RESUMEN
Objective To explore the methods of internal fixation for femoral neck fractures and evaluate the biomechanical characteristics of the interlocking expanding compressive screw (IECS)of Type HZS. Methods Based on the special biomechanical characteristics of the femoral neck fracture, the device of internal fixation was designed to consist of main screw, bifurcate screw, boost screw cap, washer, compressive screw cap, oblique interlocking screw and main screw cap. Its biomechanical performances were evaluated through comparison with those of the dynamic compressive screw (DCS), twin compressive screw (2CS) and three cannulated screws (3CS) respectively. Results The mechanical performances of the femoral neck fracture fixed with the interlocking expanding compressive screw were superior to those of the others in displacement ,axial and level stiffness, torsional strength and stiffness and terminal loading. Conclusion Interlocking expanding compressive screw can efficiently withstand the splitting, torsional, shearing, tensional and compressive forces in the fracture, and is simple, safe and easy to use. [