Abnormal healing of fractures has been divided into three groups: delayed healing, reactive and non-reactive pseudoarthrosis. There are many transitions between these. Routine radiography can only classify these after their morphological appearance. Angiography is able to provide information regarding the vitality of major and minor fragments according to the type of para- and interfragment vascularisation; in some cases there may also be some neovascularity. The potential for union depends directly on the vascularisation of the surrounding muscles, of the subcutaneous tissues and of the skin. Vascular changes result in the formation of an autonomous circulation, independent dynamically of the vessels in the extremity and which can guarantee an increased saturation during healing by new bone formation. Angiography can provide an estimate of the likelihood of union and thereby provide a prognosis; it can also help to predict the fate of autotransplants and the strength of surgically reconstructed bone, since inadequate circulation may result in devitalisation of fragments.