Failure analysis in 316L stainless steel supracondylar blade plate

A 316L stainless steel blade plate implant used for fixation of a femoral fracture in a female patient failed catastrophically at four months of service. The failure examination included visual inspection, chemical analysis, metallography, hardness testing, as well as macroscopic observations using scanning electron microscope with EDS (energy-dispersive X-ray spectroscopy). The visual inspection and X-ray radiography images exhibited that there was heterogeneous bone callus formation and the fixation screws showed surface damage by fretting wear. On the other hand, SEM results showed evidence of fatigue based on the characteristics of the fracture surfaces. It was observed that the particular high curvature femur of the patient resulted in high tensile stress between bone and screws threads. It promoted rapid losing of primary fixation and subsequently generated a high stress concentration in the plate at cantilever which resulted in premature failure by fatigue.