ESPE Abstracts

Objective and hypotheses: A retrospective review of bone morbidity in a contemporary cohort of boys with Duchenne muscular dystrophy (DMD) managed in a Scottish tertiary neuromuscular centre.

Method: Clinical details and results of bone surveillance were obtained in 47 boys, aged 9 years (2–16). DXA bone mineral content (BMC) at total body (TB) and lumbar spine (LS) were adjusted for bone area. Fractures were classified based on radiological confirmation. Results are in median (range).

Results: 39/47(82%) were on steroid therapy and 26/47 (55%) were ambulant. All were treated with vitamin D (800–1000 units/day). Of 35 who had vitamin D measured, 5 (14%) had a level<25 nmol/l. 5/10 (50%) of those >14 years had delayed puberty and had testosterone therapy. 12 (26%) sustained a total of 15 symptomatic fracture events. 12/15 (80%) were appendicular fractures (AF) and 3/15 (20%) were vertebral fractures (VF). AF occurred at a median age of 6 years (2.5, 14). The fracture distributions were 7 (58%) tibia/fibula, 3 (25%) femur and 2 (17%) humerus/radius/ulna. Mechanisms of injuries were 11 (92%) minor fall and 1 (8%) occurred while being lifted. Median length of steroid exposure was 4 years (0, 10). 7/9 (75%) were ambulant prior to fracture. 2/7 (29%) lost ambulation after fracture. 3/12 (21%) of AF occurred in steroid naïve ambulant boys <3 years. DXA and vitamin D level within 1 year of AF showed TB BMC SDS 0.1(−0.8, 1.0) and LS BMC SDS −0.2 (−1.2, 1.0). Vitamin D level was <25 nmol/l in 2/10 (20%). VF occurred at a median age of 11 years (9, 13). 2/3 were ambulant. Median length of steroid exposure was 6 years (5, 8). DXA within 1 year of VF showed TB BMC SDS 0.3 (−0.2, 1.1) and LS BMC SDS −0.1 (−0.6, 0.8). None had vitamin D<25 nmol/l.

Conclusion: Symptomatic VF occur in older children, with longer duration of steroid therapy. AF occur in younger boys and can also present in very young, ambulant, steroid naïve boys. Coincidental severe vitamin D deficiency or reduced BMC were not common findings at a fracture event.