In this study the authors hypothesized that for frontal crashes, the driver was more likely to sustain foot injury than the front seated passenger and the right foot was more likely to be injured than the left because the driver's right foot was positioned in dorsiflexion and eversion during the crash and less able to tolerate crash forces. Seventeen Crash Injury Research and Engineering Network (CIREN) frontal crashes were studied to document the circumstances and resulting foot injuries. National Automotive Sampling System (NASS) data was sampled to determine frequencies of injury to foot side and occupant position. Biomechanically, matched pairs of cadaveric feet were tested in compression with one in dorsiflexion, and the other dorsiflexion and eversion. Results showed that drivers were more likely than passengers to sustain a foot or ankle injury and this was almost exclusively due to a higher frequency of right foot injuries in drivers. Braking, with significant toepan intrusion, was associated with an increase in both right and left foot injuries in drivers. Biomechanically, 9 of 15 pairs tested provided useable data. There was a significant decrease in load to failure between specimens forced into dorsiflexion and eversion (mean, 4107N, sd = 1630N) compared with dorsiflexion alone (mean, 6468N, sd = 2435N, p + 0.001). The majority (16 of 17) of foot injuries in the CIREN cases were to drivers of which 13 injured their right foot and ankle. An implication of this work is that if thresholds based on data from dorsiflexion and compression loading are used to predict foot and ankle injury in frontal crashes they may not represent that population of drivers who are braking at the time of the crash and could suffer injuries at forces lower than current threshold values. (Author/publisher)
Abstract