Zero-profile expandable intervertebral spacer devices for distraction and spinal fusion and a universal tool for their placement and expansion

An expandable intervertebral fusion device comprising:

• a first movable portion extending from a first end to a second end, wherein the first movable portion has first and second end portions positioned at the first and second ends, respectively, and has first and second side portions extending between the first and second end portions, wherein the first movable portion has a first vertebral body engagement surface and has a first interior surface positioned on an opposite side of the first movable portion from the first vertebral body engagement surface, wherein the first movable portion defines a first gap at the first end between the first and second side portions, wherein the first movable portion defines first and second linkage arm connection holes;
• a second movable portion extending from a third end to a fourth end, wherein the second movable portion has third and fourth end portions positioned at the third and fourth ends, respectively, and has third and fourth side portions extending between the third and fourth end portions, wherein the second movable portion has a second vertebral body engagement surface and has a second interior surface positioned on an opposite side of the second movable portion from the second vertebral body engagement surface, wherein the second movable portion defines a second through-hole between the third and fourth end portions and between the third and fourth side portions that extends through the second movable portion in a direction from the second vertebral body engagement surface to the second interior surface, wherein the second movable portion defines third and fourth linkage arm connection holes, wherein the first movable portion is aligned with the second movable portion such that the first end of the first movable portion is axially aligned with the third end of the second movable portion and the second end of the first movable portion is axially aligned with the fourth end of the second movable portion;
• and
• an expansion mechanism configured to move the first movable portion and the second movable portion with respect to each other to expand the expandable intervertebral fusion device, wherein the expansion mechanism comprises:
• a plurality of linkage arms connected to the first and second movable portions at the first, second, third, and fourth linkage arm connection holes;
• a rotation screw having a first screw end and a second screw end, wherein the rotation screw has a tool receiving indentation at the first screw end and has a threaded shaft portion extending along at least part of the rotation screw between the first screw end and the second screw end, wherein the rotation screw extends along and rotates about a rotation screw axis;
• and
• a linkage connector positioned inside a space defined between the first and second movable portions, wherein the linkage connector is operably connected to the rotation screw, wherein the linkage connector is operably connected to a first end of at least a first linkage arm of the plurality of linkage arms such that the first end of the first linkage arm is pivotably connected to the linkage connector and a second end of the first linkage arm is pivotably connected to the first and second linkage arm connection holes of the first movable portion, and wherein rotation of the rotation screw forces the linkage connector to move along the rotation screw axis and pivot the first linkage arm to push the first movable portion away from the second movable portion to expand the expandable intervertebral fusion device.

A system comprising:

• an expandable intervertebral fusion device comprising first and second movable portions and an expansion mechanism configured to move the first movable portion with respect to the second movable portion, wherein the expansion mechanism comprises at least a rotation screw having a screw head and a threaded shaft, wherein the expandable intervertebral fusion device defines first and second tool engagement indentations on first and second sides of the expandable intervertebral fusion device;
• a first tool having a first proximal end, a first distal end, and a first elongate body between the first proximal end and the first distal end, wherein the first tool defines a first tool axis from the first proximal end to the first distal end, wherein the first tool includes first and second engagement prongs positioned at the first distal end on opposite sides of the first tool axis, wherein the first tool defines a first tool passage that extends through the first tool from a first tool passage inlet at the first proximal end to a first tool passage outlet at the first distal end, wherein the first tool outlet is positioned between the first and second engagement prongs;
• a second tool having a second proximal end, a second distal end, and a second elongate body between the second proximal end and the second distal end, wherein the second tool defines a second tool passage that extends through the second tool from a second tool passage inlet at the second proximal end to a second tool passage outlet at the second distal end, and wherein an outer diameter of the second elongate body is less than an inner diameter of the first tool passage of the first tool such that the second elongate body can pass through the first tool passage;
• and
• a third adjusting tool having a third proximal end and a third distal end, wherein the third adjusting tool includes a third handle positioned at the third proximal end, a screw engagement portion positioned at the third distal end, and a third shaft extending from the third handle to the screw engagement portion, and wherein an outer diameter of the third shaft is less than an inner diameter of the second tool passage of the second tool such that the third shaft can extend through the second tool passage while the second tool is positioned in the first tool passage of the first tool.