A lower leg prosthesis, for an amputee who has at least one leg having a leg stump, has a distal end and a proximal end. The distal end is connectable to an artificial foot. The proximal end is connectable to the leg stump via a stump socket. A use condition of the lower leg prosthesis includes the distal end being connected to the artificial foot and the proximal end being connected to the leg stump via the stump socket. The lower leg prosthesis includes a mechanism which is configured such that, in the use condition of the prosthesis and in an upright position of the amputee with the artificial foot in contact with a floor and in response to a rotative movement of the leg stump around its corresponding hip joint by the amputee with the artificial foot still in contact with the floor, the rotative movement being at least in a frontal plane of the amputee and in a first rotation direction within the frontal plane, the lower leg prosthesis rotates the artificial foot relative to the floor in a second rotation direction within the frontal plane. The first rotation direction is opposite the second rotation direction.
