A graft distribution system, comprising; a central beam having a proximal portion having an end, a grafting portion having a top and a bottom, a distal portion having a end, a central beam axis, a graft distribution channel having an entry port at the end of the proximal portion, a top exit port at the top of the grafting portion, and a bottom exit port at the bottom of the grafting portion; and, a laterovertically-expanding frame having a lumen, a first top beam, a second top beam, a first bottom beam, and a second bottom beam, each having a proximal portion and a distal portion, and each connected to each other at their respective proximal portions and distal portions with connector elements to form the laterovertically-expanding frame that is reversibly collapsible from an expanded state into a collapsed state, the expanded state having a central axis and an open graft distribution window that at least substantially closes upon the reversible collapse, the bone graft distribution window defined by the connector elements and opening upon expansion of the laterovertically-expanding frame; the laterovertically-expanding frame is adapted for receiving an insertion of the central beam to form the graft distribution system; and the graft distribution system is adapted to receive and distribute bone graft material through the central beam in an intervertebral space of a subject for a spinal fusion, characterised in that, the connector elements are struts (191,193,195,197) configured to have a cross-sectional aspect ratio of longitudinal thickness (Lt) to transverse thickness (Tt) adapted to maintain structural stiffness in the laterovertically-expanding frame in a direction perpendicular to the central frame axis of the expanded state of the frame, the cross-sectional aspect ratio (Lt:Tt) ranging from 1:2 to 1:8. a central beam having a proximal portion having an end, a grafting portion having a top and a bottom, a distal portion having a end, a central beam axis, a graft distribution channel having an entry port at the end of the proximal portion, a top exit port at the top of the grafting portion, and a bottom exit port at the bottom of the grafting portion; and, a laterovertically-expanding frame having a lumen, a first top beam, a second top beam, a first bottom beam, and a second bottom beam, each having a proximal portion and a distal portion, and each connected to each other at their respective proximal portions and distal portions with connector elements to form the laterovertically-expanding frame that is reversibly collapsible from an expanded state into a collapsed state, the expanded state having a central axis and an open graft distribution window that at least substantially closes upon the reversible collapse, the bone graft distribution window defined by the connector elements and opening upon expansion of the laterovertically-expanding frame; the laterovertically-expanding frame is adapted for receiving an insertion of the central beam to form the graft distribution system; and the graft distribution system is adapted to receive and distribute bone graft material through the central beam in an intervertebral space of a subject for a spinal fusion,