A robotic surgical assembly includes a slave manipulator with an actuator, a pushing device connected to the actuator, a sensor detecting a contact force on the pushing device, a position sensing system, and a control unit. A surgical instrument is detachable to the slave manipulator and separated from the slave manipulator by a sterile barrier. The surgical instrument includes a frame; an articulated link; a tendon associated with the actuator, having proximal and distal portions secured to the link. A transmission device in contact with the tendon proximal portion exerts a traction action. The transmission device has one degree of freedom of motion relative to the frame. The pushing device releasably and selectively connects with the transmission device to transmit a pushing action to the transmission device through the sterile barrier. An elastic device biases the transmission device to exert a traction action on the tendon.