Expandable interbody fusion device

An expansion member for sequential insertion into a space between opposing tissue surfaces to be distracted, comprising:

• an elongated body having an upper surface and an opposite lower surface;
• at least one cavity defined in one of said upper surface and said lower surface;
• and
• at least one resilient prong defined in and projecting beyond the other of said upper surface and said lower surface, wherein said at least one prong is oriented such that when two of said expansion members are immediately adjacent and substantially co-extensive, at least a portion of said at least one prong of one expansion member is disposed within said at least one cavity of the other expansion member.

An expandable interbody fusion device (IBFD) for implantation into the intradiscal space between two opposing vertebral bodies of a spine, comprising:

• a first endplate member having an outer surface for contacting one vertebral body in a spine;
• a second endplate member having an outer surface for contacting an opposing vertebral body in said spine, said second endplate member being movable in an expansion direction relative to said first endplate member toward the opposing vertebral body;
• an expansion member configured to be introduced between said first endplate member and said second endplate member in an insertion direction that is substantially perpendicular to said expansion direction, to thereby move said first and second endplate members relatively apart in said expansion direction upon introduction;
• and
• an interlocking prong and cavity engagement defined between said expansion member and said second endplate member to prevent relative movement of said expansion member relative to said second endplate member in a direction opposite said insertion direction when said expansion member is substantially co-extensive with said second endplate member,
• wherein said expansion member includes a surface facing said second endplate member and said second endplate member has a surface facing said expansion member;
• and
• said cavity is defined in said facing surface of said second endplate member and said prong projects beyond said facing surface of said expansion member into said recess when said expansion member is substantially co-extensive with said second endplate member.

An expandable interbody fusion device (IBFD) for implantation into the intradiscal space between two opposing vertebral bodies of a spine, comprising:

• a first endplate member having an outer surface for contacting one vertebral body in a spine;
• a second endplate member having an outer surface for contacting an opposing vertebral body in said spine, said second endplate member being movable in an expansion direction relative to said first endplate member toward the opposing vertebral body;
• at least one expansion member configured to be slidingly introduced between said first endplate member and said second endplate member in an insertion direction that is substantially perpendicular to said expansion direction, to thereby move said first and second endplate members relatively apart in said expansion direction during sliding introduction;
• and
• cooperating locking structure between said expansion member and said first endplate member and said second endplate member to restrict relative movement in multiple degrees of freedom, including at least one interlocking element that is resiliently deflectable in the expansion direction.