Injuries to the kidney vary from mild contusions to complete maceration of the entire renal mass. The majority occur in men, owing not only to greater exposure and more strenuous physical activity but also to the more inflexible muscular fixation of the kidney.
Injuries to the kidney are divided into open, or penetrating, and closed, or nonpenetrating, wounds. During peacetime the majority of renal injuries are of the closed type, occurring in civilians and resulting from traffic and industrial accidents and not infrequently from vigorous athletic activity, particularly football. Usually these injuries are slight, causing some pain and hematuria and requiring only expectant treatment. In wartime the incidence of penetrating wounds increases, and these are mainly gunshot injuries, due either to rifle bullets or to shrapnel. Apparently the location and protective covering of the kidneys prevent them from being injured by other types of war wounds, such as air and