Intervertebral spacer system having an integrated ramp expansion mechanism and stepped ratchet locking mechanism
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- INGENIUM SPINE LLC
- Filing Date
- 2023-12-22
- Publication Date
- 2026-07-21
AI Technical Summary
Existing intervertebral spacers face challenges in maintaining the desired lordotic angle and ensuring robust locking mechanisms that withstand compressive forces while maximizing bone graft material contact, often compromising spacer size and durability.
An expandable intervertebral spacer system with an integrated expansion mechanism and ratcheting locking mechanism, featuring upper and lower plates connected by a hinge, ramps for expansion, and a ratchet locking mechanism with sawtooth posts secured by a torsion spring, allowing for controlled expansion and secure locking.
The system effectively maintains the desired lordotic angle and ensures strong, durable locking, maximizing bone graft material exposure and contact with vertebrae, while withstanding compressive forces over the patient's lifetime.
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Abstract
Description
[Technical Field]
[0001] The present invention relates to an intervertebral spacer for orthopedic spinal surgery, and more particularly to a spinal implant system having a spacer with an integrated angled expansion mechanism and stepped ratchet locking mechanism. [Background technology]
[0002] Interbody fusion is a type of spinal surgery that removes all or part of a degenerated disc between two adjacent vertebrae in a patient's spine. After the disc is removed, an expandable device is inserted into the intervertebral space between the adjacent vertebrae to force the vertebrae apart and maintain the intervertebral space. Bone graft material is filled into and around the spacer, providing a scaffold for new bone formation. The spacer is placed between the vertebrae and secured to the vertebrae above and below with fixation devices such as screws or barbs. The spacer is effective in aligning the spine and maintaining the intervertebral space. Additional surgical instruments, such as rods, plates, hooks, and wires, can be used to support the vertebral structures during the healing process. During the healing process, the adjacent vertebrae are fused into a single, integrated structure.
[0003] The spacer is typically expanded by a removable fitting that engages an expansion mechanism within the spacer's body. The user uses the tool to incrementally expand the spacer to the appropriate height to maintain the desired intervertebral spacing. After the spacer has expanded to the appropriate height, the expansion tool is removed.
[0004] Lordosis refers to a concave, backward curvature of the spine. While some degree of spinal curvature is desirable for spinal health and patient comfort, excessively small or large curvatures can cause problems. When implanting a device between two vertebrae, the lordotic angle of the disc space being repaired must be properly set not only relative to the two surrounding vertebrae, but also relative to any adjacent vertebrae that may be affected as a result of the implantation. To achieve the desired lordotic angle, it is desirable to have an expandable intervertebral implant. .
[0005] It is desirable for the spacer to be locked at the desired height and angle after expansion. The locking mechanism must be strong enough to withstand the compressive forces between the vertebrae, and the framework must be robust enough to withstand collapse or other failure over the patient's lifetime. While strength and durability are extremely important, a balance must be struck because making the spacer unnecessarily rigid compromises the size of the cavity within the spacer to hold the bone graft material.
[0006] It is an object of the present invention to provide an expandable lordotic interbody spacer system having an integrated expansion mechanism and ratcheting locking mechanism, which is expanded by a mating expansion instrument. Another object of the present invention is to maximize the contact surface between the bone graft material and the patient's vertebrae and tissue. Summary of the Invention [Means for solving the problem]
[0007] The expandable intervertebral spacer system has an integrated expansion mechanism, a ratcheting locking mechanism, and a mating expansion tool. The spacer has upper and lower plates forming a cage surrounding a cavity. The top, bottom, and sides of the cage have openings for receiving bone graft material. An upper angled portion extends from the upper plate into the cage, and optionally, a lower angled portion extends from the lower plate into the cage. The upper and lower plates are connected to each other at the proximal end of the cage by a hinge, which allows the upper plate to be forced away from the lower plate and lock the plates at a predetermined angle relative to each other.
[0008] The cage is expanded by the interlocking expansion device, which inserts a push rod into an opening at the proximal end of the cage, forcing it against a ramp or ramps within the cage. As the push rod extends distally within the cage, the tip of the push rod and the ramps cooperate to force the upper and lower plates apart, causing them to become non-parallel.
[0009] A support post secures the upper and lower plates at a desired distance or angle. The support post is comprised of a rotatable upper post and a fixed lower post, which use a ratchet locking mechanism to secure the upper plate at a predetermined angle relative to the lower plate. The upper and lower posts have interlocking sawtooth teeth and are biased together by a torsion spring. Optionally, the posts are surrounded by a sheath to prevent bone chips and other debris from blocking the interlocking sawtooth teeth.
[0010] In some embodiments, the insertion tool is configured to cooperate with a movable post to unlock the serrations and allow the spacer to return to its unexpanded state. [Brief explanation of the drawings]
[0011] [Figure 1] FIG. 1 is a top perspective view of a first embodiment of a spacer in an unexpanded configuration as viewed from its distal end. [Figure 2] FIG. 2 is a top perspective view of the spacer of FIG. 1 as viewed from the proximal end. [Figure 3] FIG. 3 is a side view of the spacer of FIG. [Figure 4] FIG. 4 is a side view of the spacer of FIG. 1 without the sheath. [Figure 5] FIG. 5 is a top view of the spacer of FIG. [Figure 6] 6 is a top view of the spacer of FIG. 1 taken along line AA of FIG. [Figure 7] 7 is an end view of the distal end of the spacer of FIG. 1. FIG. [Figure 8] FIG. 8 is a top perspective view from the distal end of the spacer of FIG. 1 shown in an expanded configuration and without the sheath. [Figure 9] FIG. 9 is a top perspective view of the spacer of FIG. 8 as viewed from the proximal end. [Figure 10] FIG. 10 is a side view of the spacer of FIG. [Figure 11] FIG. 11 is a side view of the spacer of FIG. 9 without the sheath. [Figure 12] FIG. 12 is a top view of the spacer of FIG. [Figure 13] 13 is a top view of the spacer of FIG. 1 taken along line BB of FIG. [Figure 14] 14 is an end view of the distal end of the spacer of FIG. 9. FIG. [Figure 15] FIG. 15 is a top perspective view of the distal end of a second embodiment of a spacer in an unexpanded configuration. [Figure 16] FIG. 16 is a top perspective view of the spacer of FIG. 15 as viewed from the proximal end. [Figure 17]17 is a side view of the spacer of FIG. 15. FIG. [Figure 18] FIG. 18 is a side view of the spacer of FIG. 15 without the sheath. [Figure 19] FIG. 19 is a top view of the spacer of FIG. [Figure 20] 20 is a top view of the spacer of FIG. 15 taken along line CC of FIG. 17. FIG. [Figure 21] 21 is an end view of the distal end of the spacer of FIG. 15. FIG. [Figure 22] FIG. 22 is a top perspective view of the distal end of the spacer of FIG. 15 in the expanded configuration. [Figure 23] 23 is a top perspective view of the spacer of FIG. 22 as viewed from the proximal end. [Figure 24] 24 is a side view of the spacer of FIG. 22. FIG. [Figure 25] FIG. 25 is a side view of the spacer of FIG. 22 without the sheath. [Figure 26] FIG. 26 is a top view of the spacer of FIG. [Figure 27] 27 is a top view of the spacer of FIG. 22 taken along line DD of FIG. 24. FIG. [Figure 28] 28 is an end view of the distal end of the spacer of FIG. 22. FIG. [Figure 29] FIG. 29 is a perspective view of the insertion tool. [Figure 30] FIG. 30 is a side view of the shaft assembly and clamp collar of the insertion tool. [Figure 31] FIG. 31 is a perspective view of a threaded clamping nut. [Figure 32] FIG. 32 is a cross-sectional top view of the clamp arm before the tab is clamped by the cage. [Figure 33] FIG. 33 is a top cross-sectional view of the clamp arm after the tab has been clamped by the cage. [Figure 34] FIG. 34 is a top perspective view showing the clamp arm in the open state approaching the cage. [Figure 35] FIG. 35 is a top perspective view of the clamping arm in a clamping position relative to the cage. [Figure 36] FIG. 36 is a top perspective view of the clamp arm holding the cage. [Figure 37] FIG. 37 is a top perspective view of the insertion tool and the spacer of the first embodiment as viewed from the proximal end. [Figure 38] FIG. 38 is a cross-sectional side view of the insertion tool showing the push rod and spacer of the first embodiment. [Figure 39] FIG. 39 is a cross-sectional view of the insertion device of FIG. 37, showing the spacer removed. [Figure 40] FIG. 40 is a side view of the push rod extending partially into the spacer of the first embodiment. [Figure 41] FIG. 41 is a side view of a push rod extended in the spacer of the first embodiment a sufficient distance to expand the spacer to a desired height. [Figure 42] FIG. 42 is a side view of the push rod removed from the spacer of the first embodiment, with the spacer in an expanded, desired height and locked position with bone graft material. [Figure 43] FIG. 43 is a side view of the push rod and spacer of the second embodiment. [Figure 44] FIG. 44 is a cross-sectional view of the insertion tool and spacer of the second embodiment. [Figure 45] FIG. 45 is a cross-sectional view of a push rod used with the spacer of the second embodiment. [Figure 46] FIG. 46 is a side view of a push rod extending partially into a spacer of the second embodiment. [Figure 47] FIG. 47 is a side view of a push rod extended in the spacer of the second embodiment a sufficient distance to expand the spacer to a desired height. [Figure 48]FIG. 48 is a side view of the push rod removed from the spacer of the second embodiment, with the spacer in an expanded, desired height and locked position with bone graft material. [Figure 49] FIG. 49 is a side view of an unlocking cable attached to the ratchet-type locking mechanism of the spacer of the second embodiment. [Figure 50] FIG. 50 is an enlarged view of the circled area in FIG. 49, showing the unlocking cable attached to the ratchet locking mechanism. [Figure 51] FIG. 51 is a side view of an unlocking cable attached to the ratchet-type locking mechanism of the spacer of the second embodiment. [Figure 52] FIG. 52 is a side view of the insertion tool and spacer, showing the unlocking cable attached to the ratcheting locking mechanism of the second embodiment spacer. [Figure 53] FIG. 53 shows the unlocking cable shown in FIG. 52 in a state where it has been disengaged from the ratchet locking mechanism and withdrawn. [Figure 54] FIG. 54 is a schematic diagram of a portion of a strut. [Figures 55A-55D] 55A-55D are side views of locking mechanisms with different numbers of engaged saw teeth. [Figure 56] Figure 56 shows the effect of sawtooth not at 90 degrees to the strut. [Figure 57] FIG. 57 is a perspective view of a torsion spring. [Figure 58] FIG. 58 is a schematic diagram of a spacer in an unexpanded state inserted between two vertebrae. [Figure 59] FIG. 59 is a schematic illustration of the spacer of FIG. 58 in an expanded state. [Figure 60] FIG. 60 is a top view of the spacer of the third embodiment. [Figure 61] FIG. 61 is a side view of the spacer of FIG. DETAILED DESCRIPTION OF THE INVENTION
[0012] The expandable intervertebral spacer system includes a spacer 10 having an integrated expansion mechanism, an integrated ratcheting locking mechanism, and a mating insertion instrument. The spacer 10 is inserted into a patient in an unexpanded state by a removable mating insertion instrument 50. The insertion instrument 50 includes a push rod 51 and, optionally, an unlocking mechanism.
[0013] The spacer includes an upper plate 11 and a lower plate 12, which together form a cage 13 that encloses a cavity. The top, bottom, and sides of the cage 13 are provided with openings, referred to herein as cutouts 18, which allow bone graft material 44 to easily fill the cavity between the plates, thereby increasing the surface exposure of the graft material to the patient's vertebrae. In some embodiments, the cage is substantially rectangular, as shown in FIGS. 1 and 15. In another embodiment, the cage 13 is barbell-shaped, and the upper and lower plates 11, 12 have a central spine connecting the proximal hinge region and the distal ratchet region (see FIGS. 60-61).
[0014] The proximal end 15 of the cage 13 has a clamping slot 16 that is gripped by an insertion tool, as described in more detail below. The distal end 14 of the spacer 10 is the leading edge when inserting the device between vertebrae and is typically rounded to facilitate insertion. The distal end 14 is typically solid to prevent foreign material from entering the cavity from the patient's body during insertion, but may optionally have a notch. The proximal end 15 of the spacer 10 is open to accommodate an insertion tool. This opening is referred to as the device's notch 18. Bone graft material, which is filled into and around the spacer, provides a scaffold for new bone formation. This bone graft material may be cancellous bone, cortical bone, or both, and is preferably autograft or allograft tissue.
[0015] Cage 13 includes one or more ramps. In one embodiment, each ramp has a first portion connected to a second portion that extend from the plate to which the ramp is attached, forming a V-shape or solid wedge shape. The first portion of the ramp slopes into the cage from the proximal end to the distal end of the cage. The second portion of the ramp slopes away from the plate. In yet another embodiment, the ramp has a single leg that slopes from the proximal end to the distal end of the cage.
[0016] The ramps are preferably V-shaped, with no material below the apex of the V, minimizing weight and maximizing the cage's volume for bone graft material. In another embodiment, the ramps are solid wedge-shaped, with the V-shaped portion filled with material to form a triangle. The apex of the ramps can be rounded, approximating a U-shape, instead of a sharp point. Each ramp extends from the upper plate, lower plate, or both, rather than from both sides of the cage, so that the top, bottom, and sides of the cage are not solid but have cutouts 18. The cutouts 18 on the top, bottom, and all sides of the cage 13 allow the bone graft material to fill from each surface, exposing the bone graft material to the patient's vertebrae. The cutouts on the top, bottom, and all sides of the cage maximize exposure of the bone graft material to the patient's tissue.
[0017] The ramps extend inward from the top and bottom of the cage, rather than from the sides. In a first embodiment, the upper ramp 31 extends into the cavity from the upper plate 11, and the lower ramp 32 extends into the cavity from the lower plate 12 (see FIGS. 1-14). Each ramp may be the same length as the entire length of the cage from the proximal end to the distal end, or may be shorter than the entire length of the cage 13, as shown in FIGS. 1-13. Whether the ramps are located near the longitudinal centerline of the cage or on the periphery, they are preferably equidistant from the centerline.
[0018] The upper and lower plates 11, 12 are connected at the proximal end of the cage 13 by a hinge 40, which allows the upper plate 11 to be forced apart from the lower plate 12 at a predetermined angle, as described in more detail below. As shown, the hinge 40 is typically a pin hinge that fits into barrel-shaped slots in the upper and lower plates, holding the plates together and allowing them to pivot away from each other. Alternatively, two pivot hinges can be provided on either side of the proximal end of the cage to connect the plates together.
[0019] In a second embodiment, only one ramp extends into the cavity from either the upper or lower plate. In a preferred embodiment, shown in Figures 15-28, an upper ramp 31 extends into the cavity from the upper plate 11. The upper ramp 31 may be the same length as the entire cage length from proximal to distal end, or may be shorter than the entire length of the cage 13, as shown in Figures 15-27. The single ramp is located on the longitudinal centerline of the cage, which promotes uniform upward movement of the upper plate during expansion and prevents side-to-side rolling.
[0020] In another embodiment, two ramps extend into the cavity from either the upper or lower plate, and the ramps are equidistant from the longitudinal centerline of the cage, whether located near the centerline or at the periphery.
[0021] The upper plate 11 and the lower plate 12 are separated and held apart by a ratchet-type locking mechanism 19. The locking mechanism 19 provides rigid and balanced support between the plates through at least one support post 20. Each support post 20 has two sawtooth posts 21, 22 that move relative to each other and cooperate to fix the upper plate 11 at a desired angle relative to the lower plate 12 (see Figures 54 and 55). One sawtooth post 21 is movable and can rotate toward or away from the other sawtooth post 22. The sawtooth post 22 is fixed. Preferably, the movable post 21 projects from the upper plate 11 into the cage 13, and the fixed post 22 projects from the lower plate 12 into the cage 13.
[0022] Struts 21, 22 are biased toward one another by a helical torsion compression spring 25, which applies a torque or rotational force about the spring's axis to movable strut 21. The torsion spring is shown in FIG. 57. At rest, movable strut 21 is pressed against fixed strut 22 within strut 20 by torsion spring 25. As the upper and lower plates are forced apart, the torsion spring compresses, forcing struts 21, 22 apart and unlocking. Once the upper and lower plates are separated the desired distance, the torsion spring relaxes, re-engaging the sawtooth of the strut, securing the upper and lower plates at the desired distance. Some figures show an embodiment in which the coils of torsion spring 25 extend slightly above upper plate 11, thereby maximizing the open volume of cage 13. In another embodiment, the torsion spring 25 is positioned lower within the cage 13, with the coil spring either flush with the top surface of the top plate 11 or positioned below the top surface of the top plate 11.
[0023] In another embodiment, instead of torsion springs biasing posts 21, 22 together, plates 11, 12 are biased away from each other by a linear spring positioned vertically between the upper and lower plates, which forces the teeth of posts 21, 22 together and locks them into place.
[0024] Each sawtooth is generally triangular, with one side extending away from the support at an angle of approximately 90-106 degrees. This portion is referred to herein as the horizontal edge 35. In one embodiment, the horizontal edge is perpendicular to the support and parallel to the upper and lower plates 11 and 12 (see FIG. 54). In another embodiment, the horizontal edge is greater than 90 degrees relative to the support, with angle θ representing the angular difference from vertical (see FIG. 56). The angle θ represents the angular offset between a line from the center to the root and a line from the origin to the tip, where the origin is the point where the step joins the support. The other edge of the sawtooth is at a complementary angle relative to the support and is referred to herein as the beveled edge 36. The teeth of one support interlock with the teeth of the adjacent support. When the sawtooths are engaged, the horizontal edge 35 of each tooth seats against one or more horizontal edges 35 of the opposing support. This secures the upper and lower plates relative to each other, locking the plates together. The greater the angle θ between the horizontal edge 35 and the posts, the greater the force required to separate the posts 21, 22 from each other. Expanding a cage with a horizontal edge angle greater than 90 degrees requires pushing the ramps apart further to clear the lip of the steps than with a 90-degree horizontal edge. The posts then slide into engagement. Interlocking posts with angles θ greater than 0 degrees create an interlocking force that presses the steps together, improving the safety of the locking mechanism.
[0025] The asymmetrical shape of the sawtooth allows the plates to be incrementally forced apart, one sawtooth at a time, with a ratcheting motion. The cooperating shape of the sawtooth forces the posts 21, 22 apart when the upper and lower plates are forced apart by the expansion mechanism. As the upper plate is forced apart from the lower plate, the angled edges of the teeth on the upper post slide against the angled edges of the teeth on the lower post, causing the upper post to rotate away from the lower post enough to release the horizontal edges of the teeth that had been interlocking, as described in more detail below.
[0026] The height of the sawtooth determines the spacing (increment) between the plates; the lower the tooth height, the smaller the spacing at each increment. The number and height of the teeth determine the maximum spacing between the plates. At maximum extension, it is preferred that at least two teeth are engaged on each strut.
[0027] The width of the posts 20 varies depending on the size of the spacer and ranges from approximately 2 mm to 6 mm. In one embodiment, the horizontal edge 35 of each sawtooth is 1.5 mm deep and 4 mm wide. Assuming two sawtooths engage per post, the minimum total contact area is 6 mm. 2 (2 sawtooth x 1.5mm deep x 4mm wide). If the compressive strength of titanium alloy is 850MPa, the breaking load will be 10,200N. Therefore, the locking mechanism can withstand the compressive force between the vertebrae and the cage without causing breakage or other failure of the spacer over the patient's lifetime.
[0028] To minimize the number of moving parts and maximize tooth size and therefore compressive strength, it is preferable to space and secure the plates with a single post at the distal end. In some embodiments, two posts can be used, for example, one post at each corner of the distal end of the cage.
[0029] Optionally, to prevent bone chips and other debris from blocking the engagement of the saw teeth, each post or entire locking mechanism can be surrounded by a sheath 24. The sidewall thickness of the sheath 24 is preferably less than 1 mm.
[0030] The spacer 10 is inserted into the patient in an unexpanded state by a removable insertion tool 50 (see FIGS. 29 and 37). The insertion tool 50 has clamp arms 55 and 56, a push rod 51, and optionally an unlocking cable within a hollow shaft 52 that serves as a lumen through which the insertion tool components act on the spacer. In a preferred embodiment, the push rod 51 is positioned within the hollow shaft between and coaxially with the clamp arms. The unlocking cable may be positioned within the hollow shaft to the side of or between the clamp arms, but preferably passes through a central lumen of the insertion tool.
[0031] Clamp arms 55 and 56 are shown in Figures 29-36. The clamp arms have tabs at the ends that fit into clamp slots 16 at the proximal end of cage 13, allowing the insertion tool to securely hold the cage during insertion and release the cage after insertion. The tabs on the clamp arms are inserted into the clamp slots and closed by moving clamp collar 57 toward the end of the clamp arm. Clamp collar 57 is moved on the clamp arm by rotating threaded cylindrical portion 58. Rotating cylindrical portion 58 in a first direction moves collar 57 toward the cage, clamping the tabs within the cage's clamp slots. Rotating cylindrical portion 58 in the opposite direction moves collar 57 away from the cage, releasing the tabs from the cage's clamp slots.
[0032] The cage is clamped by an insertion tool and inserted between two vertebrae of the patient. The cage is movable between a collapsed configuration in which the upper and lower plates are parallel and an expanded configuration in which the upper and lower plates are not parallel. During expansion, the plates 11 and 12 separate at their distal ends, forming an opening, referred to herein as the notch 18. The threaded handle 54 is rotated to extend the push rod 51 into the cage 13, achieving expansion. The push rod does not rotate but moves within the hollow shaft 52 toward the cage. The distal end of the push rod is wide enough to cooperate with the bevel or bevels and accommodate the opening in the proximal end of the cage. The distal end of the push rod is preferably rounded, but may also be pointed or flat.
[0033] A push rod 51 fits into each embodiment. In a first embodiment of a spacer with two ramps, the push rod 51 has an articulated end, as shown most clearly in Figures 38 and 39. As the push rod 51 is extended into the cage, the articulated tip rides up onto the lower ramp 32 between the upper and lower ramps, forcing the upper and lower plates apart (see Figures 40-41). After the upper and lower plates are secured at the desired angle, the push rod 51 is withdrawn (see Figure 42). Bone graft material 44 is then filled into the spacer.
[0034] In a second embodiment of a spacer having a single ramp, as shown in Figures 43-45, the push rod 51 preferably does not have an articulated end. As the push rod 51 is extended into the cage, it slides along the lower plate 12 below the upper ramp 31, forcing the upper and lower plates apart as it moves distally within the cage (see Figures 46-47). After the upper and lower plates are secured at the desired angle, the push rod 51 is withdrawn (see Figure 48). Bone graft material 44 is then filled into the spacer.
[0035] Optionally, an unlocking cable 53 is disposed within the cannulated push rod 51 (see FIGS. 49-52). The unlocking cable 53 is attached to the movable post 21 by a connection 61. The connection is preferably threaded, although other fastening means may be used. When the cable is pulled proximally, the movable post 21 rotates away from the fixed post 22, disengaging the saw teeth, which returns the upper plate to a lower position relative to the lower plate, reducing the angle between the plates. To remove the cable from the post, the cable is unlocked and pulled out of the cage (FIG. 53).
[0036] After the spacer is in the desired position, the threaded barrel is rotated to release the clamping arms from the cage and the insertion tool is removed from the patient.
[0037] Spacers are made of biocompatible materials, typically titanium or titanium alloys, and are available in a variety of sizes. Spacers typically measure 26-30 mm in length and 10-11 mm in width. Table 1 shows exemplary size ranges, and the spacer height (h), width (w), and length (l) are shown in Figures 4 and 5.
[0038] [Table 1]
[0039] While the general shape of the vertebrae 9 is consistent across patients, the specific size, shape, lordosis, and condition of the cancellous bone vary from patient to patient. The size, shape, and placement of the spacer are influenced by these biological factors. Each plate can be flat, concave, or convex, depending on the shape that most closely resembles the surface curvature of the patient's vertebrae.
[0040] Figure 58 shows a single unexpanded spacer 10 inserted between two vertebrae 9 spaced a distance d1 apart. Figure 59 shows a single spacer 10 in an expanded state between two vertebrae 9, forcing the vertebrae 9 apart by a distance d2 and an angle α1.
[0041] While there have been shown and described what are presently considered to be the preferred embodiments of the invention, those skilled in the art will recognize that various changes and modifications can be made thereto without departing from the true scope of the invention, and that equivalents may be substituted for elements of the invention. It is therefore intended that the invention not be limited to the particular embodiments disclosed, but rather that it will include all embodiments that fall within the scope of the appended claims.
Claims
1. 1. An expandable intervertebral spacer system, comprising: a) upper and lower plates forming a cage having a proximal end, a distal end, a top, a bottom, and four sides; b) a first ramp extending from the upper plate or the lower plate of the cage into the cage; c) a hinge connecting the upper plate and the lower plate at the proximal end; d) struts disposed at the distal end, the struts comprising a movable strut having sawtooth and a fixed strut having sawtooth; e) a torsion spring configured to bias the movable strut against the fixed strut, whereby the movable strut and the fixed strut cooperate to secure the upper and lower plates a desired distance apart; and A system having:
2. 10. The system of claim 1, wherein the top, bottom, and at least three of the four sides of the cage have cutouts.
3. 2. The system of claim 1, wherein the torsion spring exerts a rotational force on the movable post about its longitudinal axis.
4. 10. The system of claim 1, wherein the cage has a longitudinal centerline, and the first ramp is located on the centerline.
5. 10. The system of claim 1 further comprising: a second ramp extending into the cage from the same plate from which the first ramp extends; The cage has a longitudinal centerline, and the first and second ramps are positioned on opposite sides of the centerline and spaced equidistant from the centerline.
6. 10. The system of claim 1 further comprising: a removable insertion instrument having an extendable push rod insertable from the proximal end between the upper and lower plates and cooperating with the first ramp to force the upper and lower plates apart.
7. 7. The system of claim 6, wherein the insertion tool further comprises: The system further comprises an unlocking cable that removably engages with the movable post.
8. 10. The system of claim 1, wherein the cage is movable between a collapsed configuration and an extended configuration, and in the extended configuration, the upper plate and the lower plate are non-parallel.
9. 1. An expandable intervertebral spacer system, comprising: a) upper and lower plates forming a cage having a proximal end and a distal end; b) a first ramp extending from the upper plate or the lower plate into the cage; c) a second ramp extending into the cage from the other of the upper plate or the lower plate, the second ramp extending from a different plate than the first ramp extending from, the cage having a longitudinal centerline, the first and second ramps being disposed parallel to the longitudinal centerline; and d) a hinge connecting the upper plate and the lower plate at the proximal end; e) struts disposed at the distal end, the struts including a movable strut with sawtooth and a fixed strut with sawtooth; f) a torsion spring configured to bias the movable strut against the fixed strut, whereby the movable strut and the fixed strut cooperate to secure the upper plate and the lower plate a desired distance apart; and A system having:
10. 1. An expandable intervertebral spacer system, comprising: A spacer, a) upper and lower plates forming a cage having a proximal end, a distal end, a top, a bottom, and four sides; b) a first sloped portion extending from an upper portion of the cage into the cage, and a second sloped portion extending from a lower portion of the cage into the cage; c) a hinge connecting the upper plate and the lower plate at the proximal end; d) struts disposed at the distal end, the struts comprising a movable strut having sawtooth and a fixed strut having sawtooth; e) a torsion spring configured to bias the movable strut against the fixed strut, whereby the movable strut and the fixed strut cooperate to secure the upper and lower plates a desired distance apart; and A system having:
11. 11. The system of claim 10, wherein the top, bottom, and at least three of the four sides of the cage have cutouts.
12. 11. The system of claim 10, wherein the torsion spring exerts a rotational force on the movable post about its longitudinal axis.
13. 11. The system of claim 10, further comprising: a removable insertion instrument having an extendable push rod with a distal end, the push rod insertable from the proximal end between the upper and lower plates and cooperating with the first ramp to force the upper and lower plates apart.
14. 14. The system of claim 13, wherein the insertion tool further comprises: The system further comprises an unlocking cable that removably engages with the movable post.
15. 11. The system of claim 10, wherein the spacer is movable between a collapsed configuration and an expanded configuration, and in the expanded configuration, the upper plate and the lower plate are non-parallel.
16. 1. An expandable intervertebral spacer system, comprising: a) an upper plate having an upper sloped portion extending toward a lower plate; b) the lower plate having a lower sloped portion extending toward the upper plate, the upper plate and the lower plate forming a cage having a proximal end and a distal end; c) a hinge connecting the upper plate and the lower plate at the proximal end; d) a strut disposed at the distal end, the strut comprising a movable strut with sawtooth and a fixed strut with sawtooth; e) a torsion spring configured to bias the movable strut against the fixed strut, such that the movable strut and the fixed strut cooperate to secure the upper and lower plates a desired distance apart; and a removable insertion tool having an extendable push rod with a distal end, the push rod insertable from the proximal end between the upper and lower plates and cooperating with the first ramp to force the upper and lower plates apart; and and The push rod has an articulated structure at the tip end. system.
17. 1. An expandable intervertebral spacer system, comprising: a) upper and lower plates forming a cage having a proximal end, a distal end, a top, a bottom, and four sides; b) a ramp extending from the upper plate or the lower plate of the cage into the cage; c) a hinge connecting the upper plate and the lower plate at the proximal end; d) a strut disposed at the distal end, the strut comprising a movable strut with sawtooth and a fixed strut with sawtooth; e) a torsion spring configured to bias the movable strut against the fixed strut, whereby the movable strut and the fixed strut cooperate to secure the upper and lower plates a desired distance apart; and f) a removable insertion tool having an extendable push rod insertable from the proximal end between the upper and lower plates and cooperating with the ramp to force the upper and lower plates apart; and A system having:
18. 18. The system of claim 17, wherein the top, bottom, and at least three of the four sides of the cage have cutouts.
19. 18. The system of claim 17, wherein the insertion tool further comprises: The system further comprises an unlocking cable that removably engages with the movable post.
20. 18. The system of claim 17, wherein the cage is movable between a collapsed configuration and an expanded configuration, and in the expanded configuration, the upper plate and the lower plate are non-parallel.
21. 1. An expandable intervertebral spacer system, comprising: a) upper and lower plates forming a cage having a proximal end, a distal end, a top, a bottom, and four sides; b) a ramp extending into the cage from the top or bottom of the cage; c) a hinge connecting the upper plate and the lower plate at the proximal end; d) struts disposed at the distal end, the struts including a movable strut with sawtooth and a fixed strut with sawtooth; i) each sawtooth has a horizontal edge; ii) the horizontal edges of the sawtooth on the fixed post are at an angle of greater than 90 degrees to the fixed post; iii) the horizontal edges of the serrations on the movable post are inclined relative to the movable post at an angle complementary to the serrations on the fixed post; The support pillar; e) a torsion spring configured to bias the movable strut against the fixed strut, whereby the movable strut and the fixed strut cooperate to secure the upper and lower plates a desired distance apart; and A system having: