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Childhood Fracture History Tied To Low BMD, Osteoporosis Later


 

NASHVILLE, TENN. — A history of fracture in childhood and adolescence may be a marker for osteoporosis later in life, suggest study findings presented at the annual meeting of the American Society for Bone and Mineral Research.

Girls with fractures have lower gains in bone mineral density (BMD) and lower bone mineral mass at pubertal maturity, especially at sites containing predominantly trabecular bone, said Dr. Serge L. Ferrari, professor of medicine at the Service of Bone Diseases at the Geneva University Hospital.

The researchers followed 125 girls from prepuberty to pubertal maturity, assessing BMD using dual x-ray absorptiometry at both fractured and nonfractured sites including the ultradistal radius, proximal radius, femur trochanter, lumbar spine, femur neck, and femur diaphysis. Questionnaires were used to assess calcium intake, and both children and parents were interviewed to monitor for any accidents, falls, or fractures.

During an average of 8.5 years follow-up, 59 fractures occurred in 42 girls, 48% of the fractures involved the forearm and/or the wrist.

Before puberty and at the age of peak height velocity, BMD values at the proximal radius tended to be lower in girls with fractures. At pubertal maturity, BMD in girls with fractures was significantly lower at the ultradistal radius, femur trochanter, and lumbar spine. BMD at the femur neck and femur diaphysis were not significantly different between the two groups at pubertal maturity.

Girls with fractures also had significantly less BMD gain throughout puberty at the lumbar spine (−8%) and ultradistal radius (−12%), compared with those without a history of fracture. This trend almost reached significance at the femur trochanter and the proximal radius.

Using Cox proportional hazard models, the researchers identified four factors that were significantly associated with decreased hazard ratios for fractures: radial diaphysis BMD at baseline and BMD gain (over puberty) at the ultradistal radius, lumbar spine, or femur trochanter.

BMD measurements at all sites were highly correlated between baseline and pubertal maturity. There were also within-trait correlations between mature daughters and their mothers, yielding heritability estimates of 80%–90% for the hip, spine, and proximal radius. This suggests a strong genetic component for BMD.

Fractures are common in childhood and adolescence, with one in three girls and one in two boys having a traumatic fracture as they grow. Three-quarters of these fractures are in the upper limbs.

Studies have suggested there is underlying fragility involved in traumatic fractures of childhood and adolescence. The peak incidence of traumatic fractures coincides with the age of peak height velocity, the age at which longitudinal growth is fastest. And the age of peak height velocity precedes the age of peak bone mass velocity, when most bone mass is acquired, by about 1 year. The hypothesis follows that bone fragility at peak height velocity results from a transient deficit in bone mineral accrual relative to bone size.

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