Definition and classification of fracture non-unions.

Classifications in general provide relevant information for clinical purposes to compose a suitable treatment strategy and for research purposes to be able to define comparable study groups. Two distinct types of non-unions are described in the established literature. In the first type the ends of the fragments are hypervascutar or hypertrophic and are capable of biologic reaction. In the second type the ends of the fragments are avascular or atrophic and are inert and incapable of biologic reaction. Hypervascular as well as avascular non-unions may be complicated by the presence of infection, poor soft-tissue quality, short peri-articular fragments or significant deformity, demanding mu[ti-stage treatment strategies with concomitant worsened prognosis and subsequent increased frequency of amputation.