Bone density in ambulatory and immobile children.

Lumbar spine bone density was measured by dual X-ray absorptiometry (DXA) in 20 healthy prepubertal children and 10 children who were immobile or less mobile. Immobility was caused by cerebral palsy in seven children and myelomeningocele in three. Areal bone density as measured by DXA was strongly related to the measures of body size. When bone measurements were corrected for bone volume, there was no difference in bone density between healthy control subjects and immobile children with neuromuscular disease an unexpected result.