title: A case-control study of fractures in men with idiopathic osteoporosis: fractures are associated with older age and low cortical bone density.
abstract: OBJECTIVE
  To determine biochemical, radiological and micro-architectural bone factors related to fragility fractures in idiopathic male osteoporosis (IMO) patients. IMO is a rare disorder characterized by low areal bone mineral density (aBMD) (Z-score<-2) occurring in men after excluding secondary causes of low BMD.
  
  
  METHODS
  We conducted a case-control study in 31 patients with fragility fracture (IMO F+) that had occurred after the age of 40 years and 37 without fracture (IMO F-). We first compared IMO group to 40 age-matched disease-free men. We measured aBMD and bone micro-architectural indices at distal radius and tibia sites with a HR-pQCT scan (XtremeCT) using standard and extended cortical analysis. Urine and blood samples were collected in order to determine the levels of bone-turnover markers and the potential determinant of bone fragility. Models of analysis of covariance, including age, height and weight as adjustment factors, were used to compare the groups.
  
  
  RESULTS
  Compared to their controls, IMO patients showed marked disturbance of their micro-architectural parameters at tibia and radius affecting both trabecular and cortical parameters. IMO F+ subjects were significantly older than IMO F- subjects (58 ± 8 vs. 53 ± 9 yrs, p=0.01). BMD Z-score at the total-hip was significantly lower in IMO F+ (-1.3 ± 0.5 vs. -0.9 ± 0.8 g/cm(2), p=0.01). After adjustment, trabecular micro-architectural parameters, biochemical markers and hormonal parameters were not different in the 2 groups. At distal tibia, cortical v-BMD was significantly lower in IMO F+ patients (799 ± 73 vs. 858 ± 60 mg/cm(3), p=0.03), while cortical thickness was not different.
  
  
  CONCLUSIONS
  Our results show that patients with IMO display a marked disturbance of trabecular and cortical bone micro-architecture, and that age and low cortical density are determinants of the fracture occurrence.
authors.affiliation: INSERM U606 and Univ Paris Diderot, Sorbonne Paris Cité, Bone and Joint Laboratory, 75010 Paris, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Ostertag
authors.forename: Corinne
authors.initials: C
authors.lastname: Collet
authors.forename: Christine
authors.initials: C
authors.lastname: Chappard
authors.forename: Sylvie
authors.initials: S
authors.lastname: Fernandez
authors.forename: Eric
authors.initials: E
authors.lastname: Vicaut
authors.forename: Martine
authors.initials: M
authors.lastname: Cohen-Solal
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: de Vernejoul
mesh_terms: D000328:Adult; D000368:Aged; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D050723:Fractures, Bone / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000150:complications*; D014057:Tomography, X-Ray Computed