Fatigue failure of noncemented porous-coated implants. A retrieval study.
The causes of mechanical failure of five noncemented porous-coated components were studied. There were two cobalt-chromium alloy and three titanium alloy implants which fractured after 12 to 48 months. The implants included one acetabular component, and one femoral condylar, one patellar and two tibial components. Examination of the fractured surfaces revealed fatigue to be the mechanism of failure in all cases. The porous coating and the processes required for its fabrication had resulted in weakening and reduction of substrate thickness. Additional factors were stress concentration due to limited, localised bone ingrowth, and some features of the design of the implants.
Cook
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SD
Department of Orthopaedics, School of Medicine, Tulane University, New Orleans, Louisiana 70112.
Thomas
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KA
D000368:Aged; D001843:Bone Cements; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008670:Metals / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D016348:Osseointegration; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D013499:Surface Properties
D001843:Bone Cements; D008670:Metals