Objective: To understand the potential fracture mechanism of sternal wires, we collected extracted stainless steel sternal wires from patients with sternal dehiscence following open-heart operations. Surface alterations and fractured ends of sternal wires were inspected and analyzed.
Methods: Eight fractured and 12 non-fractured wires extracted from five patients (closure method: figure-of-eight or straight twisted; two without and three with mediastinitis) with mean implantation interval of 13.2+/-4.2 days (range 8-20 days) were studied by various techniques. The extracted wires were cleaned and the fibrotic tissues were removed. Irregularities and fractured ends were assayed by scanning electron microscopy and energy dispersive X-ray analysis (EDXA).
Results: All examined fractured wires showed the presence of severe transversal cracks and crevice corrosion. EDAX revealed aluminum oxide inclusion on the fractured surface.
Conclusions: The synergic effect of stress and poor wire quality could be the precursors of material failure for the sternal wire.