Case report: High chromium and cobalt levels in a pregnant patient with bilateral metal-on-metal hip arthroplasties

Pregnancy, Hip Pain, and Total Hip Replacement

➤ Young women who are 15 to 45 years of age and undergo total hip replacements are at increased risk for revision compared with women >75 years of age.➤ Among women of childbearing age with a total hip replacement, 12% to 17% will later have at least 1 pregnancy.➤ Young women who undergo total hip replacement do not have an increased risk of pregnancy complications.➤ Of the 60% of women who experienced pain with a total hip replacement during pregnancy, 21% had persisting pain, and 4% reported the pain as severe.➤ Women who have a total hip replacement and later experience pregnancy and childbirth have no increased risk of pregnancy complications or increased revision rates; there was no effect of the mode of delivery on revision rates or complications including fracture, dislocation, or loosening, according to the limited studies available.

Metal-on-metal (MoM) hip implants and pregnancy: are MoM implants good for mom?-a systematic review

Metal-on-metal (MoM) bearing surfaces were historically used for young patients undergoing total hip arthroplasty (THA), and remain commonplace in modern hip resurfacing. A substantial number of female patients with MoM bearings subsequently gave birth following implantation of the bearings before a full understanding of metal ions exposure in these patients was established. In theory, it has been postulated that metal ions released from such implants may cross the placental barrier and cause harm to the fetus. In light of this potential risk, recommendations against the use of MoM components in women of child-bearing age have been advocated. The purpose of this systematic review was to evaluate: (I) the MoM bearing types and ion levels found; (II) the concentrations of metals in maternal circulation and the umbilical cord; and (III) the presence of abnormalities in the fetus or delivered child. A comprehensive literature review was conducted of studies published between January 1st, 1975 and April 1st, 2019 using specific keywords. We defined the inclusion criteria for qualifying studies for this review as follows: (I) studies that reported on the women who experienced pregnancy and who had a MoM hip implant; (II) studies that reported on maternal metal ions blood and umbilical cord levels; and (III) studies that reported on the occurrence of fetal complications. Data on cobalt and chromium ion levels in the maternal blood and umbilical cord blood, as well as the presence of adverse effects in the infant were collected. Age at parturition and time from MoM implant to parturition were also collected. A total of six studies were included in the final analysis that reported on a total of 21 females and 21 infants born. The mean age at parturition was 31 years (range, 24 to 41 years), and the mean time from MoM implantation to parturition was 47 months (range, 11 to 119 months). Maternal blood cobalt levels were found as a weighted average of 34.09 µg/L (0.425 to 138 µg/L), while umbilical cord blood cobalt levels were found to be 22.61 µg/L (0.52 to 51.11 µg/L). Cobalt levels were reduced by an average of 34% between maternal and umbilical cord blood. Maternal cord blood chromium levels were found as a weighted average of 18.18 µg/L (0.225 to 75 µg/L), while umbilical cord chromium levels were found to be 3.96 µg/L (0.14 to 11.96 µg/L). Chromium levels were reduced by an average of 78% between maternal and umbilical cord blood. No cobalt or chromium was detected in the umbilical cord blood of three patients. Out of the 21 infants born to women with MoM implants, 20 were born healthy with no adverse effects or complications. Only one complication was recorded in single infant that did not appear to be related to the maternal MoM implant. To date, there is a lack of consensus as to whether MoM hip arthroplasty implants are to be avoided in the child-bearing female population and whether they constitute a hazard to the fetus in utero. Both chromium and cobalt ions were markedly reduced in levels when transitioning from maternal to cord blood. In particular, chromium showed a greater reduction on average than cobalt (78% vs. 34%). Based on the current evidence, there appears to be no correlation between the presence of metal ions in umbilical cord blood and complications, as none of the infants experienced abnormalities uniquely attributable to the presence of metal ions.

Environmental and occupational exposure of metals and female reproductive health

Untainted environment promotes health, but the last few decades experienced steep upsurge in environmental contaminants posing detrimental physiological impact. The responsible factors mainly include the exponential growth of human population, havoc rise in industrialization, poorly planned urbanization, and slapdash environment management. Environmental degradation can increase the likelihood of human exposure to heavy metals, resulting in health consequences such as reproductive problems. As a result, research into metal-induced causes of reproductive impairment at the genetic, epigenetic, and biochemical levels must be strengthened further. These metals impact upon the female reproduction at all strata of its regulation and functions, be it development, maturation, or endocrine functions, and are linked to an increase in the causes of infertility in women. Chronic exposures to the heavy metals may lead to breast cancer, endometriosis, endometrial cancer, menstrual disorders, and spontaneous abortions, as well as pre-term deliveries, stillbirths. For example, endometriosis, endometrial cancer, and spontaneous abortions are all caused by the metalloestrogen cadmium (Cd); lead (Pb) levels over a certain threshold can cause spontaneous abortion and have a teratogenic impact; toxic amounts of mercury (Hg) have an influence on the menstrual cycle, which can lead to infertility. Impact of environmental exposure to heavy metals on female fertility is therefore a well-known fact. Thus, the underlying mechanisms must be explained and periodically updated, given the growing evidence on the influence of increasing environmental heavy metal load on female fertility. The purpose of this review is to give a concise overview of how heavy metal affects female reproductive health.

In utero deposition of trace elements and metals in tissues

INTRODUCTION

All animals, including humans, are exposed to heavy metals which are known to accumulate in different tissues, especially in bone. During pregnancy, the maternal bone turnover is increased and the metals in the mother's body can be mobilized into the bloodstream. Heavy metals in maternal blood are known to pass through the placenta to the fetal blood and finally, deposited to bone tissue. However, there are no studies on the concentration of metals in the fetal solid tissues and until now, the rate of metal transfer from mother to fetus is not exactly known.

MATERIALS AND METHODS

Samples of the blood, liver, placenta, and three different bones were collected from 17 pregnant ewes and their 27 fetuses. The animals had no known exposure to heavy metals. The concentrations of Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sb, Sn, Sr, Te, Ti, Tl, V, and Zn were analyzed using ICP-MS.

RESULTS AND DISCUSSION

The concentration of Sb, Sn, Te, and Tl were under the detection limit in all the samples. The other metals were found in all maternal and fetal tissues, suggesting that all detectable metals cross the placenta. Blood concentrations were low compared to solid tissue concentrations. The concentrations of essential elements varied between maternal and fetal tissues, which could be explained by biological differences. The differences in concentrations of non-essential elements between the ewe and fetuses were smaller. The most significant differences were between maternal and fetal concentrations of Ba and Sr, which is at least partly explained by the mineralization degree of the bone.

CONCLUSION

Heavy metals accumulate in fetal solid tissues in sheep that are not directly exposed to heavy metals. Because of the differences in anatomy between human and sheep placenta, the accumulation in the tissue of human fetuses should be extrapolated cautiously. However, there might be some clinical relevance for fertile aged women who are exposed to heavy metals, such as women who work in the metal industry or who have undergone joint replacement surgery.

Driving electrochemical corrosion of implanted CoCrMo metal via oscillatory electric fields without mechanical wear

Decades of research have been dedicated to understanding the corrosion mechanisms of metal based implanted prosthetics utilized in modern surgical procedures. Focused primarily on mechanically driven wear, current fretting and crevice corrosion investigations have yet to precisely replicate the complex chemical composition of corrosion products recovered from patients' periprosthetic tissue. This work specifically targets the creation of corrosion products at the metal on metal junction utilized in modular hip prosthetics. Moreover, this manuscript serves as an initial investigation into the potential interaction between implanted CoCrMo metal alloy and low amplitude electrical oscillation, similar in magnitude to those which may develop from ambient electromagnetic radiation. It is believed that introduction of such an electrical oscillation may be able to initiate electrochemical reactions between the metal and surrounding fluid, forming the precursor to secondary wear particles, without mechanically eroding the metal's natural passivation layer. Here, we show that a low magnitude electrical oscillation (≤ 200 mV) in the megahertz frequency (10⁶ Hz) range is capable of initiating corrosion on implanted CoCrMo without the addition of mechanical wear. Specifically, a 50 MHz, 200 mVpp sine wave generates corrosion products comprising of Cr, P, Ca, O, and C, which is consistent with previous literature on the analysis of failed hip prosthetics. These findings demonstrate that mechanical wear may not be required to initiate the production of chemically complex corrosion products.

Total Hip Revision with a Custom Acetabular Component and Femoral Allograft-Prosthetic Composite as Salvage for Failed Unstable Megaprosthesis in an Adolescent Patient: A Case Report at 19-Year Follow-up Duration

CASE

A 13-year-old girl presented after a right proximal femur replacement after proximal femoral resection for treatment of an Ewing sarcoma. She presented after multiple episodes of recurrent instability with her hip endoprosthesis chronically dislocated. Her hip was revised to a custom, constrained metal-on-metal acetabular component with a small iliac flange. The femoral component was revised to an allograft-prosthetic composite. She has been free of malignancy recurrence, implant failure, or dislocation at 19-year follow-up duration.

CONCLUSION

Dislocation of the prosthetic hip can be a challenging postoperative complication, particularly when associated with a tumor megaprosthesis in a pediatric age group. This is further compounded in the presence of deficient pelvic bone stock. Restoration of bone stock is optimal, but when impossible, custom components may be necessary to establish hip stability.

An integrated benefit-risk assessment of cobalt-containing alloys used in medical devices: Implications for regulatory requirements in the European Union

In 2017, the European Union (EU) Committee for Risk Assessment (RAC) recommended the classification of metallic cobalt (Co) as Category 1B with respect to its carcinogenic and reproductive hazard potential and Category 2 for mutagenicity but did not evaluate the relevance of these classifications for patients exposed to Co-containing alloys (CoCA) used in medical devices. CoCA are inherently different materials from Co metal from a toxicological perspective and thus require a separate assessment. CoCA are biocompatible materials with a unique combination of properties including strength, durability, and a long history of safe use that make them uniquely suited for use in a wide-range of medical devices. Assessments were performed on relevant preclinical and clinical carcinogenicity and reproductive toxicity data for Co and CoCA to meet the requirements under the EU Medical Device Regulation triggered by the ECHA re-classification (adopted in October 2019 under the 14th Adaptation to Technical Progress to CLP) and to address their relevance to patient safety. The objective of this review is to present an integrated overview of these assessments, a benefit-risk assessment and an examination of potential alternative materials. The data support the conclusion that the exposure to CoCA in medical devices via clinically relevant routes does not represent a hazard for carcinogenicity or reproductive toxicity. Additionally, the risk for the adverse effects that are known to occur with elevated Co concentrations (e.g., cardiomyopathy) are very low for CoCA implant devices (infrequent reports often reflecting a unique catastrophic failure event out of millions of patients) and negligible for CoCA non-implant devices (not measurable/no case reports). In conclusion, the favorable benefit-risk profile also in relation to possible alternatives presented herein strongly support continued use of CoCA in medical devices.

Congenital anomalies in the offspring of women with total hip replacement: a nationwide register study in Finland

BACKGROUND

Few previous studies have analysed the possible teratogenic effect of maternal total hip replacement (THR) on congenital anomalies. The aim of this study was to estimate the risk of major congenital anomalies in the offspring of women with THR. Furthermore, we compared the risks based on type of implant (metal-on-metal [MoM]/non-MoM).

METHODS

The study population for this register-based cohort study was gathered from six Finnish national registers. All fertile-aged females who underwent THR from 1980 to 2007 and three reference females for each THR patient without THR were selected. THR operation day was the start of the follow-up for both groups. Information on pregnancies, induced abortions (IA) and congenital anomalies was gathered for the years 1987-2007 and the proportions of congenital anomalies were compared.

RESULTS

In the THR group, 2429 women had 256 pregnancies, 205 (80.1%) deliveries and 51 (19.9%) IAs. In the reference group, 7276 women had 1670 pregnancies, 1443 (86.4%) deliveries and 236 (13.6%) IAs. There was no difference in the incidence of major anomalies between the THR (3.5%, n = 9) and the reference group (3.6%, n = 60), p = 0.91. In the THR group, there was no difference in the risk of major anomalies between the patients with a MoM-THR (10.5%, 2/19) and those with a non-MoM (2.9%, 7/241) (OR 3.93, 95% confidence interval 0.76-20.2; p = 0.13).

CONCLUSIONS

Reassuringly, maternal THR does not appear to increase the risk of major congenital anomalies or pregnancies ending due to suspected foetal anomalies. Studies with larger study populations are needed to further assess the risk of anomalies in the offspring of women having MoM-THR.

Investigation of the effects of electrochemical reactions on complex metal tribocorrosion within the human body

Although total hip arthroplasty (THA) is considered to be the most successful orthopedic operation in restoring mobility and relieving pain, common Metal-on-Metal (MoM) implants developed in the past decade suffer from severe inflammatory reactions of the surrounding tissue caused by the premature corrosion and degradation of the implant. A substantial amount of research has been dedicated to the investigation of mechanically driven fretting and crevice corrosion as the primary mechanism of implant failure. However, the exact mechanism by which hip implant breakdown occurs remains unknown, as current in vitro fretting and crevice corrosion studies have failed to completely replicate the corrosion characteristics of recovered implants. Here, we show that minor electric potential oscillations on a model hip implant replicate the corrosion of failed implants without the introduction of mechanical wear. We found in a controlled lab setting that small electrical oscillations, of similar frequency and magnitude as those resulting from ambient electromagnetic waves interacting with the metal of the implant, can force electrochemical reactions within a simulated synovial fluid environment that have not been previously predicted. In lab testing we have shown the replication of titanium, phosphorous, and oxygen deposition onto the surface of ASTM astm:F75 CoCrMo metal alloy test specimens, matching the chemical composition of previously retrieved wear particles from failed patient prosthetics. Our results demonstrate that the electrical activity and ensuing electrochemical activity excites two corrosion failure modes: direct dissolution of the medically implantable alloy, leaching metal ions into the body, and surface deposition growth, forming the precursor of secondary wear particles. We anticipate our findings to be the foundation for the future development and testing of electrochemically resistant implantable material.

A hazard evaluation of the reproductive/developmental toxicity of cobalt in medical devices

Cobalt (Co) is an essential element with human exposure occurring from the diet, supplement ingestion, occupational sources, and medical devices. The European Chemical Agency (ECHA) recently voted to classify Co metal as a Reproductive Hazard Category 1B; presumed human reproductive toxicant due to adverse testicular effects in male rodents. A weight of evidence evaluation of the preclinical reproductive and developmental toxicity studies and available clinical data was performed to critically evaluate the relevance of this proposed classification for Co in medical devices. Reproductive responses to Co are limited to the male testes and sperm function following high systemic exposure in rodents, only at Co concentrations/doses that result in overt toxicity (i.e., above the maximum tolerable dose (MTD)). The potential mechanisms of Co reproductive/developmental toxicity, including its indirect mode of action in the testes and relevance to humans, are discussed. The available preclinical and clincial evidence suggests that it would be more appropriate to classify Co as a Reproductive Hazard Category 2 compound: suspected human reproductive toxicant and, in the case of Co-containing medical devices, it should not be considered a reproductive hazard.

Alterations in Blood Metabolic Parameters of Immature Mice After Subchronic Exposure to Cobalt Chloride

The wide use of cobalt (Co) in food, industry, and medical devices requires full elucidation of its biological effects on tissues and organs. The aim was to assess serum metabolic alterations in immature mice after subchronic exposure to CoCl₂. Pregnant ICR mice were subjected to a daily dose of 75 mg cobalt chloride/kg body weight (CoCl₂x6H₂O) 2-3 days before they gave birth, and treatment continued until days 25 and 30 after delivery. The compound was dissolved in and obtained with regular tap water. ICP-DRC-MS analysis showed significantly elevated serum Co²⁺ and diverse alterations in metabolic parameters of 25- and 30-day-old pups after exposure to CoCl₂. Cholesterol and urea levels were significantly elevated in day 25 mice while HDL-C and LDL-C were reduced. In day 30, Co-exposed mice LDL-C and triglycerides were significantly increased while the total cholesterol level remained unchanged. Alkaline phosphatase was significantly reduced in day 25 Co-exposed mice. Blood glucose level of Co-exposed mice remained close to the untreated controls. Total protein content was slightly increased in day 30 mice. Co-exposure reduced albumin content and albumin/globulin ratio but increased significantly globulin content. Co administration showed strong correlation with cholesterol, urea, and HDL-C in both day 25 and 30 mice. Inverse correlation was found with alkaline phosphatase and albumin for day 25 and with triglycerides, globulin, and total protein content in day 30 Co-exposed mice. Subchronic CoCl₂ exposure of immature mice induced significant changes in key metabolic parameters suggesting possible further disturbances in energy metabolism, osteogenesis, and reproduction.

F-18 FDG PET brain imaging in symptomatic arthroprosthetic cobaltism

PURPOSE

Imaging studies of cobalt toxicity from cobalt-chromium alloy arthroprosthetics have focused on the local intra-articular and peri-articular presentation from failing joint replacements. Most studies investigating neurological findings have been small case series focused on the clinical findings of memory loss, diminished executive function, tremor, hearing and vision loss, depression, and emotional lability. This study utilizes software-based quantitative analysis of brain metabolism to assess the degree of hypometabolism and areas of susceptibility, determine if a pattern of involvement exists, and measure reversibility of findings after prosthetic revision to cobalt-free appliances.

METHODS

Over 48 months, 247 consecutive patients presenting to an orthopedic clinic with an arthroprosthetic joint containing any cobalt-chromium part were screened with whole blood and urine cobalt levels. A clinically validated inventory of 10 symptoms was obtained. Symptomatic patients with a blood cobalt level above 0.4 mcg/L or urine cobalt greater than 1 mcg/L underwent F-18 FDG PET brain imaging. Analysis was performed with FDA-approved quantitative brain analysis software with the pons as the reference region. Control group was the normal brain atlas within the software.

RESULTS

Of the 247 consecutively screened patients, 123 had blood and urine cobalt levels above the threshold. The 69 scanned patients had statistically significant regional hypometabolism and higher symptoms inventory. Fifty-seven patients were retained in the study. Distribution of hypometabolism was in descending order: temporal, frontal, Broca's areas, anterior cingulate, parietal, posterior cingulate, visual, sensorimotor, thalamic, and lastly caudate. Metal-on-metal (MoM) and metal-on-plastic (MoP) joint replacements produced similar patterns of hypometabolism. Of 15 patients with necessary revision surgery, 8 demonstrated improved metabolism when later re-scanned.

CONCLUSION

All scanned patients had regions of significant hypometabolism. Neurological toxicity from elevated systemic cobalt levels following arthroprosthetic joint replacement has a pattern of regional susceptibility similar to heavy metals and solvents, differing from classical dementias and may occur at blood and urine cobalt levels as low as 0.4 mcg/L and 1 mcg/L, respectively. Presently accepted thresholds for cobalt exposure and monitoring may need revision. Quantitative F-18 FDG PET brain imaging may aid in the decision process for treatment options and timing of possible medical versus surgical intervention.

A Systematic Review of Systemic Cobaltism After Wear or Corrosion of Chrome-Cobalt Hip Implants

Objectives

We sought to synthesize data on systemic arthroprosthetic cobaltism, a recently described syndrome that results from wear or corrosion of chrome-cobalt hip components.

Methods

We conducted a systematic literature review to identify all reported cases of systemic arthroprosthetic cobaltism. To assess the epidemiologic link between blood cobalt levels (B[Co]), we developed a symptom scoring tool that evaluated 9 different symptom categories and a category of medical utilization.

Results

We identified 25 patients reported between 2001 and 2014 with a substantial increase in case reports over the past 3 years. Symptoms were diverse and involved the hip (84%), cardiovascular system (60%), audiovestibular system (52%), peripheral motor-sensory system (48%), thyroid (48%), psychological functioning (32%), visual system (32%), and the hematological, oncological, or immune system (20%). The mean latency from implantation to presentation or revision was 41 months (range, 9–99 months). The mean B[Co] was 324 μg/L and 4 patients had levels less than 20 μg/L. The B[Co] but not blood chromium level was highly associated with a quantitative measure of overall symptom severity (r², 0.81; P < 0.001). Mean B[Co] and symptom scores were substantially higher in patients with revisions of failed ceramic-on-ceramic prostheses than those with primary metal-on-metal prostheses.

Conclusions

Systemic arthroprosthetic cobaltism is an increasingly recognized complication of wear or corrosion of chrome-cobalt hip implants, may involve a large number of organ systems, and may occur with relatively low B[Co]. There is an urgent need to better define the overall scope of the problem and to develop screening and management strategies.

Human biomonitoring to evaluate exposure to toxic and essential trace elements during pregnancy. Part A. concentrations in maternal blood, urine and cord blood

Exposures to toxic elements or deficiencies of essential elements during pregnancy may be associated to various birth complications or even diseases in early life. The aim of this paper was to assess the concentrations of selected toxic (As, Cd, Cr, Hg, Ni, Pb) and essential trace elements (Co, Cu, Mn, Se and Zn) in blood and urine samples of delivering women at different periods of gestation and cord blood, as well as to evaluate the placental permeability for these elements. A total of 53 women participating in the HEALS-EXHES study were enrolled. In particular, 48 blood samples from 1st trimester of pregnancy, 40 blood samples at delivery, and 31 cord blood at delivery were collected. Moreover, mothers' urine were sampled at the 1st (53 samples), 2nd (53 samples) and 3rd trimester (49 samples) of pregnancy. Results showed that Hg and Mn levels in cord blood were about 2.0 times higher than in maternal blood, suggesting that these elements may be transferred from mother to fetus. The cord blood levels of As and Pb were lower (ca. the 65%) than those in maternal blood, showing that the placenta modulates the rate of transfer for these elements. Essential elements as Cu and Zn showed significantly lower levels in cord than in maternal blood suggesting that the transplacental transfer of these nutrients was very limited. In addition, correlation between paired maternal and cord blood samples for As, Hg and Pb was statistically significant indicating that the fetal body burden may reflect the maternal exposure. Cadmium, Co, Cr, Ni and Se levels did not show significant correlations between maternal and cord blood. Maternal urinary concentrations of trace elements, including As, Cr, Cu, Hg, Se and Zn decreased along pregnancy, which may cause variations in fetal exposure. The levels of toxic and essential elements in maternal blood and urine, as well as in cord blood, were for most elements at the lower end of the ranges found in the scientific literature not being of special concern for pregnant women and the unborn.

Pregnancy outcome in women after total hip replacement: A population-based study

OBJECTIVE

Only a few small studies have been published on pregnancies after total hip replacement (THR), and they have reported no adverse pregnancy outcomes after THR. The aim of our study was to evaluate whether maternal THR affects pregnancy outcomes on a population-based level.

STUDY DESIGN

Data for this nationwide register-based cohort study have been collected from four national registries in Finland from 1980 to 2007. All females who had undergone THR during that period formed the patient group, and three controls for each patient without THR were selected. Patient group comprised 2429 women, 719 (29.6%) of whom had 1190 pregnancies ending in singleton deliveries. Of those births, 986 were before THR and 204 after THR. The control group comprised 7276 women, 2805 (38.6%) of whom had 5112 pregnancies ending in singleton deliveries, 3695 occurred before the index date (time point when THR took place within the patient group) and 1417 after. Logistic regression model was used to analyze univariable and adjusted odds ratios (aOR) for adverse neonatal outcomes after maternal THR compared with controls. Data were adjusted using the following variables: maternal age, smoking, rheumatoid arthritis.

RESULTS

Stillbirth was more common in the patient group compared with control group 4 (2.0%) vs 8 (0.6%) p = 0.02. Moreover, neonates in the patient group were more likely to be born preterm (aOR 3.58, p=<0.001), small for gestational age (aOR 2.83, p = 0.006) and low birthweight (aOR 4.79, p=<0.001), compared to control group. Trial of labor more likely ended in emergency cesarean section in the patient group than in the control group 39 (28.9%) vs 150 (11.6%), p=<0.001. Adverse pregnancy outcome was more common after THR also when compared to pregnancies before THR.

CONCLUSIONS

Neonates born after maternal total hip replacement have an increased risk of stillbirth, small for gestational age, low birthweight and preterm birth. Trial of labor is more likely to end in emergency cesarean section.

Biomonitoring method for the analysis of chromium and cobalt in human whole blood using inductively coupled plasma - kinetic energy discrimination - mass spectrometry (ICP-KED-MS)

The Centers for Disease Control and Prevention developed a biomonitoring method to rapidly and accurately quantify chromium and cobalt in human whole blood by ICP-MS. Many metal-on-metal hip implants which contain significant amounts of chromium and cobalt are susceptible to metal degradation. This method is used to gather population data about chromium and cobalt exposure of the U.S. population that does not include people that have metal-on-metal hip implants so that reference value can be established for a baseline level in blood. We evaluated parameters such as; helium gas flow rate, choice and composition of the diluent solution for sample preparation, and sample rinse time to determine the optimal conditions for analysis. The limits of detection for chromium and cobalt in blood were determined to be 0.41 and 0.06 μg/L, respectively. Method precision, accuracy, and recovery for this method were determined using quality control material created in-house and historical proficiency testing samples. We conducted experiments to determine if quantitative changes in the method parameters affect the results obtained by changing four parameters while analyzing human whole blood spiked with National Institute of Standard and Technology traceable materials: the dilution factor used during sample preparation, sample rinse time, diluent composition, and kinetic energy discrimination gas flow rate. The results at the increased and decreased levels for each parameter were statistically compared to the results obtained at the optimized parameters. We assessed the degree of reproducibility obtained under a variety of conditions and evaluated the method's robustness by analyzing the same set of proficiency testing samples by different analysts, on different instruments, with different reagents, and on different days. The short-term stability of chromium and cobalt in human blood samples stored at room temperature was monitored over a time period of 64 hours by diluting and analyzing samples at different time intervals. The stability of chromium and cobalt post-dilution was also evaluated over a period of 48 hours and at two storage temperatures (room temperature and refrigerated at 4°C). The results obtained during the stability studies showed that chromium and cobalt are stable in human blood for a period of 64 hours.

A Prospective Study of Serum Trace Elements in Healthy Korean Pregnant Women

This prospective study sought to investigate serum levels of trace elements (cobalt, copper, zinc, and selenium) and to assess their effects on pregnancy and neonatal outcomes. Serum levels of trace elements in 245 Korean pregnant women (median gestational age at delivery was 39 + 4 weeks and interquartile range was 38 + 4–40 + 1 weeks) were compared with those of 527 general adults and those of previous studies in other ethnic groups. Pregnancy and neonatal outcomes including gestational diabetes, preeclampsia, neonatal birth weight, and congenital abnormalities were assessed. The median serum trace element concentrations of all pregnant women were: cobalt: 0.39 μg/L (interquartile range, IQR 0.29–0.53), copper: 165.0 μg/dL (IQR 144.0–187.0), zinc: 57.0 μg/dL (IQR 50.0–64.0), and selenium: 94.0 μg/L (IQR 87.0–101.0). Serum cobalt and copper concentrations were higher in pregnant women than in the general population, whereas zinc and selenium levels were lower (p < 0.01). Concentrations of all four trace elements varied significantly during the three trimesters (p < 0.05), and seasonal variation was found in copper, zinc, and selenium, but was not observed for cobalt. The prevalence of preeclampsia was significantly lower with high copper (p = 0.03). Trace element levels varied by pregnancy trimester and season, and alteration in copper status during pregnancy might influence pregnancy outcomes such as preeclampsia.

A Miniaturized Therapeutic Chromophore for Multiple Metal Pollutant Sensing, Pathological Metal Diagnosis and Logical Computing

The efficacy of a miniaturized unimolecular analytic system is illustrated. The easily accessible therapeutic chromophore "temoporfin", which responds differentially to bound metals at multiple wavelengths of Q-band absorption using chemometric analysis, expeditiously detects and discriminates a wide range of metals regarded as priority pollutants in water and hence may also be used for diagnosis of medically relevant metals in human urine. The molecule was further investigated as an electronic logic device, e.g. keypad lock device, to authorize multiple highly secure chemical passwords for information protection.

[Complications of metal-on-metal tribological pairing]

BACKGROUND

Metal-on-metal (MoM) tribological pairing results in less volumetric abrasion than pairing with the conventionally used polyethylene and is associated with a lower risk of material failure compared to other hard-hard pairings. An increased frequency of problem cases in recent years has led to a great increase in uncertainty. Against this background in this article the current aspects of epidemiology, etiology, diagnostics and treatment of complications in MoM hip joint endoprostheses will be discussed.

EPIDEMIOLOGY AND ETIOLOGY

Based on the results from national endoprosthesis registers and selected clinical studies an evaluation of the rate of local complications from MoM tribological pairings was undertaken. A differentiation was made between MoM pairings in pedicled small head prostheses (≤ 32 mm), large head (> 32 mm) and surface replacement (OFE) endoprostheses. Each year MoM endoprostheses release on average 10(12)-10(14) cobalt (Co) and chromium (Cr) nanoparticles per patient. This release of metal ions and particles can lead to a variety of tissue reactions.

DIAGNOSTICS

A differentiation must be made between regular routine diagnostics within the framework of implant follow-up screening and specific investigations due to the occurrence of complaints. The diagnostics for patients treated with MoM hip endoprostheses consists of a standardized step-wise approach considering possible differential diagnoses and the utilization of modern laboratory chemical and radiological methods. When problems occur, a differentiation should preferentially be made between complaints not caused by metal and mechanical problems (e.g. prosthesis loosening and impingement) and symptoms due to periprosthetic infections.

THERAPY OF COMPLICATIONS

The normal standards for hip endoprosthetics are also valid for periprosthetic infections, fractures and other general complications. Specific measures are, however, necessary for complications due to metal-specific risks.

Childhood development after maternal metal-on-metal hip resurfacing

Metal-on-metal (MoM) hip resurfacing has been used in many young, active patients, including women of childbearing age. While ion levels have been measured in mothers with MoM hip resurfacing and their babies, little is known about how these ions affect child development. Out of 1300, MoM hip resurfacing surgeries, we had 48 women of childbearing age (defined as 40 years of age or younger at the time of surgery). These women were contacted to see if they had had pregnancies after their surgery, and those who had were sent surveys asking about their pregnancies and the development of their children. Eleven women reported pregnancies, and eight returned the surveys. There were no significant differences between women with pregnancies and those without pregnancies in any demographic or clinical measures. From the eight women who completed surveys, there were seventeen pregnancies resulting in fourteen births. There were complications in three of the births resulting in two premature births, but no children were born with birth defects. Overall, the children appear to be developing normally. Based on this unique data, we do not feel that MoM hip resurfacing is contraindicated for women of childbearing age, but power analyses show that we cannot draw conclusive results from our sample. We recommend that other groups publish their own data to allow us to generate sufficient sample sizes to draw meaningful conclusions.

[Metal ion concentrations in patients with metal-metal bearings in prostheses]

Increased wear leads to elevated systemic and local metal ion concentrations for patients treated with metal-on-metal bearings. The local metal ion content in the close environment of the joint replacement (e.g. joint aspirate or tissue) is several times higher compared to the systemic metal content (e.g. in blood or serum). As a result of increased metal ion levels, local and systemic effects, such as osteolysis, pseudotumors, sensitization or in rare cases toxicity may occur. Although the definition of a specific threshold to define clinical problems is difficult due to a lack of sensitivity, the systemic metal concentration is frequently measured clinically. Currently a threshold for cobalt and chromium between 4 µg/l and 7 µg/l is under debate. Very high levels (≥ 20 µg/l) or a steady increase over time should be a warning sign; however, metal ion levels should not be interpreted as a single diagnostic tool but rather in the entire context of the clinical, radiological and cross-sectional imaging, metal artefact reduction sequence (MARS) magnetic resonance imaging (MRI), ultrasound and computed tomography (CT) findings.