FRACTOGRAPHIC INVESTIGATION OF FAILURES IN 316L STAINLESS STEEL ORTHOPEDIC CONDYLAR BLADE

In this paper, premature fracture of two condylar blade plates that failed inside the thigh of two separate patients is investigated. Condylar blade plates made of 316L austenitic stainless steel are widely used for internal fixation and repair of femoral fractures in orthopedic surgery. Fracture of such plates could have serious consequences such as the need for repeated surgery, extra unwanted complications and extension of the healing period. In addition to selecting the proper plate for fixation, the fixation technique has significant influence on the forces applied to the plate and affects the healing process. The failure investigation mainly included chemical analysis, metallography, hardness testing, as well as macroscopic and microscopic fractographic observations using stereomicroscope and scanning electron microscope, respectively. Based on the results of fractographic studies, fatigue fracture mechanism was identified as the primary cause of failure. Fatigue crack initiation was found to take place at relatively sharp corners around the designed central holes on the condylar blade plates, which acted as stress raisers on the reduced cross sections. Since prior to healing, the loads are primarily transferred through the plates, proper post-operative immobilization can be effective in preventing fatigue failure of the plates