An orthosis including arms held in place on body parts by a respective fastening member and interconnected by a pivot joint adjacent to a body joint. For bending of the body parts required during normal movement, the pivot joint is formed by a central adjusting ring bordered by both arms. One arm includes an axle ring which is coaxial to the adjusting ring. The other arm includes a ring bearing, which is eccentric to the axle ring. The ring bearing is pivotable with respect to a rotational plane of the axle ring by rotating the adjusting ring in such a way and at such an angle that the arm, supported by the ring bearing in conjunction with the body part retained by it, assumes a pivoting position of this body part depending on the rotation angle of the adjusting ring in relation to the arm connected to the axle ring.