An orthosis for increasing range of motion of a body joint. The orthosis includes a rotational linkage mechanism having a driving link and a driven link configured for rotation about a joint axis. The driven link is selectively attachable to a body part to rotate the body part about the joint axis. A dynamic force mechanism is operatively connected between the driving link and driven link to impart a dynamic force upon the driven link when the driving link rotates relative to the driven link and the driven link resists rotation with the driving link due to a resistance force imparted on the driven link by the body part reaching a maximum range of motion. The dynamic force is transferred through the driven link to the body part.
