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Diamond is a highly favourable material for cutting tools, particularly in ultra-precision machining to produce highly accurate freeform surfaces with mirror-like finishing. Unfortunately, diamond cutting tools undergo catastrophic wear when machining transition metals such as iron, cobalt, nickel, etc. The underlying wear mechanism is understood to involve dissociation of carbon atoms from the diamond lattice, i.e. graphitization. Existing approaches of wear reduction aim at reducing chemical reactivity generally through process modifications. In this work, the effectiveness of ion implantation as a tool modification methodology is studied on the gallium ion irradiated diamond tools. Wear occurrences are compared between irradiated diamond and unmodified diamond using thermal analytical techniques and micromachining experiments. Calorimetric tests showed a more than 40% increase in activation energy required for graphitization with a Ga ion dose of 1 × 1013 ions/cm2 at 30 keV. Significant improvements in the wear resistance of an irradiated diamond tool are also observed in micromachining tests with the reduction in workpiece adhesion that indicates potentially lower heat generation at the tool-chip interface for the graphitization process. Ab initio calculations suggest an increased stability against exfoliation with the reduction in surface energy, which influences the surface-to-surface interaction between diamond and catalytic iron. Image 1037 [ABSTRACT FROM AUTHOR]

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. 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. [ABSTRACT FROM AUTHOR]

The combination of biodegradable metals and additive manufacturing (AM) leads to a revolutionary change of metal implants in many aspects including materials, design, manufacturing, and clinical applications. The AM of nondegradable metals such as titanium and CoCr alloys has proven to be a tremendous success in clinical applications. The AM of biodegradable metals including magnesium (Mg), iron (Fe), and zinc (Zn) is still in its infancy, although much progress has been made in the research field. Element loss and porosity are common processing problems for AM of biodegradable metals like Zn and Mg, which are mainly caused by evaporation during melting under a high-energy beam. The resulting formation quality and properties are closely related to material, design, and processing, making AM of biodegradable metals a typical interdisciplinary subject involving biomaterials, mechanical engineering, and medicine. This work reviews the state of research and future perspective on AM of biodegradable metals from extensive viewpoints such as material, processing, formation quality, design, microstructure, and properties. Effects of powder properties and processing parameters on formation quality are characterized in detail. The microstructure and metallurgical defects encountered in the AM parts are described. Mechanical and biodegradable properties of AM samples are introduced. Design principles and potential applications of biodegradable metal implants produced by AM are discussed. Finally, current research status is summarized together with some proposed future perspectives for advancing knowledge about AM of biodegradable metals. Rapid development of research and applications on biodegradable metals and additive manufacturing (AM) has been made in recent years. Customized geometric shapes of medical metals with porous structure can be realized accurately and efficiently by laser powder bed fusion (L-PBF), which is beneficial to achieve reliable stress conduction and balanced properties. This review introduces the development history and current status of AM of biodegradable metals and then critically surveys L-PBF of Mg-, Fe-, and Zn-based metals from multiple viewpoints including materials, processing, formation quality, structural design, microstructure, and mechanical and biological properties. The present findings are summarized together with some proposed future challenges for advancing AM of biodegradable metals into real clinical applications. [ABSTRACT FROM AUTHOR]

A metal implant was placed in an acrylic phantom to enable quantitative analysis of the metal artifact reduction techniques used in computed tomography (CT) scanners from three manufacturers. Two titanium rods were placed in a groove in a cylindrical phantom made by acrylic, after which the groove was filled with water. The phantom was scanned using three CT scanners (Toshiba, GE, Siemens) under the abdomen CT setting. CT number accuracy, contrast-to-noise ratio, area of the metal rods in the images, and fraction of affected pixel area of water were measured using ImageJ. Different iterative reconstruction, dual energy, and metal artifact reduction techniques were compared within three vendors. The highest contrast-to-noise ratio of three scanners were 85.7 ± 8.4 (Toshiba), 85.9 ± 11.7 (GE), and 55.0 ± 14.8 (Siemens); and the most correct results of metal area were 157.1 ± 1.4 mm2 (Toshiba), 155.0 ± 1.0 (GE), and 170.6 ± 5.3 (Siemens). The fraction of affected pixel area obtained using single-energy metal artifact reduction of Toshiba scanner was 2.2% ± 0.7%, which is more favorable than 4.1% ± 0.7% obtained using metal artifact reduction software of GE scanner (p = 0.002). Among all quantitative results, the estimations with fraction of affected pixel areas matched the effect of metal artifact reduction in the actual images. Therefore, the single-energy metal artifact reduction technique of Toshiba scanner had a desirable effect. The metal artifact reduction software of GE scanner effectively reduced the effect of metal artifacts; however, it underestimated the size of the metal rods. The monoenergetic and dual energy composition techniques of Siemens scanner could not effectively reduce metal artifacts. [ABSTRACT FROM AUTHOR]

Introduction: Prior to being largely abandoned due to unacceptably high failure rates and the adverse physiologic reactions to metal ions, metal-on-metal (MoM) total hip arthroplasty (THA) and hip resurfacing (HR) were in widespread use throughout the USA, and the potential benefit of decreased volumetric wear rates made it of particular interest to those who serve a young active population, such as military surgeons. The aim of our study was to determine the revision rate of metal on metal hip implants performed at our military institution and obtain current patient reported outcomes from this cohort.Materials and Methods: We conducted a retrospective review of patients who underwent MoM total hip arthroplasty (THA) or hip resurfacing (HR) at our institution from 2006 to 2012. Revision status and component type were determined, and patients were contacted to obtain current HOOS JR scores.Results: We identified 103 THAs in 88 patients and 38 HRs in 33 patients, with mean follow up of 10.2 years. Average age at time of surgery was 48 years, and 85% of the patients were male. The mean HOOS JR score in the THA and HR groups were 84.9 ± 17.6 and 75.8 ± 24.9, respectively (p = 0.38), and were not significantly lower in those who were revised. Two THA revisions occurred for metallosis and one for aseptic loosening of the femoral component. One HR revision occurred for breach of the anterior femoral neck, and one occurred for heterotopicossification.Conclusions: Revision rates of MoM THA and HR in this young, predominantly male population were 2.9% and 5.3%, respectively, and patients maintained generally good hip-specific outcomes. [ABSTRACT FROM AUTHOR]

Metal implants not only deteriorate image quality, but also increase radiation exposure. The purpose of this study was to evaluate the effect of metal hip prosthesis on absorbed radiation dose and assess the efficacy of organ dose modulation (ODM) and metal artifact reduction (MAR) protocols on dose reduction. An anthropomorphic phantom was scanned with and without bilateral metal hip prostheses, and surface and deep level radiation doses were measured at the abdomen and pelvis. Finally, the absorbed radiation doses at pelvic and abdominal cavities in the reference, ODM, and two MAR scans (Gemstone spectral imaging, GE) were compared. The Mann Whitney-U test and Kruskal-Wallis test were performed to compare the volume CT dose index (CTDIvol) and mean absorbed radiation doses. Unilateral and bilateral metal hip prostheses increased CTDIVOL by 14.4% and 30.5%, respectively. MAR protocols decreased absorbed radiation doses in the pelvis. MAR showed the most significant dose reduction in the deep pelvic cavity followed by ODM. However, MAR protocols increased absorbed radiation doses in the upper abdomen. ODM significantly reduced absorbed radiation in the pelvis and abdomen. In conclusion, metal hip implants increased radiation doses in abdominopelvic CT scans. MAR and ODM techniques reduced absorbed radiation dose in abdominopelvic CT scans with metal hip prostheses. [ABSTRACT FROM AUTHOR]

We compared the outcome of Nd:YAG laser therapy with stent placement for malignant central airway obstruction (CAO) at our center over a 10-year period. This is a retrospective review of patients undergoing Nd:YAG laser therapy or self-expanding metal stent (SEMS) placement for malignant CAO between November 2007 and October 2017. Seventy-two patients were recanalized for malignant CAO. The median (range) age was 63 (23-86) years, with 49 (68%) males. Patients underwent either laser therapy alone (N = 36), stent placement alone (N = 30), or both (N = 6). The wavelength of Nd:YAG laser used was 1064 nm, and median (range) laser energy used was 25 (15-35) W, in 377 (115-1107) pulses. Fifty-one (71%) patients died with median survival of 7.2 months. In subgroup analysis, 21 (58.3%) vs. 25 (83.3%), p = 0.03 patients died in the "laser resection" vs. "stent placement" group with longer median survival of 12.4 months in the former vs. 4.5 months, p = 0.0004 in the later. Esophageal cancer and left main bronchus involvement were significantly more common (10 (33.3%) vs. 0, p = 0.0001, and 16 (53.3%) vs. 8 (22.2%), p = 0.01), in the stent placement vs. laser resection group, respectively. Trachea or main bronchi involvement and respiratory failure on presentation requiring mechanical ventilation correlated with poorer survival. The immediate restoration of luminal patency, complication rate, and 30-day mortality was similar among the two groups. The median (range) energy used for laser therapy was 25 (15-35) W. Median of 377 pulses was used for the duration of 287.5 s. The results were compared using a Wilcoxon two-sample test, and Fischer exact test with p values considered indicative of a significant difference if less than 0.05. In patients requiring recanalization of malignant CAO, the extrinsic compression from esophageal cancer, trachea or main bronchi involvement, respiratory failure on presentation requiring mechanical ventilation, and stent placement correlated with poorer survival. Interventional pulmonology training program should emphasize on dedicated training in laser therapy as it is associated with improved survival. [ABSTRACT FROM AUTHOR]

Purpose: The Varian Halcyon includes an ultrafast 6 MV flattening filter free (FFF) cone-beam computed tomography (MV-CBCT). Although a kV-CBCT add-on is available, in the basic configuration MV is used for image guided radiotherapy (IGRT). We characterized the MV-CBCT imager in terms of reproducibility, linearity, field of view (FOV) dependence, detectability of soft-tissue, and the effect of metal implants. The performance of the MV-CBCT in the clinic, including resulting dose to organs, is also discussed herein. Methods: A Gammex phantom was scanned using a Halcyon MV-CBCT and a 120 kVp Siemens Definition Edge CT. Mean and standard deviation of Hounsfield Units (HUs) for different electron density relative to water ( ρ e W ) inserts were extracted. Doses to clinical patients due to MV-CBCT are calculated within Eclipse during treatment planning. Results: A stable and near-linear HU-to- ρ e W curve was obtained using the MV-CBCT. As the scan length increased from 10 to 28cm, the linearity of curve improved while the mean HUs decreased by 30%. All soft tissue inserts in the Gammex phantom were distinguishable. A crescent artifact affected HU measurements by up to 40 HUs. Soft-tissue contrast was sufficient for clinical online image-guidance in the low dose (5 MU) mode. Mean doses per fraction to organs-at-risk (OARs) were as high as 6 cGy for head and neck, 5 cGy for breast, and 4 cGy for pelvis patients. Metal rods did not affect HU values or introduce noticeable artifacts. Conclusions: Halcyon's MV-CBCT has sufficient soft tissue contrast for IGRT and lacks metal-induced artifacts. Even though the absolute HU values vary with phantom size and scanning length, the HU-to- ρ e W conversions are linear and stable day-to-day. In clinical cases, highest tissue doses from MV-CBCT ranged from 2-7cGy per fraction for various treatment sites, which could be significant for some organs at risk. Dose to out-of-treatment-field organs can be limited by reducing the scan length definition during planning and using the low dose mode. The high quality imaging mode did not provide material advantages over the low dose mode. Adequate IGRT was successfully delivered to multiple tumor sites using MV-CBCT. [ABSTRACT FROM AUTHOR]

Background: Polysensitivity is defined as three or more positive patch test reactions. The role of filaggrin gene (FLG) loss‐of‐function mutations in patients with polysensitivity has not been studied when barrier bypass and possible preceding barrier damage have been excluded. Objectives: To determine whether FLG loss of function mutations play a role in patients with multiple contact sensitivities when barrier bypass is excluded. Methods: One hundred and sixty‐nine patients with three or more, non‐cross‐reacting, positive patch test reactions were prospectively enrolled in this study. Exclusion criteria were a history of hand dermatitis, nickel and metal implants, and stasis dermatitis. Subjects were patch tested with the North American extended patch test series, and with other relevant haptens. DNA was obtained and sequenced for the following FLG loss‐of‐function mutations: R501X, 2282del4, R2447X, and S3247X. Results: One hundred and sixty‐five patients were genotyped for the four FLG mutations. There was a significant association between R501X mutation and polysensitivity. For the other three tested mutations, there were no significant associations with polysensitivity. When all mutations were combined, there was a significant association between loss‐of‐function FLG mutations and polysensitivity in patients with a history of atopic dermatitis. Conclusion: When skin barrier bypass is excluded, there is a significant association between polysensitivity and FLG loss‐of‐function mutations. [ABSTRACT FROM AUTHOR]

Background: This study aims at investigating cup survival of porous tantalum revision cups and identifies risk factors for failure.Methods: We retrospectively reviewed 41 patients treated between 2010 and 2012. Main indications were aseptic loosening in 83% and two-stage exchange after periprosthetic joint infection in 17% of cases. Mean follow-up period was 72 months. Femoral megaprostheses were used in 13% of cases. Most defects were classified as Paprosky 3b (29%). Function was assessed using the Harris Hip score.Results: Aseptic cup survivorship was 80% at 104 months (95% Confidence Interval 67.4-92.4). Overall implant survival was 73%. Major bone loss defects (Paprosky types 2c to 3b) were associated with a significantly higher rate of failure than minor defects (P = 0.002). There were eight cases of aseptic loosening (19.5%) and two of infection (4.9%). Previous surgeries, indication for acetabular revision, patient-related risk factors and use of megaprostheses did not significantly influence implant survival. The Harris Hip Score improved from a median of 40 (Interquartile range 31-45) to 82 (interquartile range 65-88) postoperative (P < 0.0001).Conclusions: In summary, the use of porous tantalum metal implants in acetabular revision surgery achieves good to excellent short- term and mid-term functional results and an acceptable complication rate relative to the extent of defect and previous surgery. However, one should be aware of potential limitations of the implants in addressing large defects and discontinuity. [ABSTRACT FROM AUTHOR]

Periprosthetic joint infections continues to be a common complication in total joint arthroplasty, resulting in significant morbidity, mortality, and additional cost. Trabecular metal implants with an internal cemented interface may be customizable drug delivery devices with an ingrowth interface. Thirty‐six acetabular implants were assembled in vitro, half with a trabecular metal shell and half without. The antibiotic loaded bone cement was prepared via three different mixing techniques and at two different mixing times. Mixing time had a significant effect on the total amount of gentamicin eluted. The long mixing protocol eluted up to 126% (p = 0.001) more gentamicin than the short mixing protocol at 4 h and 192% (p < 0.001) more at 7 days. Hand or mechanical mixing technique had no significant effect on elution at 4 h. At 7 days, the mechanical mixing system under vacuum eluted over 50% (p = 0.031) more gentamicin than without a vacuum and nearly 60% (p = 0.040) more gentamicin than hand mixing. The use of a trabecular metal shell had no significant effect on the bulk elution of gentamicin at 4 h (p > 0.05) but significantly reduced total gentamicin elution under certain mixing protocols at 7 days. A possible optimization strategy to improve elution kinetics would be to use a long mixing time with a mechanical mixing system under vacuum. The establishment of trabecular metal as an effective delivery vehicle for antibiotics makes possible an entirely new class of drug eluting device designs. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [ABSTRACT FROM AUTHOR]

Purpose: The increased use of CAD systems can generate doubt about the accuracy of digital impressions for angulated implants. The aim of this study was to evaluate the accuracy of different impression techniques, two conventional and one digital, for implants with and without angulation. Materials and Methods: We used a polyurethane cast that simulates the human maxilla according to ASTM F1839, and 6 tapered implants were installed with external hexagonal connections to simulate tooth positions 17, 15, 12, 23, 25, and 27. Implants 17 and 23 were placed with 15° of mesial angulation and distal angulation, respectively. Mini cone abutments were installed on these implants with a metal strap 1 mm in height. Conventional and digital impression procedures were performed on the maxillary master cast, and the implants were separated into 6 groups based on the technique used and measurement type: G1 – control, G2 – digital impression, G3 – conventional impression with an open tray, G4 – conventional impression with a closed tray, G5 – conventional impression with an open tray and a digital impression, and G6 – conventional impression with a closed tray and a digital impression. A statistical analysis was performed using two‐way repeated measures ANOVA to compare the groups, and a Kruskal‐Wallis test was conducted to analyze the accuracy of the techniques. Results: No significant difference in the accuracy of the techniques was observed between the groups. Therefore, no differences were found among the conventional impression and the combination of conventional and digital impressions, and the angulation of the implants did not affect the accuracy of the techniques. Conclusions: All of the techniques exhibited trueness and had acceptable precision. The variation of the angle of the implants did not affect the accuracy of the techniques. [ABSTRACT FROM AUTHOR]

Metallosis is a well-known complication of metal-on-metal total hip and knee arthroplasties. However, there are few reports of metallosis after arthroplasty of non-weight bearing joints. We report a case of severe metallosis that is considered to be caused by the mal-rotational alignment of the ulnar component after unlinked total elbow arthroplasty. When the joint was opened, we observed a black clay-like lesion that had expanded in the joint. Although mild deformity of the polyethylene insert was observed, there was no defect on the surface of the metal implant on macroscopic observation. Investigation of the removed prosthesis showed concentric sliding marks at the tapered working part between the humeral stem and condylar component indicating that metallosis was caused by abrasion at the junction. Surgeons should be aware of potential complications at the junction of the stem and condylar component when using a modular design. [ABSTRACT FROM AUTHOR]

Abstract Ti6Al4V-alloy is commonly used in dental and orthopedic applications where tribochemical reactions occur at material/bone interface. These reactions are one of the main concerns regarding Ti6Al4V implants due to the generation of wear particles, linked to the release of metallic ions in toxic concentration which occurs when TiO 2 passive film is destroyed by means of wear and corrosion simultaneously. In the present study, a multi-material Ti6Al4V-PEEK cellular structure is proposed. Selective Laser Melting technique was used to produce Ti6Al4V dense and cellular structured specimens, whilst Hot-Pressing technique was employed to obtain multi-material Ti6Al4V-PEEK structures. This study investigates the tribocorrosion behavior of these materials under reciprocating sliding, comparing them with commercial forged Ti6Al4V. Open-circuit-potential was measured before, during and after sliding while dynamic coefficient of friction was assessed during sliding. The results showed an improved wear resistance and a lower tendency to corrosion for the multi-material Ti6Al4V-PEEK specimens when compared to dense and cellular structures mono-material specimens. This multi-material solution gathering Ti6Al4V and PEEK, besides being able to withstand the loads occurring after implantation on dental and orthopedic applications, is a promising alternative to fully dense metals once it enhances the tribocorrosion performance. Graphical abstract fx1 Highlights • Ti6Al4V dense and cellular structures were produced by Selective Laser Melting. • PEEK was introduced into these structures via Hot-Pressing (Ti6Al4V-PEEK structures). • PEEK addition led to an OCP decrease during sliding and increased wear resistance. Ti6Al4V-PEEK structures displayed an enhanced tribocorrosion performance. • This multi-material is a promising alternative to currently used orthopedic solutions. [ABSTRACT FROM AUTHOR]

As a biodegradable metal implant material with mechanical properties closest to those of natural bone, the degradation rate of magnesium (Mg) alloy is so fast in body fluid environment. Therefore, the preparation of a coating on Mg alloy surface to improve its corrosion resistance has become a research focus. In the study, Mg-2Zn-Mn (ZM21) alloys and micro-arc oxidation (MAO) are used as the substrate and surface modification method, respectively. Then, the influence of sodium fluoride (NaF) concentration in silicate basic electrolyte on the corrosion resistance and biodegradability of MAO coatings are investigated. The results show that (1) When NaF concentration increases to 1.0 g/L, the thickening and hydrophilic effect of MAO coating are more obvious. (2) Adding 1.0 g/L NaF makes excellent corrosion resistance and great adhesion, because F- can enhance discharge and refine sparks to enhance the interface adhesion and form a more uniform surface. (3) Excessive NaF concentration (＞ 1.0 g/L) can decrease the breakdown voltage, produce the abundant discharge channels, and degrade the coating quality. (4) The remarkable reduced weight loss rate and pH value of MAO samples after immersion shows the certain biological safety. (5) Cytotoxicity and cell adhesion test proves the available biocompatibility. [Display omitted] • In situ growth of MgO/MgF 2 /Mg 2 SiO 4 /MgSiO 3 MAO coatings are achieved. • NaF can enhance discharge, refine spark, thicken coating and improve hydrophilic. • The addition of 1.0 g/L NaF makes the superior corrosion resistance. • The quality of the coating is degraded when NaF concentration ＞ 1.0 g/L. • Adding 1.0 g/L NaF makes the lower degradation rate and a certain biological safety. [ABSTRACT FROM AUTHOR]

Patients with metal implants having high atomic numbers (Z eff) can be encountered in radiotherapy applications. These heterogeneous structures cause dose perturbations at the bone-tissue interface. These perturbations are undesired due to the lack of accurate dose calculation and contouring process through a higher image quality. In this study, the effect of 6–18 MV photon irradiation on hexagonal boron nitride (h-BN) in comparison with titanium and stainless-steel implants was proposed as an implant material due to its biocompatibility and low Z eff. First, h-BN material was characterized and its mass attenuation coefficient was determined. Then, the percent depth doses (PDD) were obtained for the implant materials. Next, the dose distributions were evaluated with both TPS using CT images and TLDs. A dose perturbation was not observed at the interface for h-BN material different from the metal implants as seen from the PDD distributions. The change in PDD varied between 1 and 3% for h-BN with respect to RW3 slab phantom, which was 4–7 times lower than that of metal implants, depending on the material thickness. No metal artifact was seen at h-BN implants compared to metal implants. Homogenous dose distribution was also seen from the isodose lines on the CT images, while dose perturbations were more pronounced in metal implants. In addition, a more severe dose reduction at the metal implant/bone tissue interface was observed at 6 MV photon beam energy compared to 18 MV. In contrast, no dose change was observed for the h-BN material at each photon beam energy. Hence, an accurate dose calculation can be done for h-BN as a result of these advantages. The results showed that, due to its biocompatible property, h-BN material can be evaluated as an implant material in radiotherapy applications if its mechanical properties were further improved. • h-BN, a low atomic number material, was proposed as an implant in this study. • PDDs behind the h-BN material was similar to the tissue equivalent RW3 phantom. • Dose distributions were obtained by a homemade phantom (LEP) using TPS and TLD. • A dose perturbation was not observed at the interface for h-BN material. • No metal artifact was seen in the CT image of h-BN compared to the metal implants. [ABSTRACT FROM AUTHOR]

In fracture fixation, biodegradable implant materials are an interesting alternative to conventional non-biodegradable materials as the latter often require a second implant removal surgery to avoid long-term complications. In this study, we present an in silico strategy to design/study biodegradable metal implants focusing on mandibular fracture fixation plates of WE43 (Mg alloy). The in silico strategy is composed of an orchestrated interaction between three separate computational models. The first model simulates the mass loss of the degradable implant based on the chemistry of Mg biodegradation. A second model estimates the loading on the jaw plate in the physiological environment, incorporating a phenomenological dynamic bone regeneration process. The third model characterizes the mechanical behavior of the jaw plate and the influence of material degradation on the mechanical behavior. A sensitivity analysis was performed on parameters related to choices regarding numerical implementation and parameter dependencies were implemented to guarantee robust and correct results. Different clinical scenarios were tested, related to the amount of screws used to fix the plate. The results showed a lower initial strength when more screw holes were left open, as well as a faster decrease over time in strength due to the increased area available for surface degradation. The obtained degradation results were found to be in accordance with previously reported data of in vivo studies with biodegradable plates. The combination of these three models allows for the design of patient-specific biodegradable fixation implants able to deliver the desired mechanical behavior tuned to the bone regeneration process. [ABSTRACT FROM AUTHOR]

This study evaluates the impact of a scanner-integrated, customized clinical decision support system (CDSS) on the acquisition technique, scan range, and reconstruction in thoracoabdominal CT. We applied CDSS in contrast–enhanced examinations of the trunk with various clinical indications on a recent scanner with the capability of dual-energy CT (DECT), anatomic landmark detection (ALD), and iterative metal-artifact reduction (MAR). Simple and comprehensive questions about the patient's breath hold capability, the anatomical region of interest, and metal implants can be answered after the localizer. The acquisition technique (single energy, SECT, or dual energy), scan range (chest-abdomen-pelvis or chest-abdomen), and reconstruction technique (with or without MAR) were then automatically adapted in the examination protocols in coherence with these selections. Retrospectively, we compared the usage rates for these techniques in 624 examinations on the study scanner with 740 examinations on a comparable scanner without CDSS. Subgroup analysis of effective dose (ED), scan duration, and image quality (IQ) was performed in the study group. CDSS leads to an increased usage rate of DECT (64.4% vs. 2.8%) and MAR (75.4% vs. 44.0%). All scan range adaptations by ALD were successful. The resulting subjective IQ between single energy and DECT acquisitions was comparable (all p > 0.05). Scan duration was significantly longer in DECT than in SECT (16.9 s vs. 6.5 s; p < 0.001). However, the objective IQ was significantly higher in DECT (CNRD 2.1 vs. 1.8; p < 0.01), and the ED significantly lower (6.7 mSv vs. 7.6 mSv; p = 0.004). CDSS for thoracoabdominal CT leads to a substantially increased usage rate of innovative techniques during acquisition and reconstruction. Patients with adapted protocols benefit from improved image quality and increased post-processing options at lower radiation doses. [ABSTRACT FROM AUTHOR]

Bionic functional coating plays a pivotal role in promoting internal fixation treatment of bone fracture. However, post-traumatic microenvironment characterized by hypoxia and acidic milieu, as well as high oxidative stress, may largely weaken the function of established coatings. Herein, we anchor two-dimensional H-silicene nanosheet (H-Si) onto hydroxyapatite (HA)-coated metal implant to develop a H-Si@HA composite coating. Benefiting from the intrinsic pH-responsive characteristics, the H-Si@HA maintains stable structure and functionalities in acidic milieu and simulates the superoxide dismutase and peroxidase-like activities, resulting in reactive oxygen species depletion, high oxidative stress suppression and further reversal of the acidic microenvironment. Meanwhile, H-Si@HA protects cells by inducing cellular autophagy. Sequentially, Si4+ release accompanying the degradation of the H-Si in neutral milieu promotes fracture healing by improving osteogenic-related gene expression of bone mesenchymal stem cells (BMSCs) and SOD1 expression of osteoprogenitor cells. Particularly, differentiated gene expression of BMSCs by the H-Si@HA coating was identified using absolute quantitative transcriptome sequencing, revealing that the H-Si could effectively modulate the expression of core mRNAs which are highly associated with osteogenesis and bone formation through regulating autophagy. Such a self-degradable nanoarmor coating illustrates the great clinic potential to achieve hierarchical and synergistic effect of fracture healing promotion. [Display omitted] • The bionic coating demonstrates a hierarchical and synergistic effect of fracture healing promotion by H-Si intervention. • The unique pH-responsive feature enables excellent bone regeneration performance. • The underlying molecular mechanism of regulating differentiation of BMSCs induced by H-Si nanosheet is initially revealed. [ABSTRACT FROM AUTHOR]

In this paper, two III-V material-based junctionless tunnel FET devices, D-1 and D-2, are proposed. The proposed device D-1 has a low bandgap (GaSb-based) dual source and a higher bandgap (GaAs-based) T-channel junctionless, and the proposed device D-2 has the same architecture as D-1 in addition to a metal strip implant in the gate oxide near both source regions. Due to junctionless architecture, the proposed D-1 and D-2 eliminate random dopant fluctuations (RDF), remove the need for high thermal budgeting, and give better performance with less variability. The wide bandgap (GaAs) T-channel and the drain region formed far from the gate fully suppress the ambipolarity for both the proposed D-1 and D-2. The low-bandgap GaSb material in the source improves the ON current for D-1 and D-2. Compared to the conventional junctionless TFET (JL-TFET), the proposed D-2 (even at a lower bias of 0.5 V) improves the ON current by 1.7 times and the ION/IOFF ratio by 216.66 times, with a much-reduced average subthreshold swing value of 32.7 mV/dec compared to 70 mV/dec of the conventional JL-TFET. Furthermore, the proposed D-2 also provides much improved RF performance with a higher transconductance (gm) of 147.8 μs, higher cut-off frequency (fT) of 32.26 GHz, a higher gain-bandwidth product (GBW) of 3.52 GHz, higher transconductance-frequency product (TFP) of 286 GHz, and a lower transit time (τ) of 5 × 10–12 s. Furthermore, we analyze various linearity parameters such as gm2, gm3, VIP2, VIP3, IIP3, and IMD3 for both D-1 and D-2, and our findings indicate that D-2 exhibits improved linearity performance. • Two Novel Ⅲ-Ⅴ compound semiconductor material-based junctionless TFET devices (D-1 and D-2) are proposed. • Proposed devices address limitations of conventional TFETs, including low ON current, ambipolarity, fabrication-related issues, and poor RF performance. • Junctionless behavior eliminates random dopant fluctuation (RDF) and suppresses the need for a high thermal budget, resulting in improved performance and reduced variability. • The use of Ⅲ-Ⅴ GaSb with a lower energy bandgap enhances the ON current for the proposed structures. • A metal strip implant in the oxide near sources (Device D-2) further improves ON current, subthreshold swing (SS), and RF performance parameters. [ABSTRACT FROM AUTHOR]

The article discusses the partnership between Lithoz, a global leader in ceramic 3-D printing, and the U.S.-based biomaterial specialist Himed to advance research in the field of 3-D printing of medical bioceramics.

Purpose This paper aims to review the latest applications in terms of three-dimensional printed (3DP) metal implants in orthopedics, and, importantly, the design of 3DP metal implants through a series of cases operated at The Second Hospital of Jilin University were presented.Design/methodology/approach This paper is available to practitioners who are use 3DP implants in orthopedics. This review began with the deficiency of traditional prostheses and basic concepts of 3DP implants. Then, representative 3DP clinical cases were summarized and compared, and the experiences using customized prostheses and directions for future potential development are also shown.Findings The results obtained from the follow-up of clinical applications of 3DP implants show that the 3D designed and printed metal implants could exhibit good bone defect matching, quick and safe joint functional rehabilitation as well as saving time in surgery, which achieved high patient satisfaction collectively.Originality/value Single center experiences of 3DP metal implants design were shared and the detailed technical points between various regions were compared and analyzed. In conclusion, the 3DP technology is infusive and will present huge potential to reform future orthopedic practice. [ABSTRACT FROM AUTHOR]

Background/purpose: Percutaneous coronary intervention (PCI) is the preferred strategy for treatment of saphenous vein graft (SVG) disease. However, there remains ongoing debate on whether drug-eluting stents (DES) or bare-metal stents (BMS) should be used during SVG-PCI.Methods/materials: We performed a meta-analysis of randomized controlled trials (RCTs) comparing DES and BMS for SVG-PCI. The primary end point was major adverse cardiac events (MACE), defined as composite of all-cause death, myocardial infarction (MI) or repeat revascularization. Secondary end points included individual MACE components, cardiac death and stent thrombosis (ST).Results: Six RCTs including 1582 patients (50% receiving DES) met inclusion criteria. MACE occurred in 31% (244/797) patients receiving DES and 36% (281/785) patients receiving BMS (median follow-up, 12-35 months). There was no significant difference in MACE between DES and BMS (Odds Ratio (OR) 0.62, 95%CI 0.36-1.09, p = 0.10, I2 = 77%). However, for individual components of MACE, DES was associated with a significant reduction in repeat revascularization (OR 0.53, 95%CI 0.29-0.97, p = 0.04, I2 = 73%). There was no difference in all-cause death (OR 1.30, 95%CI 0.77-2.20, p = 0.33, I2 = 40%), MI (OR 0.68, 95%CI 0.38-1.25, p = 0.22, I2 = 56%), cardiac death (OR 1.08, 95%CI 0.45-2.64, p = 0.86, I2 = 42%) or ST (OR 0.89, 95%CI 0.37-2.17, p = 0.80, I2 = 35%) between stents.Conclusions: Although there was no significant difference in MACE, DES is associated with a reduction in repeat revascularization compared with BMS in pooled randomized trials for SVG-PCI. The high occurrence of MACE in both stent platforms highlights the need for novel therapeutic approaches to improve clinical outcomes following SVG intervention.Summary: We performed a meta-analysis of randomized controlled trials comparing DES and BMS for SVG-PCI. There was no significant difference in MACE between DES and BMS. However, for individual components of MACE, DES was associated with a significant reduction in repeat revascularization. The high occurrence of MACE in both stent platforms highlights the need for novel therapeutic approaches to improve clinical outcomes following SVG intervention. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Evolution of metal implants progressively shifted the focus from adequate mechanical strength to improved biocompatibility and absence of toxicity and, finally, to fast osseointegration. Recently, new frontiers and challenges of Ti implants have been addressed to improvement of bioactivity, fighting of bacterial infection and biofilm formation, as well as modulation of inflammation. This is closely related to the clinical demand of multifunctional implants able to simultaneously have a number of specific responses with respect to body fluids, cells (osteoblasts, fibroblasts, macrophages) and pathogenic agents (bacteria, viruses). This complex system of multiple biological stimuli and surface responses is a major arena of the current research on biomaterials and biosurfaces. This review covers the strategies explored to this purpose since 2010 in the case of Ti and Ti alloys, considering that the number of related papers doubled about in the last seven years and no review has comprehensively covered this engaging research area yet. The different approaches followed for producing multifunctional Ti-based surfaces involve the use of thick and thin inorganic coatings, chemical surface treatments, and functionalization strategies coupled with organic coatings. Statement of Significance According to the clinical demand of multifunctional implants able to simultaneously have a number of specific responses with respect to body fluids, cells and pathogenic agents, new frontiers of Ti implants have been addressed to improvement of bioactivity, fighting of bacterial infection and biofilm formation, as well as modulation of inflammation. Literature since 2010 is here reviewed. Several strategies for getting bioactive and antibacterial actions on Ti surfaces have been suggested, but they still need to be optimized with respect to several concerns. A further step will be to combine on the same surface a proven ability of modulation of inflammatory response. The achievement of multifunctional surfaces able to modulate inflammation and to promote osteogenesis is a grand challenge. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT: Pulse lavage (PL) debridement and antibiotic loaded calcium sulfate beads (CS‐B) are both used for the treatment of biofilm related periprosthetic joint infection (PJI). However, the efficacy of these alone and in combination for eradicating biofilm from orthopaedic metal implant surfaces is unclear. The purpose of the study was to understand the efficacy of PL and antibiotic loaded CS‐B in eradicating bacterial biofilms on 316L stainless steel (SS) alone and in combination in vitro. Biofilms of bioluminescent strains of Pseudomonas aeruginosa Xen41 and a USA300 MRSA Staphylococcus aureus SAP231 were grown on SS coupons for 3 days. The coupons were either, (i) debrided for 3 s with PL, (ii) exposed to tobramycin (TOB) and vancomycin (VAN) loaded CS‐B for 24 h, or (iii) exposed to both. An untreated biofilm served as a control. The amount of biofilm was measured by bioluminescence, viable plate count and confocal microscopy using live/dead staining. PL alone reduced the CFU count of both strains of biofilms by approximately 2 orders of magnitude, from an initial cell count on metal surface of approximately 109 CFU/cm2. The antibiotic loaded CS‐B caused an approximate six log reduction and the combination completely eradicated viable biofilm bacteria. Bioluminescence and confocal imaging corroborated the CFU data. While PL and antibiotic loaded CS‐B both significantly reduced biofilm, the combination of two was more effective than alone in removing biofilms from SS implant surfaces. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2349–2354, 2018. [ABSTRACT FROM AUTHOR]

Purpose: In this study, we investigated the differences in hyperthermia treatment (HT) quality between treatments applied with different hyperthermia systems for sub-superficial tumours in the head and neck (H&N) region. Materials and methods: In 24 patients, with a clinical target volume (CTV) extending up to 6 cm from the surface, we retrospectively analysed the predicted HT quality achievable by two planar applicator arrays or one phased-array hyperthermia system. Hereto, we calculated and compared the specific absorption rate (SAR) and temperature distribution coverage of the CTV and gross tumour volume (GTV) for the Lucite cone applicator (LCA: planar), current sheet applicator (CSA: planar) and the HYPERcollar (phased-array). Results: The HYPERcollar provides better SAR coverage than planar applicators if the target region is fully enclosed by its applicator frame. For targets extending outside the HYPERcollar frame, sufficient SAR coverage (25% target coverage, i.e. TC25 ≥ 75%) can still be achieved using the LCA when the target is fully under the LCA aperture and not deeper than 50 mm from the patient surface. Conclusion: Simulations predict that the HYPERcollar (hence also its successor the HYPERcollar3D) is to be preferred over planar applicators such as LCA and current sheet applicator in sub-superficial tumours in the H&N region when used within specifications. [ABSTRACT FROM AUTHOR]

Introduction: Additive manufacturing, also known as 3D printing (3DP), is becoming increasingly available to surgeons throughout the world due to recent advancements in technology. 3D printing can produce complex free-form structures that would be impossible using conventional subtractive manufacturing. This offers the possibility to create implants that are better suited to the irregular anatomic shapes found in the human body. The present study aims to examine the surgical outcomes associated with the use of 3D printed metal implants and uncover the value of 3D printing in musculoskeletal surgery. Methods: A systematic review of published literature was performed in June 2017 using the PRISMA protocol. Online bibliographic databases such as MEDLINE, Embase, Scopus, CINAHL, and Cochrane were used to identify studies involving surgical implantation of 3D printed metal implants in musculoskeletal surgery. References from relevant studies were scanned for additional articles. Two reviewers independently screened results. Full-text articles were analyzed for eligibility. A total of 24 studies were included for data abstraction. Results were collected and qualitatively analyzed. Results: Of the 25 articles included, there were 17 case reports, 4 case series, 2 retrospective cohorts and 3 prospective cohorts. Of these articles, the majority of 3DP was done with electron beam melting (EBM) with Ti6Al4V. Orthopaedic, neurosurgical, plastic, and maxillofacial surgery articles were included in the review. All studies concluded that 3D printed implants had favourable post-operative outcomes. Some advantages included the reduction of operative time, improved osseointegration through custom implant porosity, improved fixation, decreased stress shielding, better cosmetic appearance, improved functional outcome, and limb salvage. Additional cost and time required to design and print the implants were reported as potential drawbacks to 3D printing. Discussion/Conclusions. The applications of 3D printing in musculoskeletal surgery are promising and have the potential to alter future surgical practice. However, there is a lack of quality research in the literature assessing the use of 3D printed implants. Further research is needed to evaluate the use of 3D printing in musculoskeletal surgery to understand its potential effects on surgical practice. [ABSTRACT FROM AUTHOR]

Ions released from metal implants have been associated with adverse tissue reactions and are therefore a major concern. Studies with macrophages have shown that cobalt, chromium, and nickel ions can activate the NLRP3 inflammasome, a multiprotein complex responsible for the activation of caspase-1 (a proteolytic enzyme converting pro-interleukin [IL]-1β to mature IL-1β). However, the mechanism(s) of inflammasome activation by metal ions remain largely unknown. The objectives of the present study were to determine if, in macrophages: 1. caspase-1 activation and IL-1β release induced by metal ions are oxidative stress-dependent; and 2. IL-1β release induced by metal ions is NF-κB signaling pathway-dependent. Lipopolysaccharide (LPS)-primed murine bone marrow-derived macrophages (BMDM) were exposed to Co2+ (6–48 ppm), Cr3+ (100–500 ppm), or Ni2+ (12–96 ppm), in the presence or absence of a caspase-1 inhibitor (Z-WEHD-FMK), an antioxidant (L-ascorbic acid [L-AA]), or an NF-κB inhibitor (JSH-23). Culture supernatants were analyzed for caspase-1 by western blotting and/or IL-1β release by ELISA. Immunoblotting revealed the presence of caspase-1 (p20 subunit) in supernatants of BMDM incubated with Cr3+, but not with Ni2+ or Co2+. When L-AA (2 mM) was present with Cr3+, the caspase-1 p20 subunit was undetectable and IL-1β release decreased down to the level of the negative control, thereby demonstrating that caspase-1 activation and IL-1β release induced by Cr3+ was oxidative stress-dependent. ELISA demonstrated that Cr3+ induced the highest release of IL-1β, while Co2+ had no or limited effects. In the presence of Ni2+, the addition of L-AA (2 mM) also decreased IL-1β release, below the level of the negative control, suggesting that IL-1β release induced by Ni2+ was also oxidative stress-dependent. Finally, when present during both priming with LPS and activation with Cr3+, JSH-23 blocked IL-1β release, demonstrating NF-κB involvement. Overall, this study showed that while both Cr3+ and Ni2+ may be inducing inflammasome activation, Cr3+ is likely a more potent activator, acting through oxidative stress and the NF-κB signaling pathway. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop and validate a novel analytical procedure for determination of total chromium and Cr(III) and Cr(VI) species released from metal implants into whole blood and joint effusion. Firstly, the ion-pair chromatographic method employing reversed-phase high-performance liquid chromatography inductively coupled plasma mass spectrometry (ICP-MS) for analysis of species was developed. Secondly, all samples, protein and low molecular fractions were analyzed for their total chromium content using ICP-MS. This new measurement procedure was validated by the following parameters: limit of detection (0.13 μg L -1 for Cr(III), 0.14 μg L -1 for Cr(VI)), linearity of calibration, trueness (recovery 84–92%), intermediate precision (RSD < 5%). We determined statistically significantly higher chromium levels in joint effusion samples obtained from patients in comparison with a control group. On the other hand, no relevant difference among the concentrations of both species and total chromium in blood was observed. Our results show that the majority of chromium is present in the trivalent form and bound to proteins. This speciation study is rare in the field of speciation analysis in clinical samples. It is characterized by very fast and simple sample preparation without any changes in distribution or stability of both Cr forms and efficient simultaneous analysis of Cr species. [ABSTRACT FROM AUTHOR]

Purpose: Cervical disc arthroplasty has been a popular alternative to traditional arthrodesis treatment for maintaining postoperative cervical spine mobility. However, certain adverse reactions to cervical disc arthroplasty have emerged during the last few decades.Methods: Metallosis or metalloma is a rarely reported complication after spinal fusion or spinal arthroplasty surgery. We report on the first metallosis case occurring in a patient who received Bryan Disc implantation approximately 8 years earlier. She was involved in a traffic accident and sustained a whiplash injury to the cervical spine one and a half years ago. The traumatic Bryan Disc loosening developed after the traffic accident, causing metallosis.Results: To the best of our knowledge, this is the first reported case of spinal metallosis caused by the Bryan Disc. A series of metallosis cases reported in the literature are also reviewed.Conclusions: Although uncommon, intraspinal metallosis or metalloma should be considered as an infrequent cause of delayed neurological symptoms after spinal surgery involving metallic instrumentation, especially after disc arthroplasty. Once metallosis is suspected, immediate metallic implant removal is mandatory for definite diagnosis and treatment. [ABSTRACT FROM AUTHOR]

Purpose: Metal implants have been used to treat adolescent idiopathic scoliosis since the 1960s. Only recently, however, it has the issue of metal-bone breakdown secondary to metal corrosion in situ come to light, raising concerns of possible long-term complications from the resulting metallosis and inflammation of spinal tissues. We present a case of a patient with neurological deficit, pain, and disability with Harrington rod in place for over 30 years, to bring attention to the issue of bio-corrosion of metal implants and its effect on human tissue. We call attention to the need for protocols to better diagnose and treat these patients.Methods: We provide a complete review of the history and clinical manifestations as well as serum metal, X-ray, and CT/myelogram test results.Results: A 52-year-old female with spinal fusion and Harrington rod presents with pain, lymphedema, disability, and neurological deficits including thoracic outlet syndrome, hyperreflexia, peripheral muscle weakness and atrophy, hypertonicity, Raynaud's phenomenon, and balance and gait abnormalities. Serum chromium levels were elevated (26.73 nmol). X-rays showed no evidence of rod breakdown. Serial X-rays can demonstrate subtle corrosive changes but were not available. Adhesive arachnoiditis was diagnosed via CT/myelogram.Conclusion: We hypothesize that bio-corrosion is present in this case and that it is associated with intraspinal metallosis. Trauma secondary to a motor vehicle accident, as well as arachnoiditis, and their possible effects on this case are outlined. Challenges in proper diagnosis and management are discussed. [ABSTRACT FROM AUTHOR]

Current metal implants (e.g. stents) covered with drug-eluting coatings are not robust for long-term usage. Other types and methods of coatings are needed, especially ones that are not prone to activity loss in vivo. In this paper, the method of stainless steel (SS) coating with poly(ethylene glycol) dimethacrylate (PEGDMA) with the use of electropolymerization (EP) is presented. The application of a specific and simple reaction mixture enabled the production of SS-PEGDMA materials that possessed a homogenous surface. The polymer coating was durable for 28 days of constant washing. The resulting materials were non-toxic and haemolysis did not occur after incubation with blood. Moreover, because the coating filled up scratches present on bare SS and hydrophilized the SS surface, it reduced fibrinogen adsorption five times in comparison to SS and, unlike on SS, no platelet activation was detected. The presented method is a very promising candidate for scale up due to its simplicity and low cost. [ABSTRACT FROM AUTHOR]

The infection of dental implants may cause severe inflammation of tissue and even bone degradation if not treated. For titanium implants, a new, minimally invasive approach is the electrochemical removal of the biofilms including the disinfection of the metal surface. In this project, several parameters, such as electrode potentials and electrolyte compositions, were varied to understand the underlying mechanisms. Optimal electrolytes contained iodide as well as lactic acid. Electrochemical experiments, such as cyclic voltammetry or measurements of open circuit potentials, were performed in different cell set-ups to distinguish between different possible reactions. At the applied potentials of E  < −1.4 V, the hydrogen evolution reaction dominated at the implant surface, effectively lifting off the bacterial films. In addition, several disinfecting species are formed at the anode, such as triiodide and hydrogen peroxide. Ex situ tests with model biofilms of E. coli clearly demonstrated the effectiveness of the respective anolytes in killing the bacteria, as determined by the LIVE/DEAD™ assay. Using optimized electrolysis parameters of 30 s at 7.0 V and 300 mA, a 14-day old wildtype biofilm could be completely removed from dental implants in vitro . [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the primary, initial stability of Porous Tantalum Trabecular Metal™ implants (TM) compared with Tapered Screw Vent® implants (TSV) with different diameters, inserted in two bone densities. Methods: A total of 160 implants (80 TM and 80 TSV) with narrow (3.7 mm) and conventional (4.1 mm) diameters and the same length (10 mm) were placed in artificial bone blocks representing bone qualities II and IV. The implant stability was evaluated by insertion torque (IT) and Resonance Frequency Analysis. Statistical analysis was performed with non‐parametric Kruskal–Wallis test with Dunn post‐test for the differences between groups. Results: The results showed higher ISQ values in dense bone compared with soft bone for all the groups (P < 0.05). Conventional‐diameter implants (TSV and TM) showed higher ISQ and IT values compared with narrow implants (TSV and TM) in dense and soft bone (P < 0.05). Tapered TSV implants showed higher stability in soft bone compared with TM implants (P < 0.05). In dense bone, differences were not observed between narrow TSV 3.7 mm and TM 3.7 mm implants (P > 0.05). Conclusions: Within the limitations of this study, it can be concluded: In dense bone blocks, the wider diameter implants are more stable than narrow implants.In soft bone blocks, the tapered TSV implants are more stable than TM implants. [ABSTRACT FROM AUTHOR]

In the presence of metal implants, metal artifacts are introduced to x-ray computed tomography CT images. Although a large number of metal artifact reduction (MAR) methods have been proposed in the past decades, MAR is still one of the major problems in clinical x-ray CT. In this paper, we develop a convolutional neural network (CNN)-based open MAR framework, which fuses the information from the original and corrected images to suppress artifacts. The proposed approach consists of two phases. In the CNN training phase, we build a database consisting of metal-free, metal-inserted and pre-corrected CT images, and image patches are extracted and used for CNN training. In the MAR phase, the uncorrected and pre-corrected images are used as the input of the trained CNN to generate a CNN image with reduced artifacts. To further reduce the remaining artifacts, water equivalent tissues in a CNN image are set to a uniform value to yield a CNN prior, whose forward projections are used to replace the metal-affected projections, followed by the FBP reconstruction. The effectiveness of the proposed method is validated on both simulated and real data. Experimental results demonstrate the superior MAR capability of the proposed method to its competitors in terms of artifact suppression and preservation of anatomical structures in the vicinity of metal implants. [ABSTRACT FROM AUTHOR]

The occurrence of pseudotumors currently constitutes an important topic of interest among orthopaedic surgeons who prefer metal on metal arthroplasty and especially hip resurfacing arthroplasty. Adverse reactions to metal ions are associated with the formation of such lesions and the orientation of implants has also been implicated in their pathogenesis. The diagnosis of pseudotumors is as difficult as complex. There is a variety of symptoms and patients with mild or tolerable pain may not seek medical attention. Revision surgeries may be the only solution in some cases. The goal of this article is to review the clinical presentation, prognosis of pseudotumors and associated complications, based on evidence published in the literature. [ABSTRACT FROM AUTHOR]

Treatment of prosthetic joint infections often involves multiple surgeries and prolonged antibiotic administration, resulting in a significant burden to patients and the healthcare system. We are exploring a non-invasive method to eradicate biofilm on metal implants utilizing high-frequency alternating magnetic fields (AMF) which can achieve surface induction heating. Although proof-of-concept studies demonstrate the ability of AMF to eradicate biofilm in vitro, there is a legitimate safety concern related to the potential for thermal damage to surrounding tissues when considering heating implanted metal objects. The goal of this study was to explore the feasibility of detecting acoustic emissions associated with boiling at the interface between a metal implant and surrounding soft tissue as a wireless safety sensing mechanism. Acoustic emissions generated during in vitro and in vivo AMF exposures were captured with a hydrophone, and the relationship with surface temperature analyzed. The effect of AMF exposure power, surrounding media composition, implant location within the AMF transmitter, and implant geometry on acoustic detection during AMF therapy was also evaluated. Acoustic emissions were reliably identified in both tissue-mimicking phantom and mouse studies, and their onset coincided with the implant temperature reaching the boiling threshold. The viscosity of the surrounding medium did not impact the production of acoustic emissions; however, emissions were not present when the medium was oil due to the higher boiling point. Results of simulations and in vivo studies suggest that short-duration, high-power AMF exposures combined with acoustic sensing can be used to minimize the amount of thermal damage in surrounding tissues. These studies support the hypothesis that detection of boiling associated acoustic emissions at a metal/tissue interface could serve as a real-time, wireless safety indicator during AMF treatment of biofilm on metallic implants. [ABSTRACT FROM AUTHOR]

The presence of ionic titanium in the serum of patients with titanium implants is currently unexplained. This is presumed due to corrosion, and yet the serum titanium concentration measured in patients is far greater than that predicted by its solubility. The binding of titanium ion as Ti(IV) to human transferrin (hTF) in serum indicates that Ti(IV) ions interact with human physiology. This is an intriguing finding since there is currently no known role for titanium ions in human physiology. Thus, understanding the factors that determine in vivo titanium ion release is relevant to further understanding this metal’s interactions with human biochemistry. The present study sought to determine the extent of titanium ion release of into human serum in vitro, and the role of citrate, lactate and hTF in this process. It was found that, when surgical devices of commercially pure titanium were placed into human serum, citrate and lactate concentrations were the prime determinants of titanium release. Crystallography revealed Ti(IV) bound to hTF in the presence of citrate alone, signalling that citrate can act as an independent ligand for Ti(IV) binding to hTF. Based on these findings, a two-stage process of titanium ion release into human serum that is dependent upon both citrate and hTF is proposed to explain the ongoing presence of titanium ion in human subjects with implanted titanium devices. [ABSTRACT FROM AUTHOR]

Background: This study investigated the design and osseointegration process of transitive porous implants that can be used in humans and all trabecular and compact bone structure animals. The aim was to find a way of forming a strong and durable tissue bond on the bone–implant interface. Methods: Massive and transitive porous implants were produced on a direct metal laser sintering machine, surgically implanted into the skulls of sheep and kept in place for 12 weeks. At the end of the 12-week period, the Massive and porous implants removed from the sheep were investigated by scanning electron microscopy (SEM) to monitor the osseointegration process. Results: In the literature, each study has selected standard sizes for pore diameter in the structures they use. However, none of these involved transitional porous structures. In this study, as opposed to standard pores, there were spherical or elliptical pores at the micro level, development channels and an inner region. Bone cells developed in the inner region. Transitive pores grown gradually in accordance with the natural structure of the bone were modeled in the inner region for cells to develop. Due to this structure, a strong and durable tissue bond could be formed at the bone–implant interface. Conclusions: Osseointegration processes of Massive vs. porous implants were compared. It was observed that cells were concentrated on the surface of Massive implants. Therefore, osseointegration between implant and bone was less than that of porous implants. In transitive porous implants, as opposed to Massive implants, an outer region was formed in the bone–implant interface that allowed tissue development. [ABSTRACT FROM AUTHOR]

Introduction: More than 50% of patients with esophageal cancer already have inoperable disease at the time of diagnosis. Controversy surrounds the outcomes of patients with advanced esophageal cancer who receive palliative care by either stent alone or stent plus an additional modality. We set out to perform a systematic review and meta-analysis of studies assessing the use of metal stents as treatment options for symptomatic improvement, survival, and adverse events.Methods: We searched Embase, MEDLINE, and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception until January 14, 2016, as well as other databases for randomized controlled trials (RCTs) comparing esophageal stent versus either esophageal stent plus brachytherapy, radiotherapy, or chemotherapy. For quality assurance purposes throughout the systematic review, multiple independent extractions were performed, and the process was executed as per the standards of the Cochrane collaboration. Primary outcomes were mean change in dysphagia score, overall survival, and quality of life. Secondary outcomes were adverse events including fever, severe pain, aspiration, fistula, stent migration, perforation, and restenosis.Results: Eight RCTs enrolling 732 patients were included with three distinct comparisons: stents combination therapy vs stents alone (5 studies, n = 417), stents alone versus brachytherapy alone (2 studies, n = 274), and stents + brachytherapy vs brachytherapy alone (1 study, n = 41). Stents combination therapy was defined as stents plus radiotherapy, chemotherapy, or both. Mean change in dysphagia scores favored stents combination therapy versus stents alone, and the effect was seen in patients surviving longer than 3 months. Stents combination therapy was also associated with a more favorable overall survival. The risks of stent migration, aspiration pneumonia, and restenosis were lower in the stents combination group compared to stents alone, while the risks of severe pain, hemorrhage, and fistula formation were higher. Changes in dysphagia scores and overall survival did not differ significantly in the brachytherapy-alone vs stents-alone comparison. The risk of fistula formation and hemorrhage were higher in the stents-alone group, while the risk of perforation was lower, compared to brachytherapy alone. Quality of life improvements were seen in all treatment groups, but were not pooled in analysis due to differing methods of measurement.Discussion: While there appears to be no immediate short-term differences, those who live longer than 3 months experience a significant improvement in dysphagia score using a stents combination therapy approach vs stents alone. The combination therapy significantly improves the overall survival as well as showed improvements in quality of life scores. Larger randomized controlled trials are needed to assess improvements in dysphagia score, overall survival, quality of life, and adverse events. [ABSTRACT FROM AUTHOR]

The focal metallic cartilage resurfacing is a surgical method that offers an appropriate step between the biological techniques and arthroplasty in middle-aged patients with full-thickness cartilage defects. The advantages of this technique are that it addresses the defect, respects healthy tissues and provides stability and contoured surface similar to a full arthroplasty. A systematic review was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Two reviewers (MM and DC) independently conducted the search using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews (CDSR). These databases were searched for the terms hemicap knee implant and unicap knee implant and knee focal metallic implant. From the initial 21 studies that were evaluated, 10 were eligible for analysis. Considering both the HemiCAP focal implant and the HemiCap® Wave patellofemoral prosthesis, we found a lack of mid- to long-term clinical outcomes in well-designed prospective clinical studies. No Level I or II studies were found, while the limited number of patients who were included undermines the overall clinical results of these studies. The progression of osteoarthritis, the persisting pain and the subsequent high revision or failure rates in the limited available studies with long-term follow-up, seem to be the major drawbacks of these partial resurfacing techniques. Utilization of partial resurfacing for femoral or patellofemoral compartments results in good short-term outcome for middle-aged patients as a step between biological technique and total knee arthroplasty. The surgeon should be cognizant and also notify the patient of the high failure rates that are reported in the literature in mid- to longterm follow-up and ultimately, the decision to perform partial resurfacing should be taken by both the patient and the orthopedic surgeon. [ABSTRACT FROM AUTHOR]

ABSTRACT: A novel computational model of implant migration in trabecular bone was developed using smoothed‐particle hydrodynamics (SPH), and an initial validation was performed via correlation with experimental data. Six fresh‐frozen human cadaveric specimens measuring 10 × 10 × 20 mm were extracted from the proximal femurs of female donors (mean age of 82 years, range 75–90, BV/TV ratios between 17.88% and 30.49%). These specimens were then penetrated under axial loading to a depth of 10 mm with 5 mm diameter cylindrical indenters bearing either flat or sharp/conical tip designs similar to blunt and self‐tapping cancellous screws, assigned in a random manner. SPH models were constructed based on microCT scans (17.33 µm) of the cadaveric specimens. Two initial specimens were used for calibration of material model parameters. The remaining four specimens were then simulated in silico using identical material model parameters. Peak forces varied between 92.0 and 365.0 N in the experiments, and 115.5–352.2 N in the SPH simulations. The concordance correlation coefficient between experimental and simulated pairs was 0.888, with a 95%CI of 0.8832–0.8926, a Pearson ρ (precision) value of 0.9396, and a bias correction factor Cb (accuracy) value of 0.945. Patterns of bone compaction were qualitatively similar; both experimental and simulated flat‐tipped indenters produced dense regions of compacted material adjacent to the advancing face of the indenter, while sharp‐tipped indenters deposited compacted material along their peripheries. Simulations based on SPH can produce accurate predictions of trabecular bone penetration that are useful for characterizing implant performance under high‐strain loading conditions. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1114–1123, 2018. [ABSTRACT FROM AUTHOR]