Synchrotron analysis of human organ tissue exposed to implant material

Imaging and speciation of intracellular metallic implant debris using synchrotron-based X-ray fluorescence micro-spectroscopy: a study of two cases

Debris generated from total hip arthroplasty (THA) components made from metal alloys can cause, in some cases, inflammatory cell (e.g., macrophages) responses that lead to adverse local tissue reactions (ALTR) and implant failure. The lack of information on intracellular chemical alterations of metal debris has hindered the understanding of the pathogenesis of ALTR. The goal of this study was to characterize intracellular debris within macrophages using Synchrotron imaging and spectroscopy. We studied periprosthetic tissues of two retrieved THAs with (1) a metal-on-metal (MoM) articulation and (2) a metal-on-polyethylene (MoP) articulation exhibiting corrosion of the metal femoral head. The MoM-THA exhibited different valence states of chromium- and cobalt-containing debris, suggesting three different moieties: Cr2O3, CrPO4, and an alloy-oxide mixture. The findings further suggest that Cr2O3 formed in the tribological interfaces of the implant, while CrPO4 is a by-product of the phagocytosis process of cobalt alloy-containing debris. Titanium debris appeared to occur in a mixed crystalline/amorphous oxide state. It remains unclear if this chemical state results from the tribochemical processes at the implant surface or intracellular alterations. The MoP-THA specimen exhibited no intracellular particulate debris associated with macrohpages, indicating that the ALTR may be entirely triggered by metal ionic species in this case. A better understanding of in vivo chemical alteration of implant debris will aid in assessing the risk for ALTR during implant design and material choice. However, various techniques are needed to accurately determine the interaction between metal particles and the inta- and extra-cellular environment.

In Utero Nano-Titanium Dioxide Exposure Results in Sexually Dimorphic Weight Gain and Cardiovascular Function in Offspring

Engineered nanomaterials (ENM) are capable of crossing the placental barrier and accumulating in fetal tissue. Specifically, the ENM nano-titanium dioxide (nano-TiO2), has been shown to accumulate in placental and fetal tissue, resulting in decreased birthweight in pups. Additionally, nano-TiO2 is an established cardiac toxicant and regulator of glucose homeostasis, and exposure in utero may lead to serious maladaptive responses in cardiac development and overall metabolism. The current study examines weight gain and cardiac function in male and female Sprague-Dawley rats exposed to 12 mg/m3 nano-TiO2 or filtered air for 6 non-consecutive days in utero between gestational days 12-19. These animals were randomly assigned to receive a grain-based or high-fat diet (60%) between postnatal weeks 12-24 to examine the propensity for weight gain and cardiac response as adults. Our results show a sexually dimorphic response to weight gain with male rats gaining more weight after high-fat diet following in utero nano-TiO2 exposure, and female rats gaining less weight on the high-fat diet respective of exposure. Male rats exposed to nano-TiO2 in utero had reduced ejection fraction prior to diet when compared to air controls. Female rats subjected to in utero nano-TiO2 exposure showed a significant decrease in cardiac output following 12 weeks of high-fat diet. Development of cardiovascular impairments and ultimately cardiac dysfunction and disease following in utero exposures highlights the need for occupational and environmental monitoring of nanoparticulate exposure.

The Influence of Blood Titanium Levels on DNA Damage in Brazilian Workers Occupationally Exposed to Different Chemical Agents

Occupational exposure to pollutants may cause health-damaging effects in humans. Genotoxicity assays can be used to detect the toxic effects of pollutants. In the present study, we evaluated genetic damage in three populations occupationally exposed to benzene, pyrenes, and agrochemicals and assessed the possible influence of titanium (Ti) co-exposure. A total of 275 subjects were enrolled in this study. The occupationally exposed population was composed of 201 male individuals, divided into three different groups: gas station attendants (GSA group) (n = 76), taxi drivers (TD group) (n = 97), farmers (farmers group) (n = 28), and control (n = 74). Biomarkers of exposure and effect were investigated such as AChe, BuChE, t,t-muconic acid (t,t-MA), and 1-hydroxypyrene (1-OHP). Ti levels in blood were higher in all the workers compared with the control group. DNA damage evaluated by comet assay was higher in the taxi drivers and farmers than in the controls, and the frequency of micronucleate buccal cells was higher in the gas station attendants and taxi drivers than in the controls. Correlations were found among occupational exposure time and biomarkers of exposure, genotoxicity biomarkers, and blood Ti levels. Our results demonstrated Ti co-exposure in the gas station attendants, taxi drivers, and farmers, and blood Ti levels were linked with the respective biomarkers of exposure. Additionally, tools through machine learning corroborated these findings, and Ti was the factor that contributed to DNA damage. Thus, the present study indicates the role of Ti in occupational settings and interactions with already known major xenobiotics present in the occupational environment contributing to genotoxicity.

Whole Blood Metal Levels in the Setting of an Oncologic Endoprosthesis: Is There Cause for Concern?

BACKGROUND

Massive modular endoprostheses have become a primary means of reconstruction after oncologic resection of a lower extremity tumor. These implants are commonly made with cobalt-chromium alloys that can undergo wear and corrosion, releasing cobalt and chromium ions into the surrounding tissue and blood. However, there are few studies about the blood metal levels in these patients.

QUESTION/PURPOSE

What is the whole blood cobalt and chromium ion level in patients with massive modular endoprostheses?

METHODS

We performed a cross-sectional study of our total joints registry to identify patients with a history of an endoprosthetic reconstruction performed at our institution. Patients who were alive at the time of our review in addition to those undergoing an endoprosthetic reconstruction after an oncologic resection were included. Whole blood samples were obtained from 27 (14 male and 13 female) patients with a history of a lower extremity oncologic endoprosthesis. The median time from surgery to blood collection was 8 years (range 6 months to 32 years). Blood samples were collected and stored in metal-free ethylenediaminetetraacetic acid tubes. Samples were analyzed on an inductively coupled plasma mass spectrometer in an International Organization for Standardization seven-class clean room using polytetrafluoroethylene-coated instruments to reduce the risk of metal contamination. The analytical measuring range was 1 to 200 ng/mL for chromium and cobalt. Cobalt and chromium levels were considered elevated when the blood level was ≥ 1 ppb.

RESULTS

Cobalt levels were elevated in 59% (16 of 27) of patients, and chromium levels were elevated in 26% (seven of 27). In patients with elevated metal ion values, 15 of 17 patients had a reconstruction using a Stryker/Howmedica Global Modular Replacement System implant.

CONCLUSION

Blood metal levels were elevated in patients who received reconstructions using modular oncology endoprostheses Future work is needed to establish appropriate follow-up routines and determine whether and when systemic complications occur because of elevated metal levels and how to potentially address these elevated levels when complications occur. Prospective and retrospective collaboration between multiple centers and specialty societies will be necessary to address these unknown questions in this potentially vulnerable patient group.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Detailed insight into chromium species released from failed CoCrMo implants: Ex vivo periprosthetic tissues study

This unique study provides information on Cr species and their distribution in periprosthetic tissues of patients with metal-on-polyethylene joint implants. Co-Cr-Mo alloy has been widely used in joint replacement and represents a source of metal derived species. In the case of chromium, previous studies on periprosthetic tissues revealed mainly Cr(III) distribution, whereas the potential release of carcinogenic Cr(VI) species has been still a subject of debate. Here, an analytical approach utilizing speciation and fractionation was developed to analyze periprosthetic tissue samples collected from wide range of patients with failed total hip or knee replacements. The results reveal that Cr(III) is mainly released in the form of insoluble CrPO₄ and Cr₂ O₃ particles. The highest Cr contents were found in periprosthetic tissues of patients suffering from aseptic loosening and having more Cr-based implants in the body. Cr species penetrated tissue layers, but their levels decreased with the distance from an implant. The detailed speciation/fractionation study carried out using the set of consecutive periprosthetic tissues of a patient with extensive metallosis showed the presence of trace amounts of free Cr(III), nanoparticles, and metal-protein complexes, but the majority of Cr still occurred in CrPO₄ form. Carcinogenic Cr(VI) species were not detected. Up to date, there is no published human tissue study focused on the detailed speciation of both soluble and insoluble Cr-based species in the context of failing total hip and knee replacements.

Nickel-free high-nitrogen austenitic steel outperforms CoCrMo alloy regarding tribocorrosion in simulated inflammatory synovial fluids

CoCrMo alloys are well-established biomaterials used for orthopedic joint replacement implants. However, such alloys have been associated with clinical problems related to wear and corrosion. A new generation of austenitic high-nitrogen steels (AHNSs) has been developed for biomedical applications. Here, we have addressed influences of hyaluronic acid, combined with inflammatory (oxidizing) conditions, on tribocorrosion of the high-nitrogen FeCrMnMoN_0.9 steel (DIN/EN X13CrMnMoN18-14-3, 1.4452), and of the low carbon CoCrMo_0.03 alloy (ISO 5832-12). We aimed to elucidate critical and clinically relevant conditions affecting the implant's performance in certain orthopedic applications. Tribocorrosion tests were conducted in triplicate, with discs under reciprocating sliding wear against a ceramic ball. Different lubricants were prepared from standardized bovine serum solution (ISO 14242-1), with variable additions of hyaluronic acid (HA) and hydrogen peroxide (H₂ O₂ ). Test conditions were: 37°C, 86,400 cycles, 37 N load (20-40 MPa after run-in phase). Volumetric wear was quantified; surfaces were evaluated by electrochemical parameters and microscopy/spectroscopy analyses (SEM/EDS). Factorial analysis of variance tests was conducted to examine the effects of HA, H₂ O₂ , and test material on wear- and corrosion-related dependent variables. Tribocorrosion performances of CoCrMo_0.03 and FeCrMnMoN_0.9 were comparable in fluids without H₂ O₂ . With higher H₂ O₂ concentrations, tribocorrosion increased for CoCrMo_0.03 , while this was not the case for FeCrMnMoN_0.9 . HA significantly enhanced wear of CoCrMo_0.03 in the absence of H₂ O₂ , while it mitigated the tribocorrosive action of 3 mM H₂ O₂ ; HA had no impact on FeCrMnMoN_0.9 . These results indicate a favorable performance of FeCrMnMoN_0.9 compared to CoCrMo_0.03 , and encourage further research on AHNS for certain orthopedic applications.

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.

Analysis of retrieved STRYDE nails

Aims

The aim of this study was to present the first retrieval analysis findings of PRECICE STRYDE intermedullary nails removed from patients, providing useful information in the post-market surveillance of these recently introduced devices.

Methods

We collected ten nails removed from six patients, together with patient clinical data and plain radiograph imaging. We performed macro- and microscopic analysis of all surfaces and graded the presence of corrosion using validated semiquantitative scoring methods. We determined the elemental composition of surface debris using energy dispersive x-ray spectroscopy (EDS) and used metrology analysis to characterize the surface adjacent to the extendable junctions.

Results

All nails were removed at the end of treatment, having achieved their intended lengthening (20 mm to 65 mm) and after regenerate consolidation. All nails had evidence of corrosion localized to the screw holes and the extendable junctions; corrosion was graded as moderate at the junction of one nail and severe at the junctions of five nails. EDS analysis showed surface deposits to be chromium rich. Plain radiographs showed cortical thickening and osteolysis around the junction of six nails, corresponding to the same nails with moderate – severe junction corrosion.

Conclusion

We found, in fully united bones, evidence of cortical thickening and osteolysis that appeared to be associated with corrosion at the extendable junction; when corrosion was present, cortical thickening was adjacent to this junction. Further work, with greater numbers of retrievals, is required to fully understand this association between corrosion and bony changes, and the influencing surgeon, implant, and patient factors involved.

Cite this article: Bone Jt Open 2021;2(8):599–610.

Semi-Automated Determination of Heavy Metals in Autopsy Tissue Using Robot-Assisted Sample Preparation and ICP-MS

The endoprosthetic care of hip and knee joints introduces multiple materials into the human body. Metal containing implant surfaces release degradation products such as particulate wear and corrosion debris, metal-protein complexes, free metallic ions, inorganic metal salts or oxides. Depending on the material composition of the prostheses, a systemic exposure occurs and may result in increasing metal concentrations in body fluids and tissues especially in the case of malfunctions of the arthroplasty components. High concentrations of Cr, Co, Ni, Ti and Al affect multiple organs such as thyroid, heart, lung and cranial nerves and may lead to metallosis, intoxications, poly-neuropathy, retinopathy, cardiomyopathy and the formation of localized pseudo tumors. The determination of the concentration of metals in body fluids and tissues can be used for predicting failure of hip or knee replacements to prevent subsequent severe intoxications. A semi-automated robot-assisted measurement system is presented for the determination of heavy metals in human tissue samples using inductively coupled plasma mass spectrometry (ICP-MS). The manual and automated measurement processes were similarly validated using certified reference material and the results are compared and discussed. The automation system was successfully applied in the determination of heavy metals in human tissue; the first results are presented.

In Vivo Corrosion of Sleeved Ceramic Femoral Heads: A Retrieval Study

BACKGROUND

The purpose of this study was to evaluate a series of retrieved sleeved ceramic femoral heads used in total hip arthroplasty (THA) and determine qualitative and quantitative damage and corrosion patterns.

METHODS

An IRB-approved implant retrieval database was utilized to identify all sleeved ceramic femoral heads collected from 1995 to 2004. There were 16 implants with an average duration of in situ of 70 months (range, 13-241 months). The femoral stem was known in 14 cases and was titanium alloy in each of those cases. None were revised for metal-related complications. Ten implants (63%) were from primary THAs, and 6 (38%) were from revision THAs. Damage and corrosion were qualitatively graded using a modified Goldberg method. A quantitative assessment was performed with a coordinate measurement machine (CMM).

RESULTS

Among the 16 retrieved implants, 1 (6%) demonstrated severe Grade 4 corrosion, 5 (31%) had moderate Grade 3 corrosion, 5 (31%) had mild Grade 2 corrosion, and 5 (31%) had no visible corrosion at the inner sleeve that interfaces with the stem trunnion. The only case of grade 4 corrosion occurred in the only head-sleeve in the study that was not factory assembled and was mated with a titanium molybdenum zirconium ferrous (TMZF) alloy stem. The mean maximum linear corrosion depth at the taper interface, as measured by the CMM, was 7.7 microns (range, 0.9-32.9 microns).

CONCLUSION

This study is the first to quantify corrosion at the titanium interface of sleeved ceramic femoral heads. Potentially clinically significant damage and corrosion patterns were observed in a few failed retrievals; however, the majority of cases demonstrated minimal or no damage.

No association between blood count levels and whole-blood cobalt and chromium levels in 1,900 patients with metal-on-metal hip arthroplasty

Background and purpose - The accelerated wear of poorly functioning metal-on-metal (MoM) hip implants may cause elevated whole-blood cobalt (Co) and chromium (Cr) levels. Hematological and endocrinological changes have been described as the most sensitive adverse effects due to Co exposure. We studied whether there is an association between whole-blood Co/Cr levels and leukocyte, hemoglobin, or platelet levels. Patients and methods - We analyzed whole-blood Co and Cr values and complete blood counts (including leukocytes, hemoglobin, platelets) from 1,900 patients with MoM hips. The mean age at the time of whole-blood metal ion measurements was 67 years (SD 10). The mean time from primary surgery to whole-blood metal ion measurement was 8.2 years (SD 3.0). The mean interval between postoperative blood counts and metal ion measurements was 0.2 months (SD 2.7). Results - The median Co value was 1.9 µg/L (0.2-225), Cr 1.6 µg/L (0.2-125), mean leukocyte count 6.7 × 10⁹/L (SD 1.9), hemoglobin value 143 g/L (SD 13), and platelet count 277 × 10⁹/L (SD 70). We did not observe clinically significant correlations between whole-blood Co/Cr and leukocyte, hemoglobin, or platelet counts. Interpretation - Elevated whole-blood Co and Cr values are unlikely to explain abnormal blood counts in patients with MoM hips and the reason for possible abnormal blood counts should be sought elsewhere.

Ion-exchange HPLC-ICP-MS: A new window to chromium speciation in biological tissues

The presented work proposes a novel analytical ICP-MS-based approach for the accurate and precise chromium speciation in biological tissues. The determination of total Cr(VI) and soluble Cr(III) species was carried out by alkaline EDTA extraction followed by their separation using ion-exchange high-performance liquid chromatography inductively coupled plasma mass spectrometry (IE-HPLC-ICP-MS). The developed method was validated according to the procedure given in the United States Food and Drug Administration guideline on the validation of bioanalytical methods. Validation parameters included limit of detection (≤ 0.03 μg g^-1), limit of quantification (≤ 0.08 μg g^-1), linearity (r ≥ 0.9998), intra-day and inter-day accuracy (86-110%) and precision (≤ 10%), extraction recovery (89-110%), carry-over effect and sensitivity. In addition, special attention was paid to the study of chromium species interconversion and the elimination of spectral interferences. Moreover, the validated ICP-MS method employing microwave acid digestion was used to determine the total Cr content in collected fractions. Finally, the whole ICP-MS-based methodology was applied to the analyses of two certified reference materials of hepatopancreas tissue. Obtained results indicated that the majority of chromium in biological tissues is bound to the solid residue, Cr(VI) was determined in none of the samples investigated. This is the first study focusing on soluble Cr(III), total Cr(VI), and total bound Cr species in biological tissues. It is characterized by efficient sample preparation and fast simultaneous analysis of Cr species with parallel total Cr analysis serving for chromium balance evaluation.

Cobalt and Chromium Ion Release in Metal-on-Polyethylene and Ceramic-on-Polyethylene THA: A Simulator Study With Cellular and Microbiological Correlations

BACKGROUND

The aims of this study were to determine the levels of cobalt (Co) and chromium (Cr) ions generated in simulators from metal-on-polyethylene (MoP) and ceramic-on-polyethylene (CoP) constructs. Furthermore, we aimed to investigate the cytotoxic effect of these ion levels on native tissues and their potential to modify periprosthetic joint infection risk.

METHODS

We used in vitro culture of human adipose-derived mesenchymal stem cells (AMSCs) and Staphylococcus epidermidis cultures, respectively. Ten hip simulator constructs (5 MoP and 5 CoP) were assembled and run for 1,000,000 cycles in bovine serum and evaluated for CoCr concentration. Cytotoxicity and growth impact on AMSCs and S. epidermidis was compared between CoCr and inert silicon dioxide.

RESULTS

After 1,000,000 cycles, mean MoP and CoP Co concentration was 2264 and 0.6 ng/mL, respectively (P < .001). Mean MoP and CoP Cr concentration was 217 and 4.3 ng/mL, respectively (P < .001). Mean MoP Co:Cr ratio was 10:1. Co ions were significantly more toxic to human AMSCs than control silicon dioxide in a dose-response manner (P < .001). S. epidermidis growth was not significantly impacted by Co concentrations observed in the simulators.

CONCLUSION

MoP constructs built in ideal conditions generated substantial CoCr debris, highlighting a baseline risk with these implants that may be exacerbated by host factors or imperfect surgical technique. Evaluation of impact on AMSCs suggests that debris levels produced under simulator conditions can be cytotoxic. In addition, these concentrations did not potentiate or inhibit S. epidermidis growth, suggesting that elevated periprosthetic joint infection rates with adverse local tissue reaction are related to other factors potentially associated with tissue necrosis.

Blood and plasma titanium levels associated with well-functioning hip implants

BACKGROUND

Hip implants are usually manufactured from cobalt-chromium and titanium alloys. As the implants wear and corrode, metal debris is released into the surrounding tissue and blood, providing a potential biomarker for their function. Whilst there are laboratory reference levels for blood cobalt and chromium in patients with well and poorly functioning hip implants, there are no such guidelines for titanium. This is despite the increasing use of titanium implants worldwide.

PATIENTS AND METHODS

We recruited a consecutive series of 95 patients (mean age 71 years, mean time after surgery 8.5 years) with one hip implant type, inserted by the same surgeon. We assessed clinical and radiological outcome, and measured blood and plasma titanium using high resolution inductively-coupled plasma mass spectrometry.

RESULTS

The upper normal reference limit for blood and plasma titanium was 2.20 and 2.56 μg L^-1, respectively, and did not differ significantly between males and females.

CONCLUSION

We are the first to propose a laboratory reference level for blood and plasma titanium in patients with well-functioning titanium hip implants. This is an essential starting point for further studies to explore the clinical usefulness of blood titanium as a biomarker of orthopaedic implant performance, and comes at a time of considerable controversy regarding the use of certain titanium alloys in hip arthroplasty.

Improving our understanding of metal implant failures: Multiscale chemical imaging of exogenous metals in ex-vivo biological tissues

Biological exposures to micro- and nano-scale exogenous metal particles generated as a consequence of in-service degradation of orthopaedic prosthetics can result in severe adverse tissues reactions. However, individual reactions are highly variable and are not easily predicted, due to in part a lack of understanding of the speciation of the metal-stimuli which dictates cellular interactions and toxicity. Investigating the chemistry of implant derived metallic particles in biological tissue samples is complicated by small feature sizes, low concentrations and often a heterogeneous speciation and distribution. These challenges were addressed by developing a multi-scale two-dimensional X-ray absorption spectroscopic (XAS) mapping approach to discriminate sub-micron changes in particulate chemistry within ex-vivo tissues associated with failed CoCrMo total hip replacements (THRs). As a result, in the context of THRs, we demonstrate much greater variation in Cr chemistry within tissues compared with previous reports. Cr compounds including phosphate, hydroxide, oxide, metal and organic complexes were observed and correlated with Co and Mo distributions. This variability may help explain the lack of agreement between biological responses observed in experimental exposure models and clinical outcomes. The multi-scale 2D XAS mapping approach presents an essential tool in discriminating the chemistry in dilute biological systems where speciation heterogeneity is expected. SIGNIFICANCE: Metal implants are routinely used in healthcare but may fail following degradation in the body. Although specific implants can be identified as 'high-risk', our analysis of failures is limited by a lack of understanding of the chemistry of implant metals within the peri-prosthetic milieu. A new approach to identify the speciation and variability in speciation at sub-micron resolution, of dilute exogenous metals within biological tissues is reported; applied to understanding the failure of metallic (CoCrMo) total-hip-replacements widely used in orthopedic surgery. Much greater variation in Cr chemistry was observed compared with previous reports and included phosphate, hydroxide, oxide, metal and organic complexes. This variability may explain lack of agreement between biological responses observed in experimental exposure models and clinical outcomes.

Blood titanium level as a biomarker of orthopaedic implant wear

BACKGROUND

Joint replacement implants are usually manufactured from cobalt-chromium or titanium alloys. After the device is implanted, wear and corrosion generate metal particles and ions, which are released into local tissue and blood. The metal debris can cause a range of adverse local and systemic effects in patients.

RESEARCH PROBLEM

In the case of cobalt and chromium, a blood level exceeding 7 μg L^-1 indicates potential for local toxicity, and a failing implant. It has been repeatedly suggested in the literature that measurement of titanium could also be used to assess implant function. Despite an increasing interest in this biomarker, and growing use of titanium in orthopaedics, it is unclear what blood concentrations should raise concerns. This is partly due to the technical challenges involved in the measurement of titanium in biological samples.

AIM

This Review summarises blood/serum titanium levels associated with well-functioning and malfunctioning prostheses, so that the prospects of using titanium measurements to gain insights into implant performance can be evaluated.

CONCLUSION

Due to inter-laboratory analytical differences, reliable conclusions regarding "normal" and "abnormal" titanium levels in patients with orthopaedic implants are difficult to draw. Diagnosis of symptomatic patients should be based on radiographic evidence combined with blood/serum metal levels.

Systemic cobaltism manifesting as oral mucosal discoloration and metallic gustation after metal-on-metal hip resurfacing

Systemic cobaltism is a debilitating complication of metal-on-metal (MoM) arthroplasty. In this report, we review a case of a 54-year-old female with metallosis from a MoM hip resurfacing and varying degrees of black discoloration of her tongue and metallic gustation as a result of systemic cobaltism. After explanting the metal components, thorough debridement, and conversion to ceramic-on-polyethylene arthroplasty, the patient's oral mucosal discoloration and metallic gustation resolved. This represents the first documentation of systemic cobaltism from MoM hip resurfacing manifesting as oral mucosal discoloration and metallic gustation with resolution after explant, debridement, and conversion to ceramic-on-polyethylene total hip arthroplasty.