Failure Analysis of Some Orthopedic Implants (Analyse de Rupture de Quelques Protheses Orthopediques).
Author | : |
Publisher | : |
Total Pages | : 55 |
Release | : 1980 |
Genre | : |
ISBN | : |
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The latest information indicates that over 2500 orthopedic implant malfunctions may occur each year in Canada. Several orthopedic implants which failed in service have been examined in the Structures and Materials Laboratory, National Aeronautical Establishment, National Research Council of Canada. Two classes of material were studied, wrought stainless steel, type 316L and a cast Co-Cr-Mo alloy. In each case where fracture of the device occurred, fatigue striations were detected, indicating that fatigue was a primary mechanism of failure. Other problems were detected in each class of material; corrosion in the stainless steel and porosity in the cobalt-based alloy. Due to problems with corrosion, it is recommended that type 316L stainless steel should not be used when there is a possibility of the implant remaining in the body for an extended period of time (say over 18 months). Also, there should be some control over the allowable porosity levels in cast cobalt-base alloys. It is shown, for example, that the porosity levels can be dramatically reduced by controlling the cooling rate during the casting process. Recent trends in orthopedic implant technology are briefly described, particularly the processing of metal powders which gives a uniform microstructure resulting in better strength and fatigue resistance. At the end of the report, a bibliography of over 240 papers in nine different categories covers the properties and performance of metals and alloys used as orthopedic implants.