The bone plate, nail and external fixation apparatus have been indtroduced for the union of the fractured bones. decently, the extemal fixation technique has been revived, especially for the healing of the fractured tibia, femur, pelvis and forearm bones. The device was intended to neutralise a comminuted fracture by provision of interfragmentary compression. Numerous different types of external fixatlon apparatuses have been developed in U.S.A. and other European countries. However, in our country, the apparatuses have been imported and utiliced for the surgical application without any experimental confirmation.

For the elucidation of the usage of imported external fixation devices, the stiffness of the external fixation devices (Orthofix, Monofixateure, and Hoffmann) were analysed experimentally. MTS and universal testing machine(UTM) were used for the exporimental analysis under the different loading conditions of axial compression, antero-posterior and medio-lateral bending. Furthermore, the stiffness and yielding load of the laboratory developed unilateral type of external fixation device were compared with those of the imported ones. In addition to this, the configuration of laboratory developed device was changed for the parametric study under the axial compression. The stiffness and yielding load of the laboratory developed device were sufficient for surgical application. However, the weight of our laboratory developed model is 1.2 times the average weight of imported ones. The reduction of weight may be needed for more convenient surgical application.