Skeletal health in Duchenne dystrophy: bone-size and subcranial dual-energy X-ray absorptiometry analyses.

Introduction: We performed subcranial and bone-size-adjusted whole body dual-energy X-ray absorptiometry (DXA) to evaluate skeletal health in Duchenne dystrophy (DMD). Methods: Total body bone mineral density (TBBMD)-for-age, subcranial, and size-adjusted DXA analyses were performed on 22 DMD patients (5-17 years) and compared with 267 controls from a database. The skull contribution to total body bone mineral content (TBBMC) and corticosteroid effects were also examined. Results: DMD boys had deficits in TBBMD-for-age (Z=-1.2), which increased with age. The skull's contribution to TBBMC decreased from 45% to 15% with growth. Z-scores for subcranial skeleton were significantly lower than TBBMC-for-area and TBBMD-for-age. Conclusions: Size-adjusted and subcranial analyses improve evaluation of whole body DXA. DMD boys have low BMD for size not commensurate with total body areal BMD-for-age. Bone fragility fractures in DMD may result from both decreased BMD and smaller bones. This information is vital to determine appropriate intervention. Muscle Nerve 49:512-519, 2014