The Design Of Femur Neck Screws System And Biomechanical Study In Fixing Femoral Neck Fracture In Children

Objectives: To provide the data for the design of the internal fixation device for the treatment of femoral neck fracture in children,we measured the anatomic data of the proximal femur parameters and investigated its geometric characters in Chinese children (5~7years); Design a new type of screw instrument for femoral neck fracture in children; To decide if the Femur Neck Screws can provide stable fixation stability in fixing femoral neck fracture in children through comparative biomechanical study.Methods:1.Anatomical MeasurementAnatomic data of the proximal femur was measured in 35 normal Chinese children cadavers ,we compared and analyzed the anatomic data with the imageology result.2.Design of the Femur Neck Screws SystemBased on the anatomical datas and the biomechanical characters of the proximal femur,a new type of instruments is designed for the treatment of femoral neck fracture in children.3.Biomechanical Study of the Femur Neck Screws in fixing Femoral Neck Fracture in Children.Using a paired experimental design,one member of each matched pair was randomly assigned to be fixed with the Femur Neck Screws and the contralateral group was fixed with Kirschner wires.Six matched pairs of the fracture models specimens tested in two modes:⑴the anti-axial compression tests.⑵anti-torsion test.The index included the axial stiffness, the torsional stiffness. We compared the index of our instruments with Kirschner wires.Result:1. Anatomical Measurement a: 21.84±3.96mm; b: 65.39±14.24mm;c: 24.36±4.19mm;d: 35.80±8.81mm; e: 141.51±6.70°; f: 54.74±11.84mm2. Design of the Femur Neck Screws SystemWe design the Femur Neck Screws into left and right uses in our research.The specially cancellated bone screw was upgraded from typical cancellated bone screw of AO company,and it has a smooth anterior extremity and the top designed into the cone sharp.The special design can avoid epiphyseal disk damage. The triangle screws in the proximal femur which show 3-dimension fixation can be stably fix fracture .3.Biomechanical Study of the Femur Neck Screws in fixing Femoral Neck Fracture in ChildrenThe value of axial stiffness was 190.74±20.88N/mm (Femur Neck Screws group),138.95±15.19N/mm(Kirschner wires group),There are different in statistic(P<0.05). The stiffness of Femur Neck Screws in resisting to rotation were stronger than that of the Kirschner wires. There is significance between two Groups(Femur Neck Screws group:0.18±0.045Nm/degree, Kirschner wires group: 0.12±0.036Nm/degree,P<0.05).Conclusion:1. It measures the anatomic data of the proximal femur parameters in Chinese children (5-7years),and this research provide the basis for the design and use of the instruments and add the content for anatomy.2. The Femur Neck Screws for children is a new type of ideal internal fixation device and its biomechanical property can meet the reestablishment of femoral neck fracture in children.3. The Femur Neck Screws for children could be taken as an ideal instrument with good biomechanical feature for the fixation of femoral neck fracture in Children.