Prediction of injuries to the heart and thoracic aorta in unrestrained drivers.

The purpose of the study was to investigate factors predicting injuries to the heart and/or thoracic aorta (H/TA) of unrestrained drivers in frontal motor vehicle collisions. We retrospectively analyzed findings of forensic autopsies of 37 unrestrained drivers of automobiles without airbags involved in frontal collisions. Mechanisms of injury, injury severity, presence of major injuries, and the number of fractured ribs were examined in each case. Victims were subdivided for comparison into those with (19 cases) and without (18 cases) H/TA injuries. The injury severity score and the abbreviated injury scale of the chest were significantly higher in persons with H/TA injuries (65.3+/-15.7 and 5.4+/-0.9) than in persons without (31.6+/-22.0 and 1.8+/-1.9). Because univariate analysis showed that the presence of multiple fractured ribs was an important predictor of H/TA injuries, we examined the relation between H/TA injuries and the number of fractured ribs. Copas's nonparametric smooth binary regression model showed that H/TA injuries were more likely in persons with eight or more fractured ribs. The presence of eight or more fractured ribs predicts H/TA injuries in unrestrained drivers.