Levels of systemic metal ions in patients with intramedullary nails.

BACKGROUND: It is being increasingly recognized that orthopedic implants are associated with adverse tissue responses, mediated by degradation products. Recent interest has been focused on the production of metal ions from hip arthroplasty. Few studies have reviewed fracture fixation devices and their metal ion production. METHODS: 61 subjects were enlisted into the study, with 3 subgroups. 21 subjects had Russell-Taylor intramedullary tibial nails in situ for 26 (21-32) months (316LVm stainless steel), 20 subjects had TriGen intramedullary tibial nails in situ for 43 (35-51) months (Ti-6Al-4V titanium alloy), and the remaining 20 subjects did not have any implant in situ and served as controls. Blood samples were taken and serum chromium, molybdenum, titanium, aluminium, and vanadium concentrations were measured using inductively coupled plasma (ICP) techniques. RESULTS: The 3 groups were matched for age, sex, and BMI. The subjects with Russell-Taylor nails had elevated levels of chromium (0.10 microg/L) with median concentrations 2.5 times higher than those of the control group. The subjects with TriGen nails had less significantly elevated levels of titanium (6.5 microg/L). INTERPRETATION: Stainless steel implants show significant differences from titanium implants in the dissemination of metal ions. Although the levels of chromium were elevated, the overall levels were modest when compared to published data regarding metal ion release and hip arthroplasty. Intramedullary nails are, however, often used in younger patients. If not removed, they may result in prolonged exposure to metal ions.

Acute inflammatory response does not affect erythrocyte concentrations of copper, zinc and selenium.

BACKGROUND & AIMS: Measuring the nutritional status of trace elements in plasma is invalidated in the presence of a systemic inflammatory response. We examined the potential of erythrocytes to assess copper, zinc and selenium status in such situations. METHODS: Venous blood samples were withdrawn pre-operatively and at 12, 24, 48, 72 and 168 h post-operatively from 11 patients (6 males and 5 females) who were admitted for elective knee arthroplasty. C-reactive protein, albumin, copper, zinc, selenium and iron were measured in plasma and erythrocytes. RESULTS: Plasma zinc and selenium concentrations fell significantly: 95% confidence intervals (CI)=-32% to -44% and -22% to -36%, respectively. Copper concentrations fell transiently and then increased significantly: CI=12-43%. No significant changes were seen in trace element concentrations in erythrocytes expressed either as a ratio of haemoglobin or iron concentration. Erythrocyte iron levels correlated significantly with haemoglobin (r=0.93). CONCLUSIONS: Plasma concentrations of copper, zinc and selenium are unreliable markers of status in patients with an acute inflammatory response. Erythrocyte concentrations of these trace elements may provide a more reliable measure in long-term studies of patients with a chronic systemic inflammatory response. Iron can be used instead of haemoglobin as the denominator when expressing erythrocyte concentrations of trace elements.

Age dependence of potentially toxic elements (Sb, Cd, Pb, Ag) in human liver tissue from paediatric subjects.

Toxic elements are present at low concentrations in the environment. This work was undertaken to investigate the age dependence of the liver content of selected elements in paediatric populations, as an index of internal exposure. Liver samples were collected at autopsy from 157 subjects, aged < 1 day to 6 years, as part of investigations on a possible role of Sb compounds in sudden infant death syndrome (SIDS). In addition to Sb, the concentrations of Ag, Cd and Pb were also determined by inductively coupled plasma mass spectrometry on the remaining digest. Comparison of 95% confidence intervals of the median concentrations of the four elements suggested that there were no differences between the two categories of cause of death, SIDS or those who had died of an identified disease. Cadmium, lead and antimony median concentrations were lower than corresponding values observed in adult populations. Silver concentrations were significantly higher at birth and decreased with age. Cadmium levels were almost negligible in neonates and infants, but increased in older children. The finding of non-negligible concentrations of both Ag and Pb in neonatal liver provides further direct evidence that these elements cross the human placental barrier. The reported data, by far the largest collection observed in subjects less than 1 year old, are the result of exposure, during pregnancy and in early childhood, to present levels of these elements in the environment. They can serve as a reference to compare post-mortem values from individuals or groups of subjects in this age range when an exposure risk is suspected and to highlight trends in human exposure.