Expanding orthopedic implant
An expandable intervertebral implant having an upper body portion, a lower body portion opposite the upper body portion, a wedge member connecting the upper body portion to the lower body portion, a nose member having a tapered distal end and a proximal end opposite the distal end, and an actuator disposed between the nose member and the wedge member, for translation of the wedge member along a longitudinal axis of the implant. A pin connects to the actuator for positioning the nose member relative to the actuator. Translation of the wedge member along the longitudinal axis of the implant displaces the upper body portion and the lower body portion away from each other, thereby expanding the intervertebral implant.
1. An expandable intervertebral implant comprising:
an upper body portion;
a lower body portion opposite the upper body portion;
a wedge member connecting the upper body portion to the lower body portion;
a nose member having a tapered distal end and a proximal end opposite the distal end, the nose member slidably connected to the upper body portion and the lower body portion; and
an actuator disposed between the nose member and the wedge member for translation of the wedge member toward the nose member;
wherein translation of the wedge member along a longitudinal axis of the implant displaces the upper body portion and the lower body portion away from each other, thereby expanding the implant,
wherein the wedge member comprises a leading wedge, a pair of intermediate wedges with a gap in between, and a trailing wedge connected together by a pair of rails, and
wherein a first wedge of the pair of the intermediate wedges on an anterior side of the implant is shorter in height than a second wedge of the pair of intermediate wedges on a posterior side of the implant.
2. The implant of claim 1 , further comprising a bone graft window in at least one of the upper body portion and the lower body portion.
3. The implant of claim 1 , wherein at least one of the upper body portion and the lower body portion comprises a corrugated surface.
4. The implant of claim 1 , wherein the actuator is threadably connected to the wedge member such that rotating the actuator translates the wedge member toward the nose member.
5. The implant of claim 1 , wherein dovetails on the wedge member hold and slidably connect the upper body portion and the lower body portion to the wedge member.
6. The implant of claim 1 , wherein dovetail grooves on the nose member hold and slidably connect the upper body portion and the lower body portion to the nose member.
7. The implant of claim 1 , wherein a drive end of the actuator opposite the nose member is configured to connect with an insertion tool for insertion of the implant between vertebrae.
8. The implant of claim 1 , wherein a head of the actuator, opposite the wedge member, is located in the nose member.
9. The implant of claim 1 , wherein the actuator by turning advances the wedge member toward the nose member to expand the implant, and both the actuator and the wedge member have threads to thereby advance the wedge member when the actuator is turned.
10. The implant of claim 1 , further comprising a pin, wherein the pin maintains a position of the nose member relative to the actuator once the implant has been assembled, the position being offset from a longitudinal axis of the wedge member.
11. The implant of claim 1 , wherein, on a posterior side of the implant, plural dovetail grooves in the nose member respectively hold and slidably connect the upper body portion and the lower body portion to the nose member.
12. The implant of claim 1 , wherein a through-hole in the wedge member comprises a passageway for an insertion tool to connect to and turn the actuator.
13. The implant of claim 1 , further comprising a frictional bearing contacting the actuator and providing a frictional force retarding movement of the upper body portion relative to the lower body portion.
14. The implant of claim 13 , wherein the frictional bearing is compressible.
15. The implant of claim 11 , wherein the first wedge has a) an upper half with a superior dovetail disposed inside a graft window and b) a lower half with an inferior dovetail groove disposed outside the graft window.
16. The implant of claim 11 , wherein the second wedge has a) an upper half with a superior dovetail disposed outside a graft window and b) a lower half with an inferior dovetail disposed outside the graft window.
17. The implant of claim 1 , wherein in a collapsed state, on a posterior side of the implant, an upper ramp extending downward from the upper body portion overlaps a lower ramp extending upward from the lower body portion, and an upper dovetail groove in the upper ramp on the posterior side engages the superior dovetail inside the graft window, and a lower dovetail groove in the lower ramp on the posterior side engages an inferior dovetail that is disposed outside a graft window.
18. The implant of claim 1 , wherein, on an anterior side of the nose member, a dovetail groove comprises a slot to receive therein a head of the actuator.
19. The implant of claim 1 , wherein at least one of the upper body portion and the lower body portion has an asymmetric graft window with a larger opening to a first side of the implant extending along a length of the wedge member than to a second side of the implant opposite the first side.
20. The implant of claim 1 , wherein at least one of the upper body portion and the lower body portion has an asymmetric graft window with a larger opening to an anterior side of the implant than to a posterior side of the implant.