The device according to the disclosure is for stabilising a patient in a desired position during X-ray knee imaging. By default, a tibial inclination angle of 10° is envisaged, as according to statistics this constitutes an inclination for the ideal imaging of the knee joint space. This angle as well as the foot rotation angle are adjustable. The device is suitable for a majority of different body heights and shapes. Equipment sensors determine the achievement of the desired position and this is confirmed to the X-ray technician by means of an acoustic and optical transducer.