The paper describes the injury risk of the knee joint in traffic accidents. It focuses on vulnerable road users in car collisions. The situation for knee injuries has been influenced by the changing shapes of vehicles over the last decades. An analysis of real world accidents was carried out by ARU-MUH on the methodology of in-depth-investigation by GIDAS (German-In-Depth-Accident-Study). The data were collected based on the spot documentation in time after an accident event. Accident documentations from 1985 to 2003 are used for this study. In order to determine the influences for the knee injury pattern, two different groups of accident data were compared: years 1985 to 1993, and 1995 to 2003. The vulnerable road users were distinguished as pedestrians, motorcyclists and bicyclists. Only those accidents were selected that involved cars (vans included).
It was found that the highest frequency of knee joint injuries can be established for motorized twowheelers, i.e. 42% of motorcyclists suffered knee injuries in accidents 1985-1993 compared to 36% in 1995-2003. The lowest frequency can be established for pedestrians, where 22% were injured at the knee in the course of accidents in 1995-2003. The study describes the frequencies of knee injuries in total (soft tissue lesions, ligament tears and fractures) as well as for the different bony and ligamental parts of the knee joint (condyle, patella and tibia) found between 0.5 to 2.6% in the accident sample as a representative value for different kinds of vulnerable road users. The accident severity conditions under which such injuries happened are shown, along with a causation/mechanisms analysis. In case of a serious injury (AIS 2/3) for pedestrians, fractures of tibia head can often be observed (50.8 %), for motorcyclists, tendon ruptures and ruptures of anterior cruciate ligament are very frequent (36.7% / 20.9%). The study shows that there is currently a low overall injury risk for the knee of vulnerable road users in car collisions. Therefore the findings are significant regarding the widespread opinion on risk in literature. The long-term documentation of real world accidents within GIDAS pointed out that the developments in car front shape designing are responsible for the significant reduction of knee injury risk during the last decades.