A case-control study of fractures in men with idiopathic osteoporosis: Fractures are associated with older age and low cortical bone density

摘要

Objectives: 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±9yrs, p=0.01). BMD Z-score at the total-hip was significantly lower in IMO F+ (-1.3±0.5 vs. -0.9±0.8g/cm2, 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±60mg/cm3, p=0.03), while cortical thickness was not different. Conclusion: 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.