动力交叉螺钉应用于不稳定型股骨颈骨折的生物力学分析.

BACKGROUND: The femoral neck system is a novel fixation device for unstable femoral neck fractures. OBJECTIVE: To compare and analyze the mechanical stability of three kinds of internal fixation in Pauwels III unstable femoral neck fractures by finite element method. METHODS: On the basis of the validated femoral finite element model (intact group), the model was cut to make a Pauwels III 70° unstable fracture of the femoral neck. Different internal fixation models were implanted to simulate clinical surgery. This study established femoral neck system fixation (model A), inverted triangular cannulated screw fixation (model B) and 4 diamond-shaped cannulated screw fixation (model C). All the nodes under the distal end of the femur were restrained for the three groups of models, and 700 N, 1 400 N and 2 100 N compressive loads were applied to the femoral head. Through calculation and analysis, the Von Mises stress distribution and deformation of each group of models were observed, and the mechanical stability of each group of models was compared. RESULTS AND CONCLUSION: (1) The maximum deformation of the three groups of models under various loads occurred in the femoral head. When compressed for 2 100 N, the deformation of model A was 2.06 mm less than that of intact group 2.17 mm, while the deformations of model B and model C were both higher than that of intact group, with the distributions of 2.39 mm and 2.33 mm. (2) Under various loads, the stress in model A group was also the smallest. Under 2 100 N, the stress peak in model A was 297.31 MPa, distributed at the joint position of anti-rotation screw and locking screw, while the stress peak in model B was 543.18 MPa, distributed at the fracture joint position of the third screw in the inverted triangle. However, the deformation and stress of model C were intermediate between model A and model B, and the maximum stress peak value was distributed at the bottom hollow of the cannulated screw fracture, reaching 315.61 MPa at 2 100 N. (3) The compressive stiffness and stress analysis of models of the three groups showed that model A < model C < model B. (4) It is concluded that the mechanical stability of femoral neck system for femoral neck fracture is better than that of three and four cannulated screws fixation, and it can effectively prevent femoral neck shortening. Femoral neck system is a recommended internal fixation method for unstable femoral neck fractures. [ABSTRACT FROM AUTHOR]