Metal Ions from Implants Migrate from Mother to Child

Hip replacement patients with metal-on-metal (MoM) implants pass metal ions to their infants during pregnancy, according to a new study.

Researchers at Rush University Medical Center (RUSH, Chicago, IL, USA) evaluated three patients who had either a unilateral MoM primary total hip arthroplasty or unilateral MoM hip resurfacing joint replacement, and no other metal implant in the body. The implant group's metal ion levels were compared within the group, between mothers and their infants, and to those of a control group comprising seven women of child-bearing age who did not have any metal implants, and their infants. For all subjects, maternal and umbilical cord blood was obtained at the time of delivery and tested for blood serum concentrations of titanium, nickel, cobalt, and chromium using inductively coupled plasma mass spectrometry (ICP-MS), a highly sensitive technique that can detect trace amounts of metals in biological samples.

The study results showed that mothers with MoM implants and their offspring had elevated chromium and cobalt levels, compared to the cohort without metal implants. Additionally, a correlation existed between maternal and infant cobalt and chromium levels in the implant group, while the control group showed no such correlation. Offspring of women with MoM implants had about half the levels of cobalt in their bloodstream as their mothers, and approximately 15% of their mother's chromium levels, while there was no significant difference among ion levels between mothers and infants in the control group. There was no statistically significant difference in levels of titanium or nickel among any of the cohorts. The study was presented at the annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS), held during March 2010 in New Orleans (LA, USA).

"Although the affects of metal ions in maternal and fetal subjects are unknown, the fact that the placenta is not a complete barrier to the transport of these metals is noteworthy,” said lead author and study presenter Joshua Jacobs, M.D., a professor orthopedic Surgery at Rush. "As metal-on-metal implants increase in popularity and use, especially among young, active patients, women of child-bearing age and their doctors should be aware of these findings when considering their hip replacement implant options.”

Related Links:
Rush University Medical Center