An intervertebral fusion implant for fusion of two adjacent vertebrae, comprising a base piece and a cover piece, which are each designed to bear on a facing end plate of one of the adjacent vertebrae, wherein the cover piece is adjustable in height with respect to the base piece, wherein a ratchet mechanism, provided between base piece and cover piece, effects a stepped adjustment of height and secures an adopted height against reversal. In this way, a defined expansion can be achieved that is dependent on the number of actuations. A precise control of the state of expansion is permitted, specifically in a purely haptic manner. Moreover, a locking of the adopted state of expansion is achieved with the ratchet mechanism.
