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Response and vulnerability of the ankle joint in simulated footwell intrusion experiments~A study with cadavers and dummies
Technical Paper
2001-06-0212
Sector:
Language:
English
Abstract
The prevention of lower extremity injuries to front seat car
occupants is a priority because of their potential to cause
long-term impairment and disability. To determine the types and
mechanisms of lower extremity injuries in frontal collisions,
studies under controlled test conditions are needed. Sled tests
using belt-restrained cadavers and dummies were conducted, in which
footwell intrusion was simulated via a plane surface or simulated
brake pedal. Human cadavers in the age range from 30 to 62 years
and Hybrid III dummies were used.
The footwell intrusion had both translational (135 mm) and
rotational (30 degrees) components. Maximum footwell intrusion
forces and accelerations were measured. The lower legs were
instrumented with accelerometers and a ""six
axis'' force-moment transducer was mounted in the mid shaft
of the left tibia. Maximum footwell intrusion forces between 7.4
and 20 kN and accelerations between 31 and 132 g were measured,
with the greater values corresponding to the dummy experiments. The
maximum axial forces in the tibia amounted to 3.4 - 4.9 kN and the
resultant maximum moments were between 61 and 450 Nm. The dummies
exhibited significantly higher values than the cadavers.
In the cadaver tests the ankle was dorsiflexed from a neutral
position by between 55 and 66 degrees due to the intrusion. The
forcing of the ankle joint beyond its normal maximum dorsiflexion
angle of approximately 20 degrees results in cartilage contusions,
shearing off of the talus and the tibia, fractures of the medial
and lateral malleoli, and laceration of the spring ligament. The
degree of injury severity depended upon the amount of dorsiflexion
and the age. The brake pedal simulation resulted in greater
dorsiflexion than the plate intrusion and thereby in a higher
injury severity.