Low torque levels can initiate a removal of the passivation layer and cause fretting in modular hip stems

S. Y. Jauch, L. G. Coles, L. V. Ng, A. W. Miles, H. S. Gill

Research output: Contribution to journalArticle

18 Citations (Scopus)
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Abstract

Taper connections of modular hip prostheses are at risk of fretting and corrosion, which can result in reduced implant survival. The purpose of this study was to identify the minimum torque required to initiate a removal of the passivation layer at the taper interface as a function of assembly force and axial load.
Titanium stems and cobalt-chromium heads were assembled with peak impaction forces of 4.5 kN or 6.0 kN and then mounted on a materials testing machine whilst immersed in Ringer’s solution. The stems were subjected to an axial load (1 kN or 3 kN) along the taper axis. After a period of equilibration, a torque ramp from 0 to 15 Nm was manually applied and the galvanic potential continuously recorded.
Prostheses assembled with a force of 6 kN required a significantly higher torque to start a removal of the passivation layer compared to those assembled with 4.5 kN (7.23 ± 0.55 Nm vs. 3.92 ± 0.97 Nm,p = 0.029). No influence of the axial load on the fretting behaviour was found (p = 0.486).
The torque levels, which were demonstrated to initiate surface damage under either assembly force, can be readily reached during activities of daily living. The damage will be intensified in situations of large weight and high activity of the patient or malpositioning of the prosthesis.

Original languageEnglish
Pages (from-to)1140-1146
JournalMedical Engineering & Physics
Volume36
Issue number9
Early online date19 Jul 2014
DOIs
Publication statusPublished - Sep 2014

Fingerprint

Torque
Passivation
Hip
Axial loads
Prostheses and Implants
Hip prostheses
Materials Testing
Hip Prosthesis
Architectural Accessibility
Corrosion
Materials testing
Chromium
Activities of Daily Living
Cobalt
Prosthetics
Titanium
Weights and Measures
Survival

Cite this

Low torque levels can initiate a removal of the passivation layer and cause fretting in modular hip stems. / Jauch, S. Y.; Coles, L. G.; Ng, L. V.; Miles, A. W.; Gill, H. S.

In: Medical Engineering & Physics , Vol. 36, No. 9, 09.2014, p. 1140-1146.

Research output: Contribution to journalArticle

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