An implant (1) includes a body (5) and intermediate and side walls (15, 16, 17) forming anchoring parts able to be anchored on portions of lamina (101). The anchoring parts are "inverted U"-shaped, so that, when the body (5) is arranged in the implantation position, the direction of engagement of these walls on the portions of lamina (101) is parallel to the cranial-caudal direction of the vertebral column, i.e. the general longitudinal direction of the vertebral column, and the central body (5) includes mounting element (3) allowing one or more grafts (103) to be mounted thereon that can extend from one resected surface (102) of a portion of lamina (101) to the resected surface (102) of the other portion of lamina (101), so that the ends of that or those grafts (103) can be situated, after placement, in the immediate vicinity of the resected surfaces (102).
