The invention concerns an accessory for bone surgery, advantageously for operative arthroscopy, suitable for positioning and attaching a bone fragment on a target bone surface. This accessory (1) comprises a body of a sighting body (3) comprising at least one sighting hole (37) which opens on the two end faces (31, 32), and a feeler member (4), extending in protrusion from the front end face (31) of said sighting body (3). A front end face (31) of said sighting body (3) and a lower face (411) of said feeler member (4) together form a dihedral receiving surface (D) against which said bone fragment (F) is intended to bear. This accessory (1) also comprises pressing means (5) capable of temporarily maintaining said bone fragment (F) bearing against said dihedral receiving surface (D).
