Arrangement for an instrument which comprises or is connected to a driving-in tool

Arrangement for an instrument which comprises or is connected to a driving-in tool for an element on or in the form of an implant or drill for bone, in which the tool comprises an electric motor which can be controlled by a control unit, and in which a unit which senses feed current in the electric motor and, depending on sensing of the feed current, emits a signal depending on the torque of the electric motor, which signal represents a torque curve or torque-angle curve, and in which a display unit is arranged so as to display fully or partly a driving-in function performed, according to one or more of the following alternatives:

• a) at least one of the sensing and display unit determines a quality of the tightening function by means of a scale based on a slope of said torque curve or said torque-angle curve, wherein a flatter slope represents lower quality of the tightening function and a steeper slope represents higher quality of the tightening function;
• b) a calculating unit in one of the sensing unit and the display unit is arranged so as to determine, in the driving-in function, a frictional resistance which exists for the element, when the element is in the form of a screw, during driving-in of the element in order to make possible the application of a desired loading which brings about secure locking by means of tension or elasticity movements in material of the element;
• c) the sensing unit senses torque generated by the electric motor during drilling in the bone of a hole for a screw tap or a threaded implant, and that the display unit indicates, depending on the sensing of the feed current, a torque-time curve, wherein a quality of the bone can be read off during drilling based on the torque-time curve;
• d) the sensing unit senses torque generated by the electric motor during tapping of the implant into the bone, and that a calculating unit in one of the sensing and the display unit, is arranged so as to establish, in the driving-in function, whether the implant is rotating without following a pitch of the implant in an axial direction and threads are thereby being destroyed in the bone, in which case a warning signal is given to a user or rotation of the implant is stopped.