Regional changes in bone area and bone mineral content in boys with duchenne muscular dystrophy receiving corticosteroid therapy.

ABSTRACT

OBJECTIVE: To examine the functional and skeletal effects of 30 months of steroid treatment in boys with Duchenne muscular dystrophy. STUDY DESIGN: Lumbar spine (L(2)L(4)) and subcranial dual energy X-ray absorptiometry scanning was performed on 25 boys (mean age 7.4 years) at baseline and after 30 months of steroid treatment. RESULTS: At baseline, L(2)L(4) bone mineral content (BMC) was significantly low for projected bone area although appropriate for reduced lean body mass (LBM). Subcranial bone area for height and subcranial BMC for area and LBM were all significantly reduced. After 30 months of steroid therapy there was a significant increase in subcranial bone area for height but a significant reduction of subcranial BMC for area. At the lumbar spine there were no significant changes in bone area but small increases in L(2)L(4) BMC both for bone area and LBM. CONCLUSION: At baseline reduced mechanical load from diminished muscle function results in narrow light bones more noticeable in the subcranial region than the lumbar spine. Increases observed in subcranial bone area at 30 months suggest a gradual adaptation to increased gravitational load whereas at the spine there were no apparent detrimental effects on bone after 30 months of steroid therapy.