Biomechanical comparison using finite element analysis of different screw configurations in the fixation of femoral neck fractures

Abstract

Abstract. In this research, biomechanical behaviors of five different configurations of screws used for stabilization of femoral neck fracture under axial loading have been examined, and which configuration is best has been investigated. A point cloud was obtained after scanning the human femoral model with a three dimensional (3-D) scanner, and this point cloud was converted to a 3-D femoral model by Geomagic Studio software. Femoral neck fracture was modeled by SolidWorks software for five different configurations: dual parallel, triple parallel, triangle, inverted triangle and square, and computer-aided numerical analysis of different configurations were carried out by ANSYS Workbench finite element analysis (FEA) software. For each configuration, mesh process, loading status (axial), boundary conditions and material model were applied in finite element analysis software. Von Mises stress values in the upper and lower proximity of the femur and screws were calculated. According to FEA results, it was particularly advantageous to use the fixation type of triangle configuration. The lowest values are found as 223.32 MPa at the lower, 63.34 MPa at the upper proximity and 493.24 MPa at the screws in triangle configuration. This showed that this configuration creates minimum stress at the upper and lower proximity of the fracture line. Clinically, we believe that the lowest stress values which are created by triangle configuration encompass the most advantageous method. In clinical practices, it is believed that using more than three screws does not provide any benefit. Furthermore, the highest stresses are as follows: at upper proximity 394.79 MPa in triple parallel configuration, for lower proximity 651.2 MPa in square configuration and for screw 2459 MPa in inverted triangle.

Use of the finite element analysis to determine stresses in the knee joints of osteoarthritis patients with different Q angles

“…After recording the images of the patients in Digital Imagining and Communications in Medicine (DICOM) format, they were transferred to MIMICS software [10], and 3D Stereolithography (STL) models were obtained. Those data were processed in GEOMAGIC STUDIO software [11], and then the 3D models of the femur, tibia, fibula and patella in Initial Graphics Exchange Specification (IGES) format were recorded and transferred to SOLIDWORKS software [11]. Soft tissues (cartilage, meniscus and patellar…”

Response concerning ‘Letter to editor’ by Ni et al. (2017), Arch Orthop Trauma Surg. DOI 10.1007/s00402-017-2710-2

“…However, we have explained about this situation that "Gok and Inal researched what the best stable fixation practice might be by applying five different screw configuration types on the femoral neck fracture model with finite element analysis (FEA) method." in the last paragraph of introduction section [3]. We think that is been overlooked during the reading of Ni et al…”

Анализ Основных Причин Несращений И Способов Остеосинтеза Переломов Шейки Бедра

“…Численное конечно-элементное моделирование остеосинтеза перелома шейки бедра различными конфигурациями стягивающих фиксаторов проведено Gok с соавт. [15]. Сравнивались треугольные конфигурации, вертикальное расположение двух и трех фиксаторов, а также четырехугольная конфигурация (рис.…”

“…Конфигурации стягивающих винтов, исследованные Gok и соавт. [15] Система «кость-фиксаторы» нагружалась статической нагрузкой 350 Н, рассматривались задачи о контактном взаимодействии фиксаторов и костных отломков. Костная ткань рассматривалась как изотропный и однородный материал с постоянными модулями упругости губчатой и кортикальной костной ткани.…”

“…Результаты для фиксаторов диаметром 6,5 и 7,0 мм оказались схожими. Клинические результаты говорят о том, что более трех фиксаторов использовать нецелесообразно ввиду высокой травматичности операции [15].…”