Expandable implant for the spinal column

A combination of an expandable implant and an operating instrument, the expandable implant comprising an upper plate and a lower plate which extend in the xy plane and which serve for anchoring on/in vertebral support surfaces, the expandable implant further comprising at least three gears which are coupled to each other, wherein the gears serve to expand the expandable implant, each gear having a threaded spindle and a threaded sleeve with corresponding inner thread, wherein the pitch of one thread is different from the pitch of the other threads, the operating instrument being engageable with the expandable implant for use in expanding the expandable implant, the operating instrument comprising a handpiece having a longitudinal axis, a gear drive connected to the handpiece for driving one of the gears of the expandable implant, means for securing the gear drive to the expandable implant, and means for moving the expandable implant laterally relative to the longitudinal axis of the handpiece while keeping the handpiece stationary, wherein the moving means comprises a rotatable toothed wheel portion and wherein the rotatable toothed wheel portion is driven by an actuation rod.