Chromium speciation in the blood of metal-on-metal hip implant patients

ABSTRACT

The objective of this study was to determine the valence state of chromium (Cr) in the blood of individuals with Cr-containing metal hip implants. Serum and red blood cell (RBC) Cr concentrations from 52 patients with Cr-containing total hip arthroplasties were measured preoperatively and at 3, 12, and 24 months postoperatively. Geometric mean and median pre-surgery serum Cr concentrations were consistently below 0.2 µg/L, while geometric mean and median pre-op RBC Cr concentrations were typically about four- to six-fold higher than the serum values. A significant 5- to 13-fold increase was found in the mean and median serum Cr concentrations three months post-surgery, with an 8- to 18-fold rise at 12 and 24 months, respectively. Steady-state serum concentrations were reached between 3 and 12 months. In contrast, there were no marked differences in mean and median RBC Cr concentrations pre- and post-surgery. Slope regression analysis for our data was similar to those reported for Cr(III) in spiked blood samples. The analysis showed that Cr released from hip implants preferentially distributed into serum and not RBC, indicating that the form of Cr present in blood of hip implant patients was in the form of non-toxic Cr(III). Our findings indicate that blood Cr concentrations Cr(III) associated with metal implants do not pose an adverse health risk to patients, which is in agreement with findings published by most investigators.

KEYWORDS:

• Chromium
• Cr(III)
• Cr(VI)
• hip implant
• analytical chemistry
• RBC
• metal-on-metal

Disclosure statement

All the authors were employed by Cardno ChemRisk at the time of manuscript preparation. Cardno ChemRisk is a consulting firm that provides scientific advice to the government, corporations, law firms and various scientific/professional organizations. Cardno ChemRisk has been engaged by DePuy Orthopaedics, Inc., a manufacturer of prosthetic devices, some of which contain cobalt and chromium, to provide general consulting and expert advice on scientific matters, as well as litigation support. This paper was prepared and written exclusively by the authors, without comment by DePuy employees or counsel. Any significant review or input by other Cardno ChemRisk employees who are not authors is described in the References. It is likely that this work will be relied upon in medical research, nutrition research and litigation. One of the authors (D. J. Paustenbach) has previously testified on behalf of DePuy in hip implant litigation. It is possible that any or all of the authors may be called upon to serve as expert witnesses on behalf of DePuy. Funding for the preparation of this paper was provided by DePuy. The preparation of the paper, including conduct of the literature review, review of the individual papers, integration and synthesis of the findings, the conclusions drawn and recommendations made are the exclusive professional work product of the authors and may not necessarily be those of their employer or the financial sponsor of the review.

Additional information

Funding

Funding for the preparation of this manuscript was provided by DePuy Orthopaedics, Inc.