An arthrodesis implant (1) allowing promoting the bone fusion of two bones is provided, the implant (1) comprising: a rigid and non-deformable anchoring body (4), designed to ensure the anchoring of the implant (1) in a first bone (2), and a deformable portion (5) designed to ensure the anchoring of the implant (1) in a second bone. The deformable portion (5) comprises at least two anchoring arms (9, 10) which protrude beyond the anchoring body (4) from the base end (7) of the anchoring body (4), the anchoring arms (9, 10) being separated from each other by a free space (E) so as to be able to be brought closer to each other by deformation of the anchoring arms under the action of the second bone. At least one of the anchoring arms (9, 10) is provided with a longitudinal reinforcing fin protruding beyond the anchoring arm (9, 10) from a lateral side (20) of the anchoring arm (9, 10).