Computer aided analysis of biomechanical performance of schanz screw with different additive manufacturing materials used in pertrochanteric fixator on an intertrochanteric femoral fracture (corrosion resistance approach).

This study examines the use of computer-aided analysis to evaluate the biomechanical performance of Schanz screws made from different additive manufacturing materials (Ti6Al4V, 316 L, Inconel 625, and Inconel 718) in a pertrochanteric fixator for the treatment of intertrochanteric femoral fractures. Intertrochanteric fractures (ITFs) are severe traumas often seen in the elderly population and can lead to serious consequences. The primary objective of ITF surgery is to provide stability and allow for early ambulation and rehabilitation. The Pertrochanteric Fixator is a surgical implant used to treat hip fractures near the greater trochanter, and is attached to the femur with screws. The procedure is performed under general anesthesia and typically takes 1-2 h. Possible complications include infection, nerve injury, and hardware failure. The aim of this study is to evaluate the biomechanical performance of Schanz screw using computer-aided analysis, comparing the effects of various additive manufacturing materials including Ti6Al4V, 316 L, Inconel 625 and Inconel 718 in a pertrochanteric fixator for intertrochanteric femoral fractures. Additionally, this study will also consider the corrosion resistance of these materials to ensure long-term durability and effectiveness in a clinical setting. The stress values mentioned for the implant materials are as follows. Ti6Al4V: 153.33 MPa, 316 L: 180.98 MPa, Inconel 625: 158.94 MPa, Inconel 718: 148.91 MPa. Higher stress values indicate a greater load transfer to the bone, which can potentially lead to stress shielding. Stress shielding occurs when an implant bears a significant portion of the load that should be transferred to the bone. This reduced stress at the fracture site can prevent the healing process, as bones require adequate stress levels for optimal remodeling and regeneration.

Biomechanical Effects of Angiotensin 1-7 in Diabetes Rats Femur / Efectos Biomecánicos de la Angiotensina 1-7 en el Fémur de Ratas Diabéticas

SUMMARY: It is known that diabetes mellitus has late complications, including microvascular and macrovascular diseases. Diabetes can affect bones through biochemical markers of bone structure, density, and turnover. This study aimed to biomechanically investigate the bone-protective effects of angiotensin 1-7 (Ang 1-7), one of the active peptides in the renin-angiotensin system, in rats with diabetes. Thirty male Wistar albino rats, three months old and weighing 250-300 g, were divided into four groups: diabetes, Ang 1- 7, diabetes plus Ang 1-7, and control. One month later, diabetes developed in rats; the rats were sacrificed, and their right femur was removed. Three-point bending biomechanical tests were performed on the femurs. The diabetic group had significantly higher bone fragility than the other groups (Pr >.05). Bone fragility was lower, and bone flexibility was higher in the Ang 1-7 groups (Pr>F value 0.05). As a result of our study, the effect of Ang 1-7 on the bones of rats with diabetes was investigated biomechanically. Ang 1-7 has a protective impact on the bones of rats with diabetes.

Se sabe que la diabetes mellitus tiene complicaciones tardías, incluyendo enfermedades microvasculares y macrovasculares. La diabetes puede afectar los huesos a través de los marcadores bioquímicos de la estructura, la densidad y el recambio óseo. Este estudio tuvo como objetivo investigar biomecánicamente los efectos protectores en los huesos de la angiotensina 1-7 (Ang 1-7), uno de los péptidos activos en el sistema renina-angiotensina, en ratas con diabetes. Treinta ratas albinas Wistar macho, de tres meses de edad y con un peso de 250-300 g, se dividieron en cuatro grupos: diabetes, Ang 1-7, diabetes más Ang 1-7 y control. Un mes después, se desarrolló diabetes en ratas; se sacrificaron los animales y se extrajo su fémur derecho. Se realizaron pruebas biomecánicas de flexión de tres puntos en los fémures. El grupo diabéticos tenía una fragilidad ósea significativamente mayor que los otros grupos (Pr > 0,05). La fragilidad ósea fue menor y la flexibilidad ósea fue mayor en los grupos Ang 1-7 (valor Pr>F 0,05). Como resultado de nuestro estudio, se determinó biomecánicamente el efecto de Ang 1-7 en los huesos de ratas con diabetes. Se concluye que Ang 1-7 tiene un impacto protector en los huesos de ratas diabéticas.

Adaptive analysis of cortical plasticity with fMRI in full face and arm transplants.

The aim of this study is to examine cortical plasticity and to analyze cortical reorganization following hand and facial transplantation, using functional magnetic resonance imaging. Patients who had undergone full-face transplantation, hand transplantation and scapular arm replantation, as well as healthy controls, participated in the study. The perioral area and volar surfaces of the index finger and thumb were stimulated and images were acquired using 3 T functional MRI. The areas of the somatosensory cortex representing the hand and face are different in size and shape due to experience-dependent plasticity. Therefore, a new and more adaptive volume of interest analysis was created whereby the radiuses of the VOI masks were defined by the peak intensity of subsequent clusters. For each control subject, the distribution of activated voxels was observed for various cluster defining thresholds in order to determine the mean number of activated voxels for each stimulation inside the defined region. The determined numbers of voxels per subject were extracted from the defined regions using a binary search algorithm. Subsequently, the distances between the weighted centers of the extracted regions were calculated and compared. In transplant patients, the weighted centers of the hand and face clusters were separated at same-sized volumes. Two of the rehabilitated full-face transplant patients converge to the range of the controls. As a result, the weighted distribution of somatotopy indicated previous and present cortical reorganization. Additionally, referred sensation was assessed in two full-face transplant and one replant patient with activation clusters partially in BA40 in the Inferior Parietal Lobule.

Comparison of two different bowel anastomosis types using finite volume method.

The purpose of this study was to compare side-to-side and functional end-to-end anastomosis techniques that are commonly used in bowel surgery. Considering the dimensions of these two different anastomosis models, SolidWorks program was used for 3 D studies. Intra-intestinal flow analyzes were performed based on the finite volume method using Ansys Fluent, a computational fluid Dynamics (CFD) program. The flow velocity, pressure, turbulent knetic energy, turbulence vortex distribution, vortex viscosity and wall shear stresses for each model were calculated in results of the analysis for the side-to-side and functional end-to-end anastomosis technique. Due to the geometrical structure of the functional end - to - end anastomosis model, turbulence and hence the vortex formation is less than the side - to - side anastomosis technique. Because intersect area of bowels has wider in functional end - to - end anastomosis model, flow become easier than other. In surgical practice, functional end-to-end anastomosis is preferred over side-to-side anastomosis because of the low probability of leakage. It can be noted that the functional end - to - end anastomosis technique will be safer because of less turbulence, based on the data of fluid flow velocities, pressure, turbulent knetic energy, turbulence vortex distribution, vortex viscosity and wall shear stresses in the anastomosis.

Comparison of Biomechanical Effects of Different Configurations of Kirschner Wires on the Epiphyseal Plate and Stability in a Salter-Harris Type 2 Distal Femoral Fracture Model.

BACKGROUND: We sought to investigate the different configurations of Kirschner wires used in distal femur Salter-Harris (SH) type 2 epiphyseal fracture for stabilization after reduction under axial, rotational, and bending forces and to define the biomechanical effects on the epiphyseal plate and the fracture line and decide which was more advantageous. METHODS: The SH type 2 fracture was modeled using design software for four different configurations: cross, cross-parallel, parallel medial, and parallel lateral with two Kirschner wires, and computer-aided numerical analyses of the different configurations after reduction were performed using the finite element method. For each configuration, the mesh process, loading condition (axial, bending, and rotational), boundary conditions, and material models were applied in finite element software, and growth cartilage and von Mises stress values occurring around the Kirschner wire groove were calculated. RESULTS: In growth cartilage, the stresses were highest in the parallel lateral configuration and lowest in the cross configuration. In Kirschner wires, the stresses were highest in the cross configuration and lowest in the cross-parallel and parallel lateral configurations. In the groove between the growth cartilage and the Kirschner wire interface, the stresses were highest in the parallel lateral configuration and lowest in the cross configuration. CONCLUSIONS: The results showed that the cross configuration is advantageous in fixation. In addition, in the SH type 2 epiphyseal fracture, we believe that the fixation shape should not be applied in the lateral configuration.

Comparison of effects of different screw materials in the triangle fixation of femoral neck fractures.

In this study, biomechanical behaviors of three different screw materials (stainless steel, titanium and cobalt-chromium) have analyzed to fix with triangle fixation under axial loading in femoral neck fracture and which material is best has been investigated. Point cloud obtained after scanning the human femoral model with the three dimensional (3D) scanner and this point cloud has been converted to 3D femoral model by Geomagic Studio software. Femoral neck fracture was modeled by SolidWorks software for only triangle configuration and computer-aided numerical analyses of three different materials have been carried out by AnsysWorkbench finite element analysis (FEA) software. The loading, boundary conditions and material properties have prepared for FEA and Von-Misses stress values on upper and lower proximity of the femur and screws have been calculated. At the end of numerical analyses, the best advantageous screw material has calculated as titanium because it creates minimum stress at the upper and lower proximity of the fracture line.

Comparison of the biomechanical effects of pertrochanteric fixator and dynamic hip screw on an intertrochanteric femoral fracture using the finite element method.

BACKGROUND: This study was conducted to examine and compare the pertrochanteric fixator (PTF) and dynamic hip screw (DHS). METHODS: AnsysWorkbench, a commercial finite element based program, was used to investigate the biomechanical parameters of femoral fractures and implants. The human femoral model was scanned and a femoral intertrochanteric fracture was created. Von Mises stress, von Mises strain, and shear and deformation forces on the upper and lower parts of the fracture line; and the von Mises stress, von Mises strain parameters of the screws and implant bodies during axial loading were calculated and compared. RESULTS: It was determined that the magnitude of displacement forces along the fracture line was lower in PTF. Regarding the von Mises stress and von Mises strain values on the implant bodies, the DHS body had higher levels compared with the PTF body. CONCLUSION: This study demonstrated that PTF is more favorable than DHS for early axial loading and ambulation.