Compromised trabecular microarchitecture and lower finite element estimates of radius and tibia bone strength in adults with turner syndrome: A cross-sectional study using high-resolution–pQCT

Abstract

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 (À15%) and tibia (À13%) (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 (À32% in radius, À36% in tibia, both p < 0.0001). Trabecular integrity was compromised in TS patients with lower bone volume per tissue volume (BV/TV) (À27% in radius, À22% in tibia, both p < 0.0001), trabecular number (À27% in radius, À12% 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 (À11%) and tibia (À16%) (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. ß

Clinical practice guidelines for the care of girls and women with Turner syndrome: proceedings from the 2016 Cincinnati International Turner Syndrome Meeting

“…Their BMD may appear falsely reduced when evaluated by DXA due to the small bone size accompanying short stature and the differences in bone geometry due to SHOX deficiency (427). Furthermore, quantitative CT (QCT) evaluation of BMD has shown normal trabecular bone density (428) with falsely reduced cortical bone mineral content due to the partial volume effect (429), while high-resolution peripheral QCT has shown compromised microarchitecture and lower bone strength in both the tibia and radius (430). Therefore, radiographic evaluation of BMD may be difficult to interpret.…”

Impact of Growth Hormone on Adult Bone Quality in Turner Syndrome: A HR-pQCT Study

“…After correcting for size differences between groups, the percentage of women with TS classified as osteoporotic via DXA dropped from 20 to 5 % [15]. Literature suggests TS subjects have lower aBMD, compromised cortical [16][17][18] and trabecular [7] bone as well as lower estimates of bones strength [7] compared with control groups. The effects of GH on volumetric bone density and bone micro-architecture remain unclear.…”

“…In addition, methods such as finite element (FE) analysis provide a subject-specific bone strength estimate [6]. One study using HR-pQCT of TS subjects has been performed [7] identifying micro-architectural deficits; however, the authors did not assess whether GH treatment influences those changes.…”

The assessment of skeletal status in young patients with Turner syndrome by 2 densitometric techniques: Phalangeal quantitative ultrasound and dual energy X-ray absorptiometry

“…23 Also, the studies that used pQCT, a method which is able to independently provide measurements of 3-dimensional bone density and an assessment of trabecular and cortical bone density, have revealed significantly reduced cortical volumetric BMD (vBMD) and cortical thickness at some sites, and lower bone strength. [20][21][22] Holroyd et al showed by this method not only a significant reduction in cortical vBMD at the proximal radius, but in cortical thickness as well (Z-score of −2.58 and −2.89, respectively). 9 Moreover, they found no differences in the total vBMD Z-score or the trabecular vBMD Z-score at the distal radius.…”

“…Although the majority of studies indicate that the abnormalities seem to be only in cortical bone, some studies show compromised trabecular microarchitecture in patients with TS. 20,21 However, reduced cortical BMD in young TS patients is not proven to lead to increased fractures. [22][23][24] We assessed the skeletal status of a group of young females with TS at 2 different skeletal sites using 2 different densitometric techniques.…”