Original Articles
Bone mineral density and body composition in boys with distal forearm fractures: A dual-energy x-ray absorptiometry study☆,☆☆

https://doi.org/10.1067/mpd.2001.116297Get rights and content

Abstract

Objective: To determine whether boys with distal forearm fractures differ from fracture-free control subjects in bone mineral density (BMD) or body composition. Study design: A case-control study of 100 patients with fractures (aged 3 to 19 years) and l00 age-matched fracture-free control subjects was conducted. Weight, height, and body mass index were measured anthropometrically. BMD values and body composition were determined by dual-energy x-ray absorptiometry. Results: More patients than control subjects (36 vs l4) were overweight (body mass index >85th percentile for age, P < .001). Patients had lower areal (aBMD) and volumetric (BMAD) bone mineral density values and lower bone mineral content but more fat and less lean tissue than fracture-free control subjects. The ratios (95% CIs) for all case patients/control subjects in age and weight-adjusted data were ultradistal radius aBMD 0.94 (0.91-0.97); 33% radius aBMD 0.96 (0.93-0.98) and BMAD 0.95 (0.91-0.99); spinal L2-4 BMD 0.92 (0.89-0.95) and BMAD 0.92 (0.89-0.94); femoral neck aBMD 0.95 (0.92-0.98) and BMAD 0.95 (0.91-0.98); total body aBMD 0.97 (0.96-0.99), fat mass 1.14 (1.04-1.24), lean mass 0.96 (0.93-0.99), and total body bone mineral content 0.94 (0.91-0.97). Conclusions: Our results support the view that low BMC, aBMD, and BMAD values and high adiposity are associated with increased risk of distal forearm fracture in boys. This is a concern, given the increasing levels of obesity in children today. (J Pediatr 2001;139:509-15)

Section snippets

Patients with fractures

In order to recruit l00 patients, we invited all boys aged 3 to 19 years with a Dunedin home address (n = 112) and distal forearm fractures (radius, ulna, or both) confirmed by x-ray films, who were discharged from our only hospital between March 1998 and May l999, to take part in our study. Children with these fractures are generally treated as outpatients, although some are admitted to hospital for manipulation of their bones under general anesthesia. All case patients received a light

Recruitment

We recruited 104 of 112 case patients with distal forearm fracture who were seen consecutively (92.9% participation). Non-white subjects (n = 4) were excluded because of difficulties in recruiting control subjects of the same ethnicity. We approached 110 fracture-free boys to act as control subjects and enrolled 102. Two were excluded because they were unsuitable age matches for their case patients.

General health and age of participants

The participants were generally in good health, and there were no significant group differences

Discussion

These findings suggest that low bone density, high BMI, and high adiposity each increase fracture risk, consistent with our recent observations in young girls.4 Our finding that aBMD is lower in case patients than control subjects is in agreement with a large body of work in adults11, 12 and supports the view that less dense bone fractures more readily than stronger bone. The lower aBMD values of boys with fractures are not explained by differences in bone size, because volumetric BMAD

Acknowledgements

We thank the staff of the Fracture Clinic of Dunedin Hospital and all participating children and their families for willing cooperation.

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    ☆

    Supported by Health Research Council of New Zealand.

    ☆☆

    Reprint requests: Ailsa Goulding, PhD, FACN, Department of Medicine, University of Otago, PO Box 913, Dunedin, New Zealand.

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