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

1 . 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.

2 . The medical system according to claim 1 , wherein the predetermined analysis time window is defined by a starting point comprising at least one of the emission of the at least one ultrasound location signal or the detection of a first target location echo, and a duration between 1 μs and 100 μs.

3 . The medical system according to claim 1 , for locating the entry point and for identifying the path of the surgical instrument in a bone structure serving as the first anatomical structure, the body part further comprising a soft tissue structure serving as the second anatomical structure, wherein the location measurement device is adapted to emit an ultrasonic wave of a frequency between 100 kHz and 10 MHz.

4 . The medical system according to claim 1 , wherein the location measurement device comprises at least one ultrasonic transducer arranged on the body, the body having an emission-reception surface in contact with the at least one ultrasonic transducer and adapted to emit the at least one ultrasound location signal and to receive the at least one reflected location signal, the emission-reception surface positioned at the distal end of the body on the external surface of the body.

5 . The medical system according to claim 4 , wherein the at least one ultrasonic transducer is arranged at a distance from the distal end of the body, the body having a transmission member adapted to transmit the at least one ultrasound location signal and the at least one reflected location signal, the transmission member in contact with the at least one ultrasonic transducer and defining the emission-reception surface.

6 . The medical system according to claim 5 , wherein the tool further comprises:

at least one first electrode having a first contact surface arranged at the distal end of the body on the external surface of the body so as to come into contact with the first anatomical structure;

at least one second electrode having a second contact surface arranged at the distal end of the body on the external surface of the body so as to come into contact with the first anatomical structure at a distance from the first contact surface;

a layer of electrically insulating material interposed between the at least one first and second electrodes; and

an electric measurement device adapted to measure continuously and in real time an electrical characteristic representative of the capacity of the first anatomical structure for conducting electric current between the first and second contact surfaces,

wherein the layer of electrically insulating material forms the transmission member, and

wherein the emission-reception surface is arranged between the first and second contact surfaces.

7 . The medical system according to claim 6 , wherein the at least one first electrode is cylindrical and extends along the central axis, and the at least one second electrode is annular and extends along the central axis around the at least one first electrode, the layer of electrically insulating material being annular and extending along the central axis around the at least one first electrode and inside the at least one second electrode.

8 . The medical system according to claim 4 , wherein the body comprises an inner body member and an outer body member that is adapted to receive the inner body member, the body having an assembled state wherein the inner body member is inside the outer body member, and a detached state wherein the inner body member and outer body member are separated from each other, the at least one ultrasonic transducer being mounted on at least one of the inner body member or the outer body member.

9 . The medical system according to claim 1 , wherein the tool further comprises a handle adapted to be gripped by a user's hand and which extends from the body, the handle comprising a housing adapted to receive at least a portion of at least one of the location measurement device or the location processing device.

10 . An assembly comprising:

the medical system according to claim 1 ; and

a surgical instrument adapted to penetrate the first anatomical structure of the body part of the patient, the first anatomical structure comprising a bone structure.

11 . The assembly according to claim 10 , wherein the body of the tool is adapted to penetrate the first anatomical structure, the tool forming the surgical instrument.

12 . A method making use of the medical system according to claim 1 for locating the entry point of the surgical instrument into the first anatomical structure of the body part of the patient, and for identifying the path of the surgical instrument in the first anatomical structure, the method comprising the steps of:

in at least one site of the external surface of the first anatomical structure, emitting from the distal end of the body the at least one ultrasound location signal in the first anatomical structure, and receiving the at least one reflected location signal corresponding to the reflection of the portion of the at least one ultrasound location signal at the at least one interface;

at each site, comparing each of the echoes of the at least one reflected location signal received by the location measurement device within the predetermined analysis time window to the defined location threshold; and

emitting the 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.

13 . The method according to claim 12 , wherein the first anatomical structure is a bone structure and the at least one second anatomical structure is a soft tissue structure.