The Rhine knee (or Rhine's knee, in GermanRheinknie) is the name of a few bends in the Rhine river.
Rhine knee at Basel
In Basel the Rhine changes its westerly direction of flow to a northerly direction, along the borders of France and Germany, to flow to the North Sea. From a political viewpoint the Rhine knee is near the tripoint of France, Germany and Switzerland. Therefore, this region is called Regio TriRhena.