At the moment of occurrence of a fragility hip fracture, men have higher mechanical properties values in comparison with women
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
BMC Musculoskeletal Disorders 2013, 14:295 doi:10.1186/1471-2474-14-295Published: 16 October 2013
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.
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.
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.
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.