US20230013496A1

US20230013496A1 - Adjustable spinal implants, associated instruments and methods

Info

Publication number: US20230013496A1
Application number: US17/865,736
Authority: US
Inventors: Guntmar Eisen; Markus Salvermoser
Original assignee: Blue Ocean Spine GmbH
Current assignee: Blue Ocean Spine GmbH
Priority date: 2021-07-16
Filing date: 2022-07-15
Publication date: 2023-01-19
Also published as: US20230015512A1

Abstract

The present disclosure provides adjustable spinal devices, instruments for implanting the spinal devices, methods for adjusting the height and/or lordosis angles of the spinal devices and methods for implanting such devices. An adjustable spinal fusion device includes an upper plate having an outer surface for placement against a first vertebral body and a lower plate having an outer surface for placement against a second vertebral body. The device further includes a first translation member configured to move longitudinally relative to the upper and lower plates to adjust a distance between the upper and lower plates and a second translation member configured to move longitudinally relative to the upper and lower plates to adjust an angle between the upper and lower plates.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. Nos. 63/222,482, 63/222,498 and 63/222,506, all of which were filed Jul. 16, 2021, and European Patent Application Nos. 21186249.5, 21186250.3 and 21186251.1, all of which were filed Jul. 16, 2021, the complete disclosures of which are incorporated herein by reference in their entirety for all purposes.

FIELD

The present disclosure relates to implantable devices for stabilizing and/or promoting the fusion of adjacent bony structures and, more particularly, to implantable spinal fusion cages that can adjust in height and angle to accommodate spacing constraints and/or address lordosis within an intervertebral space.

BACKGROUND

Implantable spinal devices can be used to treat a variety of spinal disorders, including degenerative disc disease. For example, in one type of spinal disorder, the intervertebral disc has deteriorated or become damaged due to acute injury or trauma, disc disease or simply the natural aging process. The standard treatment today may involve surgical removal of a portion, or all, of the diseased or damaged intervertebral disc in a process known as a partial or total discectomy, respectively. The discectomy is often followed by the insertion of an interbody cage or spacer to stabilize this weakened or damaged spinal region and/or to restore disc height. This cage or spacer serves to reduce or inhibit mobility in the treated area, in order to avoid further progression of the damage and/or to reduce or alleviate pain caused by the damage or injury. Moreover, these types of cages or spacers serve as mechanical or structural scaffolds to restore and maintain normal disc height, and in some cases, can also provide a space for inserting bone graft material to promote bony fusion between the adjacent vertebrae.
One of the current challenges of these types of procedures is the very limited working space afforded the surgeon to manipulate and insert the cage into the intervertebral area to be treated. Access to the intervertebral space requires navigation around retracted adjacent vessels and tissues such as the aorta, vena cava, dura and nerve roots, leaving a very narrow pathway for access. The opening to the intradiscal space itself is also relatively small. Hence, there are physical limitations on the actual size of the cage that can be inserted without significantly disrupting the surrounding tissue or the vertebral bodies themselves.
Further complicating the issue is the fact that the vertebral bodies are not positioned parallel to one another in a normal spine. There is a natural curvature to the spine due to the angular relationship of the vertebral bodies relative to one another. The ideal interbody fusion cage must be able to accommodate this angular relationship of the vertebral bodies, or else the cage will not sit properly when inside the intervertebral space. An improperly fitted cage would either become dislodged or migrate out of position, and lose effectiveness over time, or worse, further damage the already weakened area.
Another challenge with implanting interbody fusion cages is that, in order to insert the cage between the adjacent vertebra, at least a portion, if not all, of the intervertebral disc is removed to make room for the cage. The removal of the entire disc or disc portion disrupts the normal lordotic or kyphotic curvature of the spine. Traditional fusion cages do not attempt to correct this curvature, and over time as the vertebrae settle around the implanted cages, kyphotic deformity results.
It is therefore desirable to provide implantable spinal devices that have the ability to maintain and restore the normal anatomy of the fused spine segment. It is particularly desirable to provide interbody cages or spacers that not only have the mechanical strength or structural integrity to restore disc height or vertebral alignment to the spinal segment to be treated, but also can easily pass through the narrow access pathway into the intervertebral space, and accommodate the angular constraints of this space and/or correct the lordotic or kyphotic curvature created by removal of the disc.

SUMMARY

The present disclosure provides adjustable spinal devices and instruments for implanting the spinal devices. The present disclosure further provides methods for adjusting the height and/or lordosis angles of the spinal devices and methods for implanting such devices.
In one aspect, an adjustable spinal fusion device includes an upper plate component having an outer surface for placement against an endplate of a vertebral body and a lower plate component having an outer surface for placement against an endplate of a vertebral body. The device further includes a first translation member configured to move longitudinally relative to the upper and lower plates to adjust a distance between the upper and lower plates (i.e., the height of the implant); and a second translation member configured to move longitudinally relative to the upper and lower plates to adjust an angle between the upper and lower plates (i.e., the angle of lordosis of the implant). Thus, the device has a first configuration for advancing through a narrow access pathway into the intervertebral space, and a second configuration, wherein the device may be adjusted in height and/or angle to accommodate the angular constraints of this space and/or correct the lordotic or kyphotic curvature.
In embodiments, the first and second translation members are coupled to each other such that longitudinal movement of the first translation member causes longitudinal movement of the second translation member to adjust both the distance and angle between the upper and lower endplates.
In embodiments, the first translation member includes a first movable wedge having at least one angled surface. The upper and lower endplates each comprise a ramp for cooperating with the angled surface of the first movable wedge such that longitudinal movement of the first movable wedge adjusts a distance between at least a proximal portion of the upper and lower endplates. In one such embodiment, the upper and lower endplates each comprise first and second ramps extending towards each other in the proximal direction and the movable wedge comprises first and second upper angled surfaces for cooperating with the first and second ramps of the upper endplate and first and second upper angled surfaces for cooperating with the first and second ramps of the lower endplate.
In embodiments, longitudinal movement of the second translation member relative to the first translation member adjusts the angle between the upper and lower endplates. This allows for independent adjustment of the devices height and angle after it has been implanted between the vertebral bodies. The second translation member may include a second movable wedge with at least one angled surface. The upper and lower endplates may each comprise a ramp for cooperating with the angled surface of the second movable wedge of the second translation member such that longitudinal movement of the second movable wedge adjusts a distance between at least a distal portion of the upper and lower endplates.
The ramps on the upper and lower endplates may be located on the proximal and distal portions of the endplates. In certain embodiments, this allows the first movable wedge to cooperate with these ramps to move the upper and lower endplates such that they remain substantially parallel to each other (i.e., adjustment in height). In other embodiments, the first moveable wedge cooperates with the proximal endplate ramps and the second moveable wedge cooperates with the distal endplate ramps.
The device may further comprise a first rotatable shaft coupled to the first translation member for moving the first translation member in the longitudinal direction and a second rotatable shaft for moving the second translation member in the longitudinal direction. In embodiments, the first and second rotatable shafts each comprise a proximal mating feature configured for mating to an instrument such that rotation of the actuator shafts causes longitudinal movement of the translation members.
In embodiments, the first translation member comprises at least one projection, such as a pin, extending laterally away from the longitudinal axis and at least one of the upper and lower endplates comprises an opening or slot for receiving the projection. The projection(s) are configured to slide within the slot(s) to stabilize the upper and lower endplates during longitudinal movement of the first translation member. The second translation member may further comprise at least one guide arm that cooperates with at least one guide rail on the upper endplate to stabilize the upper and lower endplates during longitudinal movement of the second translation member. In embodiments, the projections and the guide arm also serve to couple the first and second translation members to the upper and lower endplates.
In embodiments, the device further comprises a stabilization plate coupled to the first rotatable shaft such that the stabilization plate remains fixed in place relative to the upper and lower endplates as the first and second translation members are moved in the longitudinal direction. The stabilization plate may comprise a hinge biased inwards towards the longitudinal axis of the device for securing the stabilization plate to the first rotatable shaft.
In certain embodiments, the stabilization plate further includes one or more projections that define a central channel extending distally towards the translation members. The first translation member comprises at least one vertical projection extending into the central channel to stabilize lateral movement of the first translation member as it is moved longitudinally relative to the endplates. The projections may also form a U-shape that provides a proximal backstop to inhibit the first translation member from advancing too far in the proximal direction. The stabilization plate may further include one or more projections or knobs extending laterally outward and at least one of the upper and lower endplates may comprise one or more internal slot(s) for receiving these knobs to stabilize the upper and lower endplates as the translation members are moved longitudinally.
In another aspect, a spinal fusion system comprises an adjustable spinal fusion device having an upper endplate with an outer surface for placement against a first vertebral body and a lower endplate with an outer surface for placement against a second vertebral body. The device includes a first translation member configured to move longitudinally relative to the upper and lower plates to adjust a distance between the upper and lower plates and a second translation member configured to move longitudinally relative to the upper and lower plates to adjust an angle between the upper and lower plates. The system further comprises an instrument having a proximal handle, an elongate shaft and an actuator within the elongate shaft coupled to the proximal handle for moving the first and second translation members longitudinally relative to the upper and lower endplates.
In embodiments, the actuator comprises a first rotatable actuator coupled to the first translation member and a second rotatable actuator coupled the second translation member. The second rotatable actuator may extend through an inner lumen in the first rotatable actuator.
In embodiments, rotation of the first actuator causes longitudinal movement of the first translation member and the second translation member to adjust the distance and angle between the upper and lower endplates. In embodiments, rotation of the second actuator causes longitudinal movement of the second translation member relative to the first translation member to adjust the angle between the upper and lower endplates.
In embodiments, the device further comprises a stabilization plate coupled to the first rotatable actuator such that the stabilization plate remains fixed in place relative to the upper and lower endplates as the first and second translation members are moved in the longitudinal direction. The instrument may comprise first and second gripping arms configured for coupling to the stabilization plate.
In embodiments, the stabilization plate comprises a hinge biased inwards towards the longitudinal axis of the device for securing the stabilization plate to the first rotatable shaft. The stabilization plate may include a projection defining a central channel and the first translation member comprises at least one vertical projection extending into the central channel, wherein the central channel stabilizes lateral movement of the first translation member. The stabilization plate may include one or more knobs extending laterally from the stabilization plate and at least one of the upper and lower endplates comprises an internal slot for receiving the at least one or more knobs to stabilize the upper and lower endplates as the first translation member is moved longitudinally.
In another aspect, an adjustable spinal fusion device comprises an upper endplate having an outer surface for placement against a first vertebral body and a lower endplate having an outer surface for placement against a second vertebral body. The lower endplate is a separate component from the upper endplate. The device further includes a translation member configured to move longitudinally relative to the upper and lower endplates to adjust a distance between at least a portion the upper and lower endplates. The translation member comprises one or more projections extending laterally from the translation member. At least one of the endplates comprises one or more slots for receiving the projection(s) to couple the upper endplate to the lower endplate.
In embodiments, the device further comprises a second translation member configured to move longitudinally relative to the upper and e lower plates to adjust an angle between the upper and lower endplates. The second translation member comprises one or more projections extending laterally from the second translation member. At least one of the endplates comprises one or more slots for receiving the projections to couple the upper endplate to the lower endplate
In embodiments, the device further comprises a stabilization plate that is a separate component as the upper and lower endplates and the translation member. The stabilization plate comprises one or more projections and at least one of the upper and lower endplates comprises one or more slots for receiving the one or more projections and coupling the stabilization member to the upper and lower endplates. The stabilization plate may also include a projection defining a central channel and the first translation member comprises at least one vertical projection extending into the central channel to couple the first translation member to the stabilization plate.
In embodiments, the device is fabricated through additive manufacturing techniques, such as 3D printing. The implant may be formed layer by layer in the longitudinal direction from the proximal end to the distal end. Upon completion of manufacturing, the upper and lower endplates are separated from each other and remain together during use by (1) the projections in the first translation member that slide through openings or slots in the endplates; and/or (2) the projections in the stabilization plate that slide through openings or slots in the endplates; and/or (3) the projections on the second translation member that move along the ramps in the endplates; and/or (4) the projections in the first translation member that slide through the central channel in the stabilization plate.
In embodiments, at least one of the upper and lower endplates comprises a surface with one or more exhaust openings for extracting metal powder from within the device. This allows more efficient extraction of metal powder that may, for example, remain in the cage after 3D printing.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. Additional features of the disclosure will be set forth in part in the description which follows or may be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a partially transparent view of a spinal fusion device with a lordosis angle;

FIG. 2 is a perspective view of the spinal fusion device of FIG. 1 in a configuration for delivery between adjacent vertebral bodies;

FIG. 3 is an exploded view of the spinal fusion device of FIG. 1 ;

FIG. 4 is a perspective view of a lower endplate of the spinal fusion device of FIG. 1 ;

FIG. 5 is a perspective view of an upper endplate of the spinal fusion device of FIG. 1 ;

FIG. 6A is a perspective view of a proximal translation member of the spinal fusion device of FIG. 1 ;

FIG. 6B is a side view of the proximal translation member of FIG. 6A;

FIG. 7 is a partial cross-sectional view of one portion of the proximal translation member of FIG. 6A;

FIG. 8 is a perspective view of a proximal rotatable shaft actuator of the spinal fusion device of FIG. 1 ;

FIG. 9 is a perspective view of a stabilization plate of the spinal fusion device of FIG. 1 :

FIG. 10A is a perspective view of a distal rotatable actuator of the spinal fusion device of FIG. 1 ;

FIG. 10B is a perspective view of a distal translation member of the spinal fusion device of FIG. 1 ;

FIG. 11A illustrates the distal translation member coupled to the distal rotatable actuator;

FIG. 11B illustrates the stabilization plate coupled to the proximal rotatable actuator;

FIG. 12 is a partial cross-sectional view of the spinal fusion device, illustrating internal threads of the proximal translation member;

FIG. 13 is a perspective view of an instrument for inserting the spinal fusion device of FIG. 1 between adjacent vertebral bodies in a patient; and

FIG. 14 is an exploded view of the instrument of FIG. 13 13 attached to the spinal fusion device;

FIG. 15 is a partially exploded side view of a distal portion of the instrument and the spinal fusion device;

FIG. 16 illustrates inner and outer rotatable shafts of the instrument of FIG. 12 ;

FIG. 17A illustrates the spinal fusion device in a configuration for insertion between adjacent vertebral bodies;

FIG. 17B illustrates the spinal fusion device with a height adjustment that increases the distance between the upper and lower endplates; and

FIG. 17C illustrates the spinal fusion device with an angle adjustment that increases the distance between distal portions of the upper and lower endplates.

DESCRIPTION OF THE EMBODIMENTS

This description and the accompanying drawings illustrate exemplary embodiments and should not be taken as limiting, with the claims defining the scope of the present disclosure, including equivalents. Various mechanical, compositional, structural, and operational changes may be made without departing from the scope of this description and the claims, including equivalents. In some instances, well-known structures and techniques have not been shown or described in detail so as not to obscure the disclosure. Like numbers in two or more figures represent the same or similar elements. Furthermore, elements and their associated aspects that are described in detail with reference to one embodiment may, whenever practical, be included in other embodiments in which they are not specifically shown or described. For example, if an element is described in detail with reference to one embodiment and is not described with reference to a second embodiment, the element may nevertheless be claimed as included in the second embodiment. Moreover, the depictions herein are for illustrative purposes only and do not necessarily reflect the actual shape, size, or dimensions of the system or illustrated components.
It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.
Referring now to FIGS. 1-3 , a spinal implant 10 according to the present disclosure is configured for placement between two adjacent vertebral bodies. In some embodiments, implant 10 is particularly useful for placement from a posterior approach outside of the facet joint (transforaminal lumbar interbody fusion or TLIF), although it will be recognized that the implants disclosed herein may be employed in a variety of different surgical approaches, such as anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF) and/or lateral lumbar interbody fusion (LLIF).
Implant 10 includes upper and lower endplates 12, 14, a distal translation member 16, a proximal translation member 18, and a proximal stabilization plate 20. The implant 10 further includes distal and proximal shaft actuators 22, 24 for longitudinally translating the distal and proximal translation members 16, 18, respectively, relative to the endplates 12, 14. Movement of the translation members 16, 18 in substantially the longitudinal direction changes the height and angle of the endplates 12, 14, as discussed in more detail below.
As shown in FIGS. 2, 4 and 5 , the upper and lower endplates 12, 14 each include an outer surface 26, 28 for contacting the surface of a vertebral body. The outer surfaces are preferably roughened with a surface treatment that facilitates attachment to the vertebral body. The surface treatment preferably creates a diamond structure (e.g., diamond 20-1.5), although other patterns are contemplated. The upper and lower endplates 12, 14 also preferably include central openings 30, 32 that extend through the entire endplates 12, 14 and, in one embodiment, are substantially aligned with each other. Similarly, the proximal translation member 18 includes a central opening or bore 34 that, in one embodiment, may be substantially aligned with the endplate openings 30, 32 (see FIG. 6A). These openings create space for the addition of bone graft or other substances into the implant, as well as to allow for bony ingrowth through the implant 10.
The upper endplate 12 includes: (1) first and second distal sloped surfaces or ramps 40, 42 that are laterally spaced from each other near either side of the upper endplate and extend towards the lower plate 14 in the proximal direction; and (2) third and fourth proximal sloped surfaces or ramps 44, 46 that are laterally spaced from each other near either side of the endplate and also extend towards the lower endplate 14 in the proximal direction. The lower endplate 14 includes: (1) first and second distal sloped surfaces or ramps 50, 52 laterally spaced from each other extending upwards towards the upper endplate 12 in the proximal direction; and (2) third and fourth proximal sloped surfaces or ramps 54, 56 that are laterally spaced from each other near either side of the endplate and also extend upwards towards the upper endplate 12 in the proximal direction. These ramps interact with wedges on the translation members to provide height and angular adjustment of the implant.
In an alternative embodiment, upper endplate 12 may include a single distal ramp and/or a single proximal ramp that extends laterally across a central portion of the endplate 12. Alternatively, endplate 12 may include more than two distal or proximal ramps.
The upper and lower endplates 12, 14 each further include a proximal cut- out 60, 62 for receiving upper and lower portions of stabilization plate 20, and vertical knobs or projections 64, 66 extending from the proximal translation member 18 (see FIGS. 6A and 6B).
As shown in FIGS. 10B and 11A, distal translation member 16 has a main body 70 positioned near the distal end of endplates 12, 14 and forming a distal portion of implant 10. Main body 70 includes a central bore 72 for receiving distal shaft actuator 22 and first and second lateral portions 74, 76 extending laterally outward from central bore 72. Lateral portions 74, 76 each further include: (1) first and second upper sloped surfaces or wedges 80, 82 laterally spaced from each other and extending downwards towards lower endplate 14 in the proximal direction; and (2) first and second lower sloped surfaces or wedges 84, 86 laterally spaced from each other and extending upwards towards upper endplate 12 in the proximal direction. Upper wedges 80, 82 are configured to contact and engage upper endplate distal ramps 40, 42, and lower wedges 84, 86 are configured to contact and engage lower endplate distal ramps 50, 52 such that movement of distal translation member 16 in the proximal direction causes the proximal ends of endplates 12, 14 to move apart from each other. This movement may cause an adjustment in height and/or angle, as discussed below.
In an alternative embodiment, distal translation member 16 may include a single distal ramp and/or a single proximal ramp that extends laterally across a central portion of the translation member 16. Alternatively, translation member 16 may include more than two distal or proximal ramps.
Lateral portions 74, 76 of distal translation member 16 also include outer guide arms 90, 92 that engage with openings, slots or grooves 94, 96 on the outer surfaces of the distal ramps on upper endplate 12 (see FIG. 5 ) to stabilize the endplates during height and angle adjustment. Specifically, these outer guide arms 90, 92 comprise substantially vertical rails 98, 100 on either side of distal translation member 16 that include projections 102, 104 designed to engage grooves 94, 96 of the upper distal endplate ramp and to ride along these ramps as distal translation member 16 is moved in the longitudinal direction.
Referring now to FIG. 10A, distal actuator shaft 22 includes a distal endplate or bolt 110, a threaded shaft 112 and a proximal mating feature, such as a shaped opening like, for example, a hexalobe 114, for mating with an instrument (discussed below). In certain embodiments, distal actuator shaft 22 is secured to the distal translation member 16 with a flexible hinge or prong 116 that is biased inwards towards the longitudinal axis of the implant to secure actuator shaft 22 to distal translation member 16. Threaded shaft 112 also extends through a distal opening 124 in proximal translation member 18 for mating with an instrument (discussed below).
As shown in FIGS. 6A, 6B and 7 , proximal translation member 18 includes a substantially cylindrical main body 120 that extends through a portion of the implant between endplates 12,14. Main body 120 has a central longitudinal bore 122 for receiving proximal and distal actuator shafts 22, 24 and a central opening 34 extending from an upper surface through to the lower surface for receiving graft material and for allowing bony ingrowth therethrough. Proximal translation member 18 includes first and second upper sloped surfaces or wedges 130, 132 that are configured to contact and engage first and second proximal ramps 44, 46 of upper endplate 12, and first and second lower surfaces or wedges 134, 136 that are configured to contact and engage first and second proximal ramps 54, 56 of the lower endplate 14 (alternatively, translation member 18 may comprise a single ramp or more than two ramps, as discussed above). Longitudinal movement of proximal translation member 18 causes these wedges to move along the ramps of the endplates, thereby moving the proximal ends of the endplates either towards or away from each other.
As shown in FIG. 7 , proximal translation member 18 further includes distal internal threads 140 that rotatably mate with threaded shaft 112 of distal actuator shaft 22 (see FIG. 12 ). Rotation of this threaded shaft 112 causes distal translation member 16 to move longitudinally relative to proximal translation member 18 and end plates 12, 14 for angle adjustment, as discussed below. Proximal translation member 18 also includes proximal internal threads 138 that are rotatably mated with a threaded shaft 150 of proximal actuator 24. Rotation of proximal actuator 24 causes proximal translation member 18 (and the distal translation member 16 therewith) to move longitudinally relative to endplates 12, 14 for height adjustment.
Proximal translation member 18 further includes one or more projections 142 extending laterally away from the translation member. Projections 142 may, for example, comprise pins having a tapered end extending away from member 18. These tapered or conical pins 142 extend through angled slots 144 (see FIG. 1 ) in upper and lower endplates 12, 14 and serve to stabilize the endplates during height and angle adjustment. In particular, proximal translation member 18 includes at least two conical pins 142 on each side, with one of the lateral pins on each side riding through slots 144 on the upper endplate and the other lateral pin riding through slots 144 on the lower endplate as translation member 18 is moved longitudinally relative to the endplates.
As shown in FIGS. 9 and 11B, stabilization plate 20 includes a central opening 160 for receiving a portion of proximal actuator shaft 24. Proximal actuator shaft 24 includes a proximal bolt 152 that is secured to stabilization plate 20 with a hinge, spring or prong 162 on the stabilization plate 20 that is biased inwards towards the longitudinal axis. Bolt 152 includes a mating feature 154 for engaging with a similar mating feature on an instrument (discussed below). Proximal actuator 24 further includes a central bore 156 for receiving an instrument to mate with distal actuator shaft 22, as discussed below.
Stabilization plate 20 is secured to proximal actuator shaft 24 such that it remains fixed in place relative to endplates 12, 14 as the translation members are moved in the longitudinal direction. Plate 20 includes two longitudinal projections 164, 166 on both of its upper and lower surfaces that extend towards the endplates to form a U-shaped projection with a central channel 168. Proximal translation member 18 includes upper and lower vertical projections 64, 66 configured to extend into these channels 168 and to move through the channels 168 as proximal translation member 18 moves in the longitudinal direction. The U-shaped projections 164, 166 and channels 168 serve to stabilize the endplates and prevent seesaw or lateral movement of proximal translation member 18. In addition, these U-shaped channels 164, 166 serve as a backstop to prevent excessive movement of the proximal translation member 18 in the proximal direction.
In addition, stabilization plate 20 may further include projections 170 extending laterally from the longitudinal projections. Projections 170 may, for example, include tapered or conical-shaped knobs. In an exemplary embodiment, plate 20 includes two such knobs on each side for a total of four conical knobs. These knobs are configured to slide within internal slots 172 on the upper and lower endplates to further stabilize the implant during height adjustment (see FIGS. 4 and 5 ).
Stabilization plate 20 may further include lateral projections 174 on either side of the plate that create two lateral grooves or channels 178, 180 for mating with a gripping arm of an insertion instrument (discussed below).
Referring now to FIGS. 13-16 , insertion instrument 200 comprises an elongated shaft 202 with a proximal handle 204 and a distal gripping element 206 for removably coupling to implant 10. Distal gripping element 206 preferably includes first and second gripping arms 208, 210 for coupling to stabilization plate 20, i.e., to the lateral channels or grooves 178, 180 created by lateral projections 174, 176 on the stabilization plate (e.g., a bayonet style connection). Distal gripping arms 208, 210 are coupled to an actuator 212 on the proximal handle 204 to move the arms 208, 210 in a substantially lateral direction relative to the longitudinal axis of the shaft 202. The arms 208, 210 can be moved together to hold the lower endplate and moved apart to release the endplate.
An inner rotatable shaft 220 extends from the handle 204 to the distal actuator 22 and an outer rotatable shaft 222 extends from the handle 204 to the proximal actuator 24. Inner and outer shafts 220, 222 are both attached to rotatable knobs 224, 226, respectively, on the proximal handle for rotating shafts 220, 222 and thereby rotating proximal and distal actuators 22, 24. Alternatively, shafts 220, 222 may be configured to move longitudinally (i.e., rather than rotate) to move the translation members.
Handle 204 includes markings or indicia 230, 232 to correlate rotation of the shafts with height and angle adjustment of the endplates. Inner shaft 220 has a female mating feature 234 that may be coupled to the male mating feature of the distal actuator (i.e., the hexalobe 114) and the outer shaft 222 has a female mating feature 236 that can be coupled to the bolt 152 on the proximal actuator 24.
Handle 204 further includes a third rotatable knob 240 coupled to the shaft 202 for rotating the shaft 202 and the endplate 10 therewith relative to the handle. This allows for rotation of the endplate without rotating the handle to facilitate ease of use during implantation.
In use, implant 10 may be advanced into an intervertebral space in a collapsed configuration (see the resting state shown in FIG. 17A). To increase the height of the implant, endplates 12, 14 are moved away from each other in a substantially parallel direction. To that end, rotatable knob 226 on handle 204 is rotated to thereby rotate outer shaft 222 of insertion instrument 200. This rotation causes proximal actuator 24 to rotate, thereby causing its threaded shaft 150 to rotate within proximal internal threads 138 of proximal translation member 18. This translates both proximal and distal translation members 16, 18 in the proximal direction. As distal translation member 16 moves in proximal direction, its upper wedges 80, 82 engage with upper endplate distal ramps 40, 42 and its lower wedges 84, 86 engage with the lower endplate distal ramps 50, 52 such that the distal ends of the endplates move apart from each other. At the same time, the wedges 130, 132, 134, 136 of the proximal translation member 18 engage the proximal ramps 44, 46, 54, 56 of the endplates to move the proximal ends of the endplates away from each other. This causes the endplates to move away from each other in a substantially parallel direction (see expanded state shown in FIG. 17B).
To adjust the angle of the endplates, rotatable knob 224 on handle 204 is rotated, causing inner shaft 234 to rotate. This rotation is translated to hexalobe 114 on distal actuator 22. As distal actuator 22 rotates, distal translation member 16 is translated in a proximal direction relative to both endplates 12, 14 and proximal translation member 18. Since proximal translation member 18 does not move, the proximal ends of the endplates remain fixed relative to each other. The upper and lower wedges of the distal translation member contact and engage the upper and lower distal ramps of the endplates, causing the distal ends of the endplates to move apart from each other, thereby adjusting the angle of the upper endplate relative to the lower endplate (the angularly adjusted state shown in FIG. 17C).
The process of height and angle adjustment may be reversible and may also be stepless, i.e., a continuous adjustment without discrete steps. Alternatively, the height and angle adjustment may be based on a series of discrete steps which correlate to discrete distances and angles of the endplates. The height and angle may be adjusted independently of each other. For example, the above process can be reversed such that the inner shaft is first rotated to adjust the angle, and then the outer shaft is rotated to adjust height.
In certain embodiments, the entire implant 10 is fabricated through additive manufacturing techniques, such as 3D printing or the like. The implant may be formed layer by layer in the longitudinal direction from the proximal end to the distal end. Upon completion of manufacturing, the upper and lower endplates are separated from each other. The endplates remain together during use by: (1) the knobs in the proximal translation member that slide through slots in the endplates; (2) the knobs in the stabilization plate that slide through slots in the endplates; (3) the side projections on the distal translation member that slide along the proximal ramps in the endplates; and (4) the upper and lower knobs in the proximal translation member that slide through the U-shaped channel in the stabilization plate.
In an exemplary embodiment, the implants are produced by Selective Laser Melting (SLM). For example, a substrate plate is fastened to an indexing table inside a chamber with a controlled atmosphere of inert gas (e.g., argon or nitrogen). Metal powder is applied flat to the substrate plate as a layer. The metal powder is preferably a titanium alloy, e.g., Ti-6Al-4V to enable biocompatibility. Each 2D slice of the cage is fused by selectively melting the metal powder via a laser. The laser has enough energy to fully melt or rather weld the metal particles to form solid metal. The substrate plate is lowered by the layer thickness (z-direction). New metal powder is applied and the process is repeated layer by layer until the part is complete. The completed part is removed from the substrate plate by cutting or breaking off.
Preferably, all components of the cage are printed nested within each other. Compared to separately 3D printing all components next to each other, a higher utilization rate can be achieved. This means that during 3D printing, a higher proportion which is melted and a lower proportion which stays as metal powder can be achieved. Thus, production time and costs can be reduced significantly.
After 3D printing, areas connecting single components of the cage are cut by electrical discharge machining (EDM) to enable their separate movement. Further, EDM can be used to realize smooth surfaces, e.g., to enable low-friction sliding of two components against each other. With EDM, the cage can also be removed from the substrate plate.
To lower production costs, several cages can be printed onto one substrate plate.
The implant may comprise one or more exhaust openings in the upper and lower endplates to allow for extraction of the metal powder remaining in the cage after 3D printing. Preferably, the exhaust opening is positioned on a lateral surface of the moving plate). It is also possible to position the exhaust opening on a horizontal surface of the cage, preferably on the base plate or on the moving plate. Preferably, the cage comprises multiple exhaust openings. Thus, more areas inside the cage are reachable and the metal powder can be extracted more efficiently. It is also possible to configure an external sliding mean, preferably a conical groove, in such a way that it can be additionally used as an exhaust opening. Therefore, the conical groove is deepened until a passage to the outside has been made.
Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the embodiment disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the embodiment being indicated by the following claims.

Claims

What is claimed is:

1. An adjustable spinal fusion device, comprising:

an upper endplate having an outer surface for placement against a first vertebral body;

a lower endplate having an outer surface for placement against a second vertebral body;

a first translation member configured to move longitudinally relative to the upper and lower endplates to adjust a distance between the upper and lower endplates; and

a second translation member configured to move longitudinally relative to the upper and lower plates to adjust an angle between the upper and lower endplates.

2. The adjustable spinal fusion device of claim 1, wherein longitudinal movement of the first translation member causes longitudinal movement of the second translation member to adjust the distance and angle between the upper and lower endplates.

3. The adjustable spinal fusion device of claim 1, wherein longitudinal movement of the second translation member relative to the first translation member adjusts the angle between the upper and lower endplates.

4. The adjustable spinal fusion device of claim 1, further comprising a first rotatable shaft coupled to the first translation member for moving the first translation member in the longitudinal direction and a second rotatable shaft coupled to the second translation member for moving the second translation member in the longitudinal direction.

5. The adjustable spinal fusion device of claim 4, wherein the first translation member includes a first movable wedge having at least one angled surface and wherein the upper and lower endplates each comprise a ramp for cooperating with the angled surface of the first movable wedge such that longitudinal movement of the first movable wedge adjusts a distance between at least a proximal portion of the upper and lower endplates.

6. The adjustable spinal fusion device of claim 5, wherein the upper and lower endplates each comprise first and second ramps extending towards each other in the proximal direction, wherein the first movable wedge comprises first and second upper angled surfaces for cooperating with the first and second ramps of the upper endplate and first and second upper angled surfaces for cooperating with the first and second ramps of the lower endplate.

7. The adjustable spinal fusion device of claim 1, wherein the first translation member comprises at least one projection extending laterally away from the first translation member and at least one of the upper and lower endplates comprises an angled slot for receiving the projection to stabilize the upper and lower endplates during longitudinal movement of the first translation member.

8. The adjustable spinal fusion device of claim 5, wherein the second translation member includes a second movable wedge with at least one angled surface and wherein the upper and lower endplates each comprise a ramp for cooperating with the angled surface of the second movable wedge of the second translation member such that longitudinal movement of the second movable wedge adjusts a distance between at least a distal portion of the upper and lower endplates.

9. The adjustable spinal fusion device of claim 8, wherein the upper and lower endplates each comprise first and second ramps extending towards each other in the proximal direction, wherein the second movable wedge comprises first and second upper angled surfaces for cooperating with the first and second ramps of the upper endplate and first and second upper angled surfaces for cooperating with the first and second ramps of the lower endplate.

10. The adjustable spinal fusion device of claim 1, wherein the second translation member comprises at least one guide arm that cooperates with at least one guide rail on the upper endplate to stabilize the upper and lower endplates during longitudinal movement of the second translation member.

11. The adjustable spinal fusion device of claim 4, further comprising a stabilization plate coupled to the first rotatable shaft such that the stabilization plate remains fixed in place relative to the upper and lower endplates as the first and second translation members are moved in the longitudinal direction.

12. The adjustable spinal fusion device of claim 11, wherein the stabilization plate includes a projection defining a central channel and the first translation member comprises at least one vertical projection extending into the central channel, wherein the central channel stabilizes lateral movement of the first translation member.

13. The adjustable spinal fusion device of claim 11, wherein the stabilization plate includes one or more knobs extending laterally from the stabilization plate and at least one of the upper and lower endplates comprises an internal slot for receiving the at least one or more knobs to stabilize the upper and lower endplates as the first translation member is moved longitudinally.

14. A spinal fusion system, comprising:

an adjustable spinal fusion device comprising:

an upper plate component having an outer surface for placement against an endplate of a vertebral body;

a lower plate component having an outer surface for placement against an endplate of a vertebral body; and

a movable wedge configured to move longitudinally relative to the upper and lower plates to adjust a distance and an angle between the upper and lower plates; and

an instrument having a proximal handle, an elongate shaft and an actuator within the elongate shaft coupled to the proximal handle and the movable wedge for translating the movable wedge longitudinally relative to the upper and lower endplates.

15. The system of claim 14, wherein the movable wedge comprises a first movable wedge, the system further comprising a second movable wedge, wherein the actuator comprises a first rotatable shaft coupled to the proximal handle the first movable wedge and a second rotatable shaft coupled to the proximal handle the second movable wedge.

16. The system of claim 14, further comprising a stabilization plate coupled to the first rotatable shaft such that the stabilization plate remains fixed in place relative to the upper and lower endplates as the first and second movable wedges are moved in the longitudinal direction, wherein the instrument further comprising first and second gripping arms configured for coupling to the stabilization plate.

17. An adjustable spinal fusion device, comprising:

a lower endplate having an outer surface for placement against a second vertebral body, wherein the lower endplate is a separate component from the upper endplate;

a translation member configured to move longitudinally relative to the upper and lower endplates to adjust a distance between at least a portion the upper and lower endplates; and

wherein the translation member comprises one or more projections extending laterally from the translation member and wherein at least one of the endplates comprises one or more slots for receiving the projections to couple the upper endplate to the lower endplate.

18. The spinal fusion device of claim 17, wherein the translation member is a first translation member for adjusting the distance between the upper and lower endplates, the device further comprising a second translation member configured to move longitudinally relative to the upper and e lower plates to adjust an angle between the upper and lower endplates.

19. The spinal fusion device of claim 18, wherein the second translation member comprises one or more projections extending laterally from the second translation member and wherein at least one of the endplates comprises one or more slots for receiving the projections to couple the upper endplate to the lower endplate

20. The spinal fusion device of claim 17, further comprising a stabilization plate that is a separate component as the upper and lower endplates and the translation member, wherein the stabilization plate comprises one or more projections and at least one of the upper and lower endplates comprises one or more slots for receiving the one or more projections and coupling the stabilization member to the upper and lower endplates.

21. The spinal fusion device of claim 20, wherein the stabilization plate includes a projection defining a central channel and the first translation member comprises at least one vertical projection extending into the central channel to couple the first translation member to the stabilization plate.

22. The spinal fusion device of claim 17, wherein at least one of the upper and lower endplates comprises a surface with one or more exhaust openings for extracting metal powder from within the device.