Elsevier

The Journal of Arthroplasty

Volume 28, Issue 8, September 2013, Pages 1259-1264
The Journal of Arthroplasty

Radiographically Undetectable Periprosthetic Osteolysis With ASR Implants: The Implication of Blood Metal Ions

https://doi.org/10.1016/j.arth.2013.02.019Get rights and content

Abstract

Patients with ASR implants (resurfacing and large-diameter (XL) metal-on-metal (MoM) total hip arthroplasty), even if asymptomatic and with a stable prosthesis, may present extremely high blood metal ion levels. We report on a consecutive series of fourteen ASR revisions, focusing on osteolysis and their radiographic correspondence and their correlation with blood metal ion levels. At revision, seven hips revealed severe periacetabular osteolysis which was radiographically undetectable in six and asymptomatic in five. Seven hips with no acetabular osteolysis had significantly lower serum Cr and Co ion concentrations (respectively 25.2, 41.1 μg/l) compared to the seven hips with severe acetabular bone loss (respectively 70.1, 147.0 μg/l). Elevated blood metal ion levels should be considered as a warning of undetectable and ongoing periprosthetic osteolysis in asymptomatic patients with ASR prosthesis.

Section snippets

Materials and Methods

This study was performed in accordance with the guidelines of MHRA for MoM joints [14].

We reviewed a consecutive series of fourteen patients (11 female and 3 male, 14 hips) who underwent revision for an ASR prosthesis failure between February 2011 and June 2012.

Three ASR resurfacings and eleven ASR-XLs were explanted. The revisions were carried out a mean of 73 months (SD 7.7) after the initial operations which were performed by the same surgeons at the same centre between April 2005 and May

Preoperative Radiographic Evaluation

Evident loosening of the acetabular components was visible on two hips trough the AP pelvic views. Defined and clear osteolysis was detectable in one hip (7%) adjacent to the cup (zone II). Three hips (21.5%) showed areas of mild bone rarefaction medially and above the cup (zone I–II–III in two hips and zone II in one) on AP views compared to the contralateral hip. These areas were not defined as osteolysis because of lack of clear outlining edges. No osteolytic signs nor bone rarefaction zones

Discussion

In vitro studies have demonstrated how higher cobalt ions concentrations inhibit primary human osteoblast and attract inflammatory and osteoclastic cells [13]. Elevated cobalt and chromium ions levels result in osteolytic reactions [12].

Thus, in the presence of an important elevation of blood metal ions concentrations in patients with MoM hip resurfacing or large-diameter MoM total hip arthroplasty there is a theoretical increased risk of periprosthetic osteolysis.

In the literature there are

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    Ethical review committee statement: Each author certifies that his institution approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained.

    Statement of the work location: This work was performed entirely at Policlinico San Donato Hospital, P.za Malan 2, 20097 San Donato Milanese, Milan, Italy.

    The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2013.02.019.

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