Fractured Whiteside Ortholoc II knee components

A comprehensive failure analysis was performed on 6 femoral components and 1 tibial component that fractured in service. All were Whiteside Ortholoc II total knee arthroplasty components, manufactured from cast cobalt-chromium-molybdenum alloy and porous coated. Fracture surface analysis revealed fa...

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Bibliographic Details
Published in:The Journal of arthroplasty 2001-10, Vol.16 (7), p.927-934
Main Authors: Swarts, Eric, Miller, Susan J., Keogh, Cathie V., Lim, Gerald, Beaver, Richard J.
Format: Article
Language:English
Subjects:
Aged
cast cobalt-chromium alloy
Chromium Alloys
Cobalt
Equipment Failure Analysis
fatigue
Female
fracture
Humans
Knee Prosthesis
Male
Microscopy, Electron, Scanning
Middle Aged
Molybdenum
Prosthesis Failure
Surface Properties
total knee arthroplasty
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Summary:A comprehensive failure analysis was performed on 6 femoral components and 1 tibial component that fractured in service. All were Whiteside Ortholoc II total knee arthroplasty components, manufactured from cast cobalt-chromium-molybdenum alloy and porous coated. Fracture surface analysis revealed fatigue-induced failure in all cases. Most fractures occurred at regions of high stress concentration, such as sharp corners, sintered beads, and thin sections. Metallurgical examination showed significant variation in grain size, interdendritic carbides, and hardness between samples. In some cases, continuous carbide networks and voids were prominent at the bead–substrate interface. Patient weight and surgical placement were identified as contributory factors in component failure. Limitations of cast cobalt-chromium-molybdenum alloy in weight-bearing applications must be emphasized, particularly when important determinants, such as design, metallurgy, and specific clinical factors, are less than optimal.
ISSN:0883-5403
1532-8406
DOI:10.1054/arth.2001.25508