Factors behind Nontraumatic Leg Pain There are numerous causes of nontraumatic leg pain, and there is no single way of classifying all of these causes info . Treatment providers develop their own individual method of help choose a diagnosis. Sometimes it can benefit to classify the potential causes based upon the right area of the leg that hurts, if the pain is in a single leg or both, whether it is linked to activity or occurs at rest, and whether underlying medical conditions exist that may precipitate leg pain. Pain in only one leg would tend to be due to local problems and not necessarily because of a systemic disease. The presumption would be that such both legs will be affected by a sickness.