The current study measures the mechanical behavior of both natural and the monobloc elastomeric disc prosthesis (CadiscTM-L) by employing a finite element method (FEM) to study the fiber-reinforced constitutive formulation provided in the literature. The three-dimensional geometry was created by computed tomography (CT) scan imaging technique. Frontal pure rotational, sagittal, and axial momentum of 7.5 N·m were applied on the top of L3 while the lower half of the L5 was fixed in all directions. This investigation was performed considering two stages: (1) intact L3–L5 lumbar spine (INT model), and (2) Cadisc implemented between L4 and L5 (IMP model). The numerical results for the INT model were validated by experimental data from the literature. Several parameters including the inter-segmental rotation, range of motion in flexion-extension, axial rotation and lateral bending were analyzed. Our numerical results show that the IMP model has a 50% reduction in the ‘range of motion’ and a 33% reduction in flexion in lateral bending compared to the INT model. These outcomes of this paper reveal the feasibility of applying a fibre-reinforced constitutive formulation to generate an accurate three-dimensional FEM model.

The effect of football neck collar on the right external carotid blood flow was investigated for ten healthy subjects using Echo-Doppler technique and computational fluid dynamics (CFD) approach. Carotid is in charge of blooding head’s parts including the brain and eyes. Hence, the evaluation of affected carotid flow by using neck collars is crucial for an improved ergonomic design. The testings were divided into three main categories; participants without wearing neck collar (Category 1), wearing neck collar (Category 2), and finally wearing neck collar with an embedded gap adjacent to the carotid artery position (Category 3). The experimental and numerical results revealed that wearing the neck collar (Category 2) reduced the average blood carotid flow by 28% compared to the case with no neck collar (Category 1). This average blood carotid flow reduction was improved by 15% when a gap separates the collar from the carotid artery position (Category 3). The results of this paper suggest a new design for the next generation of the neck collar by devising an appropriate gap near to carotid artery. The numerical results were validated and were in a reasonable agreement with the experimental data.

Development of knowledge of cardiovascular diseases and treatments strongly depends on understanding of hemodynamic measurements. Hemodynamic parameters, therefore, have been investigated using simulation-based methods. A two-dimensional model was applied for seven healthy subjects with echo-Doppler at rest. Echocardiography imaging was also utilized to gain the geometry of the aortic valve. Fluid-Structure Interaction (FSI) model was carried out, coupling an Arbitrary Lagrangian-Eulerian mesh. Pressure loads were used as boundary conditions on the valve’s ventricular and aortic sides. Pressure loads used were the calculated brachial pressures plus differences between brachial, central and left ventricular pressures. The FSI model predicted the velocity integration, stroke volume and cardiac output over a range of heart rates while rest. Numerical results generally had a difference of 5.4 to 15.87% with Doppler results. Linear correlations between numerical and clinical approaches have been applied. This makes possible predictions achieved from the FSI model to be gained which are highly accurate (e.g. correlation factor r = 0.995, 0.990 and 0.990 for velocity integration, stroke volume and cardiac output, respectively). The obtained numerical results showed that numerical methods can be combined with clinical measurements to provide good estimates of patient specific hemodynamics for different subjects.