Tuesday, April 26, 2011

Early Markers of Nephrotoxicity[kidney toxicity] in Patients With Metal-on-metal Hip Arthroplasty.

Clin Orthop Relat Res. 2010 Nov 25. [Epub ahead of print]
Nephrology and Health Sciences, University of Parma, Parma, Italy.

Abstract

BACKGROUND:

Metal ions released from arthroplasty devices are largely cleared in urine, leading to high exposure in renal tissues. Validated early markers of renal damage are routinely used to monitor workers in heavy metal industries, and renal risk can be quantified in these industries. It is unclear if the ion levels in patients with metal-on-metal hips are sufficient to cause renal damage.

QUESTION:

Does metal-on-metal (MOM) bearing use over a 10-year period lead to elevation of early renal markers compared with the levels expected in subjects with no metal exposure?

METHODS:

We retrospectively reviewed 31 patients who underwent MOM hip resurfacings 10 years earlier. Whole blood specimens were collected for metal ion analysis, serum for creatinine estimation, and urine for timed metal ion output and renal markers. The renal marker levels of 30 age- and gender-matched subjects with no metal exposure and no known renal problems or diabetes mellitus were used as controls for renal markers.

RESULTS:

Median serum creatinine level in the MOM group was 1.1 mg/dL (interquartile range, 1.0-1.2 mg/dL) and median creatinine clearance was 79.2 mL/min. In this cohort, the number of patients with markers of renal damage above the reference range was comparable to the controls. None of the renal markers were associated with metal levels.

CONCLUSION:

The absence of elevation of renal markers in this cohort 10 years after MOM bearing implantation is reassuring. However, we believe surveillance through further longer-term, large-scale controlled trials are needed to monitor this arthroplasty-induced low-intensity (but long-term) trace element exposure to rule out potential nephrotoxicity.

LEVEL OF EVIDENCE:

Level III, retrospective comparative study. See Guidelines for Authors for a complete description of levels of evidence.

[comments from connie:
  • Interesting study
  • Small population
  • I would be interested in seeing some variation on this study such as what happens if you only have one kidney? What about patients with  minor renal impairment with a MOM hip?  does it get worse?  What about autopsies on hip patients...what do the renal biopsies look like?

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