Tolerance to steering wheel-induced lower abdominal injury.

Anesthetized swine were tested for biomechanical and injury responses to lower abdominal steering wheel loading. The lower abdomens of 25 subjects were impacted with a segmented steering wheel. Tests included a wide spectrum of velocities, from 1.7 to 12.4 m/s, and forced abdominal compressions of 7.0%-54.5% of the vertical thickness of the lower abdomen. Lower abdominal injuries included contusions and lacerations of varying severity and frequency in the mesentery, the small and large bowel, the spleen, and the cecum. Logistic regression correlations were performed to assess the probability of severe and greater injury with biomechanical indices such as peak velocity of deformation (Vmax), peak compression (Cmax), peak total force (Fmax), the maximum Viscous criterion (VCmax), and the product of maximum total force and maximum compression (FmaxCmax). Although Cmax, Fmax, and, to a lesser extent, FmaxCmax correlated reasonably well with the probability of severe and greater injury, the maximum Viscous criterion (VCmax) was the best correlate, establishing VCmax as the most effective predictor of an AIS greater than or equal to 4 injury risk for steering wheel loading to the lower abdomen.