Background. Children with rheumatic diseases are at high risk for osteoporosis both from disease and corticosteroid treatment. Different methods to evaluate osteoporosis are available; all utilize ionizing radiation. U/S has been used in adults. Portability, ease, lower cost and the absence of radiation make it attractive for children.

Objectives. 1) To determine the feasibility of U/S in corticosteroid treated children with rheumatic diseases. 2) To compare U/S results to bone mineral density (BMD) measured by DEXA.

Patients/Methods. In this pilot study, we examined 13 children(10 girls) aged 6 to 18 years. Eight had juvenile dermatomyositis, 3 juvenile rheumatoid arthritis, 1 cerebral vasculitis and 1 Wegener's granulomatosus. All had initially been treated with prednisone, 2 mg/kg/day, and were on tapering schedules. Nine subjects were taking supplemental calcium and vitamin D. We measured lumbar spine (L2-L4) and total body BMD using DEXA and os calcis elasticity and density (broad band ultrasound attenuation (BUA), speed of sound (SOS) and calculated bone stiffness) using U/S (Achilles densitometer). A single expert technician performed these studies concurrently.

Results. U/S was well tolerated and well accepted. U/S took less time (5 to 10 minutes) to complete than DEXA (20 to 30 minutes). BUA was highly correlated with total body BMD (rs=0.739, p < 0.002), SOS did not correlate as well (rs=0.199, p = NS). Both BMD and U/S measures were highly correlated with age. Age correction did not change the relationship between BUA and BMD.

Conclusion. We found U/S to be a feasible and well tolerated procedure. U/S was closely related to DEXA BMD; further studies of U/S sensitivity to clinically significant BMD changes in corticosteroid treated children are essential.