DO CHILDREN WITH FRACTURES HAVE LOW BONE MINERAL DENSITY?

Abstract

To investigate whether children with fractures have a low bone mineral density, 109 children (46 female and 63 male) aged 10.5 ± 2.9 years (range 5–16) sustaining either a single fracture (n=60 patients) or multiple fractures (n=49 patients) had Bone Mineral Density measurements [BMD] (Hologic QDR4500A) of L2 to L4. The Z score {(Patient’s BMD – mean aged related BMD)/ standard deviation of that age group)} was calculated using two previously published data from Shropshire children and American children. A z score of zero indicates that the patients’ BMD is exactly on the mean. The proportion above and below zero and was compared using the binomial theorem. Comparison of frequencies between the groups was undertaken using the Chi 2 test.

In a scatter plot of z score against age, low z scores were frequent in girls under 8yrs using both reference data. In this group BMD z score was more likely to be below zero (p< 0.05). A low z score was more frequent in boys less than 8 years using American reference data but not Shropshire data. Girls and boys above 8 years did not show any evidence of low BMD. There was no difference in the frequency of low BMD in patients with multiple compared with single fracture.

Girls and possibly boys below 8 years who have sustained a fracture show evidence of low BMD. Boys at any age and girls over 8 years did not show any evidence of having low bone density. Further work is needed to establish whether this risk continues into later life. Multiple fractures do not appear to confer additional risk of low bone density.