Compromised trabecular microarchitecture and lower finite element estimates of radius and tibia bone strength in...

Although bone mass appear ample for bone size in Turner syndrome (TS), epidemiological studies have reported an increased risk of fracture in TS. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to measure standard morphological parameters of bone geometry and microarchitecture, as well as estimated bone strength by finite element analysis (FEA) to assess bone characteristics beyond bone mineral density (BMD) that possibly contribute to the increased risk of fracture. Thirty-two TS patients (median age 35, range 20-61 years) and 32 healthy control subjects (median age 36, range 19-58 years) matched with the TS participants with respect to age and body-mass index were studied. A full region of interest (ROI) image analysis and a height-matched ROI analysis adjusting for differences in body height between groups were performed. Mean bone cross-sectional area was lower in TS patients in radius (-15%) and tibia (-13%) (both p < 0.01) whereas cortical thickness was higher in TS patients in radius (18%, p < 0.01) but not in tibia compared to controls. Cortical porosity was lower in TS patients at both sites (-32% in radius, -36% in tibia, both p < 0.0001). Trabecular integrity was compromised in TS patients with lower bone volume per tissue volume (BV/TV) (-27% in radius, -22% in tibia, both p < 0.0001), trabecular number (-27% in radius, -12% in tibia, both p < 0.05), and higher trabecular spacing (54% in radius, 23% in tibia, both p < 0.01). In the height-matched ROI analysis, differences remained significant apart from total area at both sites, cortical thickness in radius, and trabecular number in tibia. FEA estimated failure load was lower in TS patients in both radius (-11%) and tibia (-16%) (both p < 0.01) and remained significantly lower in the height-matched ROI analysis. Conclusively, TS patients had compromised trabecular microarchitecture and lower bone strength at both skeletal sites, which may partly account for the increased risk of fracture observed in these patients.