An expansion member for distributing graft material through a cage and into an intervertebral space is provided. The expansion member has a central beam with an entry port in fluid communication with an exit port for distribution of the graft material. The central beam is inserted into a cage having a reversible collapse from an expanded state into a collapsed state, the expanded state forming a graft distribution window. The expanded state, for example, can be configured to open the graft distribution window which at least substantially closes upon the reversible collapse.
A variety of expandable cage improvements are provided. The cages can have a width expansion assembly that operates independently of a height expansion assembly and the wedges and ramps do not need to make contact with each other. Wedges, or movable spacers with pivotal link connections, can be used, and any portion of the cage can be expanded in width or in height in an amount that differs from other portions of the cage to provide any of a multitude of desired cage shapes. Interdigitating fingers, slidable and / or pivoting, are provided to distribute stresses over a vertebral endplate as desired.