OSTEOSYNTHESIS DEVICE FOR PROXIMAL FEMUR FRACTURE AND MASTER SCREW TYPE SCREW DEVICE FOR OSTEOSYNTHESIS DEVICE FOR PROXIMAL FEMUR FRACTURE

An embodiment of the present invention is an osteosynthesis apparatus for proximal femur fractures which has a structure in which a lag screw set and a nail are assembled by screwing. A lag screw is assembled with a key ring and a fastening nut in advance and when inserting this lag screw set into a bone, grip bars are inserted radially at a predetermined angle and direction, resulting in a strong bone holding power. Further, in a final step, a strong fixed coupling is achieved by forcibly screwing and engaging the lag screw and the fastening nut by an interference of the threads of the lag screw and the fastening nut. Thus, the osteosynthesis apparatus for proximal femur fractures has a strong bone holding power and is stable without loosening.