Method, brace (55), and system for measuring a degree of torsion or bending of a part of a human or animal body. The method comprises the steps of attaching a sensor (56) to a part of the human or animal body, obtaining calibration data of the sensor by detecting the output signal of the sensor for a well defined degree of torsion or bending of said part of the human or animal body, storing the calibration data, measuring an output signal of the sensor during torsion or bending of said part of the human or animal body, and a final step of relating said output signal of the sensor to a degree of torsion or bending by using the calibration data. The method, brace and system are characterised in that the sensor comprises an electrically conductive loop (51), the area of said loop at least partially covering said part of the human or animal body, for instance a knee, and that the sensor further comprises an output unit (57) for providing an output signal that is a measure for the inductance of the loop.
