Expandable Intervertebral Fusion Cage

An intervertebral fusion cage, comprising:

• a cage body that defines a leading end with respect to a direction of insertion into an intervertebral space, a trailing end opposite the leading end along a longitudinal direction, an upper vertebral contacting surface and a lower vertebral contacting surface spaced from the upper vertebral contacting surface along a transverse direction that is substantially perpendicular with respect to the longitudinal direction, and first and second side walls that extend between the leading end and the trailing end, the first and second side walls opposite each other along a lateral direction that is substantially perpendicular to each of the longitudinal direction and the transverse direction,
• wherein the lower and upper vertebral contacting surfaces are movable away from each other along the transverse direction so as to expand the intervertebral fusion cage from a first transverse position to an expanded transverse position, and
• wherein at least respective portions of the first and second side walls are movable away from each other different distances so as to expand the intervertebral fusion cage from a first lateral position to an expanded lateral position, whereby in the expanded lateral position the first and second side walls are spaced from each other along the lateral direction a first distance at a first location spaced from both the trailing end and a midline between the leading end and the trailing end with respect to the longitudinal direction, and the first and second side walls are spaced from each other along the lateral direction a second distance at a second location between the first location and the leading end, the second location is different than the first location, and the second distance is greater than the first distance.