Dummy measurement of chest injuries induced by two-point shoulder belts

The University of Miami's William Lehman Injury Research Center at the Jackson Memorial Medical Center conducts interdisciplinary investigations to study seriously injured restrained occupants in frontal automobile collisions. Engineering analysis of these crashes is conducted in conjunction with the National Crash Analysis Center at the George Washington University. The multidisciplinary research team includes expertise in crash investigation, crash reconstruction, computer graphics, biomechanics of injuries, crash data analysis, trauma care, and all of the medical specialties associated with the Ryder Trauma Center at Jackson Memorial Hospital. More than 350 injured occupants and their crashes have been studied in depth. The purpose of this paper is to report on an observed pattern of liver lacerations suffered by drivers wearing shoulder belts, without the lap belt fastened and to assess the ability of existing crash test dummies to measure the potential for these injuries. During the initial years of the study, 48 cases of drivers protected by shoulder belts but without the lap belt fastened met the criteria for the study. Fifty percent of these drivers suffered liver lacerations. Further study showed that 22 of the crashes involved damage to the right front of the vehicle. Among the drivers in vehicles with right front damage, 92% sustained injuries to the liver. This observation indicated that 2-point belts were most likely to produce liver injuries in low severity frontal collisions when the crash direction is 1 to 2 o'clock. An analysis of the National Accident Sampling System for the years 1988-95 indicated that liver injuries constitute about 0.5% of the injuries suffered by drivers who are in tow-away crashes. NASS data showed that the risk of chest injury is more likely among drivers with automatic shoulder belts than drivers with 3-point manual belts. The crash test dummies showed no difference in chest injury measures. Finite element computer modeling demonstrated that the high deflection of the right lower rib on the Hybrid III dummy predicts the liver injuries in the 1 o'clock crashes. These higher deflections were less apparent at the location of the center chest deflection measurement device on the Hybrid III.