IN A FINDING WITH BROAD SAFETY RAMIFICATIONS,
STUDY SAYS INFANTS' SKULLS ARE ONLY A FRACTION AS STRONG AS
ADULTS'
PHILADELPHIA - Scientists at the University of Pennsylvania
have demonstrated that an infant's skull is only a fraction
as strong as that of an adult, a finding that could greatly
enhance the safety of young children. The results, published
in the most recent issue of the Journal of Biomechanical Engineering,
indicate that at birth a child's skull has just one-eighth
the strength of an adult skull. These results are also reported
in the New York Times Science Section.
The study also found that infants' skulls can undergo six-fold
larger deformations before fracture, making blows to infants'
malleable skulls far more likely to intrude into the cranial
cavity - although its authors caution that it's not clear
whether the larger deformations necessarily result in more
severe brain injuries.
"While it's long been suspected that infants' skulls
are not only thin but also made of bone less sturdy than that
in adults' skulls, this work is the first rigorous examination
of the issue," said lead author Susan S. Margulies, Ph.D.,
an associate professor of bioengineering at Penn. "Despite
this evidence confirming the fragility of children's skulls,
researchers' understanding of the actual mechanisms of pediatric
head injury remains very limited."
Safety experts say the work should help make a variety of
products and environments safer - from children's bicycle
helmets and car seats to the surfaces upon which playgrounds
are built.
"Certainly any further information on the mechanical
properties of infant skulls will help us set standards and
modify standards as appropriate," said Walter Henderson,
a member of the public playground equipment committee of the
American Society for Testing and Materials, which sets safety
standards for products worldwide. "Very little is known
about infants' skulls, and a better body of knowledge will
help us enact better standards."
Mr. Henderson, of Henderson Consulting Services in Mechanicsburg,
Pa., said Dr. Margulies's work will likely play a role as
the ASTM reviews its playground safety standards for children
younger than 2.
A child's skull is incompletely fused at birth, and the Penn
researchers have also found that the sutures joining the skull's
bony plates have less than half the strength of the bone,
allowing the skull to deform and distort the infant brain
beneath. The skull and sutures reach adult thickness and strength
only during early adolescence.
"Unlike adults, children who suffer head injuries usually
can't reliably relay to us how their injuries happened,"
Dr. Margulies said. "To help prevent serious head injuries
among children, we'd like to know the mechanisms by which
these injuries occur, and we'd like to better understand the
mechanical properties of children's skulls."
Kirk L. Thibault, Ph.D., a former graduate student at Penn,
joined Dr. Margulies in the research. Their work was supported
by the Center for Injury Research and Prevention at the Centers
for Disease Control.
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