Abstract
Introduction: The potential adverse effects of metal ion elevation in patients with metal-metal bearings continue to be assessed. We reported earlier that metal ions cross the placenta. The present report is a comparison of the rate of transfer in 14 study patients (with MM devices) and 24 control subjects (with no metal devices).
Methods: Whole blood from concurrent specimens of maternal and umbilical cord blood obtained at the time of delivery were analysed with high resolution inductively coupled plasma mass spectrometry.
Results: Cobalt and chromium were detectable in all specimens in the control subjects and study patients. The mean difference between maternal and cord blood cobalt concentrations was 0.56 μg/l (p < 0.001) in the study group and 0.03 μg/l (p > 0.5) in the control group respectively (figure). The mean difference between maternal and cord blood chromium concentrations was 0.96 chromium (p < 0.0005) in the study group and 0.002 chromium (p > 0.5) in the control group respectively. The mean cord cobalt in the study patients was significantly higher than that in the control subjects (difference 0.38μg/l, p < 0.01) but the difference in the cord levels of chromium between study and controls (difference 0.13μg/l, p> 0.05) was not significant.
Discussion: There was almost no difference between the maternal and cord blood levels in the control group implying that the placenta offers almost no resistance to their passage in subjects without a metal device. In the study patients the mean cord cobalt level was 59% of the maternal level and the mean cord chromium level was 26% of the maternal level suggesting that the placenta exerts a modulatory effect on the rate of metal transfer when the maternal levels are higher
Correspondence should be addressed to Mr John Hodgkinson, BHS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
