Study objective. To investigate the degree and determinants of osteopenia in juvenile chronic polyarthritis.Design. Retrospective case-control study of central bone mineral density.Setting. Rheumatism Foundation Hospital and Kuopio University Hospital, Finland.Subjects. A sample of 43 girls aged 7 to 19 with juvenile chronic polyarthritis treated with systemic glucocorticoids and a control sample of 44 healthy girls matched for age.Main outcome measures. Bone mineral density and bone size (width) measured by dual-energy x-ray absorptiometry and bone volumetric density calculated as an approximation of true bone density at both the lumbar spine and femoral neck.Results. The girls with juvenile chronic arthritis had reduced bone mineral density, bone size, and bone volumetric density at both the lumbar spine and femoral neck (statistically significant findings, P = .022 for the bone size of the femoral neck and P .001 for the other parameters). At the spine, the mean bone mineral density was 80%, the mean bone size 89%, and the mean bone volumetric density 89% of the values in the control group. At the femoral neck, the values were 78%, 93%, and 83%, respectively. The groups were matched for age, but the girls with arthritis were smaller and lighter. In the juvenile arthritis group, the femoral bone mineral density and bone volumetric density and the spinal bone width correlated negatively with the mean glucocorticoid dose.Conclusion. Axial bone mineral density is clearly reduced in severe juvenile polyarthritis and is mediated by both decreased bone volumetric density and diminished growth.
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