An instrument (1, 200) for use during a surgical intervention, particularly orthopedic surgery, arranged for application to a limb (L) or another part of the body of a patient that has suffered a bone fracture, comprising:- a first and a second holding member (4, 6 204, 206) arranged to be engaged, respectively, on a first and a second portion (L1, L2 B1, B2) of said limb or another part of the body of a patient that has suffered a fracture,- an actuator (2) comprising a body (10) and a stem (12) moveable with respect to said body (10), wherein said first holding member (4, 204) is connected to said body (10) and said second holding member (6, 206) is connected to said stem (12),- an electric motor (26) coupled to a transmission (18, 40, 42) operatively connected to said stem (12),- sensor means (S) for sensing the position of said stem (12),- electronic control means (CU) operatively connected to said electric motor (26) and cooperating with said sensor means (S),wherein said electric motor (26) is controllable through said electronic control means (CU) to vary in an accurately controlled manner the relative position of said first and second portion (L1, L2 B1, B2) of said limb or another part of the body of a patient on which said first and second holding member (4, 6 204, 206) are engaged.
