Closed intramedullary nailing complicated by breakage of plastic medullary tube

Abstract

Vascular complications associated with the use of any transfixing external fixator are usually attributed to improper pin insertion technique and imprecise familiarity with cross-sectional anatomy. In the case of the Ilizarov fixator these include perforation of artery, vein, or both (Behrens, 1989; Paley, 1990, 1991a). Transfixion pin configurations utilized by ring fixators predispose to vascular injury as the pins cannot pass through completely ‘safe corridors’ while maintaining optimal stability (Behrens, 1989). In the thigh, efforts to avoid damage to major neurovascular structures by using half-pins instead of transfixing pins, have led to the development of a ‘hybrid’ configuration. This combines the axially stiffer fixation of the Hoffman-type system proximally with the elasticity of the Ilizarov radial fixator distally. The unique biomechanical property of the Ilizarov fixator permits intermittent closure of the fracture gap. This takes place through a predominantly axial telescopic motion on loading, and is due to the large deflection of the thin wires (Chao and Aro, 1989). In the hybrid configuration, cyclic loading at the fracture gap is attributable mainly to motion of the distal construct because the proximal element is relatively rigid (Paley, 199Ib). Although a late presentation of asymptomatic arterial damage at the time of wire insertion cannot be excluded, in our patient late vascular erosion should be considered. This has previously been ascribed to pulsation of an artery against an adjacent wire (Paley, 1990, 1991b). We further propose that the axial micromovement of a transfixion wire against an arterial wall may be an aggravating factor in progressive arterial erosion leading to late pseudoaneurysm formation.