If any of the remaining space betweenthe vertebral bodies is packed with bone chips, then oncehealing occurs a much greater area of the bodies will bebridged with bone and so the major concern is thesystem immediately post-operatively with the principalbone grafi/s load bearing. Implicit in the assumption thatthe graft transmits the load is the fact that the bone of thevertebral bodies on which the graft bears must alsosustain this load.