**4.4 Dupuytren's sign or piston**

The patient is placed supine with the leg flexed to 90° at the hip and knee [17]. The pelvis is fixed with the thumb of one hand resting on the anterior superior iliac spine and the index and middle fingers on the trochanter; With the other hand he takes the knee and the leg, making movements up and down (traction and pressure). If it is positive, the displacement of the greater trochanter is perceived.
