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Open Access Research article

At the moment of occurrence of a fragility hip fracture, men have higher mechanical properties values in comparison with women

Ana C Vale12, Inês P Aleixo1, Miguel Lúcio12, André Saraiva12, Joana Caetano-Lopes1, Ana Rodrigues13, Pedro M Amaral2, Luís G Rosa24, Jacinto Monteiro5, João E Fonseca13*, Maria F Vaz24 and Helena Canhão13

Author Affiliations

1 Rheumatology Research Unit, Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal

2 Instituto de Ciência e Engenharia de Materiais e Superfícies, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, Lisbon, Portugal

3 Serviço de Reumatologia e Doenças Ósseas Metabólicas, Lisbon Academic Medical Centre, Lisbon, Portugal

4 Departamento de Engenharia Mecânica, Instituto Superior Técnico, UL, Av. Rovisco Pais, Lisbon, Portugal

5 Serviço de Ortopedia, Hospital de Santa Maria, Lisbon, Portugal

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BMC Musculoskeletal Disorders 2013, 14:295  doi:10.1186/1471-2474-14-295

Published: 16 October 2013

Abstract

Background

It is well established that males have lower fracture risk in comparison with females, which suggests a higher bone resistance in men. The aim of our study was to find out if in older patients with hip fragility fractures, gender has also an impact on trabecular bone material behaviour, specifically to determine whether trabecular mechanical properties under compressive loading differ between men and women who suffered a fragility hip fracture.

Methods

Femoral epiphyses were consecutively collected during hip replacement surgery due to proximal femur fragility fracture. Trabecular bone cylinders were drilled and submitted to uniaxial compression tests and mechanical properties were assessed.

Results

Seventy-three patients, 55 women (mean age 81 years and standard deviation of 7 years) and 18 men (mean age 81 years and standard deviation of 8 years) were evaluated. The ultimate stress of trabecular bone was significantly higher in men than in women: the median values and the interquartile range (IQR) were respectively 8.04(5.35-10.90) MPa vs. 4.46(3.02-7.73) MPa, (p-value = 0.005). The same difference between male and female was observed in the Young’s modulus: 293.68(166.67-538.18) MPa vs. 174.26(73.07-322.28) MPa, (p-value = 0.028), and also in the energy to failure: 0.25(0.07-0.42) MJ/m3 vs. 0.11(0.05-0.25) MJ/m3, (p-value = 0.058). These differences were also verified after adjusting the analysis for age in a multivariate model analysis.

Conclusions

Our observations demonstrated that, even in a population who suffered a fragility hip fracture, men still have higher trabecular bone mechanical properties in comparison with women.

Keywords:
Trabecular bone; Osteoporosis; Fragility fracture; Compression; Mechanical properties