[The caput-ulnae-syndrome. Pathogenesis, clinic and therapy]

The ulnar head has a central function in stabilizing the wrist. In the treatment of caput ulnae syndrome, the radiocarpal joint must, therefore, always be considered. The integrity of the ulnar head and TFCC are of major importance for the rheumatoid wrist. Therefore, surgical treatment should be carried out early, and is indicated for drug-resistant synovitis and monarthritis of the wrist. Early synovectomy of the radiocarpal and distal radioulnar joint (DRUJ) can be done as an open procedure or, when extensor tendon synovitis is absent, as an arthroscopic procedure. In most cases, however, treatment of manifest caput ulnae syndrome, sometimes even with rupture of the extensor tendons, is necessary. In these cases, resection of the ulnar head together with a dorsal wrist stabilization is indicated. Less often, arthrodesis of the DRUJ with segmental resection of the ulna or an arthroplasty are indicated. When choosing the procedure, the type and stage of wrist changes have to be considered. The DRUJ usually has to be treated together with the radiocarpal joint. Its isolated treatment is rarely indicated.