A shared biomechanical environment for bone and posture development in children

Publication date: Available online 4 May 2017
Source:The Spine Journal
Author(s): Fábio A Araújo, Ana Martins, Nuno Alegrete, Laura D Howe, Raquel Lucas
Background ContextIn each specific habitual standing posture, gravitational forces determine the mechanical setting provided to skeletal structures. Bone quality and resistance to physical stress is highly determined by habitual mechanical stimulation. However, the relationship between bone properties and sagittal posture has never been studied in children.PurposeTo investigate the association between bone physical properties and sagittal standing postural patterns in 7-year-old children. We also analyzed the relationship between fat/fat-free mass and postural patterns.Study DesignCross-sectional evaluation.Patient SampleThis study was performed in a sample of 1138 girls and 1260 boys at 7 years of age participating in the Generation XXI study, a population-based cohort of children followed since birth (2005/6) and recruited in Porto, Portugal.Outcome MeasuresSagittal standing posture was measured through photographs of the sagittal right view of children in the standing position. Three angles were considered to quantify the magnitude of major curves of the spine and an overall balance measure (trunk, lumbar and sway angles). Postural patterns were identified using latent profile analysis in Mplus.MethodsWeight and height were measured. Total body less head fat/fat-free mass and bone properties were estimated from whole body dual energy X-ray absorptiometry scans. The associations of fat/fat-free mass and bone physical properties with postural patterns were jointly estimate in latent profile analysis using multinomial logistic regressions.ResultsThe identified patterns were labelled as Sway, Flat and "Neutral to Hyperlordotic" (in girls) and "Sway to Neutral", Flat and Hyperlordotic (in boys). In both genders, children in the Flat pattern showed the lowest body mass index and children with a rounded posture presented the highest: mean differences varying from -0.86kg/m² to 0.60kg/m² in girls and -0.70kg/m² to 0.62kg/m² in boys (vs. Sway/"Sway to Neutral"). Fat and fat-free mass were inversely associated with a Flat pattern and positively associated with a rounded posture: odds ratio (OR) of 0.23 per SD fat and 0.70 per SD fat-free mass for the Flat and 1.85 (fat) and 1.43 (fat-free) for the Hyperlordotic in boys; with similar findings in girls. The same direction of relationships was observed between bone physical properties and postural patterns. A positive association between bone (especially bone mineral density) and a rounded posture was robust to adjustment for age, height, and body composition (girls: OR=1.79, p=0.006 fat-adjusted, OR=2.00, p=0.014 fat-free mass adjusted; boys: OR=2.02, p=0.002 fat-adjusted, OR=2.42, p<0.001 fat-free mass adjusted).ConclusionsIn this population-based pediatric setting, there was an inverse association between bone physical properties and a Flat posture. Bone and posture were more strongly positively linked in a rounded posture. Our results support that both bone properties and posture mature in a shared and interrelated mechanical environment, probably modulated by pattern-specific anthropometrics and body composition.



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