Navegando por Palavras-chave "Método Dos Elementos Finitos"

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    Avaliação da densidade mineral, microarquitetura e resistência óssea de pacientes litiásicos por Tomografia Computadorizada Quantitativa Periférica de Alta Resolução (HR-pQCT) e suas relações com a calciúria
    (Universidade Federal de São Paulo (UNIFESP), 2020-07-30) Esper, Priscila Ligeiro Goncalves [UNIFESP]; Heilberg, Ita Pfeferman [UNIFESP]; Universidade Federal de São Paulo
    Low bone mineral density (BMD) at lumbar spine and femoral neck have been evidenced among nephrolithiasis patients. Histomorphometric analysis and quantitative computed tomography (qCT) have suggested the trabecular bone is most affected. The aim of the present study was to determine volumetric BMD (vBMD), bone microarchitecture, and biomechanical properties by high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite element analysis (FEA) in stone formers (SF) in comparison with healthy subjects. In addition, the association of bone parameters with urinary calcium was investigated in the SF group. Fifty-eight (58) male SF (37.2 ±9.3 years old) and 49 premenopausal female SF (34.2 ±9.1 years old) underwent HR-pQCT/FEA, as well as areal BMD (aBMD) and trabecular bone score (TBS) by Dual-energy X-ray absorptiometry (DXA), whose results were compared to age-matched controls (186 females and 97 males). Urinary excretion of calcium, urea and sodium, serum biochemical, hormonal parameters and bone markers were determined in the SF group. Three-day dietary records were obtained from SF to determine calcium intake. Male and female SF presented significantly lower aBMD by DXA compared to controls at both sites. Male SF, but not female, exhibited significantly lower TBS than controls. HR-pQCT analysis revealed male and female SF had lower trabecular number (Tb.N) and increased trabecular separation (Tb.Sp). Female SF had also lower trabecular vBMD (Tb.vBMD) and increased cortical vBMD (Ct.vBMD). Parameters of bone strength were significantly lower only in male SF compared to controls. When SF were divided in tertiles, Tb.N was lower and Tb.Sp was higher in the 3rd versus the 1st tertile at the radius. Significant inverse correlations were detected at both skeletal sites between urinary calcium and HRpQCT parameters, such as Tb.vBMD, BV/TV and Tb.N as well as direct correlations with Tb.Sp. In conclusion, the pioneering use of HR-pQCT in stone formers revealed trabecular bone impairment, especially concerning microarchitecture, at both tibia and radius, when compared to healthy subjects. Trabecular vBMD and microarchitecture alterations were associated with urinary calcium excretion. A lower TBS by DXA and lower bone strength by FEA was also disclosed in male SF compared to controls, but not in female SF, which in turn exhibited higher cortical vBMD than their controls, what could have contributed to preserve bone strength in the latter. The findings of the present study suggest that nephrolithiasis represent a potential risk of bone fractures mainly among males, due to the reduction of bone strength.