Does a childhood fracture predict low bone mass in young adulthood? - A 27-year prospective controlled study.

BACKGROUND:
A fracture in childhood is associated with low bone mineral density (BMD), but it is debated whether a fracture at growth also predicts low BMD in young adulthood. PURPOSE: To gender-specifically evaluate whether children with a fracture are at increased risk of low BMD in young adulthood.

METHODS:
Distal forearm BMD (g/cm(2) ) was measured with single photon absorptiometry (SPA) in 47 boys and 26 girls (mean age 10 years, range 3-16) with an index fracture and in 41 boys and 43 girls (mean age 10 years, range 4-16) with no fracture. BMD was re-measured mean 27 years later with the same SPA apparatus and with dual energy absorptiometry (DXA), quantitative ultrasound (QUS) and peripheral computed tomography (pQCT). Individual Z-scores were calculated using the control cohort as reference population. Data are presented as means with 95% confidence intervals (95% CI) within brackets and correlation with Pearson's correlation coefficient

RESULTS:
Boys with an index fracture had at fracture event a distal forearm BMD Z-score of -0.4 (-0.7, -0.1) and at follow-up -0.4 (-0.7, -0.1). Corresponding values in girls were -0.2 (-0.5, 0.1) and -0.3 (-0.7, 0.1). The deficit in absolute bone mass was driven by men with index fractures in childhood due to low rather than moderate or high energy. There were no changes in BMD Z-score during the follow-up period. The BMD deficit at follow-up was in boys with an index fracture verified with all advocated techniques

CONCLUSIONS:
A childhood fracture in men was associated with low BMD and smaller bone size in young adulthood while the deficit in women did not reach statistical significance. © 2012 American Society for Bone and Mineral Research.