title: At the moment of occurrence of a fragility hip fracture, men have higher mechanical properties values in comparison with women.
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.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Vale
authors.forename: Inês P
authors.initials: IP
authors.lastname: Aleixo
authors.forename: Miguel
authors.initials: M
authors.lastname: Lúcio
authors.forename: André
authors.initials: A
authors.lastname: Saraiva
authors.forename: Joana
authors.initials: J
authors.lastname: Caetano-Lopes
authors.forename: Ana
authors.initials: A
authors.lastname: Rodrigues
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Amaral
authors.forename: Luís G
authors.initials: LG
authors.lastname: Rosa
authors.forename: Jacinto
authors.initials: J
authors.lastname: Monteiro
authors.affiliation: Rheumatology Research Unit, Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal. jefonseca@netcabo.pt.
authors.forename: João E
authors.initials: JE
authors.lastname: Fonseca
authors.forename: Maria F
authors.initials: MF
authors.lastname: Vaz
authors.forename: Helena
authors.initials: H
authors.lastname: Canhão
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006620:Hip Fractures / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012727:Sex Characteristics; D013314:Stress, Mechanical