ESPE Abstracts

Background: The prevalence of vertebral fractures (VF) in Duchenne Muscular Dystrophy (DMD) is currently unknown as systematic spine imaging is rarely performed.

Objective: To determine the prevalence of VF in DMD and factors associated with VF.

Method: A prospective study utilising systematic screening with DXA vertebral fracture assessment (VFA) was performed in all 47 eligible boys. 6/47 were excluded due to spinal instrumentations and movement artefacts. Presence and grade of VF were determined by the Genant method by two independent observers and any disagreement resolved by consensus agreement with a third observer. Results expressed as median (range).

Results: Of 41 boys aged 9.9 years (5.0, 18.3), 37(90%) had been on glucocorticoid (GC) for 3.8 yrs (0.2, 13.4) and three were GC naïve. Eighteen (43.9%) boys were non-ambulant for 2.1 yrs (0.3, 6.5). Four boys were on testosterone, and nine on bisphosphonate. Height and BMI SDS were −1.5(−7.0, +2.3) and +2.0(−1.4, +4.0), respectively. Total body less head bone mineral content (BMC) SDS was −1.4(−4.3, +1.2) and lumbar spine (LS) bone mineral apparent density (BMAD) SDS was −0.8(−3.0, +0.9). Bone turnover was low with bone alkaline phosphatase and c-terminal telopeptide SDS of −1.5(−2.8, −0.3) and −2.0(−3.3, +0.1), respectively. 10/41 boys (24.3%) had non-VF only. A total of 8/41 (19.5%) had evidence of VF from DXA-VFA, including one boy with VF and non-VF. Of eight with VF, four(50%) had newly diagnosed VF identified from DXA-VFA. Of 43 VFs identified in the eight boys, 11 (26%), 21 (48%) and 11 (26%) were grade 1, 2 and 3, respectively. The distribution of VFs was bimodal with most occurring at T7 and T12. Back pain was only reported in 2/8 (25%) with VFs. There were no differences in mobility [P=0.70], 25-hydroxy-vitamin D (P=0.87) and LS-BMAD S.D.S. (P=0.73) in those with or without VF. Odds of VF increased by 1.5 times (95% CI:1.03 to 2.20, P=0.04) for every 1-year-increase in GC exposure after adjusting for GCdose, mobility, back pain and LS-BMAD SDS.

Conclusion: In this cohort of DMD boys with relatively short duration of GC exposure, VF was present in approximately 20%. Of those, half were identified only from screening DXA-VFA. DXA bone density was not discriminatory for VF. Our result provides the evidence-base for the recommendation of routine spine imaging for vertebral fractures in DMD in the new international DMD standards of care (2018).