The present study was conducted to examine the effects of body weight on intradiscal pressure (IDP) and annulus stress of intervertebral discs at lumbar spine. Three-dimensional finite element model of osseoligamentous lumbar spine was developed subjected to follower load of 500 N, 800 N, and 1200 N which represent the loads for individuals who are normal and overweight with the pure moments at 7.5 Nm in flexion and extension motions. It was observed that the maximum IDP was 1.26 MPa at L1-L2 vertebral segment. However, the highest increment of IDP was found at L4-L5 segment where the IDP was increased to 30% in flexion and it was more severe at extension motion reaching to 80%. Furthermore, the maximum annulus stress also occurred at the L1-L2 segment with 3.9 MPa in extension motion. However, the highest increment was also found at L4-L5 where the annulus stress increased to 17% in extension motion. Based on these results, the increase of physiological loading could be an important factor to the increment of intradiscal pressure and annulus fibrosis stress at all intervertebral discs at the lumbar spine which may lead to early intervertebral disc damage.

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Artificial heart valves for replacing diseased indigenous heart valves were widely used. The treatment of certain types of heart disease requires mechanical valves to be implanted operatively. Healthy cardiac valves are essential to proper cardiac function. The current study presents an investigation of the pulsatile blood flow through a bileaflet mechanical heart valve (BMHV) with a vortex generator (VG) in fully open position. A St. Jude Medical Regent valve with a diameter of 23 mm was used to mount triangular VGs as a means of improving pressure gradients and reducing turbulence. The anatomic aorta and axisymmetric aorta was computed by large eddy simulation (LES) approached. The implications for both models with VGs were observed in terms of velocity magnitude, vortices and wall shear stress. The results suggested that the anatomic aorta is prone to develop more blood clotting at the leading edge of the leaflets with 2.03 m/s. Furthermore, the anatomic aorta produces higher wall shear stress with 69Pa, which possibly contributes to a high risk of thrombosis.

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