The main objective of this study is to determine the damage tolerance, and to describe the damage mechanisms of extended human knee when it is exposed to lateral impact loads in pedestrian accidents, particularly those that occur at high velocity. An experimental method for assessing the damage tolerance of the knee region to loads acting at the extended lower extremity was developed. In-vitro experiments with human subjects were conducted where only the purest possible shearing deformation or the purest possible bending deformation affected the knee region at the time. Ten experiments at a velocity level of 40 km/h were performed in a shearing and a bending design, respectively. The peak values of the shearing force and the bending moment related to the damage of knee ligaments and bone fractures were calculated at knee joint level. Damages were assessed by dissecting the lower extremity. In general, if the extremity was exposed to dynamic loads from high velocity impact, the main damage types are fractures. When the knee joint was exposed to the purest possible shearing deformation, the most common initial damage mechanism was due to the combination of shearing and bending deformation of the knee, which resulted in articular fractures and, related to them, ligament damage (40% of cases). (A)
Abstract