Sex Differences and Growth-Related Adaptations in Bone Microarchitecture, Geometry, Density, and Strength From Childhood to Early Adulthood: A Mixed Longitudinal HR-pQCT Study

Distal forearm fractures during growth are more common in males than females. Because metaphyseal cortical bone is formed by coalescence of trabeculae emerging from the periphery of the growth plate, we hypothesized that the later onset of puberty in males produces a longer delay in trabecular bone formation and coalescence, which leaves a transient phase of high cortical porosity, low matrix mineral density, and high trabecular density relative to females. We quantified the nondominant distal radial microstructure using high-resolution peripheral quantitative computed tomography in 214 healthy Chinese boys and 219 Chinese girls aged between 7 and 17 years living in Hong Kong. Measurements of 110 slices (9.02 mm) were acquired 5 mm proximal to the growth plate of the nondominant distal radius. Porosity was measured using StrAx1.0 (Straxcorp, Melbourne, VIC, Australia) and trabecular plate and rod structure were measured using individual trabecula segmentation (ITS). Mechanical properties were estimated using finite element analysis (FEA). Results were adjusted for age, total bone cross-sectional area (CSA), dietary calcium intake, and physical activity. In boys, total bone CSA was 17.2% to 22.9% larger throughout puberty, cortical/total bone CSA was 5.1% smaller in Tanner stage 2 only, cortical porosity was 9.4% to 17.5% higher, and matrix mineral density was 1.0% to 2.5% lower in Tanner stage 2 to 5, than girls. Boys had higher trabecular rod BV/TV in Tanner stage 3 and 4, but higher trabecular plate BV/TV and plate to rod ratio in Tanner stage 5, than girls. Boys had 17.0% lower apparent modulus than girls in Tanner stage 2. A transient phase of higher porosity due to dissociation between bone mineral accrual and linear growth may contribute to higher distal radial bone fragility in Chinese boys compared to girls. © 2018 American Society for Bone and Mineral Research.

Section: Discussionsupporting

confidence: 92%

Sexual Dimorphism in Cortical and Trabecular Bone Microstructure Appears During Puberty in Chinese Children

Cheuk

Wang

et al. 2018

“…Corresponding small declines (1% to 2%) in Tb.Ar and increases (7% to 8%) in Tb.Th and Tb.Sp indicated consolidation/formation of cortex by fusion of (smaller) trabeculae because trabecular BV/TV and Tb.BMD remained unchanged. These findings add to the limited evidence characterizing bone strength and microarchitectural development during the accelerated phase of the pubertal growth spurt . Our observations appear comparable to prior prospective research indicating increases in bone strength, Ct.Th, and Tb.Th, and decrease in Tb.N in years preceding peak pubertal growth spurt (ie, APHV) .…”

Section: Discussionsupporting

confidence: 87%

“…Prospective HR‐pQCT evidence of bone strength and microarchitectural development in children and adolescents is scarce. Available evidence of bone strength development relies on mixed longitudinal cohort findings spanning from early adolescence to young adulthood . There is a need to complement this data with evidence from children and youth preceding or during the accelerated phase of the adolescent growth spurt because limb bone growth predominates during this period .…”

Section: Introductionmentioning

confidence: 99%

Reliability of Annual Changes and Monitoring Time Intervals for Bone Strength, Size, Density, and Microarchitectural Development at the Distal Radius and Tibia in Children: A 1-Year HR-pQCT Follow-Up

Bunyamin

Björkman

Kawalilak

et al. 2019

High‐resolution peripheral quantitative computed tomography (HR‐pQCT) imaging, together with computational finite element analysis (FEA), offers an attractive, noninvasive tool to quantify bone strength development in pediatric studies. Evidence of annual changes and errors in repeated HR‐pQCT measures is limited, and time intervals required to reliably capture changes in children's bone strength or microarchitecture have not yet been defined. Our objectives were: (1) to quantify annual changes in bone strength and microarchitectural properties; (2) to define precision errors for pediatric bone strength outcomes; (3) to characterize annual changes in contrast to pediatric precision errors; and (4) to estimate monitoring time intervals (MTIs) required to reliably characterize bone development at the distal radius and tibia. We obtained distal radius (7% of ulnar length) and tibia (8%) bone properties using HR‐pQCT and FEA from 38 follow‐up study participants (21 girls) at baseline (mean age 10.6 years, SD 1.7 years) and after 1 year; and from 32 precision study participants (16 girls) at baseline (mean age 11.3 years, SD 1.6 years) and after 1 week. We characterized mean annual changes (paired t tests) contrasted to pediatric precision errors (CV%RMS) and estimated MTIs. Annual increases in bone strength, total area, cortical thickness, and density ranged between 3.0% and 25.3% and 2.4% and 15.6% at the distal radius and tibia, respectively. Precision errors for all bone strength outcomes were ≤6.8% and ≤5.1% at the distal radius and tibia, respectively, and appeared lower than annual gains in bone strength at both sites. Cortical porosity decreased 19.6% at the distal radius and 6.6% at the distal tibia; these changes exceeded respective precision errors, indicating cortical bone consolidation. MTIs ranged between 0.5 years and infinity at the distal radius and 0.5 and 5.9 years at the distal tibia. Estimated MTIs suggest that pediatric bone strength, cortical bone density, and porosity development can be reliably monitored with annual measurements. © 2019 American Society for Bone and Mineral Research.

“…Our finding that MVPA positively predicted Tt.Ar at the distal tibia in early and mid‐puberty is consistent with previous studies in children and adolescents that demonstrated a positive relationship between PA (via accelerometry or self‐report) and CSA (by DXA and HSA) at the narrow neck, intertrochanter and proximal femur shaft, periosteal circumference at the tibial shaft (by pQCT), and Tt.Ar at the distal tibia (by HR pQCT) . Given that Tt.Ar at the distal tibia tends to plateau approximately 3 years after APHV, the period of accelerated growth during early and mid‐puberty represents the previously reported “window of opportunity” to enhance bone geometry through the osteogenic effect of PA …”

Section: Discussionmentioning

confidence: 84%

“…Our findings are consistent with a recent longitudinal study that used pQCT to assess bone and previous cross‐sectional studies that demonstrated a significant association between objectively measured PA (via accelerometer or pedometer) and pQCT‐ and HR‐pQCT‐ estimated bone strength. In our recent analysis of the HBSIII cohort, bone strength (F.Load by HR‐pQCT) increased by approximately 47% to 65% in boys and 59% to 91% in girls at the distal tibia and radius in the 4 years around peak growth . Considering the strong influence of maturation and other biological determinants of bone strength (ie, genetic factors account for approximately 83% of distal radius and 61% of tibial bone strength by pQCT), we view the significant relationship of MVPA with bone strength across growth in girls and boys as meaningful.…”

Section: Discussionmentioning

confidence: 93%

Physical Activity, Sedentary Time, and Bone Strength From Childhood to Early Adulthood: A Mixed Longitudinal HR-pQCT study

Gabel

Macdonald

Nettlefold

et al. 2017

Self Cite

Bone strength is influenced by bone geometry, density, and bone microarchitecture, which adapt to increased mechanical loads during growth. Physical activity (PA) is essential for optimal bone strength accrual; however, less is known about how sedentary time influences bone strength and its determinants. Thus, our aim was to investigate the prospective associations between PA, sedentary time, and bone strength and its determinants during adolescence. We used HR-pQCT at distal tibia (8% site) and radius (7% site) in 173 girls and 136 boys (aged 9 to 20 years at baseline). We conducted a maximum of four annual measurements at the tibia (n = 785 observations) and radius (n = 582 observations). We assessed moderate-to-vigorous PA (MVPA) and sedentary time with accelerometers (ActiGraph GT1M). We aligned participants on maturity (years from age at peak height velocity) and fit a mixed-effects model adjusting for maturity, sex, ethnicity, leg muscle power, lean mass, limb length, dietary calcium, and MVPA in sedentary time models. MVPA was a positive independent predictor of bone strength (failure load [F.Load]) and bone volume fraction (BV/TV) at the tibia and radius, total area (Tt.Ar) and cortical porosity (Ct.Po) at the tibia, and negative predictor of load-to-strength ratio at the radius. Sedentary time was a negative independent predictor of Tt.Ar at both sites and Ct.Po at the tibia and a positive predictor of cortical thickness (Ct.Th), trabecular thickness (Tb.Th), and cortical bone mineral density (Ct.BMD) at the tibia. Bone parameters demonstrated maturity-specific associations with MVPA and sedentary time, whereby associations were strongest during early and mid-puberty. Our findings support the importance of PA for bone strength accrual and its determinants across adolescent growth and provide new evidence of a detrimental association of sedentary time with bone geometry but positive associations with microarchitecture. This study highlights maturity-specific relationships of bone strength and its determinants with loading and unloading. Future studies should evaluate the dose-response relationship and whether associations persist into adulthood. © 2017 American Society for Bone and Mineral Research.