Proximal femur fracture risk depends on subject-specific factors such as bone mineral density and morphological parameters. Here, we aim to analyze the dependency of the femoral strength on sixteen morphological parameters. Therefore, finite-element analyses of 20 human femurs during stumbling and lateral falls on the hip were conducted. Pearson correlation coefficients were calculated and morphological parameters with significant correlations were examined in principal component analysis and linear regression analysis. The dependency of the fracture strength on morphological parameters was more pronounced during lateral falls on the hip compared to stumbling. Significant correlations were observed between the neck shaft angle (r = −0.474), neck diameter (r = 0.507), the true distance between the femoral head center and femoral shaft axis (r = 0.459), and its projected distance on the frontal plane (r = 0.511), greater trochanter height (r = 0.497), and distance between the femoral head center and a plane parallel to the frontal plane containing the projection of the femoral head center to the femoral neck axis (r = 0.669). Principal component analysis was strongly weighted by parameters defining the lever arm during a lateral fall as well as the loaded cross-section in the femoral neck.

Finite element analysis is a common tool that has been used for the past few decades to predict the mechanical behavior of bone. However, to our knowledge, there are no round-robin finite element analyses of long human bones with more than two participating biomechanics laboratories published yet, where the results of the experimental tests were not known in advance. We prepared a fresh-frozen human femur for a compression test in a universal testing machine measuring the strains at 10 bone locations as well as the deformation of the bone in terms of the displacement of the loading point at a load of 2kN. The computed tomography data of the bone with a calibration phantom as well as the orientation of the bone in the testing machine with the according boundary conditions were delivered to seven participating laboratories. These were asked to perform a finite element analysis simulating the experimental setup and deliver their results to the coordinator without knowing the experimental results. Resultantly, four laboratories had deviations from the experimentally measured strains of less than 40%, and three laboratories had deviations of their numerically determined values compared to the experimental data of more than 120%. These deviations are thought to be based on different material laws and material data, as well as different material mapping methods. Investigations will be conducted to clarify and assess the reasons for the large deviations in the numerical data. It was shown that the precision of finite element models of the human femur is not yet as developed as desired by the biomechanics community.

OBJECTIVES:Recently, more accurate description of the femoral geometry has become of interest to engineers and orthopedic surgeons. However, an appropriate database is lacking. Therefore, the aim of this study is to present morphological parameters and their correlations, which are relevant for medical issues such as impingement after total hip replacement, as well as for implant design and the etiology of hip fractures.METHODS:We investigated 12 well-known morphological parameters of the femur in 169 healthy human subjects through evaluation of 3D-reconstructed CT scans. Pearson's coefficients of correlations were calculated using a statistical t-test method for each pair of parameters.RESULTS:The mean, maximum, minimum, median, and standard deviation values are reported for all parameters. Histograms showing the distribution of each morphological parameter are also presented. It is shown that absolute and horizontal offsets, total femur length, and NCVD parameters are normally distributed, but NCDF and NCDS are not. Furthermore, an inter-correlation matrix was reported to reveal statistical correlations between these parameters. The strongest positive correlation existed between absolute offset (OSA) and horizontal offset (OSH), while the least positive correlation was found between NCDF and total femur length (TFL), and also between NCDS and NCDF. Anteversion angle (ATA) and OSA showed the least negative correlation. However, the strongest negative correlation was found between neck-shaft angle (NSA) and greater trochanter height (GTH), as well as between OSA and NCVD.CONCLUSIONS:Comprehending patients' native bone morphology, including the variations and correlations, is essential for orthopedic surgeons to undertake preoperative planning and surgery as well as to appropriately design medical devices. Thus, more population-based detailed databases are necessary. We investigated an extensive set of proximal femoral morphology parameters using a statistically standardized method to expand the existing knowledge. The results of our study can be used for diverse medical and biomechanical purposes.

Fragility fractures are a major socioeconomic problem. A non-invasive, computationally-efficient method for the identification of fracture risk scenarios under the representation of neuro-musculoskeletal dynamics does not exist. We introduce a computational workflow that integrates modally-reduced, quantitative CT-based finite-element models into neuro-musculoskeletal flexible multibody simulation (NfMBS) for early bone fracture risk assessment. Our workflow quantifies the bone strength via the osteogenic stresses and strains that arise due to the physiological-like loading of the bone under the representation of patient-specific neuro-musculoskeletal dynamics. This allows for non-invasive, computationally-efficient dynamic analysis over the enormous parameter space of fracture risk scenarios, while requiring only sparse clinical data. Experimental validation on a fresh human femur specimen together with femur strength computations that were consistent with literature findings provide confidence in the workflow: The simulation of an entire squat took only 38 s CPU-time. Owing to the loss (16% cortical, 33% trabecular) of bone mineral density (BMD), the strain measure that is associated with bone fracture increased by 31.4%; and yielded an elevated risk of a femoral hip fracture. Our novel workflow could offer clinicians with decision-making guidance by enabling the first combined in-silico analysis tool using NfMBS and BMD measurements for optimized bone fracture risk assessment.

Background: The present study contrasts the accuracy of different reconstructed models with distinctive segmentation methods performed by various experts. Seven research groups reconstructed nine 3D models of one human femur based on an acquired CT image using their own computational methods. As a reference model for accuracy assessment, a 3D surface scan of the human femur was created using an optical measuring system. Prior to comparison, the femur was divided into four areas; "neck and greater trochanter", "proximal metaphysis", "diaphysis", and "distal metaphysis". The deviation analysis was carried out in GEOMAGIC studio v. 2013 software. Results: The results revealed that the highest deviation errors occurred in "neck and greater trochanter" area and "proximal metaphysis" area with RMSE of 0.84 and 0.83 mm respectively. Conclusion: In conclusion, this study shows that the average deviation of reconstructed models prepared by experts with various methods, skills and software from the surface 3D scan is lower than 0.79 mm, which is not a significant discrepancy.

Women are interested to wear high-heeled shoes to increase their attractiveness. High-heeled shoes might create harmful effects on the musculoskeletal system. Besides earlier studies proved that the function of foot and lower extremity will change due to wearing high-heeled shoes [1,2]. Because of limitations of the experimental methods, direct measurements of internal strains and stresses of the foot are inconceivable or invasive [3]. In this research the comparison of the effect of 3 different sizes of height of high-heeled shoes on foot bones and plantar fascia is the main objective. Von-Misses stresses, strain, and arch deformation of the foot during balanced standing in women are the parameters which are investigated in this research. The output of this research is describing the effect of increasing of heel height on foot bones stresses. Mimics and ABAQUS software are employed to create a finite element (FE) model of the human ankle. MIMICS used as the segmentation software and ABAQUS used for finite element analysis (FEA). A CT (Computed Topography) scan images from the right foot of a normal female subject was imported into MIMICS. The segmented surfaces were then imported into SolidWorks CAD (Computer aided design) system to create model assembly. In order to creating tetrahedral finite element meshes the solid models of foot bones and encapsulated soft tissue structures models established in MIMICS software is imported into ABAQUS. Contact interactions among the major joints were prescribed to allow relative bone movements. The soft tissue and orthotic material were defined as hyper elastic while other tissues were idealized as homogeneous, isotropic, and linearly elastic. The ground reaction and extrinsic muscles forces for simulating the stance phase of gait were applied at the inferior ground support as a boundary condition and at their corresponding points of insertion by defining contraction forces via axial connector elements. During the balance standing condition, on half of body weight is transferred from each foot to the ground [4]. The result of this study on the shoes with heel height 1.5 inches, 2.5 inches, and 3.5 inches shows that an increase in shoe heel height resulted in a decrease in arch deformation (Figure ​(Figure1).1). There was a common rise in a peak Von-Mises stress of foot bones with increasing shoe heel height (Figure ​(Figure2).2). With 2.5 inches high-heeled shoe, the strain and the total tensional force in the plantar fascia was minimum (Figure ​(Figure33). Figure 1 Foot arch deformations during balanced standing Figure 2 Von-Mises stress of foot bones for 3 different sizes of shoe heel heights Figure 3 Average of strain in plantar fascia

Prosthetic suspension system is an important component of lower limb prostheses. Suspension efficiency can be best evaluated during one of the vital activities of daily living, i.e. walking. A new magnetic prosthetic suspension system has been developed, but its effects on gait biomechanics have not been studied. This study aimed to explore the effect of suspension type on kinetic and kinematic gait parameters during level walking with the new suspension system as well as two other commonly used systems (the Seal-In and pin/lock). Thirteen persons with transtibial amputation participated in this study. A Vicon motion system (six cameras, two force platforms) was utilized to obtain gait kinetic and kinematic variables, as well as pistoning within the prosthetic socket. The gait deviation index was also calculated based on the kinematic data. The findings indicated significant difference in the pistoning values among the three suspension systems. The Seal-In system resulted in the least pistoning compared with the other two systems. Several kinetic and kinematic variables were also affected by the suspension type. The ground reaction force data showed that lower load was applied to the limb joints with the magnetic suspension system compared with the pin/lock suspension. The gait deviation index showed significant deviation from the normal with all the systems, but the systems did not differ significantly. Main significant effects of the suspension type were seen in the GRF (vertical and fore-aft), knee and ankle angles. The new magnetic suspension system showed comparable effects in the remaining kinetic and kinematic gait parameters to the other studied systems. This study may have implications on the selection of suspension systems for transtibial prostheses. Trial registration: Iranian Registry of Clinical Trials IRCT2013061813706N1.

A generalized nonlinear model is formulated for the dynamic analysis of model 9 DOF road vehicle with active suspension systems. The model incorporates a nonlinear suspension spring and nonlinear damping force for active dampers and so, the linear model is formulated similar to Bouzara model. The active dampers are characterized by force generators in accordance with the control laws based upon suspension mass velocity. So, This paper reports on an investigation to determine the spring and damper settings that will ensure optimal ride comfort and road holding road vehicle, on different road profiles and at different speeds for linear and nonlinear vehicle models. The extent to which the ride comfort optimal suspension settings vary for roads of different roughness and varying speeds and the levels of ride comfort and road holding that can be achieved, are addressed. The issues of the best objective function to be used when optimizing and if a single road profile and speed can be used as representative conditions for ride comfort optimization of passive, semi-active and active suspensions, are dealt with. Optimization is performed with the Bees algorithm on a vibration model 9 degree of freedom for speeds ranging from 30 to 90 km/h. It is found that optimizing for a combined driver plus rear passenger seat weighted root mean square vertical acceleration rather than using driver or passenger values only, returns the best results.