Sex-, Ethnic-, and Age-Specific Centile Curves for pQCT- and HR-pQCT-Derived Measures of Bone Structure and Strength in Adolescents and Young Adults

Abstract

There are presently no adolescent centile curves for bone parameters at the tibial midshaft using peripheral quantitative computed tomography (pQCT) or at the distal radius and tibia using high-resolution pQCT (HR-pQCT). Thus, we aimed to develop sex-, ethnic-, site-, and age-specific centile curves for pQCT and HR-pQCT-derived bone outcomes for youth and young adults aged 10 to 21 years. We acquired pQCT scans (XCT3000 or XCT2000) at the tibial midshaft (50% site) and HR-pQCT scans (XtremeCT) at the distal radius (7% site) and tibia (8% site) in a convenience sample of participants in the mixed-longitudinal University of British Columbia Healthy Bones III Study. We scanned 778 10- to 21-year-olds annually for a maximum of 11 years using pQCT (413 girls, 56% Asian; 365 boys, 54% Asian; n = 3160 observations) and 349 10- to 21-year-olds annually for a maximum of 4 years using HR-pQCT (189 girls, 51% Asian; 165 boys, 50% Asian; n = 1090 observations). For pQCT, we report cortical bone mineral density (BMD), total bone cross-sectional area, and polar strength-strain index. For HR-pQCT, we report standard measures (total BMD, trabecular number, thickness, and bone volume fraction) and automated segmentation measures (total bone cross-sectional area, cortical BMD, porosity, and thickness). We applied finite element analysis to estimate failure load. We applied the lamda, mu, sigma (LMS) method using LMS ChartMaker Light (version 2.5, The Institute of Child Health, London, UK) to construct LMS tables and centile plots. We report sex- and age-specific centiles (3rd, 10th, 25th, 50th, 75th, and 97th) for whites and Asians for pQCT bone parameters at the tibial midshaft and HR-pQCT bone parameters at the distal radius and tibia. These centile curves might be used by clinicians and scientists to interpret values or better understand trajectories of bone parameters in clinical populations, those from different geographic regions or of different ethnic origins. © 2018 American Society for Bone and Mineral Research.

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

“…Image analyses (standard and advanced cortical evaluation) have been developed for mature bone, but it is unknown how accurately these methods capture immature bone properties. (28,43) Ct.BMD and Ct.TMD values reported in our study and other pediatric studies (1)(2)(3)15,17) appeared about 35% lower than those reported for young and older adults. (28,43) This difference can be partly explained by lower density in immature bone based on growth and newly formed bone tissue and partial volume effects when scanning small bones of children.…”

“…Our small sample size limited between sex comparisons of annual changes, precision errors, or MTIs. Second, inherent to any prospective scanning of growing bone, we could not scan the exact same anatomical site at the baseline and follow‐up scan because of bone growth . Third, our FE model assumed fixed, homogeneous material properties for growing cortical and trabecular bone.…”

“…Second, inherent to any prospective scanning of growing bone, we could not scan the exact same anatomical site at the baseline and follow-up scan because of bone growth. (17,38) Third, our FE model assumed fixed, homogeneous material properties for growing cortical and trabecular bone. This is relevant as we observed an annual 3% increase in Ct.TMD at both sites, suggesting an increase in tissue elastic modulus.…”

“…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 .…”

“…Available evidence of bone strength development relies on mixed longitudinal cohort findings spanning from early adolescence to young adulthood. (15)(16)(17)(18) 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. (19,20) Reported individual variation in peak velocities of limb bone growth in length may also contribute to sitespecific adaptations in bone strength development at the weight-bearing lower extremity and nonweight-bearing upper extremity; thus, evidence from both the tibia and radius are warranted.…”