In an apparatus for the
osteosynthesis of bone fractures by means of locked endomedullary nailing, a tubular nail (1), able to be inserted in a medullar channel (3) of a bone (4), has a coaxial through internal channel (2) and has transverse through holes (5a, 5b, 5c, 5d) whose axis (6a, 6b, 6c, 6d) intersects the axis (7) of the nail (1). A device for locating the axis (6a) of a predetermined hole (5a) selected between said holes (5a, 5b, 5c, 5d), along which the bone (4) is to be drilled to drive a corresponding screw for locking the nail (1) on the bone (4), comprises a source (8) of
electromagnetic power, an emitter (9) of the
electromagnetic power in the form of non ionising
electromagnetic radiation, a line (15) for transmitting the
electromagnetic power from the source (8) to the emitter (9). The emitter (9) can be inserted inside the nail (1) along the internal channel (2), from a proximal end (10) of the nail (1) at least to a working position, located on the axis (6a) of the predetermined hole (5a), in which at least part of the non ionising
electromagnetic radiation is directed from the emitter (9), through the predetermined hole (5a), on an inner superficial portion (11) of the cortex (12) of the bone (4) corresponding to the bone (6a) of the predetermined hole (5a) and generates, beyond an outer superficial portion (13) of the cortex (12) of the bone (4), also corresponding to the axis (6a) of the predetermined hole (5a), a
signal (14) detectable from the exterior having intensity distribution with
centroid in correspondence with the axis (6a) of the predetermined hole (5a).