An insertion device configured for use with an expandable cage, the insertion device comprising: a first engagement arm including a first body portion and a first proximal extension, the first body portion configured to engage a first support member of the expandable cage; a second engagement arm including a second body portion and a second proximal extension, the second body portion configured to engage a second support member of the expandable cage; and an adjustment mechanism operably coupling the first and second proximal extensions of the respective first and second engagement arms to one another, the adjustment mechanism including: an adjustment screw rotatably coupled to the first proximal extension, the adjustment screw including a shank defining threading; characterised by: the second proximal extension being disposed about the first proximal extension and slidable therealong from a free end of the first proximal extension to a fixed end of the first proximal extension to vary a spacing between the first and second engagement arms; the adjustment mechanism comprising an adjustment cylinder coupled to the second proximal extension, the adjustment cylinder defining a threaded passageway configured to receive the shank of the adjustment screw in threaded engagement therewith, wherein rotation of the adjustment screw relative to the adjustment cylinder urges the second proximal extension to translate along the first proximal extension to vary the spacing between the first and second engagement arms. a first engagement arm including a first body portion and a first proximal extension, the first body portion configured to engage a first support member of the expandable cage; a second engagement arm including a second body portion and a second proximal extension, the second body portion configured to engage a second support member of the expandable cage; and an adjustment mechanism operably coupling the first and second proximal extensions of the respective first and second engagement arms to one another, the adjustment mechanism including: an adjustment screw rotatably coupled to the first proximal extension, the adjustment screw including a shank defining threading; characterised by: the second proximal extension being disposed about the first proximal extension and slidable therealong from a free end of the first proximal extension to a fixed end of the first proximal extension to vary a spacing between the first and second engagement arms; the adjustment mechanism comprising an adjustment cylinder coupled to the second proximal extension, the adjustment cylinder defining a threaded passageway configured to receive the shank of the adjustment screw in threaded engagement therewith, wherein rotation of the adjustment screw relative to the adjustment cylinder urges the second proximal extension to translate along the first proximal extension to vary the spacing between the first and second engagement arms. an adjustment screw rotatably coupled to the first proximal extension, the adjustment screw including a shank defining threading; characterised by: the second proximal extension being disposed about the first proximal extension and slidable therealong from a free end of the first proximal extension to a fixed end of the first proximal extension to vary a spacing between the first and second engagement arms; the adjustment mechanism comprising an adjustment cylinder coupled to the second proximal extension, the adjustment cylinder defining a threaded passageway configured to receive the shank of the adjustment screw in threaded engagement therewith, wherein rotation of the adjustment screw relative to the adjustment cylinder urges the second proximal extension to translate along the first proximal extension to vary the spacing between the first and second engagement arms.