Lower leg prosthesis

A lower leg prosthesis (1) comprises a distal end (for) having an artificial foot (5) and a proximal end (for) having a stump socket (7) for connection to a leg stump of an amputee. The prosthesis comprises a mechanism (10) which is arranged such that, in use condition of the prosthesis and in an upright position of said amputee with said artificial foot resting on a floor, in response to the amputee performing a rotative movement of said leg stump around its corresponding hip joint while keeping said artificial foot resting on the floor, said rotative movement at least occurring in the frontal plane of the amputee and in one rotation direction (R1) within the frontal plane, the prosthesis causes said artificial foot to rotate relative to the floor at least in the other, i.e. opposite, rotation direction (R2) within the frontal plane.