[Roentgen diagnosis of post-traumatic radius torsion].

Especially the identification of rotational malunions on the distal radius is difficult by routine diagnosis. Long-time effects like a chronic loss of articular surface of the posttraumatic rotation on the distal radioulnar joint are of clinical importance. Evading expensive diagnostic methods like CT simulated rotational malunions of the radius are quantitatively investigated on the basis of routine X-ray pictures only. The geometrical relation between the rotational angle of the radius and the two-dimensional distance from the dorsal to the volar border of the radial notch is described by a simple trigonometrical function. Considering morphological individualities of the radial notch and the rotational angles of right and left radii rotational malunions below 10 degrees are discovered and their effects on the forearm skeleton are assessed.