WEB TEM Characterization of Nano-debris Wear Particles of a Biocompatible COC Hip Endoprostheses Components
With around 1.3 million implantations of biomaterials worldwide per year, total hip replacement (THR) is considered as one of the most frequently performed implantations of biomaterials in orthopaedics, and total hip arthroplasty (THA) is considered as one of the most successful orthopedic interventions. Ceramic-on-ceramic (COC) bearings, based in alumina or zirconia, are one of the prominent materials for such intervention. Studies about the reaction of tissues on organic and inorganic particles are a topic of a multitude of medical disciplines. Especially in the field of surgical disciplines like orthopaedics, particle studies that investigate the influence of the abrasion of different prosthetic materials on the peri-prosthetic tissue are undertaken to find out about the evidence on their respective biocompatibility. Compared to a CoCr/Polyethylene bearing with a wear rate of 200 microns/year, ceramic Alumina/Alumina bearings have a wear rate of less than 1 micron/year .
In this case study the debris particles obtained from the tissue around a patient’s damaged COC bearing were characterized in detail using Transmission Electron Microscopy (TEM) and Scanning TEM (STEM) combined with other microscopy and analysis techniques. Artificial hip components were constructed of COC bearings (femoral head and acetabular inner cup), a Ti-Al-V acetabular metal outer cup, and a corundum grit-blasted Ti-Al-V femoral stem. The aim of the study was to determine what kind of wear-debris particles were present in the tissue, what was their composition and possible crystal structure.
The nano-debris wear particles were obtained by dissolving the soft tissue sample in 95–97% sulfuric acid, washing the remains with distilled water, filtering them, and finally cleaning them with ethanol and leaving them to dry. Extracted debris particles were prepared for the TEM with the drop-casting technique on a lacy formvar/carbon-coated Cu grid and analyzed at 200 kV. The particles were mainly agglomerated, which was clearly visible from the STEM elemental mapping, and were between a few µm to around 10 nm in size (Figure 1). Their shape varied from rods, rectangular and rounded. The larger particles usually had sharp edges, and the smallest particles in the nm range were usually a rounded shape. Some particles were amorphous and some crystalline.
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|Extended Abstract||Description of 'Figure 1' which is mentioned in the abstract.||Figure 1. STEM EDS mapping with an inset TEM image in the overlay STEM map and STEM bright-field (BF) image with a line profile of one example of the debris particles obtained from the soft tissue around the damaged COC artificial hip component. The bottom-left inset image in the overlay STEM map shows components of the COC bearing.||489 KB||Download|