Failure analysis and materials characterization of hip implants

Abstract

This research focused on the microstructural characterization and failure analysis of hip implant components. The main hip components analyzed were the femoral heads and the ultra-high molecular weight polyethylene (UHMWPE) liners. Previous research has shown that hip implants tend to fail by the PE liners due to adhesive and abrasive wear, delamination, and third body particles (metals, ceramics, and PE). The methods and procedures for analyzing the said failures consisted of non-destructive and destructive evaluations. Non-destructive evaluations included of techniques such as visual characterization and dye penetrant inspection (DPI)—which displayed macroscopic surface details and presented initial clues as to the extent and causes of the failures. The use of attenuated total reflection infrared spectroscopy (ATR-IR) produced transmittance spectra for the PE liners to indicate the bonds and their associated wavelength energies. The destructive evaluations included metallography and scanning electron microscopy (SEM). These techniques revealed the microstructural characteristics of the metallic components and focused on microscopic cracks and abrasions from areas of delamination and adhesion in the samples. After further studies and analyses on the failed implants, the information and data shall be given to the collaborating orthopedic surgery group in hopes of altering new components to ensure increased implant lifetimes and less needed revision surgeries for hip replacement patients.