Metal implant segmentation in CT images based on diffusion model.

BACKGROUND: Computed tomography (CT) is widely in clinics and is affected by metal implants. Metal segmentation is crucial for metal artifact correction, and the common threshold method often fails to accurately segment metals. PURPOSE: This study aims to segment metal implants in CT images using a diffusion model and further validate it with clinical artifact images and phantom images of known size. METHODS: A retrospective study was conducted on 100 patients who received radiation therapy without metal artifacts, and simulated artifact data were generated using publicly available mask data. The study utilized 11,280 slices for training and verification, and 2,820 slices for testing. Metal mask segmentation was performed using DiffSeg, a diffusion model incorporating conditional dynamic coding and a global frequency parser (GFParser). Conditional dynamic coding fuses the current segmentation mask and prior images at multiple scales, while GFParser helps eliminate high-frequency noise in the mask. Clinical artifact images and phantom images are also used for model validation. RESULTS: Compared with the ground truth, the accuracy of DiffSeg for metal segmentation of simulated data was 97.89% and that of DSC was 95.45%. The mask shape obtained by threshold segmentation covered the ground truth and DSCs were 82.92% and 84.19% for threshold segmentation based on 2500 HU and 3000 HU. Evaluation metrics and visualization results show that DiffSeg performs better than other classical deep learning networks, especially for clinical CT, artifact data, and phantom data. CONCLUSION: DiffSeg efficiently and robustly segments metal masks in artifact data with conditional dynamic coding and GFParser. Future work will involve embedding the metal segmentation model in metal artifact reduction to improve the reduction effect.

A new suture fixation technique for the Akin osteotomy of the proximal phalanx: You don't need any implant.

BACKGROUND: Various fixation methods have been described for Akin osteotomy, based on using metal implants or transosseous sutures. The aim of this study was to evaluate radiological outcomes and complications of closing wedge Akin osteotomy based on a crossed suture configuration of the joint capsule rather than using implants. The null hypothesis is that a crossed suture has comparable radiological results to other techniques, with no additional complications. METHODS: It's a retrospective study. Patients who underwent Akin osteotomy fixed either with implant or joint capsule suture between 2015 and 2018 were included. Distal articular set angle corrections in pre- and postoperative anteroposterior foot x-rays were calculated by 2 observers. Complications, such as pain, infection, non-union and need of surgery revision, was compared at 1 year follow-up. RESULTS: 89 patients, 30 in the implant group and 59 in the suture group. Mean distal articular set angle corrections were 6.43 (SD 5.54) and 7.36 (SD 5.48) degrees in the implant and suture groups, respectively, without statistically significant differences (p 0454). Complications were 2 local pain and 1 wound infection cases in the suture and implant groups, respectively (p 0138, p 0197). CONCLUSION: Akin osteotomy with suture fixation yields comparable radiological results to metal implant fixation methods without increasing the associated complications.

Panniculitis as a manifestation of metal-associated autoimmune/inflammatory syndrome induced by adjuvants: a case-based review.

Autoimmune/inflammatory syndrome induced by adjuvants (ASIA) is associated with a hyperergic response of the immune system. The spectrum of clinical changes in ASIA is extensive and difficult to diagnose. Panniculitis is a heterogeneous group of diseases characterized by lesions of the adipose tissue. Panniculitis may become one of the signs of ASIA progress.To describe the clinical signs and morphological changes in the subcutaneous fat as a manifestation of ASIA, developing after osteosynthesis with metal structures.In this case-based review, were searched for all articles published in PubMed and Scopus databases until March, 2021 using the following keywords "panniculitis", "erythema nodosum", "Weber-Christian Disease", "idiopathic lobular panniculitis", "Autoimmune/inflammatory syndrome induced by adjuvants", "Shoenfeld's syndrome", "metal allergy" "metal implants", "metal hypersensitivity" and reviewed them. Irrelevant items and duplicates were excluded.We report a case of an adult female patient presenting with a non-healing uninfected surgical wound following implantation of metal osteosynthesis construction and panniculitis developed after surgery. A comprehensive examination of the patient to check for ASIA was conducted. Considering the medical history of exposure to metals, tissue lesions, arthralgia, myalgia, low-grade fever, the disappearance of symptoms on the background of immunosuppressive therapy suggested the diagnosis of ASIA.Report affords clinicians and pathologists additional insight into the clinical and morphological picture of ASIA-associated panniculitis which, if remain unidentified, may cause severe complications. We recommend the removal of constructions with adjuvant activity in patients with suspected ASIA-associated manifestations.

Single energy metal artifact reduction performs better than virtual monoenergetic dual-energy reconstruction in CT of the equine proximal phalanx.

Metal artifacts in CT negatively impact the evaluation of surgical implants and the surrounding tissues. The aim of this prospective experimental study was to evaluate the ability of a single energy metal artifact reduction (SEMAR™, Canon) algorithm and virtual monoenergetic (VM) dual-energy CT (DECT) scanning techniques to reduce metal artifacts from stainless steel screws surgically inserted into the equine proximal phalanx. Seven acquisitions of 18 cadaver limbs were performed on a Canon Aquilion One Vision CT scanner (Helical +SEMAR, Volume +SEMAR, Standard Helical, Standard Volume and VM DECT at 135, 120, and 105 keV) and reconstructed in a bone kernel. Blinded subjective evaluation performed by three observers indicated a significant effect of acquisition in both adjacent tissues (P < 0.001) and distant tissues (P < 0.001) and the best metal artifact reduction was seen with Helical +SEMAR and Volume +SEMAR. The subjective overall preference of CT acquisition type was (1) Helical +SEMAR, (2) Volume +SEMAR, (3) VM DECT 135 keV, (4) VM DECT 120 keV, (5) VM DECT 105 keV, (6) Standard Helical, (7) Standard Volume (P < 0.001). Unblinded objective evaluation performed by one observer showed that VM DECT 120 keV, Helical +SEMAR, and Volume +SEMAR performed similarly and were objectively the best at reducing blooming artifact. Overall, the best metal artifact reduction was obtained with SEMAR, followed by VM DECT. However, VM DECT performance varies with energy level and was associated with decreased image quality in distant tissues and artifactual overcorrection of metal artifacts at high energy levels.

Electromagnetic field exposure to human head model with various metal objects at sub-6 GHz frequencies.

In recent years, the interactions of metal objects in human body with electromagnetic fields caused by devices working at fifth-generation (5G) frequencies have been studied by various researchers. A motivation behind this research was to evaluate the human body absorption of electromagnetic energy operating at sub-6 GHz 5G applications. According to this, the specific absorption rate (SAR) caused by new generation mobile phones was investigated in human heads wearing metal-framed spectacles and having metallic implants or earrings to analyse electromagnetic field exposure. A realistic human head model, including some metal objects, was numerically calculated, and analysed in terms of non-ionizing dosimetry. Simulations were carried out with the finite integration technique (FIT) based commercial software in the frequencies of 0.9, 1.8, 2.1, 2.45, 3.5 and 5 GHz, respectively. The maximum SAR of 14 × 10-5 W/kg for 10 g average tissue was calculated at 2.45 GHz frequency in the head model with earrings. The highest electric field strength of 0.52 V/m was observed at a 1.8 GHz frequency in the head model with all metal objects equipped. Results show that metal objects such as spectacles, dental implants and earrings can cause an increase in the SAR values for external biological tissues, and metal objects can behave as a kind of shield for deeper tissues. However, the obtained values are below the limits of international organisations.

Indications for the removal of implants after fracture healing: A comparison between human and veterinary medicine.

Indications for implant removal after fracture healing are still under debate in both human and veterinary medicine. Although hardware removal is a common procedure, it should not be undertaken lightly. Intra and post-operative complications are common and a thorough evaluation of the risks and benefits should be performed. This review aimed to collect and summarise published data on the indications for implant removal in small animals, compare the collected data with human and equine medicine, and investigate the existence of guidelines for this purpose. There is no international consensual agreement for implant removal after fracture healing, neither in small animals nor in human orthopaedics. Decision-making processes are still controversial in some scenarios, thus clear evidence-based protocols for implant removal are needed.

Contact sensitization to iron: A potentially underestimated metal allergen and elicitor of complications in patients with metal implants.

BACKGROUND: Little is known about sensitization to iron (Fe) in private, occupational, and medical settings, particulary implantology. OBJECTIVES: To investigate sensitization to metals, particularly to Fe, both in pre-implant individuals with presumed metal allergy and in patients with suspected metal implant allergy. To further characterize Fe-sensitized individuals. METHODS: Analysis of patch test reactions to an Fe (II) sulfate-containing metal series in 183 consecutive patients (41 pre-implant, 142 metal implant bearers). Test readings were on day (D)2, D3, and D6. Evaluation of questionnaire-aided history of metal reactivity patterns and demographics of Fe reactors. RESULTS: Metal reactivity in pre-implant/implant/total group was: to nickel 39%/30%/32%; to cobalt 17%/15%/15%; and to chromium 7%/13%/11%. Co-sensitizations cobalt/nickel (19/58) and cobalt/chromium (11/21) were significant at P < .001; co-sensitizations Fe/nickel (4/10) and chromium/knee arthroplasty (11/73) at P = .03. Ten of 183 (5.5%) reacted to Fe (2 of 41 pre-implant patients, 8 of 142 implant bearers), with 10 reacting only on D6. Fe reactivity was highest in complicated knee arthroplasty (7/73). Further peculiarities of Fe reactors included frequent isolated Fe reactivity (6/10), occupational metal exposure (7/10), previous (par)enteral Fe substitution (6/10). CONCLUSIONS: The 5.5% prevalence of Fe reactions suggests a potentially underestimated role of this metal allergen in general and in implant bearers. The latter also shows a distinct metal sensitization pattern.

Primary Stability of Trabecular Metal Implant in Comparison to Fully Threaded Implants: In Vitro Study Simulating Immediate Implant Placement.

The aim of this study was to evaluate primary stability of 3.7-mm diameter porous tantalum Trabecular Metal (TM) implant, and compare it to fully threaded implants, in the in vitro model of immediate implant placement in the anterior maxilla. A total of 60 implants were placed into bovine ribs using surgical guides. Implants were divided in 3 groups of 20 according to the design: TM, Tapered Screw-Vent (TSV), and NobelReplace. To simulate immediate placement in anterior maxilla, implants were placed under a sharp angle toward the ribs, not fully submerged. Placement angle of 20.7° was calculated after analysis of 148 virtually planned implants on cone beam computerized tomography scans of 40 patients. No statistically significant difference in implant stability quotient (ISQ) was found between TM (65.8 ± 2.6), TSV (64.7 ± 2.7), and NobelReplace (64.6 ± 2.7). TSV implants achieved higher insertion torque (37.0 ± 4.8 Ncm) than TM (32.9 ± 5.2 Ncm) and NobelReplace (23.2 ± 3.3 Ncm). TSV had the shortest insertion time of 13.5 ± 1.0 seconds, compared to 15.2 ± 1.2 seconds for TM, and 19.7 ± 1.7 seconds for NobelReplace. Pearson correlation analysis showed significantly correlated insertion torque and ISQ values for TM group (P = .011, r = .56), a nonsignificant correlation was found for TSV and NobelReplace. The results of the present study indicate that TM implant can achieve good primary implant stability in insertion torque and resonance frequency analysis.

A new suture fixation technique for the Akin Osteotomy of the Proximal Phalanx: You don't need any implant.

BACKGROUND: Various fixation methods have been described for Akin osteotomy, based on using metal implants or transosseous sutures. The aim of this study was to evaluate radiological outcomes and complications of closing wedge Akin osteotomy based on a crossed suture configuration of the joint capsule rather than using implants. The null hypothesis is that a crossed suture has comparable radiological results to other techniques, with no additional complications. METHODS: It's a retrospective study. Patients who underwent Akin osteotomy fixed either with implant or joint capsule suture between 2015 and 2018 were included. Distal articular set angle corrections in pre- and postoperative anteroposterior foot x-rays were calculated by 2 observers. Complications, such as pain, infection, non-union and need of surgery revision, was compared at 1 year follow-up. RESULTS: 89 patients, 30 in the implant group and 59 in the suture group. Mean distal articular set angle corrections were 6.43 (SD 5.54) and 7.36 (SD 5.48) degrees in the implant and suture groups, respectively, without statistically significant differences (p 0.454). Complications were 2 local pain and 1 wound infection cases in the suture and implant groups, respectively (p 0.138, p 0.197). CONCLUSION: Akin osteotomy with suture fixation yields comparable radiological results to metal implant fixation methods without increasing the associated complications.

Effects of metal implants and validation of four treatment planning methods used for radiotherapy dose calculation.

Background: The radiotherapy treatment planning process involves target delineation and dose calculation, both of which directly depend on image quality and Hounsfield unit (HU) accuracy of computed tomography (CT) images. CT images of patients having metal implants undergo image quality deterioration and show inaccurate HU values due to various artifacts. Metal artifact reduction (MAR) is used to improve the image quality. In this study, four treatment planning methods with and without MAR, in combination with actual and assigned HU values, were analyzed for dose calculation accuracy. The aim was to study the effects of metal implants on planning CT and to evaluate the dose calculation accuracy of four treatment planning methods for radiotherapy. Materials and methods: Two phantoms with six different metal inserts were scanned in the extended HU mode, with and without MAR. Geometry verification and HU analysis of the metals and the surrounding region were carried out. Water equivalent distance (WED) measurements and dose calculation for each metal insert were done in the treatment planning system (TPS) using the anisotropic analytical algorithm (AAA). Point dose and two-dimensional dose distribution were studied. Percentage variation analysis between calculated and measured doses and gamma evaluation were conducted to determine the most suitable method for treatment planning. Conclusion: This study concludes that an MARCT image with an assigned HU similar to that of the metal implant is better for contouring and high dose calculation accuracy. If MAR is not available, the actual HU value from the extended HU CT for the metal should be used for dose calculation.

The ototoxic potential of cobalt from metal-on-metal hip implants: a pilot study on the patient-reported auditory, vestibular, and general neurological outcome.

OBJECTIVE: This study aimed to systematically investigate the ototoxic potential of cobalt in patients with a metal-on-metal (MoM) hip implant, using objective auditory and vestibular assessments and a questionnaire. The results of the objective evaluation were published previously, whereas the current study focused on the questionnaire outcome and its relationship to the blood cobalt level. Design and study sample: Twenty patients (33-65 years) with a primary MoM hip implant and 20 non-implanted control subjects, matched for age, gender, and noise exposure, received a questionnaire to evaluate the presence of several hearing and balance symptoms (part 1) and general neurological issues (part 2). RESULTS: Concerning part 1, the proportion of auditory-related symptoms in general (p = 0.022) and tinnitus (p = 0.047) was significantly higher in the MoM patient group, whereas no group difference was found for hyperacusis, increased listening effort, and decreased speech understanding. Concerning part 2, no significant group differences were detected. Within the MoM patient group, the questionnaire outcome was not significantly different between the low-exposure and high-exposure subgroups according to the blood Co level. CONCLUSIONS: In line with our previous study, these results potentially imply Co-induced impairment to the auditory system, despite the lack of a clear dose-response relationship.

Prevalence of metal hypersensitivity in patients with shoulder pathologies.

BACKGROUND: To date, medical history and dedicated questionnaires are the fastest and easiest way to assess risks of joint metal hypersensitivity. No published studies determined the overall prevalence of hypersensitivity to metals in patients with shoulder pathologies. The purpose of this study was therefore to estimate the prevalence of metal hypersensitivity reported by patients with shoulder pathologies, and to identify patients at risk of joint metal hypersensitivity based on a dedicated questionnaire. METHODS: The authors prospectively asked all adult patients consulting for shoulder pathologies between September 2018 and February 2019 at 10 centers to fill in a form. The main outcome was "reported hypersensitivity to metals," comprising belt buckles, coins, earrings, fancy jewelry, keys, leather, metallic buttons, piercings, spectacles, watch bracelets, or zips. RESULTS: A total of 3217 patients agreed to fill in the survey, aged 55 ± 16 (range, 18-101) with equal proportions of men (51%) and women (49%), and a majority of patients consulting for cuff pathology (55%). A total of 891 (28%) patients had professions considered at risk for metal hypersensitivity. The most frequently reported metal hypersensitivities were fancy jewelry (15%), earrings (13%), and watch bracelets (9%). A total of 629 (20%) patients, of which the vast majority were women, reported hypersensitivity to 1 or more metals. CONCLUSIONS: This survey of 3217 patients identified 20% who reported metal hypersensitivities, though only 2.2% had done patch tests. Matching profiles of those with positive patch tests to those with no patch tests revealed that 9.4% of the total cohort had similar sex and self-reported metal hypersensitivities. Factors associated with a positive patch test were female sex, self-reported cutaneous allergy, and self-reported metal hypersensitivity. The clinical applicability of these estimates remains uncertain as there is insufficient evidence that allergy to metal implants can be predicted by questionnaires or patch tests.

Adaptive SAR mass-averaging framework to improve predictions of local RF heating near a hip implant for parallel transmit at 7 T.

PURPOSE: Magnetic resonance imaging is used increasingly to scan patients with hip prostheses. We evaluated the reliability of 10 g-averaged specific absorption rate (SAR10g ) to predict radiofrequency (RF) heating in tissues surrounding a hip implant at 7 T in an 8-channel pTx hip coil. A new adaptive SAR mass-averaging method is proposed to improve the correlation between the distribution of mass-averaged SAR and that of tissue temperature. METHODS: Currently, RF safety standards for implants are based on temperature instead of SAR, as SAR has not been introduced with regard to exposure scenarios with implants. In this manuscript, however, adaptive SAR is proposed for fast and reliable exposure evaluation with implants, after its correlation with tissue temperature is verified. A framework to calculate adaptive SAR mass-averaging was introduced, which uses a different averaging mass in tissues surrounding the implants and was designed to prevent the temperature from exceeding 39ºC. Predictions from SAR10g and adaptive SAR were compared with thermal simulations. RESULTS: The SAR10g method failed to predict both the location and amplitude of heating in tissue near the metal implants. In some cases, the temperature far exceeded 39ºC even when SAR10g was only 70% of the maximum allowed 10 W/kg. The distributions of adaptive SAR and temperature matched in most of the configurations, and the temperature remained below 39ºC when adaptive SAR was constrained. CONCLUSION: Adaptive SAR can accurately monitor RF heating and could be used for parallel transmit at 7 T to supplement current standards.

Dual-layer spectral computerized tomography for metal artifact reduction: small versus large orthopedic devices.

INTRODUCTION: Metal artifacts limit the diagnostic utility of computerized tomography (CT) for implant-related complications. Dual-layer spectral detector CT imaging has been suggested for artifact reduction. Our objective was to evaluate the utility of spectral CT in artifact reduction in patients with small and large metal implants. METHODS: In this prospective study, patients with metallic orthopedic implants underwent CT imaging using a prototype spectral detector CT scanner. Conventional images were generated with iterative reconstruction at 120 kVp, and virtual monochromatic images were generated at 20-keV intervals between 40 to 200 keV. Conventional and monochromatic images were compared quantitatively using signal-to-noise ratio (SNR) and artifact improvement. Qualitative analysis was performed independently by two musculoskeletal radiologists and included six image quality indicators. RESULTS: A total of 12 patients were scanned. In monochromatic images, as the energy level increased, the artifact size decreased progressively (p < 0.01). When conventional and monochromatic images were compared, maximum reduction was seen at 200 keV. Using qualitative assessments, 160 and 180 keV levels had the best overall diagnostic image quality. With increased energy level, there was improvement in qualitative ratings of bone-metal interface conspicuity (p = 0.002), degree of streak artifact (p = 0.010) and trabecular bone definition at 1 cm from implant (p = 0.023), and a trend towards significance for bone definition at 5 cm, soft tissue detail and overall diagnostic quality. Subgroup analysis revealed superior artifact reduction in small implants compared to large hardware. DISCUSSION: Our results support the utility of dual-layer spectral CT in metal artifact reduction. Virtual monochromatic images were diagnostically superior, especially for smaller implants. Virtual monoenergetic images at 160-180 keV are ideal for reducing artifacts.

Five-pointed star lattice sutures for fixation of patella transverse fractures: a clinical study.

INTRODUCTION: Fixation of displaced patella fractures with metal implants may be associated with implant failure, post-operative pain, and high re-operation rate. This study reports preliminary clinical results of using five-pointed star lattice sutures for the management of patella transverse fractures. METHODS: A five-pointed star lattice suture configuration was produced intraoperatively, and 25 patients with patella transverse fractures were treated with this newly designed sutures fixation. All patients were followed up until union of the fractures or until further surgical intervention. At a mean of 1.6 years (range 0.8-2.5 years) of follow-up, the notes and plain radiographs of the 25 patients were reviewed. Bostman score was used to evaluate the therapeutic effects. RESULTS: All 25 patients experienced union of the patella fractures, with excellent knee function in 19 patients and good in 6 patients evaluated with Bostman score. CONCLUSION: The newly designed five-pointed star lattice sutures fixation may be a feasible alternative to metal implants fixation in the management of patella transverse fracture. LEVEL OF EVIDENCE: Level IV case series.

Total hip arthroplasty following failure of tantalum rod implantation for osteonecrosis of the femoral head with 5- to 10-year follow-up.

BACKGROUND: Total hip arthroplasty (THA) with failure of tantalum rod implant for osteonecrosis of the femoral head (ONFH) will be the only choice for patients. However,it remains unknown whether tantalum rod implantation has an adverse effect on the survival time of implants following conversion to THA. The aim of this study was to retrospectively evaluate the clinical and radiographic outcomes of conversion to THA in patients who were previously treated with implantation of a tantalum rod. METHODS: This study included 31 patients (39 hips), who underwent conversion to THA due to failure of core decompression with an implanted tantalum rod. Among these 31 patients, 26 patients were male and five patients were female. The mean age of these patients was 49.3 years old (range: 36-64 years old). The control group included 33 patients (40 hips), who underwent total hip replacement without tantalum rod implantation. The hip Harris score, implant wear, osteolysis, radiolucencies and surgical complications were recorded during the follow-up. The distribution of tantalum debris in the proximal, middle and distal periprosthetic femoral regions, radiolucent lines and osteolysis were analyzed on post-operative radiographs. RESULTS: There were no significant differences in Harris score, liner wear and complications between the two groups (P > 0.05). Osteolysis and radiolucent lines more likely occurred in patients with tantalum debris distributed in three regions than in one or two regions (P < 0.05). CONCLUSIONS: The mid-term clinical outcome of patients who underwent THA with tantalum rod implantation was not different from those without a tantalum rod, suggesting that tantalum debris did not increase the liner wear rate. However, the distribution of periprosthetic tantalum debris in the proximal, middle and distal femoral regions may increase the risk of femoral osteolysis and radiolucent lines.

Iterative algorithms for metal artifact reduction in children with orthopedic prostheses: preliminary results.

BACKGROUND: Increased computational power allows computed tomography (CT) software to process very advanced mathematical algorithms to generate better quality images at lower doses. One such algorithm, iterative metal artifact reduction (iMAR) has proven to decrease metal artifacts seen in CT images of adults with orthopedic implants. OBJECTIVES: To evaluate artifact reduction capability of the algorithm in lower-dose pediatric CT compared to our routine third-generation advanced modeled iterative reconstruction (ADMIRE) algorithm. MATERIALS AND METHODS: Thirteen children (11-17 years old) with metal implants underwent routine clinically indicated CT. Data sets were reconstructed with an iMAR algorithm. Hounsfield units and image noise were measured in bone, muscle and fat in the streak artifact (near the implant) and at the greatest distance from the artifact (far from the implant). A regression model compared the effects of the algorithm (standard ADMIRE vs. iMAR) near and far from the implant. RESULTS: Near the implant, Hounsfield units with iMAR were significantly different in our standard ADMIRE vs. iMAR for bone, muscle and fat (P<0.001). Noise was significantly different in standard ADMIRE vs. iMAR in bone (P<0.003). Far from the implant, Hounsfield units and noise were not significantly different for ADMIRE vs. iMAR, for the three tissue types. CONCLUSION: These preliminary results demonstrate that iMAR algorithms improves Hounsfield units near the implant and decreases image noise in bone in low-dose pediatric CT. It does this without changing baseline tissue density or noise far from the implant.

Induced histamine regulates Ni elution from an implanted Ni wire in mice by downregulating neutrophil migration.

Histamine regulates various inflammatory reactions. We have reported that the expression of histidine decarboxylase (HDC) was induced by subcutaneous implantation of nickel (Ni) wire. However, the source and functions of histamine in Ni elution and Ni wire-induced inflammation have not been completely studied. We aimed to elucidate the effects of de novo synthesized histamine on leucocyte infiltration and Ni elution. Implantation of Ni wire induced an increase in the Ni ion content of the surrounding tissues and serum and in the mRNA levels of HDC, a histamine-producing enzyme, macrophage inflammatory protein-2 (MIP-2), a chemoattractant for neutrophils, and monocyte chemoattractant protein-1 (MCP-1), a chemoattractant for monocytes. The Ni wire induced HDC expression even in mast cell-deficient WBB6F1-W/WV mice. In HDC knockout (HDC KO) mice, the Ni wire-induced increase in MIP-2 mRNA expression was significantly higher than that in wild-type mice but not MCP-1. MIP-2 expression was enhanced in histamine H2 receptor knockout (H2R KO) mice but not in WBB6F1-W/WV mice. Histamine inhibited NiCl2 -induced MIP-2 mRNA expression in mouse bone marrow-derived macrophages (BMDMs) obtained from wild-type mice; this inhibition was not observed in BMDMs from H2R KO mice. Ni elution increased in HDC KO mice, in which leucocyte infiltration also increased, and was suppressed in mice treated with neutrophil-specific antibody. These results suggest that the Ni wire induced HDC expression in non-mast cells and that, in the chronic phase of inflammation, endogenous histamine reduced Ni elution, probably through regulation of MIP-2 expression and neutrophil migration.

Are metals involved in tattoo-related hypersensitivity reactions? A case report.

BACKGROUND: Allergic reactions to tattoos are not uncommon. However, identification of the culprit allergen(s) remains challenging. OBJECTIVES: We present a patient with papulo-nodular infiltration of 20-year-old tattoos associated with systemic symptoms that disappeared within a week after surgical removal of metal osteosynthesis implants from his spine. We aimed to explore the causal relationship between the metal implants and the patient's clinical presentation. METHODS: Metal implants and a skin biopsy of a reactive tattoo were analysed for elemental contents by inductively coupled plasma mass spectrometry and synchrotron-based X-ray fluorescence (XRF) spectroscopy. RESULTS: Nickel (Ni) and chromium (Cr) as well as high levels of titanium (Ti) and aluminium were detected in both the skin biopsy and the implants. XRF analyses identified Cr(III), with Cr(VI) being absent. Patch testing gave negative results for Ni and Cr. However, patch tests with an extract of the implants and metallic Ti on the tattooed skin evoked flare-up of the symptoms. CONCLUSION: The patient's hypersensitivity reaction and its spontaneous remission after removal of the implants indicate that Ti, possibly along with some of the other metals detected, could have played a major role in this particular case of tattoo-related allergy.

Verification of Implant Surface Modification by a Novel Processing Method.

Metals have been used clinically as biomaterials, especially in the orthopaedic and dental fields. Metals used as implants wear at contact surfaces, producing metal particles and metal ions that may be harmful. Newly developed metal implants and methods of implant surface modification are currently under scrutiny. We evaluated the use of electrolytic in-process dressing (ELID) as a surface finishing method for metal implants. Metal implants processed using the ELID method (ELID group) or not processed (Non-ELID group) were inserted surgically into rabbit femurs. The rabbits were sacrificed postoperatively over a 24-week period. We assessed the concentrations of the cytokines, interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α, the resistance to implant pull-out, and histopathology at the implant site. There was no significant difference between the groups regarding the cytokine concentrations or implant pull-out resistance. Many particles indicating wear around the implant were noted in the Non-ELID group (n=10) but not the ELID group (n=13), while a fibrous membrane adhering to the every implant was noted in the ELID group. The formation of a fibrous membrane rather than metal particles in the ELID group may indicate improved biocompatibility, and it suggests that ELID may prevent corrosion in the areas of contact.