Bone Abstracts

Objectives: Children with Duchenne muscular dystrophy (DMD) receiving long-term glucocorticoid (GC) therapy are at risk for osteoporosis and fragility fractures. Recent studies showed that cortical thickness and areas were associated with increased fracture risk. Digital X-ray measurement of the cortical thickness of the metacarpal bones has a potential role as a marker for bone health in children, but has not been evaluated in DMD. The aim of this study was to compare bone age (BA) and Bone Health Index (BHI) automatically computed from hand X-ray with bone mineral density (BMD) parameters obtained by dual-energy X-ray absorptiometry (DXA).

Methods: 38 hand radiographs of boys with DMD were retrospectively analyzed by BoneXpert™ (Visiana, Holte, Denmark) to generate automated BA, BHI and Z scores. The BA and BHI data were compared with corresponding DXA measurements (performed on the same day as BA), and clinical variables including age, duration of GC therapy, and fracture history were collected. Linear correlations were performed using Pearson correlation while unpaired two-tailed t-test was used to compare metrics in patients with and without fracture.

Results: Mean chronological age was 12.9±3.9 years. BA and BHI Z scores reduced significantly with age (r=−0.58, r=−0.34, respectively). BHI Z scores were positively correlated with lumbar spine (LS) BMD height-adjusted (H) Z scores and total body (TB) BMD H Z scores (r=0.102, r=0.5, respectively; P<0.01). BA Z scores were also positively correlated with TB BMD H Z scores (r=0.374), but had a weak negative correlation with LS BMD H Z scores (r=−0.17). Patients with history of fractures (24 of 38 or 63%) had significantly lower BA Z scores, lower BHI Z scores, and lower TB BMD H Z scores than those without fractures (−2.3±1.8 vs −0.9±1.6, P=0.029; −2.4±1.1 vs −1.2±1.1, P=0.004; −3.5±2.1 vs −0.95±1.2, P=0.0003, respectively). However, there was no significant difference in LS BMD H Z scores between those with and without fractures.

Conclusions: BHI correlated with DXA readings and also fracture history. BHI can be a useful, low-cost, bone assessment tool in children with DMD.

Disclosure: The authors declared no competing interests.