Several types of external fixation devices exist among which those of Judet, Hoffmann, Wagner and Müller can be picked out, each of which has definite applications. Confronted with difficulty in the use and the defect of mechanical rigidity, we have been led to design a new type of the triangular external fixation device. As open fractures of the limbs in stage II and IV of Duparc and Cauchoix, and pseudoarthrosis infected need a considerable stability in addition to careful surgical treatment, so after a comparative mechanical study, and after codifying the most rigid installation, we have used it on several traffic accident victims.