[Destabilization of the discus articularis with rupture of the ulnar styloid apex in distal radius fracture. Diagnosis with dynamic MR].

An avulsion of the ulnar styloid apex led--because of a simultaneous rupture of the ulnar collateral ligament and a rupture of the disc's insertion in the fovea ulnaris--to a displacement of the triangular fibrocartilage. During movements in the frontal plane, the latter underwent a deformation, was displaced, compressed and blocked ulnar abduction. This pathology and the ulnar impingement could be observed in a "MRI-movie".