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Correlation between neck injury risk and impact severity parameters in low-speed side collisions
Annette Kettler1, Kai Fruth, Erich Hartwig
1Institute for Orthopedic Research and Biomechanics, University of Ulm, Ulm, Germany. annette.kettler@medizin.uni-ulm.de
Study Design:
In vitro acceleration study on human cadaveric cervical spine specimens.
Objectives:
To investigate the correlation between the risk to sustain a structural cervical spine injury and vehicle-related impact severity parameters.
Summary Of Background Data:
Impact severity parameters, such as the peak acceleration of the vehicle, its mean acceleration, and its velocity change, are often used to predict the whiplash injury risk or to objectify the patient's symptoms even though their correlation to injury is still not well understood.
Methods:
In a series of three in vitro experiments, a total of 18 human cadaveric cervical spine specimens were subjected to incremental side accelerations until structural injury occurred. While the duration of the acceleration pulse was kept constant throughout all three experiments, its shape was varied: In Experiment I, the acceleration pulse had a fast increase up to the maximum value and a fast decrease down to zero (fast-fast). Experiment II was characterized by a slow increase and fast decrease (slow-fast), and Experiment III was characterized by a fast increase and a slow decrease (fast-slow).
Results:
The specimens of Experiment II (slow-fast) sustained structural injury at a significantly higher peak acceleration of the sled (4.6 g on average) than those of Experiments I (fast-fast) (2.6 g) and III (fast-slow) (3.1 g). In contrast, mean acceleration and velocity change of the injuring impacts were almost the same in all three experiments.
Conclusion:
The injury risk to the cervical spine was predictable by the mean acceleration of the sled and since the duration of the crash pulses was constant also by its velocity change but not by its peak acceleration.