Hand X-ray metrics for assessing bone health and fracture risk in Duchenne muscular dystrophy: a cross-sectional study.

UNLABELLED: Duchenne muscular dystrophy (DMD) is an X-linked disorder associated with progressive muscle weakness and a high risk of fragility fractures, mainly due to long-term glucocorticoid therapy and reduced mobility. Dual-energy X-ray absorptiometry (DXA) is the standard for bone mineral density (BMD) assessment, but its interpretation is often limited in DMD due to scoliosis and/or surgical instrumentation. The bone health index (BHI), derived from hand X-rays using the BoneXpert® software, may provide a complementary skeletal evaluation. The aim of the study is to evaluate the relationship between BHI, bone age (BA), and DXA-derived BMD in deflazacort-treated DMD and explore their association with fracture risk. This monocentric, cross-sectional study included 41 DMD. BHI and BA were calculated from left-hand radiographs. Lumbar spine (LS) and total body less head (TB) BMD were obtained by DXA. Associations between variables were assessed using partial correlation analyses controlling for age and body size, and logistic regression was used to explore associations with fracture history. BHI SDS was below - 2 in 33% of participants. BHI SD was moderately correlated with TB BMD Z-score (r = 0.48, 95% CI: 0.17-0.71; p = 0.004). BA SD was correlated with LS BMD Z-score (r = 0.43, 95% CI: 0.04-0.66; p = 0.008). Fractures were reported in 56% of participants. None of the bone metrics showed a statistically significant association with fracture history; however, BA SD demonstrated a non-significant trend (OR = 0.41, 95% CI: 0.14-0.95; p = 0.064).

CONCLUSION: Hand X-ray-derived metrics, as BHI and BA, represent a non-invasive tool for bone health assessment in DMD. BHI may serve as a supportive biomarker when DXA is limited, and BA may carry potential as a fracture risk indicator, although prospective validation is warranted.

WHAT IS KNOWN: • Fragility fractures and low bone mineral density (BMD) are frequent in Duchenne muscular dystrophy (DMD) treated with glucocorticoids. • DXA-based bone health assessment is often limited by scoliosis in DMD.

WHAT IS NEW: • This is among the first studies to evaluate the bone health index (BHI) from hand X-rays using the BoneXpert® software in DMD, showing a moderate correlation with DXA-derived total body BMD and highlighting its potential as a complementary skeletal assessment tool. • BHI could be integrated into routine hand radiographs for bone health monitoring in DMD, particularly in cases where DXA is unavailable or cannot be interpreted.