An intervertebral arthrodesis implant (100) for implantation from, at least in part, a posterior access route, at least partly inside and through the height of a disc space between two adjacent vertebral bodies of a person's spine adult, said implant (100) comprising: a body having a front end (104) for insertion into the disc space first, a rear end (102) arranged in front of said front end (104), a longitudinal geometric axis means, and an extension between said front and rear ends of said body, said body having an upper portion (106a) adapted to contact one of the adjacent vertebral bodies, a lower portion (106b) opposite to said upper portion (106a) adapted to contact another of the adjacent vertebral bodies, and at least one lateral portion (108a), (108b) between said upper (106a) and lower (106b) portions, having each of said upper, lower and lateral portions (106a), (106b), (108a), (108b) a length and extending from said rear side (102) of said body and being separated from each other to constitute a hollow interior (103) between them, said hollow interior (103) being configured to contain within it at least part of the bone regrowth promotion material, said upper and lower portions (106a), (106b) being configured to allow bone regrowth of vertebral body adjacent to adjacent vertebral body through said body of said implant (100), each of said upper, lower and lateral portions (106a), (106b), (108a), (108b) being configured to move, at least in part, in a direction away from the middle longitudinal geometric axis allowing the expansion of the height and at least a portion of the width of said body, said upper, lower and lateral portions (106a), (10 6b), (108a), (108b) a collapsed position with respect to each other allowing a collapsed height and width of said body and an expanded position with respect to each other allowing an expanded height and width of said body, the body being expanded height and width of said body greater than the collapsed width and hei
