The invention concerns a prosthesis (P) comprising: a stem part (1) comprising: a rod (3), configured for being inserted into a medullary cavity (8) of a diaphyseal fragment (2) of a fractured long bone, for securing the stem part (1) to the diaphyseal fragment (2), and an epiphyseal end (5), fixedly secured to the rod (3) by means of at least one linker leg (7) of the stem part (1), so that a gap (9) is formed between the epiphyseal end and the rod (3) along said at least one linker leg (7)； and an implant (20) distinct from the stem part (1) and comprising: an internal part (22) located at least partially within the gap (9), and at least one fastener (24) for fastening epiphyseal fragments (4) of the fractured long bone to the stem part (1), said at least one fastener (24) being secured to the internal part.
