Biomechanics
A 58-year-old man sustains a closed midshaft femur fracture treated with an intramedullary nail. At 4 months post-operatively, radiographs show fracture non-union with a transverse break through the nail at the fracture site. The patient reports progressively increasing thigh pain over the preceding 6 weeks with no history of new trauma. Regarding fatigue failure of orthopaedic implants:
Mark each as TRUE or FALSE
Fatigue failure occurs when cyclic loading below the ultimate tensile strength causes progressive cr...
The S-N curve (Wöhler curve) plots stress amplitude against number of cycles to failure; ferrous met...
Fatigue strength increases with increasing stress concentration; sharp corners, screw holes, and sur...
Stress concentration factor (Kt) is highest at geometric discontinuities such as screw holes (Kt app...
Implant fatigue failure risk increases with non-union (prolonged cyclic loading), undersized implant...
Answer the questions to see explanations
Click T (True) or F (False) for each option