An orthotic, in particular a knee orthotic, comprises a pair of rail arms, which in each case have a pivoting first rail arm section and a second rail arm section that can be fastened to a patients body. The second rail arm section of at least one rail arm is held on the first rail arm section in a slope—adjustable manner and in a movable manner in the longitudinal direction of the rail arm and is forcibly controlled such that a pivoting of the rail arms in the flexion or extension direction is coupled both with an adjustment in the medial or lateral inclination of the second rail arm section and with a change in length of the rail arm.
