Metal Ions: A Potential Indicator of Metal-on-Metal Hip FailureMar 12, 2013
Metal-on-Metal (MoM) hip implants have come under increasing scrutiny as regulatory authorities have documented a high percentage of failure across the globe. Researchers, who performed a retrospective study, have found that a Cobalt ion levels in a patient’s blood were significantly higher in asymptomatic patients who later needed a revision of their MoM hip implant. Now researchers believe if a patient is curious about the status of their MoM hip implant, the Cobalt ion levels in their blood can be a valuable indicator of potential failure.
Researcher’s found high Cobalt ion levels in patient’s blood strongly correlated with subsequent risk of failure in both men and women. David Langton, a researcher at the University Hospital of North Tees in Middlesbrough England, said that the study “provides the first evidence that blood metal ion tests can be used as a clinical indicator of the risk of early joint failure in asymptomatic patients.” He also suggested that the study “challenges” current guidance from the FDA, which does not recommend routine metal ion testing in patients who have received MoM hip implants.
The retrospective study involved Cobalt ion testing in 278 patients who had undergone a total of 299 hip replacements, in 2002, at North Tees in England. Around 2007, after surgeons at North Tees began noticing a high rate of “unusual tissue reactions” in patients receiving MoM hip implants, they began testing all hip resurfacing patients for metal ions in their blood at routine follow-up clinic visits. Out of the 299 patients who received a MoM hip implant 41 needed revisions. Researchers then measured each patients Cobalt ion levels and developed a predictive model for failure risk. They found that while low concentrations could be reassuring to both patients and surgeons, grossly elevated levels indicate a serious risk of early prosthetic failure and would necessitate follow up procedures.
The results of the retrospective study can give many patients, who have concerns about their MoM hip implants, an indicator of their hip implant’s status.