Effects of Bisphosphonates on Bone Micro-Architecture of Children With Duchenne Muscular Dystrophy: A Prospective Comparative Study.

BACKGROUND

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder that affects dystrophin production, characterized by progressive neuromuscular dysfunction, often accompanied by osteoporosis. We prospectively evaluate the effects of bisphosphonates on bone micro-architecture reflected by trabecular bone score (TBS) of patients with DMD.

METHODS

A total of 72 male children or adolescents with DMD were included, with a mean age of 9.5 ± 1.8 years. They were divided into bisphosphonate treatment groups and control group based on areal bone mineral density (aBMD) and history of fragility fractures. Patients in bisphosphonate treatment groups randomly received intravenous infusion of 5 mg zoledronic acid (ZOL) annually or oral 70 mg alendronate weekly for three years. All patients took calcium 600 mg plus 125 IU vitamin D daily and calcitriol 0.25 μg every other day. TBS at the lumbar spine (LS) and aBMD at the LS, femoral neck (FN) and total hip (TH) were measured annually by dual-energy X-ray absorptiometry. Serum levels of β-isomerized carboxy-telopeptide of type I collagen and alkaline phosphatase were measured annually during the follow-up.

RESULTS

A total of 25 (86.2%), 26 (92.9%) and 13 (86.7%) patients in the ZOL, alendronate and control groups completed the study. After 3 years, TBS Z-score increased from baseline by 1.13 (p < 0.01), 0.68 (p < 0.01) and 0.26 (p > 0.05) in the ZOL, alendronate and control groups, respectively. The mean increase in TBS Z-score from baseline was significantly greater in both bisphosphonate treatment groups compared to the control group (p < 0.05). No significant difference was found between the ZOL and alendronate groups. LS, FN and TH aBMD increased by 35.8%, 23.7% and 34.5% in the ZOL group (all p < 0.01 vs. baseline and control group) and by 21.5%, 29.3% and 25.0% in the alendronate group (all p < 0.05 vs. baseline and control group). LS and FN aBMD Z-scores increased by 1.56 and 1.63 in the ZOL group (all p < 0.01 vs. baseline), by 1.32 and 1.48 in the alendronate group (all p < 0.05 vs. baseline). Bisphosphonates demonstrated a favourable safety profile during the study period.

CONCLUSION

This relatively long-term study confirms that zoledronic acid and alendronate are beneficial to improve micro-architecture reflected by TBS and aBMD of children or adolescents with DMD.