ABSTRACT
Objective To construct and validate a 3D finite element model of pelvis-femur-soft tissue complex including artery, and investigate the mechanical response of pelvis artery under side impact loads. Methods The 3D finite element model of the pelvis-femur-soft tissue complex was constructed from CT images of one female volunteer, including bone tissues, arteries, enveloping soft tissues, cartilage and ligaments of the pelvic joints (sacroiliac joint, hip joint and pubic symphysis). The whole model utilized linear elastic solid elements to simulate bone tissues. Nonlinear elastic connector elements were employed to represent ligaments. Soft tissues, including the cartilage, enveloping soft tissues and arteries, were modeled as solid elements with hyper-elastic material. Side impact was conducted on the complex with impact mass of 22.1 kg at the impact velocity of 3.13 and 5 m/s, respectively, and the output of the complex model was then recorded. Results Simulation results matched the results of pelvic side impact experiments reported in literature. When the complex model was impacted at the velocity of 3.31 and 5 m/s, respectively, the maximum equivalent stress of arteries was 98 and 216 kPa, and the maximum principle strain was 14.9% and 20%, respectively. The risk of artery injury was relatively low. Conclusions This established pelvis-femur-artery complex model was validated and thus reliable to be used for investigating the dynamical response and injury analysis on pelvis artery under impact loads, and provides some biomechanical foundation for predicting artery injuries.
ABSTRACT
Objective Based on the finite element method, both sacroiliac fusion and sacroiliac contact models were built to compare the biomechanical differences between the two models and to explore the biomechanical mechanism in the treatment of low back pain by sacroiliac fusion. Methods Two pelvic finite element models were constructed, including the pelvic ring, sacrum, part of the femur, ligaments, cartilage and joint contact. The sacroiliac joints were set to be contact in one model and fusion in the other, respectively. Differences in mechanical conduction on the pelvic ring and the stress on the sacroiliac cartilage under 500 N load between the two models were explored. Results For the fusion model, stresses and displacement on the sacroiliac joint were significantly lower than that of the contact model, especially on the sacroiliac cartilage, where the displacement was reduced by 261% from 0.83 mm to 0.23 mm, and the stresses reduced by 32% from 6.6 MPa to 5.0 MPa. However, the transfer of stress on the pelvic ring was relatively more concentrated in the fusion model. Conclusions Sacroiliac fusion may provide better therapeutic effects on the treatment of low back pain, but the risk of disc herniation and femoral head necrosis must be assessed seriously in advance.