Surgical instrument

1. A surgical instrument comprising:

an elongated arm extending along a longitudinal axis and having a base element and a distal end coupled to said base element via a pivot joint structure around an axis orthogonal to the longitudinal axis, said pivot joint structure including several linking elements coupled to series, wherein said linking elements comprise at least one intermediate linking element interposed between a base linking element and a distal linking element formed by the base element and the distal end respectively;

a drive shaft, coaxial with the elongated arm, comprising a universal joint structure facing the pivot joint structure; and

a distal tool coupled to the drive shaft via the universal joint structure and rotationally coupled to the distal end of the elongated arm, such that the distal tool has two rotational degrees of freedom, distinct and independent of each other, one being around an axis perpendicular to the longitudinal axis of the elongated arm and the other being around an axis collinear with a longitudinal axis of the distal tool,

wherein the universal joint structure includes a flexible drive sleeve coaxial with said pivot joint structure, said flexible drive sleeve having one end coupled to an end of the drive shaft and the other end of the flexible drive sleeve being coupled to the distal tool, so that the flexible drive sleeve transmits a rotational movement of the drive shaft around its longitudinal axis to a rotational movement of the distal tool around its longitudinal axis, in any angular position of the distal tool relative to the drive shaft, said flexible drive sleeve configured to be rigid with respect to torsional force along its longitudinal axis and deformable with respect to torsional force along any axis perpendicular to its longitudinal axis;

said surgical instrument further comprising a cable coupled to the distal end along the linking elements, said cable being configured to control an orientation of said pivot joint structure.

2. The surgical instrument of claim 1 wherein the flexible drive sleeve comprises bellows.

3. The surgical instrument of claim 1 , wherein two adjacent linking elements are mounted relative to one another through a limited pivot joint.

4. The surgical instrument of claim 3 , wherein each linking element is a hollow cylindrical element comprising two lugs extending towards the adjacent linking element, said lugs being opposite one another to define the limited pivot joint.

5. The surgical instrument of claim 1 , wherein the elongated arm is hollow and at least partially encloses the drive shaft.

6. The surgical instrument of claim 1 , wherein the drive shaft is hollow and at least partially encloses the elongated arm.

7. The surgical instrument of claim 6 , wherein the elongated arm comprises a through-hole along the longitudinal axis, one or more cables extending in the elongated arm via the through-hole.

8. The surgical instrument of claim 1 , wherein it comprises an actuating cable for actuating the distal tool extending along the longitudinal axis, the actuating cable being surrounded by a sheath.

9. The surgical instrument of claim 1 , wherein it further comprises:

a handle; and,

a transmission system,

the handle being connected to the proximal end of the elongated arm, the movements through the two degrees of freedom being connected by the transmission system to two independent movements produced at the handle.

10. The surgical instrument of claim 9 , further being arranged such that the amplitude of rotation of the tool about its longitudinal axis is not structurally limited by the transmission system.

11. The surgical instrument of claim 3 , wherein each linking element is a hollow cylindrical element comprising two lugs extending towards an adjacent linking element, wherein the lugs of said linking element are configured to cooperate with a complementary form arranged on the adjacent linking element in order to form the limited pivot joint without the need of a connecting rod.

12. The surgical instrument of claim 11 , wherein the linking elements are maintained in a nested position relative to one another by actuating cables passing through holes in the linking elements for actuation of the pivot joint.