move along the inner shaft 350 to indicate the degree of parallel expansion and / or lordosis expansion. The indicators 420, 422 may have truncated female threads that engage with the threaded portion 368 of the inner shaft 350. For example, the first expansion indicator 420 may be positioned along the threaded portion 368 of the inner shaft 350 to indicate parallel expansion, and the second expansion indicator 422 may be positioned along the outer drive gear 352 to indicate lordosis expansion. The indicators 420, 422 enable the surgeon to measure parallel expansion and lordosis expansion without requiring the counting of rotations or the measurement of fluoroscopic images.

[0073] The parallel gear shaft 356 transmits torque from the input gear 354 to the outer drive gear 352. The parallel gear shaft 356 may include a shaft having a first spur gear 424 at one end and a second spur gear 426 at the opposite end of the shaft. The first spur gear 424 is configured to mesh with a spur gear 396 on the input gear 354, and the second spur gear 426 is configured to mesh with a spur gear 378 on the outer drive gear 352. The parallel gear shaft 356 may be fixed to the housing 322 via fasteners 428, such as set screws, at each end having bearings 430 configured to allow rotation of the parallel gear shaft 356 when transmitting torque from the input gear 354 to the outer drive gear 352.

[0074] The switch assembly 358 may include a switch 440, a mounting plate 442, a switch casing 444, and a pin 446. The switch 440 may include a toggle switch pivoting around the pin 446. The switch 440 may have a forward position (e.g., parallel mode) and a rearward position (e.g., lordosis mode). The mounting plate 442 may form part of a housing 322 having a slot for receiving the switch casing 444. The switch casing 444 may include an elongated slot 448 for receiving the end of the pin 446. When the switch 440 is switched, the switch casing 444 may move to move the parallel extension gear 400 and the anti-rotation gear 410 to engage with or disengage from the inner shaft 350.

[0075] As an example, Figures 20A and 20B show the expansion of the implant 10 when in parallel mode or lordosis mode. The inner drive unit 320 engages with the actuator screw 22, and the outer drive unit 280 engages with the forward actuator nut 24. As best shown in Figure 20A, in parallel mode, both the outer drive unit 280 and the inner drive unit 320 are rotated together clockwise to expand the implant 10 in parallel. Since they move together at the same time, the actuator screw 22 (inner drive unit 320) and the outer drive unit 280 do not move relative to each other. As best shown in Figure 20B, in lordosis mode, the outer drive unit 280 is rotated clockwise, while the inner drive unit 320 is still held to expand in lordosis (or forward expansion). The actuator screw 22 (inner drive unit 320) moves forward away from the outer drive unit 280. When only the outer drive unit 280 rotates and the inner drive unit 320 remains stationary, the actuator screw 22 (inner drive unit 320) moves forward, creating separation or distance between the actuator screw 22 (inner drive unit 320) and the outer drive unit 280.

[0076] All input torque may be transmitted to the input gear 354 via a torque limiting handle 208. The input gear 354 may house a ball seal 394 to hold the torque limiting handle 208. The end of the input gear 354 may also function as a fitting cap to protect the aluminum housing 322 during fitting. The input gear 354 rotates within a PEEK bushing 406 in the housing 322 and is assembled with a retaining ring 408. A spur gear 396 on the input gear 354 engages with a spur gear 424 on a parallel shaft 356. A spur gear 426 at the opposite end of the parallel shaft 356 engages with a spur gear 378 on an outer drive gear 352, which drives the outer shaft 280 via a hexagonal drive section 380 at its distal end. This gear train, from the input gear 354 through the parallel shaft 356 to the outer drive gear 352, may be permanently coupled so that the outer shaft 280 always rotates whenever the handle 208 is rotated. Parallel expansion and forward expansion may be determined by whether the inner shaft 320 rotates with the outer shaft 280 (parallel expansion) or whether the inner shaft 320 is held stationary (forward expansion).

[0077] The parallel mode and the lordotic expansion mode can be activated by toggling switch 440. When switch 440 is in the rear position, the instrument 200 is in lordotic mode, and when switch 440 is in the front position, the instrument 200 is in parallel expansion mode. Figures 19A and 19B show the state when switch 440 is in the rear position and the instrument 200 is in lordotic expansion mode. As described herein, the rear half of the inner shaft 350 has both forward-facing teeth 372 and backward-facing teeth 374 along the toothed member 370. These teeth 372, 374 may act as clutch plates for either transmitting rotation to the inner shaft 350 or applying reverse torque to the inner shaft 350 in response to rotation. When the inner shaft is not subjected to reverse torque, the implant 10 can expand in parallel by rotating the outer drive unit 280 independently due to frictional forces within the implant 10. The spring-driven clutch plate 370 automatically engages with this reverse torque when switched to the forward curvature extension mode.

[0078] In parallel expansion mode, switch 440 is switched forward. Switch 440 pushes the anti-rotation gear 410 forward, disengaging tooth 412 from tooth 374 on the inner shaft 350. Simultaneously, the parallel expansion gear 400 shifts forward with switch 440 under spring bias from input gear 390, engaging tooth 402 with tooth 372 on the inner shaft 350. The parallel expansion gear 400 slides along the hexagonal drive 398 on input gear 354, allowing the input torque to be transmitted to the inner shaft 350, as well as to the parallel gear shaft 356, the outer drive gear 352, and ultimately to the outer drive unit 280 for parallel expansion.

[0079] In the lordosis extension mode, switch 440 is switched to the rear. Switch 440 pushes the parallel extension gear 400 to the rear, disengaging teeth 402 from teeth 372 of the inner shaft 350. This prevents the input torque from engaging with the inner shaft 350. At the same time, the anti-rotation gear 410 slides to the rear under spring bias from the housing 322, engaging teeth 412 with teeth 374 of the inner shaft 350. The anti-rotation gear 410 may also have a flattening or keying mechanism that mates with the housing 322 and prevents the housing 322 from rotating. This provides reverse torque from a state where the inner shaft 350 can rotate, thereby providing lordosis extension.

[0080] The front half of the inner drive unit 320 may be spring-biased forward and pinned to the inside of the rear half of the inner shaft 350. The inner drive unit 320 may be spring-biased to allow the inner drive unit tip 330 to easily snap into place if it becomes misaligned, and to ensure that the inner drive unit tip 330 remains engaged with the implant actuator screw 22 when the implant 10 moves from a parallel position to a forward-curved position and the actuator screw 22 moves away from the outer drive unit 280.

[0081] As best shown in Figure 18C, the expansion drive housing 322 may include two windows 346 for observing the movement of a parallel expansion indicator 420 and a lordosis indicator 422. Both of these indicators 420, 422 may be screwed onto the rear half of the inner shaft 350. The parallel expansion indicator 420 may have a flat portion that prevents rotation relative to the housing 422, so that the indicator 420 translates along the inner shaft 350 whenever the inner shaft 350 is rotated. The inner shaft 350 rotates only during parallel expansion, and therefore this translation can be used to indicate the amount of parallel expansion in the implant 10. The lordosis indicator 422 has threads that slide on the outer drive gear 352 and engage with the threads 368 of the inner shaft 350 by reaching through a slot 384 of the outer drive gear 352. The lordosis indicator 422 translates along the inner shaft 350 when there is relative rotation between the inner shaft 350 and the outer shaft 352. This occurs only when the outer drive unit 280 is rotated for lordosis expansion, and therefore this translation can be used to indicate the amount of lordosis in the implant 10. Both indicators 420, 422 may include truncated threads and spring releases to allow the indicators 420, 422 to jump over the threads 368 of the inner shaft 350 when they reach the end of their movement. This can help prevent the expansion subassembly 206 from becoming immobile if the indicators 420, 422 are not reset to zero before use. In other words, the ability of the indicators 420, 422 to jump over the threads when they hit the end of their movement prevents the inserter from becoming immobile and preventing expansion if the surgical team forgets to reset the indicators 420, 422 before the procedure.

[0082] The user can instantly switch between parallel expansion and lordosis expansion by simply toggling switch 440. This allows the surgeon to precisely fit the implant 10 to the patient's anatomical structure, thereby avoiding the additional cognitive burden on the surgeon from complex instruments. The internal expansion mechanism 326 allows parallel expansion and lordosis expansion to be performed by rotating the handle 208 in the same direction. Both the internal drive unit 280 and the external drive unit 320 are spring-driven, allowing for easy engagement with the implant 10. This reduces the surgical time required to align the drive units 280 and 320 with the implant 10.

[0083] The instrument 200 can be disassembled into multiple parts, allowing access to all areas that are difficult to clean. The instrument 200 can be completely disassembled without the need for tools, and the disassembled components are large enough to ensure that no components are lost or damaged during the cleaning process. The modular design also ensures that the instrument 200 can be easily repaired without having to discard most of the expensive instrument.

[0084] Although the present invention is 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 modifications and variations of the invention, provided that they remain within the scope of the appended claims and their equivalents. For example, it is explicitly intended that all components of the various devices disclosed above can be combined or modified in any preferred configuration.

Claims

1. An expandable implant, Upper end plate and lower end plate configured to engage with adjacent vertebrae, An actuator assembly for extending the upper and lower end plates to independently control the forward and rearward heights of the implant, comprising: a movable forward actuator, a movable rear actuator, and a stationary rear actuator positioned between the upper and lower end plates; an actuator screw that screws into a forward actuator nut located within the movable forward actuator and a rear actuator nut located within the stationary rear actuator, wherein the actuator screw screws through the movable rear actuator to translate the movable rear actuator, and the upper and lower end plates are interlocked with the movable forward actuator, the movable rear actuator, and the stationary rear actuator in an optimal mating ramp that slidably engages with each other to allow the extension of the upper and lower end plates, the mating ramp including a single-point contact ramp and a full-contact ramp, the actuator assembly comprising: An expandable implant wherein, when the actuator screw and the front actuator nut are turned together, the movable rear actuator moves toward the stationary rear actuator, forcing the upper end plate and the lower end plate apart to result in parallel expansion, and when only the front actuator nut is turned, the movable front actuator moves independently to increase the front height, resulting in an increase in the lordosis angle.

2. The expandable implant according to claim 1, wherein the single-point contact lamp includes a single contact point or edge along one lamp surface that contacts a corresponding lamp surface.

3. The expandable implant according to claim 1, wherein the full-contact lamp includes constant continuous contact between the lamp surfaces, thereby bearing most of the lifting force during expansion.

4. The expandable implant according to claim 1, wherein the single-point contact ramp is located near the side surface of the implant, and the full-contact ramp is located between the single-point contact ramps near the midline of the implant.

5. The expandable implant according to claim 1, wherein the forward actuator defines a pair of pin holes configured to receive a limiting pin that holds the forward actuator nut within the forward actuator.

6. The expandable implant according to claim 5, wherein the pin hole defines a threadless vertical slot that is substantially perpendicular to the longitudinal axis of the implant.

7. The expandable implant according to claim 5, wherein the limiting pin includes a solid body having an L-shaped notched end and an enlarged base at the opposite end.

8. The expandable implant according to claim 5, wherein when the implant is in its maximum expansion or lordosis, the limiting pin restricts the movement of the forward actuator assembly by contacting the surfaces of the upper end plate and the lower end plate.

9. Insertion and dilation devices, An insertion subassembly configured to be directly attached to an implant, the insertion subassembly comprising: an outer tube having a threaded rod and a non-threaded rod on both sides; and an insertion collar for receiving the outer tube, the threaded rod, and the non-threaded rod; An outer drive unit subassembly having an outer drive unit that can be positioned through the outer tube and a drive collar attached to the outer tube, An expansion subassembly comprising: an inner drive unit positionable through the outer drive unit; and a housing having a removable cap that houses an internal expansion mechanism configured to control both the inner drive unit and the outer drive unit, wherein the internal expansion mechanism includes an inner shaft configured to engage with the inner drive unit; an outer drive unit gear configured to engage with the outer drive unit; an input gear for transmitting torque to the inner shaft and / or the outer drive unit gear; and a switch assembly for switching between a parallel expansion mode and a forward expansion mode, An insertion and expansion device comprising a torque limiting handle configured to transmit torque to the input gear.

10. The insertion and expansion device according to claim 9, wherein the expansion mechanism rotates the inner drive unit and the outer drive unit simultaneously in parallel expansion mode, and rotates only the outer drive unit while the inner drive unit remains stationary in lordotic expansion mode.

11. The insertion and expansion device according to claim 9, wherein the internal expansion mechanism includes a parallel expansion gear defining teeth, an anti-rotation gear defining teeth, and an inner shaft including a toothed member having forward-facing teeth configured to interlock with the teeth of the anti-rotation gear and backward-facing teeth configured to interlock with the teeth of the parallel expansion gear.

12. The insertion and expansion device according to claim 11, wherein the switch assembly includes a switch, a mounting plate attached to the housing, a switch casing positioned within the mounting plate and having an elongated slot, and a pin connecting the switch to the elongated slot of the switch casing, wherein when the switch is switched, the switch casing moves to move the parallel expansion gear and the anti-rotation gear to engage with or disengage the toothed member of the inner shaft.

13. The insertion and expansion device according to claim 9, wherein the internal expansion mechanism includes a parallel gear shaft aligned parallel to the inner shaft, the parallel gear shaft includes spur gears at each end, the input gear includes a spur gear that interlocks with the spur gear at one end of the parallel gear shaft, and the outer drive gear includes a spur gear that interlocks with the spur gear at the other end of the parallel gear shaft, thereby transmitting motion from the input shaft through the parallel gear shaft to the outer drive gear.

14. An insertion and expansion device according to claim 13, wherein a parallel expansion indicator is positioned along the threaded portion of the inner shaft, and a lordotic expansion indicator is positioned along the outer drive gear, and the housing defines a pair of windows for visualizing the movement of each indicator, thereby indicating the amount of parallel expansion and / or lordotic expansion.

15. The insertion and expansion device according to claim 9, wherein the inner drive unit and the outer drive unit are spring-biased forward to maintain engagement with the implant.

16. The insertion and expansion device according to claim 9, wherein the drive collar defines four notches at 90-degree intervals, the notches are configured to engage with pins on the outer tube of the insertion subassembly, thereby locking the implant into one of four possible offset orientations.

17. The insertion and expansion device according to claim 9, wherein the outer tube includes a proximal plate defining a pair of holes and a distal plate defining a pair of holes, each of which is used to secure the threaded rod and the unthreaded rod to the outer tube, and the distal plate includes a distal surface configured to contact the implant when the distal ends of the threaded rod and the unthreaded rod engage with the implant.

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