Specific Combinations Research Articles

Electrochemical Synthesis of Ammonia via Nitrogen Reduction and Oxygen Evolution Reactions—A Comprehensive Review on Electrolyte-Supported Cells

The application of protonic ceramic electrolysis cells (PCECs) for ammonia (NH3) synthesis has been evaluated over the past 14 years. While nitrogen (N2) is the conventional fuel on the cathode side, various fuels such as methane (CH4), hydrogen (H2), and steam (H2O) have been investigated for the oxygen evolution reaction (OER) on the anode side. Because H2 is predominantly produced through CO2-emitting methane reforming, H2O has been the conventional carbon-free option thus far. Although the potential of utilizing H2O and N2 as fuels is considerable, studies exploring this specific combination remain limited. PCEC fabrication technologies are being developed extensively, thus necessitating a comprehensive review. Several strategies for electrode fabrication, deposition, and electrolyte design are discussed herein. The progress in electrode development for PCECs has also been delineated. Finally, the existing challenges and prospective outlook of PCEC for NH3 synthesis are analyzed and discussed. The most significant finding is the lack of past research involving PCEC with H2O and N2 as fuel configurations and the diversity of nitrogen reduction reaction catalysts. This review indicates that the maximum NH3 synthesis rate is 14 × 10−9 mol cm−2 s−1, and the maximum current density for the OER catalyst is 1.241 A cm−2. Moreover, the pellet electrolyte thickness must be maintained at approximately 0.8–1.5 mm, and the stability of thin-film electrolytes must be improved.

Multivariate generalized mixed-effects models for screening multiple adverse drug reactions in spontaneous reporting systems.

Introduction: For assessing drug safety using spontaneous reporting system databases, quantitative measurements, such as proportional reporting rate (PRR) and reporting odds ratio (ROR), are widely employed to assess the relationship between a drug and a suspected adverse drug reaction (ADR). The databases contain numerous ADRs, and the quantitative measurements need to be calculated by performing the analysis multiple times for each ADR. We proposed a novel, simple, and easy-to-implement method to estimate the PRR and ROR of multiple ADRs in a single analysis using a generalized mixed-effects model for signal detection. Methods: The proposed method simultaneously analyzed the association between any drug and numerous ADRs, as well as estimated the PRR and ROR for a specific combination of drugs and suspected ADRs. Furthermore, the proposed method was applied to detect drug-drug interactions associated with the concurrent use of two or more drugs. Results and discussion: In our simulation studies, the false-positive rate and sensitivity of the proposed method were similar to those of the traditional PRR and ROR. The proposed method detected known ADRs when applied to the Food and Drug Administration Adverse Event Reporting System database. As an important advantage, the proposed method allowed the simultaneous evaluation of several ADRs using multiple drugs.

Systematic detection of co-infection and intra-host recombination in more than 2 million global SARS-CoV-2 samples

Systematic monitoring of SARS-CoV-2 co-infections between different lineages and assessing the risk of intra-host recombinant emergence are crucial for forecasting viral evolution. Here we present a comprehensive analysis of more than 2 million SARS-CoV-2 raw read datasets submitted to the European COVID-19 Data Portal to identify co-infections and intra-host recombination. Co-infection was observed in 0.35% of the investigated cases. Two independent procedures were implemented to detect intra-host recombination. We show that sensitivity is predominantly determined by the density of lineage-defining mutations along the genome, thus we used an expanded list of mutually exclusive defining mutations of specific variant combinations to increase statistical power. We call attention to multiple challenges rendering recombinant detection difficult and provide guidelines for the reduction of false positives arising from chimeric sequences produced during PCR amplification. Additionally, we identify three recombination hotspots of Delta – Omicron BA.1 intra-host recombinants.

Selective herbicide safening in dicot plants: a case study in Arabidopsis.

Safeners are agrochemicals co-applied with herbicides that facilitate selective control of weeds by protecting monocot crops from chemical injury through enhancing the expression of detoxifying enzymes such as glutathione transferases (GSTs). Even though the application of safeners causes the induction of genes encoding GSTs in model dicots such as Arabidopsis thaliana, safeners do not protect broadleaf crops from herbicide injury. In this study, we proposed that the localized induction of Arabidopsis GSTs and the fundamental differences in their detoxifying activity between dicot and monocot species, underpin the failure of safeners to protect Arabidopsis from herbicide toxicity. Using the herbicide safener, isoxadifen-ethyl, we showed that three tau (U) family GSTs namely AtGSTU7, AtGSTU19 and AtGSTU24 were induced with different magnitude by isoxadifen treatment in root and rosette tissues. The higher magnitude of inducibility of these AtGSTUs in the root tissues coincided with the enhanced metabolism of flufenacet, a herbicide that is active in root tissue, protecting Arabidopsis plants from chemical injury. Assay of the recombinant enzyme activities and the significant reduction in flufenacet metabolism determined in the T-DNA insertion mutant of AtGSTU7 (gstu7) in Arabidopsis plants identified an important function for AtGSTU7 protein in flufenacet detoxification. In-silico structural modeling of AtGSTU7, suggested the unique high activity of this enzyme toward flufenacet was due to a less constrained active site compared to AtGSTU19 and AtGSTU24. We demonstrate here that it is possible to induce herbicide detoxification in dicotyledonous plants by safener treatment, albeit with this activity being restricted to very specific combinations of herbicide chemistry, and the localized induction of enzymes with specific detoxifying activities.

Reasons and Mechanisms of Development of Mastopathy (Review of Literature)

This review article examines the relationship between various etiological factors in the development of mastopathy. Multiple exogenous and endogenous risk factors disrupt the normal ratio of sex hormones, causing hyperestrogenism and hyperproliferation of the epithelium in breast tissue, which leads to the development of mastopathy. In the presence of polymorphism of coding genes (ESR1 and PRG), mastopathy also increases the risk of developing breast cancer. Disturbances in the ESR1 receptor gene (Estrogen Receptor 1) lead to changes in the sensitivity of receptors to hormones and even to its loss. According to the literature, polymorphism in the intronic region of the ESR1 gene is associated with the risk of fibrocystic mastopathy. The presence of polymorphism of the PRG (Progesterone Receptor Genes) gene may cause the occurrence of defective forms of PR (Progesterone Receptor) with disruption of the ligand- and hormone-binding zones, which is confirmed by the effects of progesterone in tissues. Thus, progesterone deficiency makes possible excessive proliferation of not only epithelial cells, but also the connective tissue component of the mammary gland. In this case, the expression of the progesterone receptor gene is regulated by the level of estrogen. The association of various combinations of predisposition genes indicates the presence of a specific combination of genotypes for each clinical and pathogenetic variant. In proliferative forms of mastopathy, foci with an excess content of estrogen receptors in the epithelium and high activity of cell proliferation and apoptosis are formed in the breast tissue; there is an increase in the content of alpha-estrogen receptors, a change in the relative content of alpha- and beta-estrogen receptors, A- and B-progesterone receptors; the sensitivity of the epithelium to estradiol increases; a complex of cyclin-dependent kinases, alpha-transforming and epidermal growth factors is activated; the proliferative activity of the epithelium increases; apoptosis processes are disrupted; vascularization of the parenchyma increases. All these pathological mechanisms that increase the risk of breast cancer have not yet been sufficiently studied both at the experimental and clinical level. In the treatment of mastopathy, diet therapy, psychological correction, hormonal drugs, non-hormonal drugs, such as vitamins, minerals, hepatoprotectors, diuretics, enzyme drugs, immunocorrectors, adaptogens, non-steroidal anti-inflammatory drugs, herbal remedies are used. The general disadvantages of most of the remedies used today are attempts to eliminate the causes of mastopathy rather than conducting pathogenetic treatment.

Unveiling the Mode of Action of Dravya Vikalpa

Shodhana-shamana is one of the treatment classifications in Ayurveda. Medicines for Shodhana can be administered in single drug or combination form. The explanation regarding formulations has been dealt in Ayurveda. Though single drugs have been indicated in various disorders, they may fail to target every stage of disease and may therefore fail in treatment. Thus, the permutation and combination of drugs can act efficiently and target every stage of disease. In the Charaka Samhita Chikitsasthana, shodhana yogas are briefly described for specific ailments, however in the Kalpasthana, dravyavikalpa are extensively explained for shodhana. It is difficult to understand choice of dravyavikalpa as there is no direct description on mode and site of action of yogas mentioned. Hence there is a need for proper understanding of the mode and site of action of various dravyavikalpa. Understanding a specific combination and its kalpana helps one understand how medicines are targeted at vitiated doshas and sthanasamshraya. To illustrate the same, Dravyavikalpa for panduroga mentioned in Charaka Samhita Kalpasthana has been taken as an example. In this study an effort will be made to analyze mode and site of action of Dravyavikalpa mentioned in Charaka Samhita Kalpasthana.
 Keywords: Dravyavikalpa, kalpana vishesha, pandu roga

Stiffening and softening of freshly prepared and aged CTA, PTMSP, and PIM‐1 films exposed to volatile compounds

AbstractGlassy polymers stiffen or soften when exposed to volatile compounds, depending on the specific combination of polymer compound and the specimen history. Relevant to the long‐term applicability of the separation membranes, three common membrane glassy polymers are studied in this work. Freshly prepared and 2‐years aged films from cellulose triacetate (CTA), poly[1‐(trimethylsilyl)‐1‐propyne] (PTMSP), and the archetypal polymer of intrinsic microporosity (PIM‐1) were tested using isothermal Dynamic Mechanical Analysis (DMA) at varied vapor activity. Vapors of organic compounds, in which the polymers do and do not dissolve in the liquid phase (solvents and nonsolvents), were studied at 40 °C, namely: dichloromethane (DCM, solvent), p‐xylene (solvent for PTMSP and PIM‐1), and methanol (nonsolvent). Functional groups of the mer units sensitive to the dissolution were identified using Raman spectroscopy. All aged films were stiffer than the freshly prepared ones. Stiffening prevailed for most freshly prepared film‐vapor pairs at low vapor saturations (activity < ≈0.4), except CTA and PIM‐1 in nonsolvent methanol vapors. Softening prevailed for the aged films and higher vapor saturations (activity > ≈0.6). Vapors of the solvents and nonsolvents did not show the expectable prevalence of softening and stiffening, respectively. Physical aging influenced the stiffening and softening of polymer glasses expectably.

Research on the control strategy of coning amount and ASU adjustment considering profile and high-order flatness cooperative control

ABSTRACT In the production of a 20-high mill, high-order flatness defects occur frequently. To achieve collaborative control of the profile and high-order flatness of a 20-high mill, an integrated coupling model of the roll system and strip has been established based on ABAQUS software. It has been found that as the coning amount of the intermediate taper roll increased, the profile evaluation index C25 decreased, while the work roll axis exhibited high-order deflection deformation, which could lead to the generation of high-order flatness defects. Subsequently, a novel control strategy of the coning amount and backup roll segmented reduction (ASU) control adjustment has been proposed to ensure that the profile evaluation index C25 meets the requirements while eliminating the risk of high-order flatness defects caused by roll shifting (coning amount) control. The specific combination form of the control strategy has been determined by using the particle swarm optimisation (PSO) algorithm. The Industrial application results show that the maximum compressive stress in the area 75 mm-300 mm away from the edge can be reduced by more than 40% after using the novel control strategy.

The Combination of University Students' Innovation Ability and Entrepreneurship Education

Under the background of current economic and social growth, innovation and entrepreneurship have become an important force to promote social progress and development. As the backbone of the future society, university students' innovative ability and entrepreneurial spirit are of great significance. This article aims to explore the combination mechanism of university students' innovation ability and enterprise education. Through in-depth theoretical analysis and empirical research, it is found that the combination of university students' innovation ability and enterprise education has important theoretical significance and practical value. It helps to cultivate innovative and entrepreneurial talents. By cultivating university students with innovative ability and entrepreneurial spirit, it can deliver more innovative talents and entrepreneurial strength to the society and promote the sustainable development of the national economy and society. At the same time, this study also reveals the problems and shortcomings of university students' innovation ability and enterprise education, and puts forward some specific combination mechanisms and optimization strategies. These conclusions provide reference for universities to carry out innovation and entrepreneurship education (IEE) and practical activities, and also provide new ideas and methods for future related research.

Impulsivity and aggression in alcohol withdrawal syndrome is modulated by the interaction of ZNF804A and mTOR polymorphism

Alcohol withdrawal syndrome (AWS) is a poorly studied phenotype of alcohol use disorder. Understanding the relationship between allelic interactions and AWS-related impulsivity and aggression could have significant implications. This study aimed to investigate the main and interacting effects of ZNF804A and mTOR on impulsivity and aggression during alcohol withdrawal. 446 Chinese Han adult males with alcohol dependence were included in the study. Impulsivity and aggression were assessed, and genomic DNA was genotyped. Single gene analysis showed that ZNF804A rs1344706 (A allele/CC homozygote) and mTOR rs1057079 (C allele/TT homozygote) were strongly associated with AWS-related impulsivity and aggression. In the allelic group, MANOVA revealed a significant gene x gene interaction, suggesting that risk varied systematically depending on both ZNF804A and mTOR alleles. Additionally, a significant interactive effect of ZNF804A rs1344706 and mTOR rs7525957 was found on motor impulsivity and physical aggression, and the ZNF804A rs1344706 gene variant had significant effects on motor impulsivity and physical aggression only in mTOR rs7525957 TT homozygous carriers. The study showed that specific allelic combinations of ZNF804A and mTOR may have protective or risk-enhancing effects on AWS-related impulsivity and aggression.

Technological upgrading along global value chains: The case of automation and digital technologies in the automotive sector in South Africa

This article contributes to the growing literature on technological upgrading along global value chains, by focusing on the adoption of automation and digital technologies at different functional stages of the automotive value chain. It explores the constant tension that firms in emerging economies face between linking up to international trade and ensuring the upgrading of indigenous firms, which depends on the relationship between lead international firms’ operations and capabilities at the local level. Drawing on extensive qualitative research in South Africa, including 39 interviews and observations at the shopfloor level, this paper examines the determinants for automation and digital technologies adoption. The finding extends existing knowledge of technological upgrading along global value chains, by examining both final assemblers and lower-tier suppliers. Four production specific drivers are identified: volume, quality, material-led adoption, and ergonomics. This paper suggests policymakers should consider sector heterogeneity and specific sector-technology combinations when designing policies to sustain digitalization and production upgrade.

Design method of extractant for liquid–liquid extraction based on elements and chemical bonds

In the petrochemical industry process, the relative volatility between the components to be separated is close to 1 or the azeotrope that systems are difficult to separate. Liquid–liquid extraction is a common and effective separation method, and selecting an extraction agent is the key to extraction technology research. In this paper, a design method of extractants based on elements and chemical bonds was proposed. A knowledge-based molecular design method was adopted to pre-select elements and chemical bond groups. The molecules were automatically synthesized according to specific combination rules to avoid the problem of "combination explosion" of molecules. The target properties of the extractant were set, and the extractant meeting the requirements was selected by predicting the correlation physical properties of the generated molecules. Based on the separation performance of the extractant in liquid–liquid extraction and the relative importance of each index, the fuzzy comprehensive evaluation membership function was established, the analytic hierarchy process determined the weight ratio of each index, and the consistency test results were passed. The results of case study based on quantum chemical analysis demonstrated that effective determination of extractants for the analysis of benzene–cyclohexane systems. The results unanimously prove that the method has important theoretical significance and application value.

Using meta-analysis and CNN-NLP to review and classify the medical literature for normal tissue complication probability in head and neck cancer

PurposeThe study aims to enhance the efficiency and accuracy of literature reviews on normal tissue complication probability (NTCP) in head and neck cancer patients using radiation therapy. It employs meta-analysis (MA) and natural language processing (NLP).Material and methodsThe study consists of two parts. First, it employs MA to assess NTCP models for xerostomia, dysphagia, and mucositis after radiation therapy, using Python 3.10.5 for statistical analysis. Second, it integrates NLP with convolutional neural networks (CNN) to optimize literature search, reducing 3256 articles to 12. CNN settings include a batch size of 50, 50–200 epoch range and a 0.001 learning rate.ResultsThe study's CNN-NLP model achieved a notable accuracy of 0.94 after 200 epochs with Adamax optimization. MA showed an AUC of 0.67 for early-effect xerostomia and 0.74 for late-effect, indicating moderate to high predictive accuracy but with high variability across studies. Initial CNN accuracy of 66.70% improved to 94.87% post-tuning by optimizer and hyperparameters.ConclusionThe study successfully merges MA and NLP, confirming high predictive accuracy for specific model-feature combinations. It introduces a time-based metric, words per minute (WPM), for efficiency and highlights the utility of MA and NLP in clinical research.

Extinction of negative conditioned stimulus valence in human fear conditioning

Fear conditioning is a common experimental paradigm for modelling the development, and exposure-based treatment, of anxiety disorders. Measures of fear such as threat-expectancy, physiological arousal, and fear ratings typically extinguish, however feared stimuli may still be evaluated negatively (i.e. retain negative valence). This systematic review provides the first investigation of the relationship between fear conditioning methodology and extinction of negative stimulus valence. Principal findings were that type of CS (conditioned stimulus) and the CS-US pairing (i.e. specific combination of CS and unconditioned stimulus) predicted extinction outcome. Extinction of absolute negative CS valence was always achieved with shape CSs; often achieved with low fear-relevant animals as CSs, and less frequently achieved with faces as CSs – particularly neutral faces paired with a shock US. Modified extinction procedures typically achieved the same outcome as standard extinction procedures, except for partially-reinforced extinction, which was less effective than standard extinction, and positive imagery training, which was more effective than standard extinction. Further studies are warranted to evaluate the influence of fear conditioning methodology on extinction of absolute negative CS valence.

Novel and reported compensatory mutations in rpoABC genes found in drug resistant tuberculosis outbreaks.

Rifampicin (RIF) is a key first-line drug used to treat tuberculosis, a primarily pulmonary disease caused by Mycobacterium tuberculosis. RIF resistance is caused by mutations in rpoB, at the cost of slower growth and reduced transcription efficiency. Antibiotic resistance to RIF is prevalent despite this fitness cost. Compensatory mutations in rpoABC genes have been shown to alleviate the fitness cost of rpoB:S450L, explaining how RIF resistant strains harbor this mutation can spread so rapidly. Unfortunately, the full set of RIF compensatory mutations is still unknown, particularly those compensating for rarer RIF resistance mutations. We performed an association study on a globally representative set of 4,309 whole genome sequenced clinical M. tuberculosis isolates to identify novel putative compensatory mutations, determine the prevalence of known and previously reported putative compensatory mutations, and determine which RIF resistance markers associate with these compensatory mutations. Of the 1,079 RIF resistant isolates, 638 carried previously reported putative and high-probability compensatory mutations. Our strict criteria identified 46 additional mutations in rpoABC for which no strong prior evidence of their compensatory role exists. Of these, 35 have previously been reported. As such, our independent corroboration adds to the mounting evidence that these 35 also carry a compensatory role. The remaining 11 are novel putative compensatory markers, reported here for the first time. Six of these 11 novel putative compensatory mutations had two or more mutation events. Most compensatory mutations appear to be specifically compensating for the fitness loss due to rpoB:S450L. However, an outbreak of 22 closely related isolates each carried three rpoB mutations, the rare RIFR markers D435G and L452P and the putative compensatory mutation I1106T. This suggests compensation may require specific combinations of rpoABC mutations. Here, we report only mutations that met our very strict criteria. It is highly likely that many additional rpoABC mutations compensate for rare resistance-causing mutations and therefore did not carry the statistical power to be reported here. These findings aid in the identification of RIF resistant M. tuberculosis strains with restored fitness, which pose a greater risk of causing resistant outbreaks.

Concurrent Developmental Regression and Neurocognitive Decline in a Child With De Novo CHD8 Gene Mutation

BackgroundAutism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder. Unique ASD subtypes have been proposed based on specific genotype-phenotype combinations. The ASD subtype associated with various chromodomain helicase DNA-binding protein 8 (CHD8) mutations has been associated with an incidence of autistic regression greater than that of all-cause ASD, but the mean age of onset of this subtype remains unknown. MethodsHere we describe a patient with a known de novo CHD8 gene mutation (heterozygous c.2565del) who experienced a profound developmental regression and neurocognitive decline at age 13 years following periods of acute viral illness. ResultsThe patient developed treatment-refractory catatonia and self-injurious behaviors leading to marked facial disfigurement. Unfortunately, interventions with immunomodulatory medications, psychotropic medications, and electroconvulsive therapy did not lead to sustained symptom improvement or a full return to baseline. ConclusionsOur case demonstrates a clinical scenario in which a devastating developmental regression and neurocognitive decline occurred with profound accentuation of previously identified autistic features at an age atypical for autistic regression, following sequential viral infections, thereby raising the question of whether immune dysregulation may be a contributing factor. Regression in patients with monogenic mutations in the CHD8 gene warrants further study to elucidate the mechanisms of illness and the anticipated developmental trajectory.

Interfacial adhesion between electrical contacts determined by surface quality

ABSTRACT Micro-Electromechanical-Relay (MER) has widely achieved application in the field of engineering thanks to the excellent features and ever-growing interest in microelectronic products. However, the adhesion phenomenon between gold-sputtered contact pairs in MER usually brings about operating failure of normally closed contacts limiting the reliability level of MER. In this paper, various contact combinations between electrical contact pairs are assembled to simulate real contact conditions, and associated failure type is built by taking advantage of mechanical adhesion theory to reveal failure mechanism about cold adhesion. It is found that the adhesion force is correlated closely with the surface roughness of contact pairs. The specific contact combination is a significant effective strategy to reduce the adhesion failure between electrical contacts.

Gut microbiota as predictors of the occurrence of high on-treatment platelet reactivity in acute ischemic stroke patients.

In this study, we aimed to investigate the association between gut microbiota and high on-treatment platelet reactivity (HTPR) in patients with acute ischemic stroke (AIS). We enrolled a total of 48 AIS patients, including 19 HTPR patients and 29 non-high on-treatment platelet reactivity (NHTPR) patients, along with 10 healthy controls. Clinical and laboratory data, as well as stool samples, were collected from all participants. The composition and function of gut microbiota were assessed using 16S rRNA sequencing. Differences in the gut microbiota between the two groups were analyzed, and a diagnostic model based on the gut microbiota was established using random forest model. HTPR patients exhibited a decreased microbial richness compared to NHTPR patients. Additionally, the relative abundance of unidentified_Clostridia and Ralstonia was lower in HTPR patients. Significant differences in biological functions, such as toxoplasmosis, were observed between the two groups. The combination of Ralstonia, unidentified-Clostridia, Mailhella, Anaerofustis, and Aggregatibacter showed excellent predictive ability for HTPR occurrence (AUC=0.896). When comparing AIS patients with healthy controls, alterations in the microbiota structure were observed in AIS patients, with imbalances in short-chain fatty acid-producing bacteria and pathogenic bacteria. Significant differences in biological functions, such as oxidative phosphorylation, were noted between the two groups. The combination of Alloprevotella, Terrisporobacter, Streptococcus, Proteus, and unidentified_Bacteria exhibited strong predictive power for AIS occurrence (AUC=0.994). This study is the first to uncover the microbial characteristics of HTPR in AIS patients and demonstrate the predictive potential of specific bacterial combinations for HTPR occurrence.

The absence of seroconversion after exposition to hepatitis C virus is not related to KIR-HLA genotype combinations (GEHEP-012 study)

Background & aimsIt has been reported that specific killer-cell immunoglobulin-like receptors (KIRs) and HLA genotype combinations, such as KIR2DS4/HLA-C1 with presence of KIRDL2 or KIRDL3, homozygous KIRDL3/HLA-C1 and KIR3DL1/≥2HLA-Bw4, are strongly associated with the lack of active infection and seroconversion after exposition to hepatitis C virus (HCV). ObjectiveTo determine whether these KIR-HLA combinations are relevant factors involved in that phenotype. Patients and methodsIn this retrospective case-control study, genotype data from a genome-wide association study previously performed on low susceptibility to HCV-infection carried out on 27 high-risk HCV-seronegative (HRSN) individuals and 743 chronically infected (CI) subjects were used. HLA alleles were imputed using R package HIBAG v1.2223 and KIR genotypes were imputed using the online resource KIR*IMP v1.2.0. ResultsIt was possible to successfully impute at least one KIR-HLA genotype combination previously associated with the lack of infection and seroconversion after exposition to HCV in a total of 23 (85.2%) HRSN individuals and in 650 (87.5%) CI subjects. No KIR-HLA genotype combination analyzed was related to the HRSN condition. ConclusionsOur results suggest that those KIR-HLA genotype combinations are not relevant factors involved in the lack of infection and seroconversion after exposition to HCV. More studies will be needed to completely understand this phenotype.

Metal interference screw fixation combinations show high revision rates in primary hamstring tendon ACL reconstruction

BackgroundDifferent fixation methods in anterior cruciate ligament reconstruction (ACLR) have been associated with different revision rates, specifically in the early postoperative period. However, most previous research has either grouped together different fixation types or evaluated femoral-sided fixation or tibial-sided fixation separately. Therefore, the purpose of this study was to determine ACL revision rates for specific combinations of femoral and tibial fixation methods within 2 years of primary hamstring tendon autograft ACLR based on data from the Swedish National Knee Ligament Registry (SNKLR).MethodsPatients that underwent primary hamstring tendon autograft ACLR between 2005 and 2018 in the SNKLR were included. The collected data included patient characteristics (age, sex, body mass index [BMI]), activity at time of injury, surgical information (concomitant injuries, time from injury to surgery, fixation types at the femur and tibia), and subsequent revision ACLR. Revision rate within 2 years of the index procedure was chosen, as ACLR fixation is most likely to contribute to ACLR revision within the first 2 years, during graft maturation.ResultsOf the 23,238 included patients undergoing primary hamstring ACLR, 581 (2.5%) underwent revision ACLR within 2 years of the index procedure. Among the combinations used for > 300 patients, the femoral metal interference screw/tibial metal interference screw fixation combination had the highest revision rate followed by metal interference screw/resorbable screw and Endobutton/AO screw fixation combinations, with respective revision rates of 4.0, 3.0, and 3.0%. The lowest revision rate within 2 years of ACLR was found in the Endobutton/metal interference screw with backup Osteosuture fixation combination, used in 433 cases, with a failure rate of 0.9%.ConclusionDifferent early ACL revision rates were found across different combinations of femoral and tibial fixation devices within 2 years of primary hamstring tendon autograft ACLR. Metal interference screw fixation, particularly when performed on both the femoral and tibial sides, most frequently resulted in revision ACLR. These findings may be helpful for surgeons in selecting appropriate fixation devices for hamstring ACLR.Level of evidenceIV