title: Reexamining the Surfaces of Bone in Boys and Girls During Adolescent Growth: A 12-Year Mixed Longitudinal pQCT Study.
abstract: We revisit Stanley Garn's theory related to sex differences in endocortical and periosteal apposition during adolescence using a 12-year mixed longitudinal study design. We used peripheral quantitative computed tomography to examine bone parameters in 230 participants (110 boys, 120 girls; aged 11.0 years at baseline). We assessed total (Tt.Ar, mm(2)), cortical (Ct.Ar, mm(2)), and medullary canal area (Me.Ar, mm(2)), Ct.Ar/Tt.Ar, cortical bone mineral density (Ct.BMD, mg/cm(3)), and polar strength-strain index (SSIp , mm(3)) at the tibial midshaft (50% site). We used annual measures of height and chronological age to identify age at peak height velocity (APHV) for each participant. We compared annual accrual rates of bone parameters between boys and girls, aligned on APHV using a linear mixed effects model. At APHV, boys demonstrated greater Tt.Ar (ratio = 1.27; 95% confidence interval [CI] 1.21, 1.32), Ct.Ar (1.24 [1.18, 1.30]), Me.Ar (1.31 [1.22, 1.40]), and SSIp (1.36 [1.28, 1.45]) and less Ct.Ar/Tt.Ar (0.98 [0.96, 1.00]) and Ct.BMD (0.97 [0.96, 0.97]) compared with girls. Boys and girls demonstrated periosteal bone formation and net bone loss at the endocortical surface. Compared with girls, boys demonstrated greater annual accrual rates pre-APHV for Tt.Ar (1.18 [1.02, 1.34]) and Me.Ar (1.34 [1.11, 1.57]), lower annual accrual rates pre-APHV for Ct.Ar/Tt.Ar (0.56 [0.29, 0.83]) and Ct.BMD (-0.07 [-0.17, 0.04]), and similar annual accrual rates pre-APHV for Ct.Ar (1.10 [0.94, 1.26]) and SSIp (1.14 [0.98, 1.30]). Post-APHV, boys demonstrated similar annual accrual rates for Ct.Ar/Tt.Ar (1.01 [0.71, 1.31]) and greater annual accrual rates for all other bone parameters compared with girls (ratio = 1.23 to 2.63; 95% CI 1.11 to 3.45). Our findings support those of Garn and others of accelerated periosteal apposition during adolescence, more evident in boys than girls. However, our findings challenge the notion of greater endocortical apposition in girls, suggesting instead that girls experience diminished endocortical resorption compared with boys.
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.|Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute, Vancouver, Canada.|Child and Family Research Institute, University of British Columbia, Vancouver, Canada.
authors.forename: Leigh
authors.initials: L
authors.lastname: Gabel
authors.affiliation: Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute, Vancouver, Canada.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Nettlefold
authors.affiliation: Centre for Clinical Epidemiology and Evaluation, Vancouver Coastal Health Research Institute, Vancouver, Canada.
authors.forename: Penelope M
authors.initials: PM
authors.lastname: Brasher
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.|Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute, Vancouver, Canada.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Moore
authors.affiliation: Centre of Health, Exercise and Sports Medicine, Department of Physiotherapy, University of Melbourne, Melbourne, Australia.
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Ahamed
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.|Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute, Vancouver, Canada.|Child and Family Research Institute, University of British Columbia, Vancouver, Canada.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Macdonald
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.|Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute, Vancouver, Canada.|Department of Family Practice, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: Heather A
authors.initials: HA
authors.lastname: McKay
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000886:Anthropometry; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000502:physiology*; D001955:British Columbia; D002648:Child; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011884:Radius / Q000000981:diagnostic imaging / Q000502:physiology; D012044:Regression Analysis; D012737:Sex Factors; D013977:Tibia / Q000000981:diagnostic imaging / Q000502:physiology; D014057:Tomography, X-Ray Computed
keywords: BONE ACCRUAL; BONE STRENGTH; GROWTH; PEAK HEIGHT VELOCITY; pQCT