Damage mechanisms at the cement-implant interface of polished cemented femoral stems

Abstract

The occurrence of damage on polished femoral stems has been widely reported in the literature, and bone cement has been implicated in a tribo-corrosive failure process. However, the mechanisms of cement-mediated damage and the impact of cement formulation on this process are not well understood. In this study, thirteen Zimmer CPT polished femoral stems and corresponding cement specimens were retrieved at revision surgery and analysed using high-resolution imaging techniques. Surface damage attributed to tribo-corrosion was observed on all stems. Corrosion product, in the form of black flaky surface debris, was observed on the surface of cement specimens; both energy-dispersive x-ray spectroscopy (EDX)and inductively coupled plasma mass spectrometry(ICP-MS) confirmed the presence of cobalt and chromium, with the ICP-MS showing much higher levels of Cr compared to Co when compared to the original stem material. Agglomerates of ZrO₂ radiopacifier were also identified on the cement surface, and in some cases showed evidence of abrasive wear; the size of these particles correlated well with elliptical pitting evident on the surfaces of the corresponding stems. This evidence supports the hypothesis that agglomerates of hard radiopacifier particles within the cement may induce a wear-dominated tribo-corrosive interaction at the stem-cement interface that damages the surface of polished CoCr femoral stems

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Identifiers

ORCID for Martin Browne: orcid.org/0000-0001-5184-050X

ORCID for James A. Milton: orcid.org/0000-0003-4245-5532

ORCID for Matthew J. Cooper: orcid.org/0000-0002-2130-2759

ORCID for Robert J. K. Wood: orcid.org/0000-0003-0681-9239

ORCID for Richard B. Cook: orcid.org/0000-0002-2468-5820

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