Medical system and method for locating an entry point of a surgical instrument in an anatomical structure and for identifying a trajectory of the surgical instrument in the anatomical structure, and assembly comprising such a medical system and a surgical instrument

A medical system for locating an entry point of a surgical instrument into a first anatomical structure of a body part of a patient, and for identifying a path of the surgical instrument in the first anatomical structure, the body part further comprising at least one second anatomical structure adjacent to the first anatomical structure and defining at least one interface therebetween, the first anatomical structure having a first acoustic impedance greater than a second acoustic impedance of the at least one second anatomical structure, the medical system comprising a tool comprising:

• a body extending along a central axis between opposite proximal and distal ends and having an external surface;
• a location measurement device adapted to, in at least one site of an external surface of the first anatomical structure:
• emit from the distal end of the body at least one ultrasound location signal adapted to propagate in the first anatomical structure and to be at least partially reflected at the at least one interface between the first anatomical structure and the at least one second anatomical structure;
• and
• receive at least one reflected location signal corresponding to a reflection of a portion of the at least one ultrasound location signal, the at least one reflected location signal comprising a plurality of echoes of amplitudes that vary over time;
• a location processing device operatively coupled to the location measurement device, the location processing device adapted to:
• compare, at each site, each of the echoes of the at least one reflected location signal received by the location measurement device within a predetermined analysis time window to a defined location threshold, the predetermined analysis time window selected based on a thickness of the first anatomical structure;
• and
• emit an information signal if no target location echo corresponding to the at least one interface between the first anatomical structure and the at least one second anatomical structure has been identified within the predetermined analysis time window, the target location echo having an amplitude which exceeds the defined location threshold,
• wherein the first anatomical structure comprises a bone structure and wherein the at least one second anatomical structure comprises a soft tissue structure.