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Realistic loads for testing hip implants
Publikationstyp
Journal Article
Date Issued
2010
Sprache
English
Author(s)
Bergmann, Georg
Graichen, Friedmar
Rohlmann, Antonius
Bender, Alwina
Heinlein, Bernd
Heller, Markus O. W.
Volume
20
Issue
2
Start Page
65
End Page
75
Citation
Bio-Medical Materials and Engineering 20 (2): 65-75 (2010)
Publisher DOI
Scopus ID
Publisher
IOS Press
The aim here was to define realistic load conditions for hip implants, based on in vivo contact force measurements, and to see whether current ISO standards indeed simulate real loads. The load scenarios obtained are based on in vivo hip contact forces measured in 4 patients during different activities and on activity records from 31 patients. The load scenarios can be adapted to various test purposes by applying average or high peak loads, high-impact activities or additional low-impact activities, and by simulating normal or very active patients. The most strenuous activities are walking (average peak forces 1800 N, high peak forces 3900 N), going up stairs (average peak forces 1900 N, high peak forces 4200 N) and stumbling (high peak forces 11,000 N). Torsional moments are 50% higher for going up stairs than for walking. Ten million loading cycles simulate an implantation time of 3.9 years in active patients. The in vitro fatigue properties of cementless implant fixations are exceeded during stumbling. At least for heavyweight and very active subjects, the real load conditions are more critical than those defined by the ISO standards for fatigue tests. © 2010 - IOS Press and the authors.
Subjects
force
Hip implant
load
telemetry
THR
DDC Class
610: Medicine, Health
620: Engineering