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Injuries to motorcyclists lead to permanent disability more often than injuries to car occupants (10 percent versus 6 percent). The use of helmets has decreased the risk of head injuries. Other injuries leading to permanent disability are currently concentrated on the extremities (about 70 percent). Almost all are due to fractures located in joints where knees, elbows, shoulders, and ankles are the modest common spots. In a study based on 200 motorcycle accidents, it was shown the existing protective clothing had no effect on the incidence of fractures to knees, elbows, and shoulders. Based on that knowledge, a new motorcycle suit was constructed. The main goal was to find a shock-absorbing material to protect knees, elbows, and shoulders in an accident. Confor Foam, a medium-density urethane foam, was tested and found to possess relevant characteristics.

The compatibility problems of the mini car in car-to-car frontal collision and car-pedestrian accident are discussed using accident data and computer simulations. In our analysis of the accident data in Japan, the number of fatalities was investigated using the vehicle masses and classes. It was found that the cars with identical mass are most compatible since the injuries per accident are minimal and injury risks to the driver in both cars are the same. The analysis of the car class indicated that the mini car and the sports utility vehicle are the most incompatible car types, with low and high aggressivity, respectively. Our accident analysis in the present study shows that the safety of mini cars is the key point in achieving the compatibility in Japan. Computer simulations using MADYMO were carried out of crashes of mini car into a rigid wall and into a large car.

Twelve volunteers participated in the experiment under the supervision of Tsukuba University Ethics Committee. The subjects sat on a seat mounted on a newly developed sled that simulated actual car impact acceleration. We selected impact speeds (4, 6 and 8 km/h), seat stiffness, neck muscle tension, and alignment of the cervical spine for the parameter study of the head-neck-torso kinematics and cervical spine responses. The effects of those parameters were studies without headrest. The muscle activity was measured with surface electromyography. The cervical vertebrae motion was recorded by cineradiography (90 frames/s X-ray) and analyzed to quantify the rotation and translation of cervical vertebrae at impact. Furthermore, the motion patterns of cervical vertebrae in the crash motion and in the normal motion were compared. Subject's muscles in the relaxed state did not affect the head-neck-torso kinematics upon rear-end impact.