Expandable fusion device and method

An intervertebral implant comprising:

• an implant body including a leading end and a trailing end, the implant body including a length that extends from the leading end to the trailing end, the implant body also including a height that is transversely oriented relative to the length;
• the implant body including an external member including a first external wall spaced apart from a second external wall, the first and second external walls having lengths that extend along the length of the implant body and heights that extend along the height of the implant body, and the first and second external wall defining inwardly facing surfaces;
• the implant body including an internal member including a first internal wall spaced apart from a second internal wall, the first and second internal walls having lengths that extend along the length of the implant body and heights that extend along the height of the implant body, and the first and second internal wall defining outwardly facing surfaces;
• the internal member being disposed within the external member with the outwardly facing surfaces of the first and second internal walls respectively opposing the inwardly facing surfaces of the first and second external walls;
• the implant body being movable from a non-expanded position to an expanded position by moving the internal and external members relative to each other to increase the height of the implant body, the internal walls maintaining an overlapped relationship with respect to the external walls as the implant body is moved between the non-expanded position and the expanded position;
• and
• the height of the implant body varying along the length of the implant body at least when the implant body is in the expanded position to provide a taper along the length of the implant body.

An intervertebral implant comprising:

• an implant body including a leading end and a trailing end, the implant body including a length that extends from the leading end to the trailing end, the implant body also including a height that is transversely oriented relative to the length, the implant body further including a width that is transversely oriented relative to the height and the length;
• the implant body including first overlapping portions and second overlapping portions, the first overlapping portions and the second overlapping portions being separated generally by the width of the implant body;
• the implant body being movable from a non-expanded position to an expanded position to increase the height of the implant body;
• the first overlapping portions sliding relative to one another when the implant body is moved from the non-expanded position to the expanded position, and the second overlapping portions also sliding relative to one another when the implant body is moved from the non-expanded position to the expanded position;
• the first overlapping portions maintaining an overlapped relationship as the implant body is moved between the expanded position and the non-expanded position;
• and
• the height of the implant body varying along the length of the implant body at least when the implant body is in the expanded position to provide a taper along the length of the implant body.

An intervertebral implant having an expanded and non-expanded configuration, the implant comprising:

• an external member including a first external wall spaced apart from a second external wall;
• an internal member including:
• a first internal wall spaced apart from a second internal wall such that the first and second internal walls are disposed within the first and second external walls;
• and
• a locking arrangement comprising at least one pin and at least one aperture in an opposing wall, wherein the at least one pin is disposed between the external member and internal member when the implant is in the non-expanded configuration, and the at least one aperture is configured to receive the at least one pin when the implant is in the expanded configuration, the locking arrangement further comprising a first locking structure spaced apart from a second locking structure, the first locking structure including:
• a first pin projecting from one of the first internal wall or first external wall and a first aperture in a first opposing wall;
• and
• a second pin projecting from one of the second internal wall or second external wall and a second aperture in a second opposing wall;
• and the second locking structure comprises:
• a third pin projecting from one of the first internal wall or first external wall and a third aperture in a third opposing wall;
• a fourth pin projecting from one of the second internal wall or second external wall and a fourth aperture in a fourth opposing wall;
• a first groove in the first opposing wall extending from the first aperture towards a base of the first opposing wall;
• a second groove in the second opposing wall extending from the second aperture towards a base of the second opposing wall;
• a third groove in the third opposing wall extending from the third aperture towards a base of the third opposing wall;
• and
• a fourth groove in the fourth opposing wall extending from the fourth aperture towards a base of the fourth opposing wall;
• wherein the first pin is positioned within the first groove, the second pin is positioned within the second groove, the third pin is positioned within the third groove, and the fourth pin is positioned within the fourth groove when the implant is in the non-expanded configuration.