Expandable intervertebral implant, inserter instrument, and related methods

Abstract

An expandable intervertebral implant includes a first endplate and a endplate, a first wedge member and a second wedge member spaced from the first wedge member that couple the first and second plates together. The first and second wedge members configured to move between a first collapsed position and a second expansion position. The implant includes an actuation member coupled to the first wedge member and the second wedge member. The first and second wedge members can be coupled to the upper and lower endplates at guide members that are asymmetric. An instrument can be coupled to the implant so as to provide a force to the actuation member that causes the wedge members to move between the collapsed position and the expansion position. The instrument can include a drive shaft and a toggle member that is configured to move the drive shaft between a first position whereby the drive shaft is configured to drive an attachment pin into the implant, and a second position whereby the drive shaft is aligned to drive the actuation member to rotate.

What is claimed: 
     
         1 . An expandable implant configured to be inserted in an intervertebral space defined between a first vertebral body and a second vertebral body, the implant comprising:
 a first endplate defining an upper bone contacting surface;   a second endplate defining a second bone contacting surface opposite the first bone contacting surface along a transverse direction;   an insertion end and a trailing end opposite the insertion end along a longitudinal direction that is perpendicular to the transverse direction;   an expansion member that defines a ramped engagement surface configured to bear against an engagement surface of one of the first and second endplates as the expansion member moves in an expansion direction with respect to the first and second endplates, thereby moving the expandable implant from a collapsed configuration to an expanded configuration,   wherein the expandable implant defines a first height from the first bone contacting surface to the second bone contacting surface in the collapsed configuration, the expandable implant defines a second height from the first bone contacting surface to the second bone contacting surface in the collapsed configuration, and the second height is greater than the first height,   wherein the expansion member mates with the first and second endplates so as to guide movement of the first and second endplates away from each other as the expansion member moves in the expansion direction, and   wherein the second endplate nests within the first endplate when the expandable implant is in the collapsed configuration.   
     
     
         2 . The expandable implant as recited in  claim 1 , wherein the first endplate has a first guide member, the second endplate has a second guide member, and the expansion member defines a first guide member and a second guide member configured to engage the first guide member of the first endplate and the second guide member of the second endplate, respectively, so as to guide movement of the first and second endplates away from each other as the expansion member moves in the expansion direction. 
     
     
         3 . The expandable implant as recited in  claim 2 , wherein the first guide member of the first endplate comprises channels sized to slidably receive the first guide member of the expansion member, and the second guide member of the second endplate comprises respective channels sized to slidably receive the second guide member of the expansion member. 
     
     
         4 . The expandable implant as recited in  claim 3 , wherein the first endplate is an upper endplate, the second endplate is a lower endplate, the first guide member of the expansion member comprises outer projections that are received in the channels of the first guide member of the upper endplate, and the second guide member of the expansion member comprises inner projections that are received in the channels of the lower endplate. 
     
     
         5 . The expandable implant of  claim 4 , wherein the inner projections are inwardly recessed with respect to the outer projections. 
     
     
         6 . The expandable implant as recited in  claim 5 , wherein the channels of the upper endplate are outer channels, and the channels of the lower endplate are inner channels that are inwardly recessed with respect to the outer channels along the lateral direction. 
     
     
         7 . The expandable implant as recited in  claim 2 , wherein the expansion member is movable in a collapse direction that causes the implant to move from the expanded configuration to the collapsed configuration, and the guide members of the expansion member apply a force to the guide members of the upper and lower endplates that draw the upper and lower endplates toward each other as the expansion member moves in the collapse direction. 
     
     
         8 . The expandable implant as recited in  claim 1 , wherein the expansion member comprises first and second expansion members that move toward each other in the expansion direction, and away from each other in the collapse direction. 
     
     
         9 . The expandable implant as recited in  claim 8 , further comprising an expansion limiter that prevents rotation of the actuator shaft in the first direction of rotation when the implant has moved to the expanded configuration. 
     
     
         10 . An implant assembly comprising:
 the expandable implant as recited in  claim 1 ; and   an instrument configured to attach to the implant and drive the expansion member to move in the expansion direction.