Stability of a cemented implant, once the stem-cement interface has debonded, is reliant upon stem geometry and surface finish. There are relatively few studies addressing the effect of cross-sectional stem shape on cemented implant fixation. The purpose of this investigation was to compare the torsional stability of five different stem cross-sectional shapes—circular, oval, triangular, rectangular with rounded edges, and rectangular with sharp edges—under monotonically increasing and cyclic loading conditions. Seven samples of each stem geometry were tested. Stems were potted in bone cement and loaded to 5 deg of rotation. For monotonic loading, torque was applied at a constant rate of 2.5 deg/min. For cyclic loading, a sine wave torque pattern was applied, with a maximum magnitude that began at 4.5 Nm for 1500 cycles and then increased by 2.25 Nm every 1500 cycles until 5 deg of rotation. The rectangular stem with the sharp edges always provided the greatest resistance to torque, followed by the rectangular with rounded edges, triangular, oval, and circular. These results, including the effects of sharp corners, may differ for modes of loading other than torsion. These experimental results support the findings of earlier finite element models, indicating stem shape has a significant effect on resistance to torsional loading.
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e-mail: stakaki@uwo.ca
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June 2007
Technical Papers
The Effect of Cross-Sectional Stem Shape on the Torsional Stability of Cemented Implant Components
Angela E. Kedgley,
Angela E. Kedgley
Biomechanical Testing Laboratory, Department of Mechanical and Materials Engineering,
e-mail: akedgley@uwo.ca
University of Western Ontario
, London, Ontario N6A 5B9, Canada
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Sarah E. Takaki,
Sarah E. Takaki
Biomechanical Testing Laboratory, Biomedical Engineering Graduate Program,
e-mail: stakaki@uwo.ca
University of Western Ontario
, London, Ontario N6A 5B9, Canada
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Pencilla Lang,
Pencilla Lang
Biomechanical Testing Laboratory, Department of Mechanical and Materials Engineering,
e-mail: plang3@uwo.ca
University of Western Ontario
, London, Ontario N6A 5B9, Canada
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Cynthia E. Dunning, Ph.D., P.Eng
Cynthia E. Dunning, Ph.D., P.Eng
Department of Mechanical and Materials Engineering,
e-mail: cdunning@eng.uwo.ca
University of Western Ontario
, London, Ontario N6A 5B9, Canada
Search for other works by this author on:
Angela E. Kedgley
Biomechanical Testing Laboratory, Department of Mechanical and Materials Engineering,
University of Western Ontario
, London, Ontario N6A 5B9, Canadae-mail: akedgley@uwo.ca
Sarah E. Takaki
Biomechanical Testing Laboratory, Biomedical Engineering Graduate Program,
University of Western Ontario
, London, Ontario N6A 5B9, Canadae-mail: stakaki@uwo.ca
Pencilla Lang
Biomechanical Testing Laboratory, Department of Mechanical and Materials Engineering,
University of Western Ontario
, London, Ontario N6A 5B9, Canadae-mail: plang3@uwo.ca
Cynthia E. Dunning, Ph.D., P.Eng
Department of Mechanical and Materials Engineering,
University of Western Ontario
, London, Ontario N6A 5B9, Canadae-mail: cdunning@eng.uwo.ca
J Biomech Eng. Jun 2007, 129(3): 310-314 (5 pages)
Published Online: November 14, 2006
Article history
Received:
March 29, 2006
Revised:
November 14, 2006
Citation
Kedgley, A. E., Takaki, S. E., Lang, P., and Dunning, C. E. (November 14, 2006). "The Effect of Cross-Sectional Stem Shape on the Torsional Stability of Cemented Implant Components." ASME. J Biomech Eng. June 2007; 129(3): 310–314. https://doi.org/10.1115/1.2720907
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