Characterization of Knee-Thigh-Hip Response in Frontal Impacts Using Biomechanical Testing and Computational Simulations by ProQuest

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                                  Stapp Car Crash Journal, Vol. 52 (November 2008), pp. 421-474
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                                            Copyright © 2008 The Stapp Association
                                                                                                                   2008-22-0017


     Characterization of Knee-Thigh-Hip Response in Frontal Impacts Using
            Biomechanical Testing and Computational Simulations
            Jonathan D. Rupp, Carl S. Miller, Matthew P. Reed, Nathaniel H. Madura, and
                                       Kathleen D. Klinich
                                  University of Michigan Transportation Research Institute

                                                  Lawrence W. Schneider
      The University of Michigan Transportation Research Institute and Department of Biomedical Engineering

                                          __________________________________

ABSTRACT – Development and validation of crash test dummies and computational models that are capable of predicting the
risk of injury to all parts of the knee-thigh-hip (KTH) complex in frontal impact requires knowledge of the force transmitted from
the knee to the hip under knee impact loading. To provide this information, the knee impact responses of whole and segmented
cadavers were measured over a wide range of knee loading conditions. These data were used to develop and help validate a
computational model, which was used to estimate force transmitted to the cadaver hip.

Approximately 250 tests were conducted using five unembalmed midsize male cadavers. In these tests, the knees were
symmetrically impacted with a 255-kg padded impactor using three combinations of knee-impactor padding and velocity that
spanned the range of knee loading conditions produced in FMVSS 208 and NCAP tests. Each subject was tested in four
conditions. Following test of whole seated cadavers, the subjects were impacted after the connection between the thigh flesh and
pelvis was cut, after the thigh flesh was removed, and after the torso was removed. Applied force and femur and pelvis
acceleration data from these tests and results of other studies were used with data on static body segment masses to develop and
validate a one-dimensional lumped-parameter model of the body. Simulation of the whole body cadaver tests performed with
this model predict that approximately 54% of the peak force applied to the knee was transmitted to the hip for all three impact
velocities.

Additional simulations with the model in which knee impact conditions were varied over a wider range of loading conditions
indicate that the percentage drop in force between the knee and the hip is relatively constant over the range of knee impact
conditions that are of interest for injury assessment. Simulation results also indicate that high-rate, short-duration knee loading
by a rigid surface is more likely to produce knee/distal femur fractures and less likely to produce hip fractures due to laxity in the
hip that delays recruitment of pelvis mass and the development of fracture-level forces at the hip until after the fracture tolerance
of the knee/femur has been exceeded.

KEYWORDS – Knee-Thigh-Hip, Knee Impact, Impact Response, Biomechanics, Injury, Hip Injury.
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INTRODUCTION                                                            per year, are to the hip/pelvis, 9,000 are to the thigh,
                                                                        and 6,000 are to the knees. The relatively high
The lower extremities are the body region that is
                                                                        frequency of hip/pelvis injuries is of particular
most likely to experience AIS 2+ injury (Kuppa et al.
                                                                        concern to clinicians and automotive safety engineers
2001). Based on an analysis of frontal crashes in
                                                                        because hip injuries are generally more difficult to
NASS (1995-2000), Rupp et al. (2002) estimated that
                                                                        treat than injuries to either the knee or thigh.
about half of all lower-extremity injuries are to the
                                                                        Furthermore, hip injuries can result in life-long
knee-thigh-hip     (KTH)     complex      and    that
                                                                        mobility impairment (Burgess et al. 1995, Read et al.
approximately 30,000 KTH injuries occur each year.
                                                                        2002, Kuppa and Fessahie 2003, Sochor et al. 2003,
Of these KTH injuries, approximately half, or 14,000
                                                                        Read et al. 2004, Sochor and Rupp 2005), and have
                                                                        significant adverse psychosocial consequences, such
      Address correspondence to Jonathan Rupp, UMTRI, 2901
 Baxter Rd. Ann Arbor, MI 48109-2150. E-mail: jrupp@umich.edu           as depression and loss of mental acuity resulting from




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422                           Rupp et al. / Stapp Car Crash Journal 52 (November 2008) 421-474



impaired mobility (Read et al. 2004, Scarboro et al.            that approximate the range of those produced in
2005).                                                          FMVSS 208 and NCAP.                Femur and pelvis
                                                                accelerations and angular velocities of the torso and
Results of tests conducted at UMTRI (Rupp et al.                pelvis were measured. The masses of th
								
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