Insufficiency fractures occur when physiological loads are applied to bone deficient in mechanical resistance. A better understanding of pelvic mechanics and the effect of bone density alterations could lead to improved diagnosis and treatment of insufficiency fractures. This study aimed to develop and validate a subject-specific three-dimensional (3D) finite element (FE) model of a pelvis, to analyse pelvic strains as a function of interior and cortical surface bone density, and to compare high strain regions with common insufficiency fracture sites. The FE model yielded strong agreement between experimental and model strains. By means of the response surface method, changes to cortical surface bone density using the FE model were found to have a 60 per cent greater influence compared with changes in interior bone density. A small interaction was also found to exist between surface and interior bone densities (< 3 per cent), and a non-linear effect of surface bone density on strain was observed. Areas with greater increases in average principal strains with reductions in density in the FE model corresponded to areas prone to insufficiency fracture. Owing to the influence of cortical surface bone density on strain, it may be considered a strong global (non-linear) indicator for insufficiency fracture risk.
authors contributed equally.
Funding InformationShandong Province Science and Technology Development Plan K E Y W O R D S : Aortic dissection; Pregnancy; Triple-branched stent graft A woman aged 36 years at 36 weeks of pregnancy sought medical attention at the Shandong Provincial Hospital affiliated to Shandong University, Shandong, China, after experiencing acute chest pain. The patient was diagnosed with chronic hypertension, severe preeclampsia, acute aortic dissection, aortic regurgitation, and heart failure. Computed tomography examination demonstrated a DeBakey type I aortic dissection that involved the origin of the innominate artery, the left common carotid artery, and the left subclavian artery. Cardiotocography monitoring revealed no obvious fetal anomalies; this was thought to result from the relatively normal uterine-placental arterial supply that was unaffected by aortic dissection. The patient underwent cesarean delivery with hysterectomy and relevant cardiovascular treatment 3 days after admission. A median sternotomy was performed under general anesthesia and total cardiopulmonary bypass was established. Subsequently, the attending obstetrician performed the cesarean delivery and hysterectomy.
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