Despite obvious clinical symptoms, dynamic, palmar instability of the ulnar head remains a diagnostic and therapeutic problem. This is demonstrated by a case of chronic, palmar instability of the ulnar head after a tear of the triangular fibrocartilage complex (TFCC). A concomitant, minimal dorsal angulation of the radius after a fracture in childhood and a general capsulo-ligamentous laxity possibly were predisposing factors. Aspects of diagnostic and therapeutic options are discussed. In our case, due to secondary arthrosis, an arthrodesis of the distal radioulnar joint combined with a stabilization of the TFCC was opted for. Although the patient is painfree and mobile, she complains of a loss of power in supination. This salvage procedure probably could have been avoided by an earlier diagnosis.