Expandable interbody spacer for spinal fusion
An expandable interbody spacer for spinal fusion includes opposing upper and lower end plates. An actuator moves the upper and lower end plates heightwise relative to one another to expand the height of the expandable interbody spacer. An end plate fastener secures the upper and lower end plates to one another and enables the upper and lower end plates to heightwise move relative to one another. The upper and lower end plates and the at least one end plate fastener are integrally formed as a single, one-piece, monolithic component. An expandable interbody space may include upper and lower end plates with overlapping anterior and posterior walls that define openings in communication with an internal chamber. An expandable interbody spacer may include a barrel nut defining a window to enable bone graft to pass therethrough and into an internal chamber.
1 . An expandable interbody spacer for spinal fusion, the expandable interbody spacer comprising:
upper and lower end plates opposing one another and defining an internal chamber therebetween sized to receive bone graft therein, each of the upper and lower end plates including an end plate body and opposite posterior and anterior walls at corresponding posterior and anterior sides of the end plate body, wherein a distance between the upper and lower end plate bodies defines a height of the expandable interbody spacer;
an actuator disposed between the upper and lower end plates, the actuator configured to move the upper and lower end plates heightwise relative to one another to expand the height of the expandable interbody spacer and configure the expandable interbody spacer between a collapsed configuration and an expanded configuration; and
at least one end plate fastener securing the upper and lower end plates to one another and enabling the upper and lower end plates to move heightwise relative to one another,
wherein the upper and lower end plates and the at least one end plate fastener are integrally formed as a single, one-piece, monolithic component,
wherein each of the posterior walls of the upper and lower end plates includes tongues and grooves mating with corresponding tongues and grooves of the other posterior wall in the collapsed configuration, and wherein each of the anterior walls of the upper and lower end plates includes tongues and grooves mating with corresponding tongues and grooves of the other anterior wall in the collapsed configuration,
wherein the tongues of the posterior walls of the upper and lower end plates overlap one another in an anterior-poster direction when the expandable interbody spacer is in the collapsed and expanded configurations, and wherein the tongues of the anterior walls of the upper and lower end plates overlap one another in an anterior- poster direction when the expandable interbody spacer is in the collapsed and expanded configurations,
wherein the at least one fastener is disposed between the anterior and posterior walls in the anterior-posterior direction.
2 . The expandable interbody spacer of claim 1 , wherein the at least one end plate fastener comprises a tension spring biasing the upper and lower end plates toward one another.
3 . The expandable interbody spacer of claim 2 , wherein the spring is a serpentine spring.
4 . The expandable interbody spacer of claim 1 , wherein the at least one end plate fastener comprises at least two end plate fasteners.
5 . The expandable interbody spacer of claim 1 , wherein the actuator includes
a drive screw including a threaded portion, the drive screw being selectively rotatable about its axis, and
at least one barrel nut comprising an internally threaded portion threaded on the screw drive, wherein rotation of the drive screw imparts translation of the at least one barrel nut along the drive screw and relative to the upper and lower implants to impart heightwise movement of the upper and lower end plates relative to one another.
6 . The expandable interbody spacer of claim 5 , wherein the at least one barrel nut comprises at least two barrel nuts.
7 . The expandable interbody spacer of claim 5 , wherein the at least one barrel nut includes a first longitudinal portion and a second longitudinal portion, wherein the internally threaded portion is disposed between the first and second longitudinal portions, wherein the first longitudinal portion defines a window to enable bone graft to pass therethrough and into the internal chamber.
8 . The expandable interbody spacer of claim 7 , wherein the first longitudinal portion has a length greater than a length of the second longitudinal portion.
9 . The expandable interbody spacer of claim 8 , wherein the axis of the drive screw is laterally offset from a central longitudinal axis of the interbody spacer.
10 . The expandable interbody spacer of claim 6 , wherein the drive screw includes two of the threaded portions and a non-threaded portion disposed between threaded portions, wherein the non-threaded portion is disposed in the internal chamber.
11 . The expandable interbody spacer of claim 1 , wherein the posterior and anterior walls of the lower plate define openings therethrough and in communication with the internal chamber to enable bone growth.
12 . The expandable interbody spacer of claim 1 , wherein the upper and lower end plates and the at least one end plate fastener are integrally formed as a single, one-piece, monolithic component by additive manufacturing.
13 . An expandable interbody spacer for spinal fusion, the expandable interbody spacer comprising:
upper and lower end plates opposing one another and defining an internal chamber therebetween sized to receive bone graft therein, each of the upper and lower end plates including an end plate body and opposite posterior and anterior walls at corresponding posterior and anterior sides of the end plate body, wherein a distance between the upper and lower end plate bodies plates defines a height of the expandable interbody spacer;
an actuator disposed between the upper and lower end plates, the actuator configured to move the upper and lower end plates heightwise relative to one another to expand the height of the expandable interbody spacer, wherein the actuator comprises:
a drive screw including a threaded portion, the drive screw being selectively rotatable about its axis;
at least one barrel nut comprising an internally threaded portion threaded on the screw drive, wherein rotation of the drive screw imparts translation of the at least one barrel nut along the drive screw and relative to the upper and lower implants to impart heightwise movement of the upper and lower end plates relative to one another, wherein the at least one barrel nut includes a first longitudinal portion and a second longitudinal portion, wherein the internally threaded portion is disposed between the first and second longitudinal portions, the first longitudinal portion defining a window to enable bone graft to pass therethrough and into the internal chamber;
a coupling coupled to the drive screw to enable rotation of the drive screw relative to the coupling, wherein the coupling defines a passage therethrough, the passage being generally aligned with the window defined by the barrel nut to enable bone graft to pass through the passage to the window; and
at least one end plate fastener securing the upper and lower end plates to one another and enabling the upper and lower end plates to move heightwise relative to one another, wherein the at least one fastener is disposed between the anterior and posterior walls in the anterior-posterior direction.
14 . The expandable interbody spacer of claim 13 , wherein the first longitudinal portion has a length greater than a length of the second longitudinal portion.
15 . An expandable interbody spacer for spinal fusion, the expandable interbody spacer comprising:
upper and lower end plates opposing one another and defining an internal chamber therebetween sized to receive bone graft therein, each of the upper and lower end plates including an end plate body and opposite posterior and anterior walls at corresponding posterior and anterior sides of the end plate body, wherein a distance between the upper and lower end plate bodies defines a height of the expandable interbody spacer;
an actuator disposed between the upper and lower end plates, the actuator configured to move the upper and lower end plates heightwise relative to one another to expand the height of the expandable interbody spacer and configure the expandable interbody spacer between a collapsed configuration and an expanded configuration; and
at least one end plate fastener securing the upper and lower end plates to one another and enabling the upper and lower end plates to move heightwise relative to one another, wherein the at least one fastener is disposed between the anterior and posterior walls in the anterior-posterior direction,
wherein the anterior walls of the upper and lower end plates include anterior overlapping portions that overlap one another and are in opposing relationship to one another in an anterior-posterior direction when the expandable interbody spacer is in the collapsed and expanded configurations,
wherein the posterior walls of the upper and lower end plates include posterior overlapping portions that overlap one another and are in opposing relationship to one another in the anterior-posterior direction when the expandable interbody spacer is in the collapsed and expanded configurations,
wherein each of the anterior and posterior walls of the lower end plate define openings therethrough and in communication with the internal chamber to enable bone growth.
16 . The expandable interbody spacer set forth in claim 15 , wherein the anterior and posterior overlapping portions comprise tongues, wherein the tongues are received in corresponding grooves defined by the posterior and anterior walls of the upper and lower end plates.