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Mandatory
motorcycle
helmet-use
legislation
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is supported by the high morbidity of
motorcycle trauma and its cost to
society. Opponents argue, however,
that the majority of motorcycle trauma
morbidity and costs are the result of
injuries to body regions other than
the head. Previous data do not address
this argument because they fail to
control for differences in non-head
injury severity (i.e., kinetic impact)
between helmeted and unhelmeted
patients. This study investigates the
impact of helmet use on the morbidity
and cost of motorcycle trauma, after
controlling for non-head
injuries. |
| A
retrospective review of all patients
admitted to Harborview Medical Center
with motorcycle trauma from 1/1/85 to
1/1/90 was performed. Non-head injury
severity was determined by calculating
an ISS that did not include head
injury. This non-head ISS was used to
control for injury severity below the
neck. Four hundred twenty-five
patients were identified. Stratified
analysis showed that helmet use
decreased the need for and duration of
mechanical ventilation, the length of
ICU stay, the need for rehabilitation,
and prevented head injury. Costs of
acute care were significantly less in
helmeted patients. Regression
analysis, controlling for age, gender,
and blood alcohol level (as well as
non-head injury severity), confirmed
that acute costs were 40% less with
helmet use. |
| The
most frequently sustained severe
injuries in motorcycle crashes are
injuries to the head, and many of
these are caused by rotational force.
Rotational force is most commonly the
result of oblique impacts to the head.
Good testing methods for evaluating
the effects of such impacts are
currently lacking. There is also a
need for improving our understanding
of the effects of oblique impacts on
the human head. Helmet standards
currently in use today do not measure
rotational effects in test dummy
heads. However rotational force to the
head results in large shear strains
arising in the brain, which has been
proposed as a cause of traumatic brain
injuries like diffuse axonal injuries
(DAI).
An
investigation was performed on a
number of well-defined impacts,
simulated using a detailed finite
element (FE) model of the human head,
an FE model of the Hybrid III dummy
head and an FE model of a helmet. The
same simulations were performed on
both the FE human head model and the
FE Hybrid III head model, both fitted
with helmets. Simulations on both
these heads were performed to describe
the relationship between load levels
in the FE Hybrid III head model and
strains in the brain tissue in the FE
human head model. In this study, the
change in rotational velocity and the
head injury criterion (HIC) value were
chosen as appropriate measurements. It
was concluded that both rotational and
translational effects are important
when predicting the strain levels in
the human brain.
The
Motorcycle Helmet information provided is for
educational information only and is not legal
advice.
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