Vascular response in fractured limbs with and without immobilisation: an experimental study on rabbits.

An experimental study was carried out on 24 rabbits in whom a fracture of the tibia was treated without plaster (group 1) and 24 rabbits in whom a plaster was applied to immobilise the fracture (group 2). The rabbits from each group were killed at varying intervals and the limbs were perfused with chromopaque so that the vascularity could be assessed by radiographs. After fracture the vascular response in limbs increased gradually from the third day, reached a peak by the end of the second week and thereafter declined gradually. The capillaries around the fracture site proliferated by the second week. When plaster was not used (group 1) dilatation of the main artery was followed by proliferation of the small and medium-sized vessels and capillaries which persisted until the tenth week. In group 2 (plaster) the vascular pattern returned to normal by the seventh week. Excess callus and delayed union was present in group 1 whereas early union with less callus formation occurred in group 2.