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1.
Bone Joint J ; 101-B(10): 1248-1255, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31564141

RESUMO

AIMS: The aim of this study was to conduct the largest low contact stress (LCS) retrieval study to elucidate the failure mechanisms of the Porocoat and Duofix femoral component. The latter design was voluntarily recalled by the manufacturer. MATERIALS AND METHODS: Uncemented LCS explants were divided into three groups: Duofix, Porocoat, and mixed. Demographics, polyethylene wear, tissue ingrowth, and metallurgical analyses were performed. RESULTS: In 104 implants, a decrease in the odds of loosening and an increase in metallosis and tissue staining in the Duofix group relative to Porocoat group was detected (p = 0.028). There was an increased presence of embedded metallic debris in the Duofix group (p < 0.001). Decreased tissue ingrowth was associated with the Duofix surface (p < 0.001). The attached beads had reduced microhardness, indicative of adverse thermal processing, which resulted in bead shedding, particulate debris, and metallosis. CONCLUSION: Hydroxyapatite coating of the LCS femoral component produced unexpected results and led to its recall. The root cause was likely a combination of retained alumina grit and a reduction in bead microhardness (mechanical strength) resulting in increased particle debris, metallosis, and early revision. The Duofix LCS femoral component was not equivalent to the Porocoat version despite its approval through the Food and Drug Administration (FDA) 510(k) equivalance approval process. Regulation of the introduction of modified existing devices needs to be improved and the Duofix LCS should have been considered to be a new device for which equivalence had not been demonstrated at the point of introduction. Cite this article: Bone Joint J 2019;101-B:1248-1255.


Assuntos
Artroplastia do Joelho/efeitos adversos , Remoção de Dispositivo , Prótese do Joelho/efeitos adversos , Falha de Prótese , Estresse Mecânico , Idoso , Austrália , Intervalos de Confiança , Análise de Falha de Equipamento , Feminino , Humanos , Modelos Logísticos , Masculino , Razão de Chances , Desenho de Prótese
2.
Braz Oral Res ; 33: e097, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31664360

RESUMO

To evaluate the torsional properties of engine-driven pathfinding instruments manufactured from different NiTi alloys - R-Pilot (tip size 12.5;.04 taper; M-Wire) and One G (tip size 14;.03 taper; Conventional NiTi). A total of 40 NiTi instruments from engine-driven pathfinding instruments (n = 20) were used. The torsion tests followed ISO 3630-1 (1992). Three millimeters of each instrument tip was fastened to a small load cell by a lever arm linked to the axis of torsion. During the test, the torsion testing machine software measured the maximum torsional strength and angle of rotation (0) before instrument failure. The fractured surface of each instrument was assessed by scanning electron microscopy (SEM). In addition, a supplementary examination was performed to measure the cross-sectional area and the metal mass volume of each instrument 3 mm from the tip. Data were analyzed using a t-test, with significance level set at 5%. R-pilot had significantly higher torsional strength than did One G (p < 0.05). Regarding the angle of rotation to fracture, One G had higher angles than did R-Pilot (p < 0.05). The supplementary examination showed that R-Pilot had the highest cross-sectional area and volume of metal mass at 3 mm from the tip (p < 0.05). R-pilot (M-Wire NiTi alloy) had a significantly higher torsional strength and One-G (superelastic NiTi alloy) had the highest angle of rotation to fracture.


Assuntos
Ligas/química , Ligas Dentárias/química , Instrumentos Odontológicos , Preparo de Canal Radicular/instrumentação , Análise de Variância , Desenho de Equipamento , Análise de Falha de Equipamento , Teste de Materiais , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Estresse Mecânico , Propriedades de Superfície , Torque
3.
Int Heart J ; 60(5): 1050-1060, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31484868

RESUMO

Edge restenosis has gained attention as a main cause of restenosis after first-generation drug-eluting stent (DES) implantation. The aim of this study was to assess the incidence of edge restenosis and identify the predictors of edge restenosis after second-generation DES implantation. Data were obtained from several postmarketing surveillance (PMS) studies on a cobalt-chromium everolimus-eluting stent (CoCr-EES; Xience V/PROMUS, Xience Prime, Xience Prime SV, and Xience Expedition SV), a second-generation DES, in Japan. Angiographic analysis was conducted at the baseline and after eight months on the following subsegments: in-stent region, proximal edge, and distal edge. Restenosis was defined as ≥ 50% diameter stenosis (DS) at follow-up. We used multivariate logistic regression (with lesions as a random effect) to compare the instances of restenosis between the proximal and the distal edges. Univariate and multivariate analyses of the risk factors for restenosis were performed for each subsegment. We analyzed 1,966 lesions in 1,687 patients. The restenosis rates at the in-stent region, proximal edge, and distal edge were 4.4%, 3.0%, and 1.1%, respectively. The risk of restenosis at the distal edge was significantly lower than that at the proximal edge, when adjusted for 13 variables. The predictors of restenosis were postprocedural % diameter stenosis (%DS), postprocedural reference diameter, ≥ 45° bending, stent overlap at the proximal edge, and postprocedural %DS at the distal edge. Our analysis of eight-month angiographic outcomes from CoCr-EES PMS demonstrated that postprocedural %DS is a major predictor of edge restenosis. Edge restenosis is more likely attributable to postprocedural angiographic results than to the patient's background.


Assuntos
Angiografia Coronária/métodos , Estenose Coronária/terapia , Stents Farmacológicos/efeitos adversos , Vigilância de Produtos Comercializados , Desenho de Prótese , Sirolimo/farmacologia , Fatores Etários , Idoso , Angioplastia Coronária com Balão/métodos , Angioplastia Coronária com Balão/mortalidade , Cromo , Cobalto , Estudos de Coortes , Reestenose Coronária/diagnóstico por imagem , Reestenose Coronária/epidemiologia , Estenose Coronária/diagnóstico por imagem , Estenose Coronária/mortalidade , Análise de Falha de Equipamento , Feminino , Hospitais Universitários , Humanos , Incidência , Japão , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Prognóstico , Sistema de Registros , Estudos Retrospectivos , Medição de Risco , Índice de Gravidade de Doença , Fatores Sexuais , Análise de Sobrevida , Resultado do Tratamento
5.
Microsc Res Tech ; 82(9): 1419-1429, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31099955

RESUMO

The purpose of this study was to: (a) evaluate the role of enamel surface roughness on bond fatigue durability and (b) evaluate statistical differences in roughness values based on measurement technique, including the use of spatial filtering for optical profilometry (OP). OptiBond XTR (Kerr Corp), Prime & Bond elect (DENTSPLY Caulk), Scotchbond Universal (3 M Oral Care), and XTR pre-etched with Ultra-Etch phosphoric acid (35%) (Ultradent) self-etch adhesives were used to treat enamel. A flat ground enamel surface was included as a control. Atomic force microscopy (AFM) and OP were used to measure the surface topography of each enamel surface following the application of adhesives. AFM, OP, and filtered OP (FOP) roughness values, where FOP was designed to only include the lateral spatial resolution consistent with AFM roughness values, were collected. Spatial resolution filtering with OriginPro was used to compare line scans from the two imaging techniques and generate the FOP group. These micro- versus nanoscale lateral roughness values were correlated with shear bond and shear fatigue strengths of the adhesives bonded to enamel. Roughness values showed differences based on measurement technique and strong correlations with bond and fatigue strength. The filtered OP group demonstrated the importance of careful usage and reporting of atomic force microscopy and OP metrics in adhesive dentistry. Best practices for surface roughness analysis were also discussed.


Assuntos
Cimentos Dentários/análise , Esmalte Dentário/ultraestrutura , Análise de Falha de Equipamento/métodos , Microscopia de Força Atômica/métodos , Imagem Óptica/métodos , Propriedades de Superfície , Humanos , Dente Molar/ultraestrutura
6.
Sensors (Basel) ; 19(9)2019 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-31075916

RESUMO

The extraction of rolling bearings' degradation features has been developed for decades. However, the degradation features always present different trends of different run-to-failure data. To find a consistent indicator of different data will be helpful to establish a general model and explore the nature of bearings' degradation. In this study, we have found there is a trend of similarity between the energy and complexity features. By using the cointegration test, we found the two kinds of features exhibit a certain degree of cointegration relationship. Fused by the cointegration method, we have obtained a novel health indicator which can depict different run-to-failure data in a unified way. The difference between the energy features and complexity features can be explained by the novel health indicator. The indicator has "two-stage" characters. The first stage is the zero-line stage and the second stage is the quickly raise stage, which presents like an exponential function. It is easy to think about using an exponential degradation model to model this indicator. Next, we have compared the indicator to root mean square (RMS) by using the exponential degradation model. It shows that the indicator is more suitable for the exponential degradation model. In this paper, we used eleven run-to-failure data to verify the generality and "two-stage" characters of the proposed indicator. The result shows that the novel indicator is general and effective and that it will promote the development of bearings' prognostics.


Assuntos
Algoritmos , Análise de Falha de Equipamento , Vibração
7.
Biomed Mater Eng ; 30(3): 297-308, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31006657

RESUMO

BACKGROUND: Breakage of joint arthroplasty components are rare, yet during an implant retrieval program we found several cases. OBJECTIVE: In this study we examined the components to determine the causes and mechanisms of breakage of these implants. METHODS: From our collection of 849 retrievals we selected 682 cases with metal parts (503 hip, 79 knee arthroplasties) and identified fractured components: seven hip resurfacing implants, five total hip replacement stems, one monopolar femoral head, and one modular revision femoral stem from. Implants were examined using optical and scanning electron microscopy; metallographic sections were prepared and samples of periprosthetic tissues underwent microscopic examination. RESULTS: In the resurfacing components breakage occurred in small stems placed in the femoral neck due to necrosis of femoral heads, with no metal flaws detected. Fatigue breakage of femoral stems was caused by presence of material flaws in the CoCrMo alloy, and corrosion. The monopolar head failed in fatigue fracture mechanism, breakage was initiated in an undercut near the taper connection for femoral component. The modular stem from Ti alloy sustained fatigue fracture induced by corrosion caused by debris from previously revised stem; no material flaws were detected in this sample. In most cases periprosthetic tissues had a morphology typical for aseptic loosening. CONCLUSIONS: In our series failure was caused by material flaws, presence of stress raisers and localized corrosion. Our findings indicate that sharp edges and other features which can act as stress raisers should be avoided in newly designed implants. Corrosion induced fracture of the modular Ti stem indicates the need for a detailed debridement of periprosthetic tissues during revision arthroplasties.


Assuntos
Prótese de Quadril , Falha de Prótese , Vitálio , Artroplastia de Quadril/efeitos adversos , Corrosão , Análise de Falha de Equipamento , Cabeça do Fêmur/patologia , Cabeça do Fêmur/cirurgia , Articulação do Quadril/cirurgia , Prótese de Quadril/efeitos adversos , Humanos , Desenho de Prótese , Falha de Prótese/efeitos adversos , Vitálio/efeitos adversos , Vitálio/química
8.
Eur J Vasc Endovasc Surg ; 57(5): 730-739, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31005510

RESUMO

OBJECTIVE: The aim was to determine whether lead containing and lead free composite garments in current use provide the level of radiation protection stated by manufacturers. METHODS: Fifteen garments, produced by five different manufacturers using eight different composites, were randomly selected for testing from four hospitals in South Australia. Labelling, material composition, design, and condition of the garments were assessed by direct garment examination, garment label, and product information. Garment attenuation was tested in a simulated angiography suite using a Siemens Ysio Max digital Xray machine. The front and back panels of each garment were tested under direct beam at 100 kVp. A Perspex phantom was used to simulate the density and scatter properties of the human abdomen. The front panels of each garment were tested under scattered radiation at Xray tube voltages of 50 and 70 kVp. RESULTS: Forty-seven per cent of front panels and 90% of back panels provided lower lead equivalence than claimed by the manufacturer. Twenty per cent of front panels and 62% of back panels tested did not meet the minimum International Electrotechnical Commission requirements for angiographic use. There was a 38 fold difference in front panel performance of garments to scatter radiation, which were all labelled 0.5 mm lead equivalence. 56% of garments had differences in scatter transmission of at least 49% when tested at 50 and 70 kVp. CONCLUSION: The results show that lead containing and lead free composite garments probably provide less radiation protection than manufacturer stated lead equivalence. The demonstrated wide variations in attenuation of scatter radiation are greater than previously reported. It was found that most garments failed to comply with labelling standards. The study highlights challenges in radiation shielding and the need to identify composites that consistently provide better attenuation per unit weight than lead.


Assuntos
Roupa de Proteção/normas , Proteção Radiológica/instrumentação , Proteção Radiológica/normas , Angiografia , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Rotulagem de Produtos/normas , Doses de Radiação , Serviço Hospitalar de Radiologia , Espalhamento de Radiação , Austrália do Sul
9.
Braz Oral Res ; 33: e028, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30994706

RESUMO

This study aimed to assess the cyclic fatigue resistance of Genius and EdgeFile X1 reciprocating instruments compared with WaveOne Gold Primary. Twenty Genius (Ultradent) 25.04, 20 Genius 30.04, 20 EdgeFile X1 (EdgeEndo) and 20 WaveOne Gold Primary (Dentsply Maillefer) instruments were included in this study and tested in a static cyclic fatigue testing device, which has an artificial stainless steel canal with a 60° angle of curvature and a 5-mm radius of curvature. All instruments were operated in reciprocation mode until fracture occurred. The number of cycles to failure (NCF) was calculated and time to fracture (TF) was recorded in seconds using a digital chronometer. The mean and standard deviations of NCF and TF were calculated for each reciprocating system and the data were subjected to Kruskal-Wallis one-way analysis of variance and to Dunn's test (p < .05) using SigmaPlot software (Systat software, CA, USA). The fractured surfaces of five instruments from each brand were randomly examined and microphotographed by a low-vacuum environmental scanning electron microscopy - SEM (Tabletop Microscope TM3030, Hitachi, Japan) to confirm the cyclic fatigue fracture. EdgeFile exhibited the highest cyclic fatigue resistance, followed by both Genius files (p < .05). Within the limitations of this in vitro study, EdgeFile X1 instruments had significantly higher cyclic fatigue resistance than did Genius and WaveOne Gold Primary instruments. The cyclic fatigue resistance of both Genius files was higher than that of WaveOne Gold Primary.


Assuntos
Instrumentos Odontológicos/normas , Níquel/química , Preparo de Canal Radicular/instrumentação , Titânio/química , Desenho de Equipamento , Análise de Falha de Equipamento , Teste de Materiais , Microscopia Eletrônica de Varredura , Valores de Referência , Estatísticas não Paramétricas , Estresse Mecânico , Propriedades de Superfície , Fatores de Tempo
10.
Arch Orthop Trauma Surg ; 139(7): 991-998, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30927062

RESUMO

BACKGROUND: Easy revisability is gaining increasingly in importance. The removal of well-fixed cemented stems is very demanding and is often associated with increased operative morbidity. Implant design may be here a decisive impact factor, and the best way to ascertain it is experimentally. Aim of this study is to assess different cemented stems of established knee revision implants in regard to their removal capability. METHODS: Based on their sagittal profile, five stem extensions from known manufacturers were divided in conical, conical-cylindrical and cylindrical designs. The pedicles were also characterized in respect to their cross section, diameter and surface roughness. The cemented stems were dismounted six times each in a reproducible biomechanical setup. The explantation energy required was determined and statistical analyzed. RESULTS: The conical shaft needed significantly the slightest explantation energy with 19.2 joules (p = 0.004). There was a strong negative linear correlation between conicity proportion and explantation energy of the cemented stems (R2 = 0.983). The removal of the three purely cylindrical shafts-regardless of their differences in diameter, cross-sectional design and surface- was the most demanding (98.3, 105, and 116.7 joules) with only secondary differences between them. CONCLUSION: The longitudinal stem profile may have a primary impact on the explantability of well-fixed cemented shafts with conical designs showing superiority. Cross-sectional profile and surface roughness had here a less decisive influence on the explantability. Surgeons can choose proper implants and removal techniques depending on potential implant-associated revision risks and re-revisions to be expected.


Assuntos
Artroplastia do Joelho , Remoção de Dispositivo/métodos , Articulação do Joelho , Prótese do Joelho , Desenho de Prótese , Reoperação/métodos , Artroplastia do Joelho/efeitos adversos , Artroplastia do Joelho/instrumentação , Artroplastia do Joelho/métodos , Fenômenos Biomecânicos , Estudos Transversais , Análise de Falha de Equipamento , Humanos , Articulação do Joelho/fisiopatologia , Articulação do Joelho/cirurgia , Prótese do Joelho/efeitos adversos , Prótese do Joelho/classificação , Teste de Materiais , Desenho de Prótese/efeitos adversos , Desenho de Prótese/métodos
11.
J Ayub Med Coll Abbottabad ; 31(1): 26-31, 2019 Jan-Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30868778

RESUMO

BACKGROUND: Most of the orthodontic cases require a long period of retention which is usually carried out with the help of fixed retainers (FR). One of the downsides of FR is that these are prone to breakages. The aim of the present study was to identify the frequency and factors associated with failure of fixed spiral wire retainers.. METHODS: A retrospective crosssectional study was conducted using orthodontic files and dental casts of 126 patients from dental clinics of a tertiary care hospital. Descriptive statistics were applied to calculate the frequency and most common site of breakages. Chi-square test was applied to compare the frequency of breakages among age groups and different retainer spans. Independent sample ttest was used to compare the mean overbite in retainer breakage and retainer intact groups. A p-value ≤0.05 was considered as statistically significant. RESULTS: The frequency of retainer breakage was found to be 53.1%. Maxillary retainer breakages were found in 41.3% subjects whereas mandibular retainer failed in 22.2% subjects. The mean survival time of retainer was 8.91±4.57 months. The detachment of the retainer from the tooth surface was the most common occurrence (86%). The most common site of retainer breakage was maxillary canine (32.5%) and mandibular central incisor (12.7%). All the subjects who had retainers extending till maxillary molars encountered breakages.. CONCLUSIONS: A longer retainer span is associated with a greater risk of breakage. Failure rate in the maxillary arch was higher than the mandibular arch. The most common sites were the maxillary canine and mandibular central incisor. The most common pattern was wire detachment.


Assuntos
Contenções Ortodônticas , Falha de Prótese , Adolescente , Criança , Análise de Falha de Equipamento , Feminino , Humanos , Masculino , Mandíbula , Maxila , Sobremordida/terapia , Estudos Retrospectivos , Fatores de Tempo , Adulto Jovem
12.
Comput Intell Neurosci ; 2019: 1383752, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30863433

RESUMO

Gearboxes are mechanical devices that play an essential role in several applications, e.g., the transmission of automotive vehicles. Their malfunctioning may result in economic losses and accidents, among others. The rise of powerful graphical processing units spreads the use of deep learning-based solutions to many problems, which includes the fault diagnosis on gearboxes. Those solutions usually require a significant amount of data, high computational power, and a long training process. The training of deep learning-based systems may not be feasible when GPUs are not available. This paper proposes a solution to reduce the training time of deep learning-based fault diagnosis systems without compromising their accuracy. The solution is based on the use of a decision stage to interpret all the probability outputs of a classifier whose output layer has the softmax activation function. Two classification algorithms were applied to perform the decision. We have reduced the training time by almost 80% without compromising the average accuracy of the fault diagnosis system.


Assuntos
Tomada de Decisões , Análise de Falha de Equipamento/instrumentação , Análise de Falha de Equipamento/métodos , Máquina de Vetores de Suporte , Algoritmos , Humanos , Redes Neurais (Computação)
13.
Acta Orthop ; 90(2): 148-152, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30739548

RESUMO

Background and purpose - International comparisons of total hip arthroplasty (THA) practices and outcomes provide an opportunity to enhance the quality of care worldwide. We compared THA patients, implants, techniques, and survivorship in Sweden, Australia, and the United States. Patients and methods - Primary THAs due to osteoarthritis were identified using Swedish (n = 159,695), Australian (n = 279,693), and US registries (n = 69,641) (2003-2015). We compared patients, practices, and implant usage across the countries using descriptive statistics. We evaluated time to all-cause revision using Kaplan-Meier survival curves. We assessed differences in countries' THA survival using chi-square tests of survival probabilities. Results - Sweden had fewer comorbidities than the United States and Australia. Cement fixation was used predominantly in Sweden and cementless in the United States and Australia. The direct anterior approach was used more frequently in the United States and Australia. Smaller head sizes (≤ 32 mm vs. ≥ 36 mm) were used more often in Sweden than the United States and Australia. Metal-on-highly cross-linked polyethylene was used more frequently in the United States and Australia than in Sweden. Sweden's 5- (97.8%) and 10-year THA survival (95.8%) was higher than the United States' (5-year: 97.0%; 10-year: 95.2%) and Australia (5-year: 96.3%; 10-year: 93.5%). Interpretation - Patient characteristics, surgical techniques, and implants differed across the 3 countries, emphasizing the need to adjust for demographics, surgical techniques, and implants and the need for global standardized definitions to compare THA survivorship internationally.


Assuntos
Artroplastia de Quadril , Prótese de Quadril , Osteoartrite , Complicações Pós-Operatórias , Reoperação/estatística & dados numéricos , Artroplastia de Quadril/efeitos adversos , Artroplastia de Quadril/instrumentação , Artroplastia de Quadril/métodos , Austrália , Análise de Falha de Equipamento , Feminino , Articulação do Quadril/cirurgia , Prótese de Quadril/classificação , Prótese de Quadril/normas , Prótese de Quadril/estatística & dados numéricos , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Osteoartrite/diagnóstico , Osteoartrite/epidemiologia , Osteoartrite/etiologia , Osteoartrite/cirurgia , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/cirurgia , Desenho de Prótese , Suécia , Estados Unidos
14.
Med Phys ; 46(4): 1896-1904, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30715736

RESUMO

PURPOSE: The aim of this work is to develop a sensitometry model of EBT2 and EBT3 radiochromic films based on the observation that radiation induces growth of two polymer color phases. METHODS: Previously published data of the active layer absorption spectrum have been used to characterize the contribution to the total absorbance of each polymer color phase. Through a prior proposed external beam therapy absorption spectrum model the total absorbance has been deconvolved into two polymer phase contributions. The integral absorbance in the visible spectrum of each color phase has been calculated and parametrized as an absorbed dose function. A sensitometry model employing linear relationships with the color phase integral absorbances has been investigated. The phase linear coefficient ratio for each color channel is proposed to be a constant. Films belonging to six different production batches, three EBT2 and three EBT3, have been used to verify this model. RESULTS: Each polymer color phase integral absorbance in the visible spectrum has been expressed as a simple saturation function of the absorbed dose to the film. The data coming from the six production batches have been fitted to the proposed sensitometry model. This model predicts the measured dose variation in the active layer light attenuation up to fluctuations attributable to uncertainties. CONCLUSIONS: The calibration curve can be written as a linear combination of simple functions describing the dose dependence of the integral absorbance of each polymer color phase. These functions are characteristics of the active layer material, and not dependent on the model and production batch. According to the proposed model, to calibrate a batch in terms of the active layer light attenuation consists of determining just one linear coefficient.


Assuntos
Dosimetria Fotográfica/instrumentação , Dosimetria Fotográfica/métodos , Imagens de Fantasmas , Polímeros/química , Calibragem , Cor , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Doses de Radiação
15.
Int Heart J ; 60(2): 318-326, 2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30745538

RESUMO

Implantable cardioverter-defibrillators (ICDs) improve survival in patients who are at risk of sudden death. However, inappropriate therapy is commonly given to ICD recipients, and this situation may be associated with an increased risk of death. This study aimed to construct a risk stratification scheme by using decision tree analysis in patients who received inappropriate ICD therapy.Mortality was calculated from a retrospective data analysis of a multicenter cohort involving 417 ICD recipients. Inappropriate therapy was defined as therapy for nonventricular arrhythmias, including sinus tachycardia, supraventricular tachycardia, atrial fibrillation/flutter, oversensing, and lead failure. Inappropriate therapy included antitachycardia pacing, cardioversion, and defibrillation. The prognostic factors were identified by a Cox proportional hazards regression analysis, and we constructed a decision tree.During an average follow-up of 5.2 years, 48 patients (12%) had all-cause death. A multivariate Cox hazard model revealed that the age (hazard ratio [HR] 1.06, P < 0.001), ln B-type natriuretic peptide (BNP) (HR 1.47, P = 0.02), nonsinus rhythm at implantation (HR 2.70, P < 0.05), and inappropriate therapy occurring during sedentary/awake conditions (HR 3.51, P = 0.001) correlated with an increased risk of mortality. An inappropriate therapy due to abnormal sensing (HR 0.16, P = 0.04) decreased the risk of mortality. Furthermore, a decision tree analysis stratified the patients well by using 4 covariates: BNP, activity at the time of inappropriate therapy, mechanism of inappropriate therapy, and baseline rhythm at ICD implantation (log-rank test, P < 0.0001).We identified the predictors of mortality in inappropriate ICD therapy recipients and constructed a risk stratification scheme by using decision tree analysis.


Assuntos
Arritmias Cardíacas , Morte Súbita Cardíaca , Desfibriladores Implantáveis/efeitos adversos , Cardioversão Elétrica/efeitos adversos , Falha de Equipamento/estatística & dados numéricos , Idoso , Arritmias Cardíacas/classificação , Arritmias Cardíacas/complicações , Arritmias Cardíacas/mortalidade , Arritmias Cardíacas/terapia , Morte Súbita Cardíaca/etiologia , Morte Súbita Cardíaca/prevenção & controle , Árvores de Decisões , Desfibriladores Implantáveis/estatística & dados numéricos , Cardioversão Elétrica/instrumentação , Cardioversão Elétrica/métodos , Análise de Falha de Equipamento/métodos , Feminino , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Medição de Risco/métodos , Fatores de Risco , Análise de Sobrevida
16.
J Card Surg ; 34(4): 208-210, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30803027

RESUMO

A 58-year-old man with multiple myeloma, prior bioprosthetic valve, spinal hardware and multiple episodes of Corynebacterium amycolatum bacteremia was found to have a well-seated valve without vegetations, paravalvular leak, abscess or degeneration over a period of 6 months on five separate transesophageal echocardiographic studies. Computed tomography angiography was performed which revealed vegetation at the level of the left ventricular outflow tract. Reoperative sternotomy and interrogation of the valve confirmed a 1.5-cm vegetation with the same bacterium. The patient underwent a redo aortic valve replacement and recovered without any complications. He has been asymptomatic and culture negative on surveillance.


Assuntos
Estenose da Valva Aórtica/cirurgia , Valva Aórtica/cirurgia , Bioprótese/efeitos adversos , Endocardite/diagnóstico por imagem , Endocardite/cirurgia , Implante de Prótese de Valva Cardíaca , Próteses Valvulares Cardíacas/efeitos adversos , Falha de Prótese/efeitos adversos , Tomografia Computadorizada por Raios X , Corynebacterium , Infecções por Corynebacterium , Endocardite/etiologia , Endocardite/microbiologia , Análise de Falha de Equipamento , Humanos , Masculino , Pessoa de Meia-Idade , Reoperação , Esternotomia , Resultado do Tratamento
17.
BMC Musculoskelet Disord ; 20(1): 60, 2019 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-30736762

RESUMO

BACKGROUND: The purpose of this study was to compare the biomechanical behaviour of two bioabsorbable interference screws with different geometries. METHODS: Two different pitch (2.5 and 5 mm) bioabsorbable interference screws, both 9 × 30 mm, were tested. Tests were performed with forty bovine digital extensor tendons and skeletally mature porcine tibiae. Two protocols of cyclic tests at 1 Hz were performed: 1000 cycles from 50 to 250 N, and 5000 cycles from 100 to 300 N (n = 10 for each type of test and screw). After the cyclic loading, a final ramp displacement until failure at 0.5 mm/s was applied. RESULTS: The stiffness after the cyclic phase of the tests was not statistically different between the two screws (1000th cycle: 2.5 mm pitch 280.3 ± 56.4 N/mm, 5 mm pitch 275.2 ± 65.0 N/mm, P = .965; 5000th cycle: 2.5 mm pitch 281.3 ± 66.4 N/mm, 5 mm pitch 286.1 ± 79.4 N/mm, P = .814). The yield load was not significantly different between the screws (1000 cycle tests: 2.5 mm pitch 482.2 ± 120.2 N, 5 mm pitch 495.9 ± 131.3 N, P = .508; 5000 cycle tests: 2.5 mm pitch 476.4 ± 65.3 N, 5 mm pitch 494.3 ± 39.2 N, P = .391). No correlation was found between the insertion torque and yield load (1000 cycle tests, R2 = 0.013; 5000 cycle tests, R2 = 0.006). CONCLUSIONS: The pitch of bioabsorbable interference screws does not seem to affect fixation strength. Also, the authors recommend not to use insertion torque alone to estimate the fixation strength.


Assuntos
Implantes Absorvíveis , Reconstrução do Ligamento Cruzado Anterior/instrumentação , Ligamento Cruzado Anterior/cirurgia , Parafusos Ósseos , Tíbia/cirurgia , Animais , Ligamento Cruzado Anterior/fisiopatologia , Reconstrução do Ligamento Cruzado Anterior/efeitos adversos , Fenômenos Biomecânicos , Bovinos , Análise de Falha de Equipamento , Desenho de Prótese , Falha de Prótese , Sus scrofa , Tíbia/fisiopatologia , Torque
18.
PLoS One ; 14(1): e0209663, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30629618

RESUMO

A variety of 7 Tesla RF coil systems have been proposed to produce spin excitation (B1+ field) and MR image acquisition. Different groups have attempted to mitigate the challenges at high and ultra-high field MRI by proposing novel hardware and software solutions to obtain uniformly high spin excitation at acceptable RF absorption levels. In this study, we extensively compare the designs of two distributed-circuit based RF coils: the Tic-Tac-Toe (TTT) head coil and TEM head coil on multiple anatomically detailed head models and in-vivo. Bench measurements of s-parameters and experimental B1+ field distribution were obtained in volunteers and compared with numerical simulations. RF absorption, quantified by both average and peak SAR, and B1+ field intensity and homogeneity, calculated/measured in terms of maximum over minimum and coefficient of variation (CV) in the region of interest (ROI), are presented for both coils. A study of the RF consistency of both coils across multiple head models for different RF excitation strategies is also presented.


Assuntos
Imagem por Ressonância Magnética/instrumentação , Imagem por Ressonância Magnética/métodos , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Cabeça , Humanos , Aumento da Imagem/métodos , Imagens de Fantasmas , Ondas de Rádio , Software
19.
Acta Orthop Traumatol Turc ; 53(2): 106-114, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30655093

RESUMO

OBJECTIVE: The aim of this study was to evaluate factors associated with the needle breakage of antegrade suture passer and the effect of intratendinous remnant needle tip on clinical outcomes after rotator cuff repair. METHODS: We retrospectively reviewed 283 patients (138 men and 145 women; mean age: 59.7 ± 9.3 years) who underwent arthroscopic repair for full-thickness rotator cuff tear. We evaluated the characteristics of 16 patients in whose needle tip had been broken and embedded and remained in the rotator cuff (remnant needle group) and compared them with the remaining 267 patients (control group). Afterwards, another 64 patients were selected from control group (1:4 matching) after propensity score matching (PSM). The groups were compared anatomically with MRI or ultrasonography and functionally (serial pain VAS and ROM; ASES, Constant, UCLA and SST scores) at a minimum follow-up of 1 year. RESULTS: The remnant needle group showed preoperative thicker tendon (6.72 mm vs 5.33 mm, p = 0.047), higher tendinosis (mean grade, 1.88 vs. 1.43, p = 0.029), and more frequent delaminated tears (p = 0.035) compared with control group. When we compare the clinical outcomes after PSM, the initial pain VAS of the remnant needle tip group was higher up to 3 months (pain VAS: 4.13 ± 2.07 vs 2.48 ± 1.61 (p = 0.032) at 5 weeks and 3.79 ± 2.12 vs 2.25 ± 1.76 (p = 0.044) at 3 months), however the difference disappeared after 6 months postoperatively. In final evaluation, there was no significant differences in every outcome parameters (all p > 0.05). CONCLUSION: Breakage of the needle of the antegrade suture passer occurred more frequently in the thicker tendon, higher tendinosis, and delaminated tears. The retained broken needle tip was associated with higher pain scores during the early postoperative period, but revealed no difference in final outcomes by using PSM. LEVEL OF EVIDENCE: Level III, Therapeutic Study.


Assuntos
Artroscopia , Agulhas/efeitos adversos , Dor Pós-Operatória , Lesões do Manguito Rotador/cirurgia , Técnicas de Sutura/instrumentação , Tendões , Idoso , Artroscopia/efeitos adversos , Artroscopia/instrumentação , Artroscopia/métodos , Análise de Falha de Equipamento , Feminino , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Dor Pós-Operatória/diagnóstico , Dor Pós-Operatória/etiologia , Período Pós-Operatório , Estudos Retrospectivos , Fatores de Risco , Tendinopatia/diagnóstico , Tendões/diagnóstico por imagem , Tendões/patologia , Fatores de Tempo , Resultado do Tratamento , Ultrassonografia/métodos
20.
Z Orthop Unfall ; 157(5): 540-547, 2019 Oct.
Artigo em Inglês, Alemão | MEDLINE | ID: mdl-30616259

RESUMO

Reasons for failure of anterior cruciate ligament (ACL) reconstructions are manifold and require a multifactorial explanatory approach. In addition to technical failures, many modifiable and non-modifiable risk factors for a new ACL injury have to be considered. Technical failures primarily include non-anatomical tibial and femoral tunnel position. In comparison to the transtibial drilling technique, the tibial tunnel-independent technique results in a more anatomical position of the femoral tunnel and should therefore be preferred. One can differentiate between non-modifiable and modifiable risk factors. At the same time, the combination of more than one risk factor increases the risk of injury significantly. Non-modifiable risk factors include genetic predisposition, female sex, young age and ligament hyperlaxity. Young age at the time of the first injury is the most important risk factor for graft failure. Modifiable risk factors include high body mass index (BMI), deficits in jump landing mechanics, a steep posterior tibial slope and narrow intercondylar notch width. Neuromuscular training or additional surgical procedures modify these risk factors and reduce the probability of further injuries. A high tibial osteotomy (HTO) is the surgical procedure of choice for a reduction in the posterior tibial slope and anterior tibial translation. In case of a tibial slope over 12°, this procedure should be considered. In revision anterior cruciate ligament reconstructions with remaining anterolateral rotatory instability, additional lateral extraarticular tenodesis should be taken into account. This is also recommended for patients participating in pivoting sports, having concomitant hyperlaxity or additional injury of peripheral structures with insufficiency of the ACL. In addition, the surface of the pitch can be modified and thus influence the risk of an ACL injury. In summary, a substantiated failure analysis is required to initiate specific and individualised therapy - not only in the case of ACL rerupture. These factors should already be considered in risk assessment during patient information.


Assuntos
Lesões do Ligamento Cruzado Anterior/cirurgia , Reconstrução do Ligamento Cruzado Anterior/efeitos adversos , Reconstrução do Ligamento Cruzado Anterior/instrumentação , Análise de Falha de Equipamento , Reconstrução do Ligamento Cruzado Anterior/métodos , Feminino , Fêmur/cirurgia , Sobrevivência de Enxerto , Humanos , Reoperação , Fatores de Risco , Ruptura , Tíbia/cirurgia
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