Mechanical implications of interfacial defects between femoral hip implants and cement: a finite element analysis of interfacial gaps and interfacial porosity.
Publication year
2008Source
Proceedings of the Institution of Mechanical Engineers Part H - Journal of Engineering in Medicine, 222, 7, (2008), pp. 1037-47ISSN
Publication type
Article / Letter to editor

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Organization
Orthopaedics
Journal title
Proceedings of the Institution of Mechanical Engineers Part H - Journal of Engineering in Medicine
Volume
vol. 222
Issue
iss. 7
Page start
p. 1037
Page end
p. 47
Subject
EBP 2: Effective Hospital Care; NCEBP 10: Human Movement & FatigueAbstract
Two types of defect between femoral hip implants and cement have been identified. Interfacial porosity arises from cement shrinkage during curing and presents as pores randomly located along the stem. Interfacial gaps are much larger stem-cement separations caused by air introduced during stem insertion. To investigate the mechanical consequences of both types of defect, a finite element analysis model was created on the basis of a computed tomography image of a Charnley-Kerboul stem, and alternating torsional and transverse loads were applied. The propagation of fatigue cracks within the cement and the rotational stability of the stem were assessed in models simulating increasing amounts of interfacial gaps and pores. Anterior gaps covering at least 30 per cent of the implant surface promoted cement cracks and destabilized the stem. Anterolateral gaps were less destabilizing, but had more potential to promote cracks. In both cases, cracks occurred mainly outside gap regions, in areas where the stem contacted the cement during cyclic loading. Although random interfacial pores did not destabilize the implant, they acted as crack initiators even at low fractions (10 per cent). In conclusion, random interfacial pores were more harmful for the cement mantle integrity than were larger regions of interfacial gaps, although gaps were more detrimental for the rotational stability of the stem.
This item appears in the following Collection(s)
- Academic publications [227881]
- Faculty of Medical Sciences [86219]
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