FAILURE ANALYSIS OF A TOTAL HIP FEMORAL COMPONENT: A FRACTURE MECHANICS APPROACH.
Quality of Health Care
Failure analysis was conducted on 21 fractured femoral components from Trapezoidal-28 total hip replacements performed at The Hospital for Special Surgery. These components were made from 316L stainless steel and had a trapezoidally shaped cross section in the neck and stem portions. Fractographic examination revealed multiple cracks on the medial side of the stems and a fracture surface with crack initiation sites from both the medial and lateral surfaces. Electron microscopy revealed striations on the fracture surfaces of both medial and lateral cracks, indicating that crack growth occurred by a fatigue fracture process in both cases. Analytical examination using curved beam theory with a bilinear stress-strain relationship predicted the medial cracks to initiate first, due to residual tensile stresses following an overload.