An interspinous implant (1), for implantation between two adjacent spines (EI, ES) that include, each, an upper edge (E2), a lower edge (E3) and two opposite lateral faces (E4, E5), in which the implant (1) is designed to be implanted from only one lateral face (E4, E5) of the spines, including: - at least one body (10) with dimensions arranged to maintain or restore a distance between the edges adjacent (E2, E3) of the two spinous processes (EI, ES) and that includes at least two wings (11, 12) that extend over the same side face of the body, so that at least a part of each wing ( 11, 12) is located along at least a part of a lateral face (E4, E5) of one of the two spinous processes (EI, ES) and, in addition, - at least one retaining element (2, 4 , 24, L) independent of the body (10), designed to retain the body (10) of the implant between the two spines, and which includes at least one insert (2) that t It has a folded position and an unfolded position, said body (10) comprises at least one passage (15) that extends through at least one part of the body, opening into the interior of at least one lateral face of the interspinous implant and dividing into two in the direction of the upper and lower spines, and allowing the insertion of said insert (2) when it is in its folded position, from the same lateral face (E4, E5) as that from which the body (10) is inserted between the spines, characterized in that: - said insert (2) includes at least two curved plates articulated around an articulation axis (250) to pivot between the folded position and the unfolded position, - said passage (15 ) has a shape, dimensions and orientation complementary to the shape, dimensions and orientation of the at least two curved plates, so that they slide through said passage (15) without deformation when said insert (2) is e n the folded position and is inserted in said passage (15), which extends said insert (2) in its deployed position, so that at least a part of these at least two
