[Fracture of the first rib due to a trivial accident]

A patient is presented with an isolated fracture of the first rib due to a fall from a bicycle. Although fractures of the first rib are often the result of high impact injury, these fractures may occur after trivial accidents and in several kinds of sports. The mechanism of fractures of the anterior rib in this typical localization is elucidated. The reason why serious neurovascular lesions are frequently seen in displaced posterior rib fractures caused by high impact injury is discussed.