A new American research has found that women with metal-on-metal (MoM) implants pass metal ions to their offspring.

The study, presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS), found elevated levels of cobalt and chromium in offspring of patients with metal-on-metal hip implants where both the socket and hip ball are metal.

Joshua J. Jacobs, Professor and Chairman of Orthopaedic Surgery at Rush University Medical Center in Chicago, said: "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.

"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."

For the study, scientists evaluated three patients who had either a unilateral (only on one hip) 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 (mean age of about 32 years) 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 data showed that mothers with MoM implants and their offspring had elevated Chromium and cobalt levels compared to the cohort without metal implants; a correlation existed between maternal and infant cobalt and chromium levels in the Implant Group, while the Control Group showed no correlation; offspring of women with MoM implants had about half the levels of cobalt in their bloodstream as their mothers and approximately 15 percent 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 differences in levels of titanium or nickel among any of the cohorts.

Dr. Jacobs said: "The next step is to find out what, if any affect metal ions have on fetal or infant development." (ANI)