Bone Abstracts

Background: DMD is a progressive neuromuscular disease often treated with oral glucocorticoids (GC) to prolong ambulation and maintain cardiovascular function. However, the osteotoxic GC effects often result in a skeleton prone to fractures. DMD boys presenting with fractures are treated with bisphosphonates (BP) but evidence of beneficial effects is limited. The aim of this work was to review the use of intravenous BPs in a group of severely affected boys with fractures.

Methods: Bone measurements by DXA, including size-adjusted lumbar spine BMD (LSBMAD), total body less head BMD (TBLHBMD) and vertebral fracture assessment were performed 12 months prior to, at start of BP therapy and 12 months later in 13, 18 and nine boys respectively.

Results: At the start of BP therapy, 12 boys were non-ambulant. 17 of the 18 boys were taking oral GC and vertebral fractures (VF) were identified in all. ten boys also suffered long bone fractures. In the group of 13 boys measured 12 months prior to BP treatment there were 35 VF (30 mild & five moderate) which increased to 59 (49 mild & 13 moderate) by the start of BP treatment. In the post treatment group of nine boys, there were 44 (34 mild & ten moderate) VF at start of BP therapy and the same number 12 months later. However, fracture severity had reduced to 39 mild & three moderate. Unfortunately, one of the moderate fractures identified before the start of therapy had deteriorated to a severe fracture during follow-up. Overall, after 12 months of BP therapy, remodelling was observed in 14 of the vertebrae and two incident fractures were identified. Although six boys were pre-treated with oral BPs, moderate VF were observed in all six at baseline. LSBMAD was within normal limits at baseline and did not change significantly at follow-up. In contrast TBLHBMD was reduced prior to treatment (P<0.001) but remained stable over the treatment period.

Conclusions: In this population, IV BPs appear to reduce fracture rate and severity. In contrast, oral BPs did not appear to protect against fracture. Importantly, for boys with DMD on long-term oral CS, LS BMAD was a poor marker of vertebral fragility.

Disclosure: The authors declared no competing interests.