Bone cement augmented proximal femoral nail antirotation for type a3.3 intertrochanteric femoral fractures in elderly: A finite element analysis / 中国组织工程研究

ABSTRACT

BACKGROUND: Osteoporosis and fracture type are two important reasons for the failure of internal fixation of proximal femoral nail antirotation. Type AO31-A3.3 intertrochanteric fracture, because of its involvement in the lateral wall, greatly increased the instability of the fracture. In addition, the elderly are mostly osteoporosis patients, so failure and postoperative complications of internal fixation of proximal femoral nail antirotation in the elderly with type AO31-A3.3 intertrochanteric fracture are higher. OBJECTIVE: To explore the difference of biomechanics between bone cement augmented and common proximal femoral nail antirotation in the treatment of type AO31-A3.3 intertrochanteric fracture. METHODS: CT data of one 75-year-old volunteer with intertrochanteric fracture were selected to import into Mimics 19.0 and Geomagic studio 2017 software to extract and optimize the three-dimensional model of the right femur. SolidWorks 2017 software was used to draw the internal fixation model and assemble it with the femur model according to the standard operation technology. The model was imported into Hypermesh 14.0 software to cut the bone to obtain the type AO31-A3.3 model with common proximal femoral nail antirotation. The cancellous bone around the proximal end of the screw blade was redefined as bone cement, which is the model of bone cement augmented proximal femoral nail antirotation. The material property parameters, boundary conditions and applied loads were set up and stored as K files respectively and imported into LS-DYNA software for solution. RESULTS AND CONCLUSION: (1) Compared with the common proximal femoral nail antirotation, the treatment of the elderly type AO31-A3.3 intertrochanteric fracture with the bone cement augmented proximal femoral nail antirotation has the advantages of lighter cutting degree of the screw blade, smaller varus, rotation angle and displacement of the femoral head and neck bone block, and better biomechanical effect. (2) The complete lateral wall can effectively support the femoral head and neck bone block and resist the skull and neck bone block as the lateral action point of three-point support. The pronation and rotation tendency can effectively prevent the head and neck screws from withdrawing. (3) The strong anchoring force of bone cement can stabilize the screw blade, enhance the internal action point of three-point support, and conduct and disperse the pressure.