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Response of the Knee Joint in Lateral Impact: Effect of Bending Moment
Technical Paper
1993-13-0007
Published September 08, 1993 by International Research Council on Biokinetics of Impact in Switzerland
Sector:
Language:
English
Abstract
During the 80's a new type of crash impact dummy, the
rotationally symmetrical pedestrian dummy (RSPD), suitable for the
assessment of car front aggressiveness in pedestrian impacts was
developed. This dummy enables measurement of biomechanical
parameters, such as forces and moments at the knee joint level
related to the injury mechanisms. To determine the resistance of
the human knee to shear force or bending moment and to describe the
injury mechanisms, it was necessary to make separate in-vitro
experiments with human cadaver specimens, where only one of those
two parameters affects the biological material at the time.
In the present study an experimental method for assessing the
tolerance to bending moment in the lateral direction of the
extended knee joint has been developed. The load response of the
lower extremity was measured by means of force transducers. The
bending moment transferred through the entire knee joint was
calculated and the motion of the specimen was registered by high
speed photography. The bending moment in the lateral direction at
the first sign of damage of the entire extended knee joint was
determined. Damages were assessed by measuring the knee joint
condition (valgus-varus and anterior drawer increment) and by
dissecting the knee region. Seventeen tests were carried out under
dynamic conditions, seven at a velocity of 16 km/h and ten at 20
km/h on human cadaver lower extremities.
The first and most common damage type to entire knee joint in
this loading configuration was stretching and rupture or avulsion
of the medial collateral ligament (MCL). These damages are
generated by dentical mechanisms i.e. tensional forces acting on
the medial knee structures. The mean peak moment correlated with
this damage mechanism was 101 (±21) Nm for an impact velocity of
16 km/h, and 123 (±35) Nm for an impact velocity of 20 km/h. The
mechanisms led to damage of the knee joint when the lower extremity
was bent approximately 10 degrees in the lateral direction at the
knee joint