Injury Risk Functions for the 5 ^th Percentile Female Upper Extremity

The widespread implementation of air bags has increased the incidence of upper extremity injuries in the automotive crash environment. The first step in reducing these injuries is to determine applicable upper extremity injury criteria. The purpose of this paper is to develop injury risk functions for the fifth percentile female forearm, humerus, wrist, and elbow. Injury tolerance data for each anatomical region were gathered from experiments with controlled impact loading of disarticulated small female cadaver upper extremities. This technique allowed for the applied load to be directly quantified. All data were mass scaled to the fifth percentile female. In order to develop the risk functions, the logit distribution was integrated for the uncensored data, while logistic regression and generalized estimating equations statistical analysis techniques were used for censored data. The risk functions predict a 50% risk of injury at 128 Nm bending of the humerus, 58 Nm bending of the forearm, 1700 N axial loading of the wrist, and 1780 N axial loading of the elbow. A modified dummy upper extremity has been designed for the evaluation of frontal and side air bag interactions, and it is recommended that the injury criteria be implemented directly in the dummy upper extremity.