[Behavior of the joint surface of the distal radio-ulnar joint in malposition of the distal radius].

Pathological changes of wrist bones and ligaments after radial fracture loco typico induce permanent functional restriction and pain. In this paper the effects of malunion on the distal radioulnar joint are investigated and osteotomic therapy of Kienböck's disease gets a new evaluation. By simulating radial malunions on anatomic forearm specimen the effects of these malunions on the contact area during supination, neutral position and pronation are measured. Isolated posttraumatic radial shortening as well as epiphyseal inclination and torsion cause a reduction of radioulnar contact. During supination and pronation the loss of radioulnar contact increases. Most significant reduction of contact takes place at a lower graduation of radial malunion. Pronatory torsion of distal radius compensates for a radioulnar contact reduction from combining dorsal inclination with radial shortening. One conclusion of this paper is an exact restitution of anatomical relations between ulnar head and radial notch after fracture of the distal radius.