Bone density, microarchitecture and estimated strength in stone formers: a cross-sectional HR-pQCT study

Background: Low areal bone mineral density (BMD), increased fracture risk and altered bone remodeling have been described among stone formers (SFs), but the magnitude of these findings differs by age, sex, menopausal status and urinary calcium (uCa). This study aimed to investigate volumetric BMD (vBMD), bone microarchitecture and biomechanical properties by high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite element analysis (FEA) in young SFs, irrespective of calciuria, further distinguishing trabecular from cortical compartments.

Methods: HR-pQCT/FEA was performed at the distal tibia (DT) and distal radius (DR) in 106 SFs (57 males and 49 premenopausal females; median age 37 years) and compared with 106 non-SFs (NSFs) retrieved from an existing database, matched for age, sex and body mass index (BMI). Biochemical/hormonal serum and urinary parameters were obtained from SFs.

Results: SFs exhibited significantly lower trabecular number (TbN) and higher trabecular separation (TbSp) than NSFs at both anatomical sites and lower cortical porosity in the DR. In a subgroup analysis separated by sex, female SFs presented significantly lower TbvBMD, relative bone volume fraction (BV/TV) and TbN and higher TbSp than NSFs at both sites, while male SFs showed significantly lower stiffness and failure load. Multivariate analysis showed TbN to be independently associated with sex and BMI at both sites and with uCa at the DR.

Conclusions: The present findings suggest that bone disease represents an early event among SFs, associated at least in part with calcium excretion and mainly characterized by trabecular bone microarchitecture impairment, especially among women, but with reduced bone strength parameters in men.