Biomechanical analysis of the computer-assisted internal fixation of a femoral neck fracture

The number and spatial configuration of the screws will affect the stability and prognosis of the fractures. In our study, we assessed the biomechanical effects of the double-head cannulated compression screw (DhCCS) and ordinary cannulated compression screw (OCCS) for the treatment of femoral neck fractures by using computer finite element analysis. The original digital imaging and communications in medicine (DICOM)data of a proximal femur were imported into Materialise's interactive medical image control system (MIMICS)software for modeling. Both DhCCS and OCCS 3D-models were obtained by using the 3D scan technique. Using the fracture model and internal fixation assembly model with an inverted triangle, two horizontal and vertical distribution were established in UG software. Next, the displacement and stress distribution were calculated in ANSYS software. The displacement value of the femoral head in the DhCCS group was smaller than that in the OCCS group, and the displacement value in the two horizontal groups was smaller than that in the vertical group. The stress distribution in the DhCCS group was concentrated on the screw rod at the fracture block and thread end, while only at the fracture block in the OCCS group. The stress in the horizontal group was more dispersed on the screws than that in the vertical group. DhCCS has reliable stability for the fixation of femoral neck fractures and applied in the clinical work and 2 horizontal fixation can be used when two screws are selected.