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Realistic loads for testing hip implants

Realistic loads for testing hip implants
Realistic loads for testing hip implants
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.
Hip implant, THR, load force telemetry
0959-2989
65-75
Bergmann, G.
0e5e06cd-2009-449f-a27c-4bcae0968a2f
Graichen, F.
d00944ed-eb6c-4262-9c04-100b4043bd31
Rohlmann, A.
3cea4cf8-5409-4adc-b889-2ad41e83c51a
Bender, A.
0db89227-3c57-4875-af86-54bafd275cee
Heinlein, B.
c22db3aa-573a-4c42-83e6-5132471a5e33
Duda, G.N.
32d09622-34ad-49dd-8314-3f61c99a764e
Heller, M.O.
3da19d2a-f34d-4ff1-8a34-9b5a7e695829
Morlock, M.M.
1aaefd6c-f853-4994-a365-5ab1f863657d
Bergmann, G.
0e5e06cd-2009-449f-a27c-4bcae0968a2f
Graichen, F.
d00944ed-eb6c-4262-9c04-100b4043bd31
Rohlmann, A.
3cea4cf8-5409-4adc-b889-2ad41e83c51a
Bender, A.
0db89227-3c57-4875-af86-54bafd275cee
Heinlein, B.
c22db3aa-573a-4c42-83e6-5132471a5e33
Duda, G.N.
32d09622-34ad-49dd-8314-3f61c99a764e
Heller, M.O.
3da19d2a-f34d-4ff1-8a34-9b5a7e695829
Morlock, M.M.
1aaefd6c-f853-4994-a365-5ab1f863657d

Bergmann, G., Graichen, F., Rohlmann, A., Bender, A., Heinlein, B., Duda, G.N., Heller, M.O. and Morlock, M.M. (2010) Realistic loads for testing hip implants. Bio-medical Materials & Engineering, 20 (2), 65-75. (doi:10.3233/BME-2010-0616). (PMID:20592444)

Record type: Article

Abstract

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.

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More information

Published date: 2010
Additional Information: Erratum in Bio-medical Materials & Engineering 2010; 20(6): 381.
Keywords: Hip implant, THR, load force telemetry
Organisations: Bioengineering Group

Identifiers

Local EPrints ID: 348523
URI: http://eprints.soton.ac.uk/id/eprint/348523
ISSN: 0959-2989
PURE UUID: bdebd498-ab84-4362-b771-8e279744bdbd
ORCID for M.O. Heller: ORCID iD orcid.org/0000-0002-7879-1135

Catalogue record

Date deposited: 14 Feb 2013 14:49
Last modified: 17 Dec 2019 01:38

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Contributors

Author: G. Bergmann
Author: F. Graichen
Author: A. Rohlmann
Author: A. Bender
Author: B. Heinlein
Author: G.N. Duda
Author: M.O. Heller ORCID iD
Author: M.M. Morlock

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