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Comput Methods Biomech Biomed Engin. 2014 Nov;17(15):1671-84. doi: 10.1080/10255842.2012.761693. Epub 2013 Feb 13.

Sensitivity analysis of a cemented hip stem to implant position and cement mantle thickness.

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1
a Engineering Sciences Unit, Faculty of Engineering and the Environment, University of Southampton , Southampton SO17 1BJ , UK.

Abstract

Patient-specific finite element models of the implanted proximal femur can be built from pre-operative computed tomography scans and post-operative X-rays. However, estimating three-dimensional positioning from two-dimensional radiographs introduces uncertainty in the implant position. Further, accurately measuring the thin cement mantle and the degree of cement-bone interdigitation from imaging data is challenging. To quantify the effect of these uncertainties in stem position and cement thickness, a sensitivity study was performed. A design-of-experiment study was implemented, simulating both gait and stair ascent. Cement mantle stresses and bone-implant interface strains were monitored. The results show that small variations in alignment affect the implant biomechanics, especially around the most proximal and most distal ends of the stem. The results suggest that implant position is more influential than cement thickness. Rotation around the medial-lateral axis is the dominant factor in the proximal zones and stem translations are the dominant factors around the distal tip.

KEYWORDS:

design-of-experiment; finite element analysis; implant alignment; sensitivity; total hip replacement

PMID:
23405986
DOI:
10.1080/10255842.2012.761693
[Indexed for MEDLINE]
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