Fourier-transform infrared spectroscopy imaging is a useful adjunct to routine histopathology to identify failure of polyethylene inlays in revision total hip arthroplasty.

The use of highly crosslinked ultra-high molecular weight polyethylene (XLPE) has significantly reduced the volumetric wear of acetabular liners, thereby reducing the incidence of osteolysis. However, contemporary components tend to generate smaller wear particles, which can no longer be identified using conventional histology. This technical limitation can result in imprecise diagnosis. Here, we report on two uncemented total hip arthroplasty cases (~7 years in situ) revised for periprosthetic fracture of the femur and femoral loosening, respectively. Both liners exhibited prominent wear. The retrieved pseudocapsular tissue exhibited a strong macrophage infiltration without microscopically identifiable polyethylene particles. Yet, using Fourier-transform infrared micro-spectroscopic imaging (FTIR-I), we demonstrated the prominent intracellular accumulation of polyethylene debris in both cases. This study shows that particle induced osteolysis can still occur with XLPE liners, even under 10 years in situ. Furthermore, we demonstrate the difficulty of determining the presence of polyethylene debris within periprosthetic tissue. Considering the potentially increased bioactivity of finer particles from XLPE compared to conventional liners, an accurate detection method is required, and new histopathological hallmarks of particle induced osteolysis are needed. FTIR-I is a great tool to that end and can help the accurate determination of foreign body tissue responses.

Revealing the complexity of meniscus microvasculature through 3D visualization and analysis.

Three-dimensional information is essential for a proper understanding of the healing potential of the menisci and their overall role in the knee joint. However, to date, the study of meniscal vascularity has relied primarily on two-dimensional imaging techniques. Here we present a method to elucidate the intricate 3D meniscal vascular network, revealing its spatial arrangement, connectivity and density. A polymerizing contrast agent was injected into the femoral artery of human cadaver legs, and the meniscal microvasculature was examined using micro-computed tomography at different levels of detail and resolution. The 3D vascular network was quantitatively assessed in a zone-base analysis using parameters such as diameter, length, tortuosity, and branching patterns. The results of this study revealed distinct vascular patterns within the meniscus, with the highest vascular volume found in the outer perimeniscal zone. Variations in vascular parameters were found between the different circumferential and radial meniscal zones. Moreover, through state-of-the-art 3D visualization using micro-CT, this study highlighted the importance of spatial resolution in accurately characterizing the vascular network. These findings, both from this study and from future research using this technique, improve our understanding of microvascular distribution, which may lead to improved therapeutic strategies.

The role of ion dissolution in metal and metal oxide surface inactivation of SARS-CoV-2.

Anti-viral surface coatings are under development to prevent viral fomite transmission from high-traffic touch surfaces in public spaces. Copper's anti-viral properties have been widely documented, but the anti-viral mechanism of copper surfaces is not fully understood. We screened a series of metal and metal oxide surfaces for anti-viral activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease (COVID-19). Copper and copper oxide surfaces exhibited superior anti-SARS-CoV-2 activity; however, the level of anti-viral activity was dependent on the composition of the carrier solution used to deliver virus inoculum. We demonstrate that copper ions released into solution from test surfaces can mediate virus inactivation, indicating a copper ion dissolution-dependent anti-viral mechanism. The level of anti-viral activity is, however, not dependent on the amount of copper ions released into solution per se. Instead, our findings suggest that degree of virus inactivation is dependent on copper ion complexation with other biomolecules (e.g., proteins/metabolites) in the virus carrier solution that compete with viral components. Although using tissue culture-derived virus inoculum is experimentally convenient to evaluate the anti-viral activity of copper-derived test surfaces, we propose that the high organic content of tissue culture medium reduces the availability of "uncomplexed" copper ions to interact with the virus, negatively affecting virus inactivation and hence surface anti-viral performance. We propose that laboratory anti-viral surface testing should include virus delivered in a physiologically relevant carrier solution (saliva or nasal secretions when testing respiratory viruses) to accurately predict real-life surface anti-viral performance when deployed in public spaces.IMPORTANCEThe purpose of evaluating the anti-viral activity of test surfaces in the laboratory is to identify surfaces that will perform efficiently in preventing fomite transmission when deployed on high-traffic touch surfaces in public spaces. The conventional method in laboratory testing is to use tissue culture-derived virus inoculum; however, this study demonstrates that anti-viral performance of test copper-containing surfaces is dependent on the composition of the carrier solution in which the virus inoculum is delivered to test surfaces. Therefore, we recommend that laboratory surface testing should include virus delivered in a physiologically relevant carrier solution to accurately predict real-life test surface performance in public spaces. Understanding the mechanism of virus inactivation is key to future rational design of improved anti-viral surfaces. Here, we demonstrate that release of copper ions from copper surfaces into small liquid droplets containing SARS-CoV-2 is a mechanism by which the virus that causes COVID-19 can be inactivated.

Successful Implant Retention in a Chronified Hematogenous Bilateral Periprosthetic Hip Joint Infection With Enterococcus faecalis.

We present a case with bilateral hematogenous hip periprosthetic joint infection with Enterococci which could be treated successfully with implant retention despite chronification and partial loosening. A debridement and replacement of the modular components was carried out with replacement of a loose acetabular cup on the right side. Considering poor local infection control, antibiotic treatment was enhanced by local application of vancomycin. In the present case, treatment of chronic enterococcal periprosthetic joint infection while preserving the implants was successful despite unfavorable odds. Considering the duration of infection, causative microorganism, and loosening of one of the implants, staged exchange of both hip replacements would have been the standard procedure. This case illustrates that some concepts have to be challenged from time to time.

Compass-like manipulation of electronic nematicity in Sr3Ru2O7.

Electronic nematicity has been found in a wide range of strongly correlated electron materials, resulting in the electronic states having-4.5pc]Please note that the spelling of the following author name(s) in the manuscript differs from the spelling provided in the article metadata: Izidor Benedicic. The spelling provided in the manuscript has been retained; please confirm. a symmetry that is lower than that of the crystal that hosts them. One of the most astonishing examples is [Formula: see text], in which a small in-plane component of a magnetic field induces significant resistivity anisotropy. The direction of this anisotropy follows the direction of the in-plane field. The microscopic origin of this field-induced nematicity has been a long-standing puzzle, with recent experiments suggesting a field-induced spin density wave driving the anisotropy. Here, we report spectroscopic imaging of a field-controlled anisotropy of the electronic structure at the surface of [Formula: see text]. We track the electronic structure as a function of the direction of the field, revealing a continuous change with the angle. This continuous evolution suggests a mechanism based on spin-orbit coupling resulting in compass-like control of the electronic bands. The anisotropy of the electronic structure persists to temperatures about an order of magnitude higher compared to the bulk, demonstrating novel routes to stabilize such phases over a wider temperature range.

Spin-orbit driven superconducting proximity effects in Pt/Nb thin films.

Manipulating the spin state of thin layers of superconducting material is a promising route to generate dissipationless spin currents in spintronic devices. Approaches typically focus on using thin ferromagnetic elements to perturb the spin state of the superconducting condensate to create spin-triplet correlations. We have investigated simple structures that generate spin-triplet correlations without using ferromagnetic elements. Scanning tunneling spectroscopy and muon-spin rotation are used to probe the local electronic and magnetic properties of our hybrid structures, demonstrating a paramagnetic contribution to the magnetization that partially cancels the Meissner screening. This spin-orbit generated magnetization is shown to derive from the spin of the equal-spin pairs rather than from their orbital motion and is an important development in the field of superconducting spintronics.

The history of the development of the regular straight stem in hip arthroplasty.

Since the middle of the 20th century, total hip arthroplasty has become a very successful treatment for all end-stage diseases of the hip joint. Charnley solved with his low frictional torque arthroplasty the problem of wear and friction with the introduction of a new bearing couple and the reduction of the head size, which set the prerequisite for the further development of stem design. This narrative review presents the major developments of regular straight stems in hip arthroplasty. It does not only provide an overview of the history but also assembles the generally scarce documentation available regarding the rationale of developments and illustrates often-unsuspected links. Charnley's success is based on successfully solving the issue of fixation of the prosthetic components to the bone, using bone cement made of polymethyl-methacrylate. In the field of cemented anchorage of the stem, two principles showing good long-term revision rates emerged over the years: the force-closed and the shape-closed principles. The non-cemented anchorage bases on prosthesis models ensure enough primary stability for osteointegration of the implant to occur. For bone to grow onto the surface, not only sufficient primary stability is required but also a suitable surface structure together with a biocompatible prosthetic material is also necessary.

Chiral and Catalytic Effects of Site-Specific Molecular Adsorption.

The changes of properties and preferential interactions based on subtle energetic differences are important characteristics of organic molecules, particularly for their functionalities in biological systems. Only slightly energetically favored interactions are important for the molecular adsorption and bonding to surfaces, which define their properties for further technological applications. Here, prochiral tetracenothiophene molecules are adsorbed on the Cu(111) surface. The chiral adsorption configurations are determined by Scanning Tunneling Microscopy studies and confirmed by first-principles calculations. Remarkably, the selection of the adsorption sites by chemically different moieties of the molecules is dictated by the arrangement of the atoms in the first and second surface layers. Furthermore, we have investigated the thermal effects on the direct desulfurization reaction that occurs under the catalytic activity of the Cu substrate. This reaction leads to a product that is covalently bound to the surface in chiral configurations.

Joint fluid concentrations of amphotericin B after local application with calcium sulphate-report of 2 cases.

Fungal periprosthetic joint infections (PJI) are difficult to treat, due to important biofilm formation and limited local penetration of systemically administered antifungals. Calcium sulphate (CaSO4 ) might be a promising carrier to increase local concentration of antifungals. We hypothesized that local amphotericin B release from CaSO4 is high enough to significantly contribute to treatment of fungal PJI. We report joint fluid and serum concentrations of amphotericin B after local application with CaSO4 as an implanted resorbable carrier material as adjunct to standard surgical and systemic antifungal treatment in two cases of PJI with Candida spp. Maximal joint fluid amphotericin B concentration was 14.01 mg/L 5 days after the second local administration of liposomal amphotericin in Case One and 25.77 mg/L 14 days after the second local administration in Case Two. Concentrations higher than minimal inhibitory concentrations (MIC) could be measured for 21 days and 17 days after local administration in Case One and Two, respectively. In Case Two, serum concentration of amphotericin B was <0.01 mg/L 3 days after local administration of 450 mg liposomal amphotericin B. No local or systemic adverse reaction was observed. Fungal PJI was successfully eradicated in both cases with a follow-up of 12 months in Case One and 20 months in Case Two. Application of amphotericin B-loaded CaSO4 was associated with joint fluid concentrations higher than minimal inhibitory concentrations for Candida spp. for approximately 3 weeks, with the advantage that the carrier material dissolves spontaneously and does not require secondary removal. Relapse of fungal infections did not occur in these two patients.

Wound fluid ceftriaxone concentrations after local application with calcium sulphate as carrier material in the treatment of orthopaedic device-associated hip infections.

AIMS: There is a considerable challenge in treating bone infections and orthopaedic device-associated infection (ODAI), partly due to impaired penetration of systemically administrated antibiotics at the site of infection. This may be circumvented by local drug administration. Knowledge of the release kinetics from any carrier material is essential for proper application. Ceftriaxone shows a particular constant release from calcium sulphate (CaSO4) in vitro, and is particularly effective against streptococci and a large portion of Gram-negative bacteria. We present the clinical release kinetics of ceftriaxone-loaded CaSO4 applied locally to treat ODAI. METHODS: A total of 30 operations with ceftriaxone-loaded CaSO4 had been performed in 28 patients. Ceftriaxone was applied as a single local antibiotic in 21 operations and combined with vancomycin in eight operations, and in an additional operation with vancomycin and amphotericin B. Sampling of wound fluid was performed from drains or aspirations. Ceftriaxone concentrations were measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS). RESULTS: A total of 37 wound fluid concentrations from 16 operations performed in 14 patients were collected. The ceftriaxone concentrations remained approximately within a range of 100 to 200 mg/l up to three weeks. The median concentration was 108.9 mg/l (interquartile range 98.8 to 142.5) within the first ten days. No systemic adverse reactions were observed. CONCLUSION: Our study highlights new clinical data of locally administered ceftriaxone with CaSO4 as carrier material. The near-constant release of ceftriaxone from CaSO4 observed in vitro could be confirmed in vivo. The concentrations remained below known local toxicity thresholds.Cite this article: Bone Joint Res 2022;11(11):835-842.

Periprosthetic Joint Infection With Actinomyces radingae May Lead to the Identification of a Neglected Source of Intraoperative Contamination.

Periprosthetic joint infection remains a major complication in arthroplasty. We present the first description of a case of periprosthetic joint infection with Actinomyces radingae, microorganism that is mostly found on the skin of the upper body and might cause particular challenges as it is difficult to culture and specify. Furthermore, a thorough microbiologic workup may indicate the source of infection. In this case, it is possible that perspiration from the surgeon was the source of intraoperative contamination. Intraoperative contamination through perspiration may be important and should be avoided by all means.

Asymptomatic Periprosthetic Joint Infection of the Hip with High-Virulence Pathogens: Report of Two Cases.

Periprosthetic joint infection (PJI) may be a life-threatening condition, particularly when caused by pathogens with high virulence, capable of developing secondary bloodstream infection. We report two cases of chronic PJI of the hip, one with Staphylococcus aureus in a 27-year-old female with severe anorexia, the other one with Staphylococcus lugdunensis in a 74-year-old female suffering from morbid obesity. Both infections did not cause relevant symptoms over time despite the absence of suppressive antibiotic treatment. To our knowledge, there are no similar cases described in the literature. While it remains difficult to recommend postponing treatment in such cases, this option may be an alternative to suppressive antibiotic therapy.

Early failure of a highly cross-linked polyethylene inlay after total hip arthroplasty probably due to insufficient irradiation.

Highly cross-linked polyethylene (XLPE) is a major advance in total hip arthroplasty (THA), as it suffers from less wear and thus is associated with lower revision rates than standard ultra-high molecular weight polyethylene. Early failures are reported rarely, and associated with specific design or manufacturing issues. We report a case requiring early revision due to adverse reaction to polyethylene particles. Investigations identified insufficient irradiation as the most probable cause of failure. Here are reported the features of a clinical case with determination of the material properties of the retrieved XLPE liner and establishment of the appropriate calibration curves as reference. Periprosthetic joint infection could be ruled out with appropriate sampling as cause for the inflammatory periarticular tumour. Histology identified a massive macrophagic reaction to micrometric polyethylene particles. No component malposition was present, nor any third-body wear. The trans-vinylene index (TVI) indicated insufficient and potentially detrimental irradiation of the polyethylene, while gel content, crystallinity, melting temperature and oxidation index remained within expected ranges. Histologically proven failure of a XLPE THA liner was identifiable despite correct implantation of the components. The cause of failure most probably was an inadequate irradiation, as indicated by determination of the TVI. This case underscores the importance of histologic workup even in aseptic revisions, and of detailed analysis of retrievals. The calibration curves provided are essential for analysis of other retrievals.

Atomic-scale imaging of emergent order at a magnetic field-induced Lifshitz transition.

The phenomenology and radical changes seen in material properties traversing a quantum phase transition have captivated condensed matter research over the past decades. Strong electronic correlations lead to exotic electronic ground states, including magnetic order, nematicity, and unconventional superconductivity. Providing a microscopic model for these requires detailed knowledge of the electronic structure in the vicinity of the Fermi energy, promising a complete understanding of the physics of the quantum critical point. Here, we demonstrate such a measurement at the surface of Sr3Ru2O7. Our results show that, even in zero field, the electronic structure is strongly C2 symmetric and that a magnetic field drives a Lifshitz transition and induces a charge-stripe order. We track the changes of the electronic structure as a function of field via quasiparticle interference imaging at ultralow temperatures. Our results provide a complete microscopic picture of the field-induced changes of the electronic structure across the Lifshitz transition.

Osteoanabolic Treatment with Teriparatide for Pathological Stress Transfer After Total Hip Arthroplasty: A Case Report.

CASE: Total hip arthroplasty with an uncemented, tapered, fluted stem was performed in a 79-year-old woman with known osteoporosis to treat an intertrochanteric fracture. Exertional thigh pain and cortical thickening developed at the tip of the stem. The patient was treated with teriparatide for a total of 2 years and became asymptomatic within months. Radiographs showed improved bone quality around the stem of the prosthesis, and dual-energy x-ray absorptiometry scans confirmed remineralization. CONCLUSION: Stem tip pain is a well-known complication of distally engaging arthroplasty implants. Various surgical options have been suggested to address this condition. Teriparatide is known to help prevent fractures and improve bone healing. This successful off-label use might be of interest for the future treatment of this biomechanical complication.

The Incidence of Severe Hypercalcaemia-Induced Mental Status Changes in Patients Treated with Antibiotic-Loaded Calcium Sulphate Depot for Orthopaedic Infections.

Local application of antibiotics with calcium-containing carrier materials (CCCM) might deliver large quantities of calcium, with some cases of hypercalcaemia reported. The incidence of symptomatic hypercalcaemia was estimated retrospectively in a consecutive, prospective series of patients treated between 10/2006 and 02/2019 with antibiotic-loaded CCCM for various orthopaedic infections. Risk factors were analysed. In the study period, 215 CCCM applications were performed. Two patients (0.9%) developed symptomatic hypercalcaemia. In one case, hypercalcaemia occurred 14 days after a second CCCM application during a staged septic hip revision. In the other case, hypercalcaemia became symptomatic six days after application of vancomycin-loaded CCCM in a component-retaining septic revision hip arthroplasty. In both cases, hypercalcemia was not imputable solely to the CCCM. Prolonged immobilization, renal impairment and other specific risk factors were present. Implantation of a CCCM for local application of antibiotics exposes the patient to large quantities of calcium during dissolution. This might induce symptomatic hypercalcaemia, a potentially life-threatening complication. The observed incidence of symptomatic hypercalcaemia remained rare (<1%). In some patients, compensatory mechanisms might be overwhelmed in the presence of other risk factors. Postoperative monitoring of calcaemia as well as elimination of risk factors is mandatory for all patients treated with CCCM.

Local antibiotic treatment with calcium sulfate as carrier material improves the outcome of debridement, antibiotics, and implant retention procedures for periprosthetic joint infections after hip arthroplasty - a retrospective study.

Purpose: Debridement, antibiotics, and implant retention (DAIR) is an established treatment modality in periprosthetic joint infections (PJIs), but success rates vary. This study compared the success of DAIR for PJIs after a total hip arthroplasty (THA), with or without local antibiotic delivery with CaSO 4 as the carrier material. Methods: A retrospective review of DAIR for PJIs after THA performed between 2010 and 2018, including 41 patients is conducted. A total of 27 patients were treated by DAIR with local antibiotics with CaSO 4 as the carrier material, and 14 patients were treated by a standard DAIR. The endpoints were treatment failure, defined as the need for a reoperation, either a second DAIR or a prosthesis removal or exchange due to persistent or recurrent infection, the initiation of a long-term suppressive antibiotic treatment, or death related to infection. Results: Considering any reoperation as an outcome, 11 of 14 cases treated without AB-CaSO 4 (79 %) and 4 of the 27 cases treated with AB-CaSO 4 failed (15 %). Considering revision as an outcome, 9 out of 14 cases treated without AB-CaSO 4 (64 %) and 4 of the 27 cases treated with AB-CaSO 4 (15 %) failed. A Kaplan-Meier survival analysis showed that local antibiotic delivery with CaSO 4 as the carrier material led to a significantly longer infection-free survival, considering any surgical revision ( p < 0.0001 ; hazard ratio 8.9 (95 % CI 2.8-28.2)) or revision with component exchange ( p = 0.0015 ; hazard ratio 5.6 (95 % CI 1.7-18.2)) as the endpoint. Conclusion: The addition of local antibiotics with CaSO 4 as the carrier material to DAIR for PJIs after THA significantly increases success rates, such as infection-free survival, any reoperation, and revision with component exchange in particular.

The different failure modes of the connecting elements of the modular hip arthroplasty revision stem Revitan.

INTRODUCTION: Fracture of the femoral stem is the cause of ~1 % of revisions after total hip arthroplasty. The risk increases intrinsically with modularity, whereby modularity is particularly useful in revision arthroplasty. We present 7 cases of failure of a specific modular, tapered, fluted, titanium alloy Revitan stem and analyse the different failure modes. METHODS: Retrospective review of all Revitan stems revised at our institutions due to implant failure and analysis of clinical presentation, diagnostic workup, and failure mode. The retrieved components were analyzed by optical and scanning electron microscopy. RESULTS: A total of 7 cases were included. There was a significant time lag between symptom onset and correct diagnosis. Conventional radiographs and low-dose CT scans (CT scout imaging) were decisive for diagnosis. All failures occurred at the level of the connection between the proximal component and the distal part of the stem. Three different failure modes were identified: loosening of the proximal component, fatigue fracture of the connection pin, and distal loosening of the connection pin. No alterations of the microstructure or deviation from manufacturing specifications regarding dimensions were observed. Failure was caused by mechanical overload. CONCLUSION: Conventional radiographs are the mainstay in identifying failed modular stems. Repeated radiographs and low-dose CT scans may be helpful additions. No single modification of the connection will address all possible failure modes. Modularity of revision stems offers advantages up until insertion of the definitive stem. Monoblock definitive stems might overcome the potential mechanical weaknesses of modularity and should be considered in relatively young, heavy and active patients.