Dissociation of modular humeral head components: A biomechanical and implant retrieval study

In vivo dissociation of the Morse-taper of shoulder arthroplasty modular humeral components has been reported. The incidence of this complication appears to be approximately 1:1000. The objective of this study was to identify conditions that might affect the Morse-taper interface strength in humeral...

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Bibliographic Details
Published in:Journal of shoulder and elbow surgery 1997-03, Vol.6 (2), p.113-124
Main Authors: Blevins, Field T, Deng, Xianghua, Torzilli, Peter A, Dines, David, Warren, Russell F
Format: Article
Language:English
Subjects:
Biomechanical Phenomena
Equipment Failure
Humans
Humerus
Joint Prosthesis - adverse effects
Materials Testing
Shoulder Joint - surgery
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Summary:In vivo dissociation of the Morse-taper of shoulder arthroplasty modular humeral components has been reported. The incidence of this complication appears to be approximately 1:1000. The objective of this study was to identify conditions that might affect the Morse-taper interface strength in humeral components. Mechanical tests were performed to load and dissociate humeral heads from the humeral stems (titanium). The effect of loading rate, load amplitude, and number of impactions was investigated. Dissociation force was measured after the taper was contaminated with water, oil, blood, and bone cement particles. The mean dissociation force after two impactions with a mallet was 2926 ± 955 N. Dissociation force was linearly proportional to impaction force. Repetitive loading beyond two impactions did not significantly increase taper strength. Contamination of the taper with as little as 0.4 ml of fluid could prevent fixation of the taper.
ISSN:1058-2746
1532-6500
DOI:10.1016/S1058-2746(97)90031-8