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Plastic waste from electrical and electronic equipment (WEEE) is growing up exponentially fast during the last two decades, mainly due to short lifetime of technological products like cellphones or computers. This situation entailed an increase in the accumulation of specific plastic materials such Acrylonitrile-Butadiene-Styrene (ABS), High Impact Polystyrene (HIPS), Polycarbonate, among others. These plastics can be recycled by themselves but their separation by type is neither easy nor economically viable, then recycling them together as a blend is the most economically viable alternative. However, mechanical properties suffer a deterioration and to enhance phase adhesion and add value to this WEEE blend, an adequate compatibilization is needed. To choose a compatibilization route an accurate comprehension of blends behavior has to be done. In this work, a systematical study of the addition compatibilization of HIPS/ABS blends was performed. Besides results were focus to WEEE recycling, in order to comprehend this complex system, virgin base materials were used. Relative amount effect on self-compatibilization was analyzed by two different HIPS/ABS blends, one with major content of HIPS and other with major content of ABS. Also, two different copolymers were used as compatibilizer, Styrene-Acrylonitrile (SAN) and Styrene-Butadiene-Styrene and the concentrations chosen were 2 and 20 wt%. The best performance was achieved for blend with major content of ABS by using 2 % of SAN, obtaining a compatibilized blend with a general improvement of mechanical properties specially toughness in a 350 % and elongation in a 77 % respect to the physical blend. [ABSTRACT FROM AUTHOR]

Objective: Atrophy of the muscles around the hip and thigh has been reported in patients with hip osteoarthritis (OA). Total hip arthroplasty (THA) reduces pain and improves quality of life and activity levels. Muscle strength of the hip and thigh also improves after THA. This study aimed to determine whether there is significant psoas muscle atrophy and to evaluate the degree of fat infiltration after unilateral hip arthroplasty., Subject and Methods: Patients who underwent unilateral total hip arthroplasty for primary hip osteoarthritis and who had lumbar vertebra magnetic resonance imaging (MRI) for any reason in the one-year preoperative and postoperative period were evaluated retrospectively. The degree of fat infiltration was also graded visually based on a modified Goutallier rating system., Results: The study was conducted with a total of 58 patients aged between 38 and 75, including 15 males and 43 females. Compared to the preoperative psoas muscle area values on the operated sides of the patients participating in the study, the decrease in the postoperative psoas muscle area was found to be statistically significant (p:0.000; p<0.05). Furthermore, the decrease in psoas muscle area on the non-operated side of the patients was also statistically significant (p:0.000; p<0.05). There was also a positive correlation between preoperative and postoperative psoas muscle areas (p:0.000; p<0.05)., Conclusion: Early identification of psoas muscle mass reduction may allow for a more proactive psoas strength improvement program to improve post-operative function and mobility., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Genc et al.)

Introduction Leg length and offset are important considerations in total hip arthroplasty (THA). Navigation systems are capable of providing intra-operative measurements of leg length and offset, and high accuracy has been shown in experimental studies. This study assesses the accuracy of an imageless navigation system with a pinless femoral array (Hip 5.1, BrainLAB, Feldkirchen, Germany) in measuring leg length and offset changes in vivo. Methods A prospective, consecutive series of 37 patients undergoing navigated THA were included in the study. Intra-operative measurements of leg length and offset were recorded using the navigation system. For each patient, pre- and post-operative digital radiographs were scaled and analyzed to provide radiographic measurements for comparison. Results Measurements of leg length change made by the navigation system showed a strong correlation with the size of change measured radiographically (R = 0.71; p<0.0001). The mean difference between the radiographic and navigational measurement was 2.6mm ± 3.0mm (0.0-16.0mm) (mean, SD, range). The navigation system was accurate to within 1mm of the radiographic measurement in 49% of cases, within 2mm in 66% of cases, and within 5mm in 89% of cases. Measurements of offset change by the navigation system also showed a correlation with radiographic measurements, albeit less pronounced (R = 0.35; p=0.035). The mean difference between navigational and radiographic measurements was 5.5mm ± 4.7mm (0.0-16.0mm) (mean, SD, range). The navigation system was accurate within 1mm of the radiographic measurement in 22% of cases, within 2mm in 35% of cases, and within 5mm in 57% of cases. Conclusions This research demonstrates in vivo that an imageless, non-invasive navigation system is a reliable tool for intra-operative leg length (accurate within 2mm) and to a lesser extent offset measurement (accurate within 5mm) when compared to standard practice of plain film radiographs., Competing Interests: The authors have declared financial relationships, which are detailed in the next section., (Copyright © 2023, Lambers et al.)

Neste trabalho foram preparados e avaliados nanocompósitos de poliestireno de alto impacto (HIPS) e nanoargila. Três tipos de argila montmorilonita modificadas com sal quaternário de amônio (OMMT), denominadas de S4, S7 e B8, e uma argila sódica NT-25 foram empregadas para a obtenção dos nanomateriais. A inserção da argila organofílica no HIPS foi feita por intercalação por solução visto que este processo permite boa dispersão da argila na matriz polimérica devido ao intumescimento desta no solvente. Este intumescimento foi avaliado segundo a metodologia de Foster, e o solvente mais adequado para estas argilas foi o clorofórmio. Os nanomateriais obtidos foram caracterizados por difração de raios X e ressonância magnética nuclear de baixo campo (RMN-BC), por meio de relaxometria, via determinação do tempo de relaxação spin-rede dos núcleos de hidrogênio da matriz polimérica. Pelos resultados obtidos concluiu-se que os nanomateriais formados eram mistos, ou seja, parte apresentava-se intercalada e parte esfoliada. Além disso, a proporção nanoargila que produziu nanocompósitos com maior grau de esfoliação foi a de 2%.

Nos últimos anos houve um grande avanço tecnológico no desenvolvimento de materiais compósitos reforçados com fibras naturais. Esse aumento do interesse das indústrias e grupos de pesquisa em desenvolver e utilizar materiais feitos a partir de matérias primas renováveis se deu principalmente pelo grande apelo mundial para a utilização de produtos naturais e pela preservação do meio ambiente. O presente trabalho visou a caracterização de compósitos reforçados com bagaço de cana em matriz de poliestireno de alto impacto (HIPS), tendo como objetivo uma possível substituição dos materiais utilizados atualmente na indústria de produtos para pet shop. Foram caracterizadas três famílias de compósitos, nas proporções de 10, 20 e 30% (m/m). Os resultados da dureza Shore A indicaram que a adição da fibra de bagaço ao HIPS não acarretou alterações nos valores da dureza nos compósitos quando comparados ao HIPS puro. E os resultados de resistência ao impacto foi possível constatar que a adição da fibra de bagaço ao HIPS acarretou uma diminuição na resistência ao impacto, quando comparados ao HIPS puro.

Existe uma tendência mundial em buscar recursos naturais alternativos em substituição às fibras sintéticas. Diante deste cenário, as fibras naturais vegetais, como por exemplo, a fibra da casca do coco verde, é uma excelente alternativa por possuírem boas propriedades mecânicas e térmicas. Essas fibras, além de seu baixo custo, são biodegradáveis e de fonte renovável. No presente trabalho foram caracterizados compósitos poliméricos de HIPS reforçados com fibras naturais provenientes da casca do coco verde. Foram caracterizadas três famílias de compósitos, nas proporções de 10, 20 e 30% (m/m). Foi possível constatar que a adição da fibra de coco ao HIPS acarretou uma diminuição na resistência ao impacto, quando comparados ao HIPS puro. Dessa forma, com a adição de fibras de coco verde no HIPS obteve-se um material com até 30% menos polímero e com propriedades mecânicas viáveis para determinadas aplicações do HIPS.

A tenacificação de termoplásticos vítreos através da adição de partículas de borracha na matriz polimérica é um processo amplamente estudado. Neste trabalho foi avaliada a recuperação das propriedades de poliestireno de alto impacto (HIPS) reciclado através da incorporação de copolímeros estireno-butadieno-estireno (SBS) de estrutura linear e radial. As blendas foram processadas em uma extrusora dupla rosca. Os copolímeros foram adicionados em teores de 5, 10 e 15% em massa. As propriedades avaliadas foram o índice de fluidez, a morfologia e o comportamento frente a ensaios de tração, flexão e resistência ao impacto das blendas formuladas. Em todos os casos, o SBS radial foi mais eficiente na recuperação das propriedades do poliestireno de alto impacto que o SBS linear quando comparadas às propriedades do HIPS reciclado.Toughening glassy thermoplastics by blending a rubbery material to the polymeric matrix has been extensively studied. In this work, we evaluated the resulting properties of recycled high impact polystyrene (HIPS), after the incorporation of either radial or linear SBS triblock copolymers. The blends were melt mixed using a twin-screw extruder. The copolymers were added at 5, 10 and 15% weight percent. The investigated properties included the determination of the melt flow index, the morphology and the mechanical behavior according to standard tension, flexion and impact methods of all formulated blends. In all cases, the radial SBS was more efficient in recovering the HIPS properties than the linear SBS, when comparing the properties of the blends with the properties of recycled HIPS.

The combustion behavior of a blend made of high impact polystyrene (HIPS) with sodium montmorillonite (MMT-Na+) and triphenyl phosphite (TPP), as a halogen-free flame retardant, is analyzed in detail in this work. The blend is processed through various extrusion methods aimed to improve clay dispersion. The UL94 method in vertical position, oxygen index and cone calorimetric measurements assess HIPS blend behavior in combustion. TGA, FTIR, SEM and X-ray measurements, together with mechanical and rheological tests evaluate the thermal degradation, morphology, intercalation and degree of dispersion of particles. The use of a static-mixing die placed at the extreme of a single screw extruder improves clay platelets distribution and reduces the peak heat release rate better than employing a twin screw extrusion process. In addition, mechanical and rheological properties are affected substantially by changing the extrusion process. A correlation between clay dispersion and HIPS fire retardant properties is found, as the peak heat release rate decreases with good clay dispersion in cone calorimetric tests.

Poliestireno de alto impacto (HIPS) é uma blenda polimérica clássica de reator produzida por polimerização in-situ de estireno em solução com borracha butadiênica. Na literatura, está bem estabelecida a importância do tamanho de partícula e da densidade da ligação cruzada da borracha na capacidade de cavitação e no controle dos mecanismos de tenacificação na matriz estirênica. No presente trabalho as técnicas de microscopia eletrônica de transmissão (MET) e espalhamento de luz laser de baixo ângulo (LALLS) foram empregadas para observar a distribuição do tamanho de partícula, e a análise digital de imagem foi aplicada para quantificar os parâmetros morfológicos nas micrografias. Medidas do tamanho de partícula e da fração aparente volumétrica de partícula foram feitas para diferentes espessuras na MET e comparadas com o parâmetro estatístico D[4,3] obtido na LALLS.High impact polystyrene (HIPS) is a classical reactor polymer blend produced by in-situ polymerization of styrene in solution with polybutadiene rubber. It is well established in the literature the importance of particle size and rubber crosslink density on the particle cavitation capability and on the controlling of toughening mechanisms in the styrene matrix. In the present work transmission electron microscopy (TEM) and low-angle laser light scattering (LALLS) were employed for investigating particle size distribution, with digital imaging being applied in the quantitative analysis of the micrographs. Measurements of apparent volume fraction and average particle size were carried out for different slice thicknesses in TEM and compared with the statistical parameter D[4,3] obtained by LALLS.

Aims: Fixation techniques used in the treatment of slipped capital femoral epiphysis (SCFE) that allow continued growth of the femoral neck, rather than inducing epiphyseal fusion in situ, have the advantage of allowing remodelling of the deformity. The aims of this study were threefold: to assess whether the Free-Gliding (FG) SCFE screw prevents further slip; to establish whether, in practice, it enables lengthening and gliding; and to determine whether the age of the patient influences the extent of glide., Methods: All patients with SCFE who underwent fixation using FG SCFE screws after its introduction at our institution, with minimum three years' follow-up, were reviewed retrospectively as part of ongoing governance. All pre- and postoperative radiographs were evaluated. The demographics of the patients, the grade of slip, the extent of lengthening of the barrel of the screw and the restoration of Klein's line were recorded. Subanalysis was performed according to sex and age., Results: A total of 19 hips in 13 patients were included. The mean age of the patients at the time of surgery was 11.5 years (9 to 13) and the mean follow-up was 63 months (45 to 83). A total of 13 FG SCFE screws were used for the fixation of mild or moderate SCFE, with six contralateral prophylactic fixations. No hip with SCFE showed a further slip after fixation and there were no complications. Lengthening occurred in 15 hips (79%), with a mean lengthening of the barrel of 6.8 mm (2.5 to 13.6) at final follow-up. Remodelling occurred in all hips with lengthening of the barrel. There was statistically more lengthening in patients who were aged < 12 years, regardless of sex (p = 0.002)., Conclusion: The FG SCFE screw is effective in preventing further slip in patients with SCFE. Lengthening of the barrel occurred in most hips, and thus allowed remodelling. This was most marked in younger children, regardless of sex. Based on this study, this device should be considered for use in patients with SCFE aged < 12 years instead of standard pinning in situ.Cite this article: Bone Joint J  2023;105-B(2):215-219.

Aims: We investigated the prevalence of late developmental dysplasia of the hip (DDH), abduction bracing treatment, and surgical procedures performed following the implementation of universal ultrasound screening versus selective ultrasound screening programmes., Methods: A systematic search of PubMed, Embase, The Cochrane Library, OrthoSearch, and Web of Science from the date of inception of each database until 27 March 2022 was performed. The primary outcome of interest was the prevalence of late detection of DDH, diagnosed after three months. Secondary outcomes of interest were the prevalence of abduction bracing treatment and surgical procedures performed in childhood for dysplasia. Only studies describing the primary outcome of interest were included., Results: A total of 31 studies were identified, of which 13 described universal screening and 20 described selective screening. Two studies described both. The prevalence of late DDH was 0.10 per 1,000 live births (95% confidence interval (CI) 0.00 to 0.39) in the universal screening group and 0.45 per 1,000 live births (95% CI 0.31 to 0.61) in the selective screening group. Abduction bracing treatment was performed on 55.54 per 1,000 live births (95% CI 24.46 to 98.15) in the universal screening group versus 0.48 per 1,000 live births (95% CI 0.07 to 1.13) in the selective screening group. Both the universal and selective screening groups had a similar prevalence of surgical procedures in childhood for dysplasia being performed (0.48 (95% CI 0.32 to 0.63) vs 0.49 (95% CI 0.31 to 0.71) per 1,000 live births, respectively)., Conclusion: Universal screening showed a trend towards lower prevalence of late DDH compared to selective screening. However, it was also associated with a significant increase in the prevalence of abduction bracing without a significant reduction in the prevalence of surgical procedures in childhood for dysplasia being performed. High-quality studies comparing both treatment methods are required, in addition to studies into the natural history of missed DDH.Cite this article: Bone Joint J  2023;105-B(2):198-208.

Aims: A national screening programme has existed in the UK for the diagnosis of developmental dysplasia of the hip (DDH) since 1969. However, every aspect of screening and treatment remains controversial. Screening programmes throughout the world vary enormously, and in the UK there is significant variation in screening practice and treatment pathways. We report the results of an attempt by the British Society for Children's Orthopaedic Surgery (BSCOS) to identify a nationwide consensus for the management of DDH in order to unify treatment and suggest an approach for screening., Methods: A Delphi consensus study was performed among the membership of BSCOS. Statements were generated by a steering group regarding aspects of the management of DDH in children aged under three months, namely screening and surveillance (15 questions), the technique of ultrasound scanning (eight questions), the initiation of treatment (19 questions), care during treatment with a splint (ten questions), and on quality, governance, and research (eight questions). A two-round Delphi process was used and a consensus document was produced at the final meeting of the steering group., Results: A total of 60 statements were graded by 128 clinicians in the first round and 132 in the second round. Consensus was reached on 30 out of 60 statements in the first round and an additional 12 in the seond. This was summarized in a consensus statement and distilled into a flowchart to guide clinical practice., Conclusion: We identified agreement in an area of medicine that has a long history of controversy and varied practice. None of the areas of consensus are based on high-quality evidence. This document is thus a framework to guide clinical practice and on which high-quality clinical trials can be developed.Cite this article: Bone Joint J  2023;105-B(2):209-214.

Aims: Eccentric reductions may become concentric through femoral head 'docking' (FHD) following closed reduction (CR) for developmental dysplasia of the hip (DDH). However, changes regarding position and morphology through FHD are not well understood. We aimed to assess these changes using serial MRI., Methods: We reviewed 103 patients with DDH successfully treated by CR and spica casting in a single institution between January 2016 and December 2020. MRI was routinely performed immediately after CR and at the end of each cast. Using MRI, we described the labrum-acetabular cartilage complex (LACC) morphology, and measured the femoral head to triradiate cartilage distance (FTD) on the midcoronal section. A total of 13 hips with initial complete reduction (i.e. FTD < 1 mm) and ten hips with incomplete MRI follow-up were excluded. A total of 86 patients (92 hips) with a FTD > 1 mm were included in the analysis., Results: At the end of the first cast period, 73 hips (79.3%) had a FTD < 1 mm. Multiple regression analysis showed that FTD (p = 0.011) and immobilization duration (p = 0.028) were associated with complete reduction. At the end of the second cast period, all 92 hips achieved complete reduction. The LACC on initial MRI was inverted in 69 hips (75.0%), partly inverted in 16 hips (17.4%), and everted in seven hips (7.6%). The LACC became everted-congruent in 45 hips (48.9%) and 92 hips (100%) at the end of the first and second cast period, respectively. However, a residual inverted labrum was present in 50/85 hips (58.8%) with an initial inverted or partly inverted LACC., Conclusion: An eccentric reduction can become concentric after complete reduction and LACC remodelling following CR for DDH. Varying immobilization durations were required for achieving complete reduction. A residual inverted labrum was present in more than half of all hips after LACC remodelling.Cite this article: Bone Joint J  2023;105-B(2):140-147.

Aims: The aim of this study was to assess the clinical and radiological results of patients who were revised using a custom-made triflange acetabular component (CTAC) for component loosening and pelvic discontinuity (PD) after previous total hip arthroplasty (THA)., Methods: Data were extracted from a single centre prospective database of patients with PD who were treated with a CTAC. Patients were included if they had a follow-up of two years. The Hip Disability and Osteoarthritis Outcome Score (HOOS), modified Oxford Hip Score (mOHS), EurQol EuroQoL five-dimension three-level (EQ-5D-3L) utility, and Numeric Rating Scale (NRS), including visual analogue score (VAS) for pain, were gathered at baseline, and at one- and two-year follow-up. Reasons for revision, and radiological and clinical complications were registered. Trends over time are described and tested for significance and clinical relevance., Results: A total of 18 females with 22 CTACs who had a mean age of 73.5 years (SD 7.7) were included. A significant improvement was found in HOOS (p < 0.0001), mOHS (p < 0.0001), EQ-5D-3L utility (p = 0.003), EQ-5D-3L NRS (p = 0.013), VAS pain rest (p = 0.008), and VAS pain activity (p < 0.0001) between baseline and final follow-up. Minimal clinically important improvement in mOHS and the HOOS Physical Function Short Form (HOOS-PS) was observed in 16 patients (73%) and 14 patients (64%), respectively. Definite healing of the PD was observed in 19 hips (86%). Complications included six cases with broken screws (27%), four cases (18%) with bony fractures, and one case (4.5%) with sciatic nerve paresthesia. One patient with concurrent bilateral PD had revision surgery due to recurrent dislocations. No revision surgery was performed for screw failure or implant breakage., Conclusion: CTAC in patients with THA acetabular loosening and PD can result in stable constructs and significant improvement in functioning and health-related quality of life at two years' follow-up. Further follow-up is necessary to determine the mid- to long-term outcome.Cite this article: Bone Jt Open  2023;4(2):53-61.

The objective of this pilot study was to evaluate, using Leventhal's self-regulatory model of illness perceptions, the effects of subjective representations of health and hip fracture on coping strategies in a sample of 52 clients more than 65 years old at the beginning of intensive hospital rehabilitation programme. The results revealed that rehabilitation clients suffering from hip fracture preserved their sense of good general and mental health. Negative representation of hip fracture was related only to perception of temporary decline in physical activity and not to perception of other personal, social and economic consequences neither to perception of their controllability. Perception of poor physical competence influenced the use of less preferred coping strategies of behavioural, mental and alcohol/drug based disengagement, and denial. Rehabilitation clients preferred those cognitive-behavioural and emotional strategies which confirmed their perception of self-efficiency and confidence in therapeutic assistance.Strategies were thus selected according to active and planned endeavour to cope, and were based on acceptance, turning to religion, focusing and venting emotions, and seeking instrumental and social support. The study confirmed the hypothesis that negative representation of hip fracture and poor sense of physical competence had a restraining effect on the use of coping strategies. There was no evidence that coping strategies of hip fracture in elderly rehabilitation clients created a specific pattern, depending on the perception of its consequences and the appraisal of possibility to regain health control. The validity of the findings is limited by a relatively small and selected sample of cognitive intact and motivated older rehabilitation clients, use of specific, non-standardised instruments, and a cross-sectional approach.

In order to produce a high quality recycled material from real deposits of electric and electronic equipment, the rate of impurities in different blended grades of reclaimed materials has to be reduced. Setting up industrial recycling procedures requires to deal with the main types of polymers presents in WEEE (Waste Electric and Electronic Equipment), particularly High Impact Polystyrene (HIPS) as well as other styrenic polymers such as Acrylonitrile-Butadiene-Styrene (ABS), Polystyrene (PS) but also polyolefin which are present into WEEE deposit as Polypropylene (PP). The production of a substantial quantity of recycled materials implies to improve and master the compatibility of different HIPS grades. The influence of polymeric impurities has to be studied since automatic sorting techniques are not able to remove completely these fractions. Investigation of the influence of minor ABS, PS and PP polymer fractions as impurities has been done on microstructure and mechanical properties of HIPS using environmental scanning electron microscopy (ESEM) in order to determine the maximum tolerated rate for each of them into HIPS after sorting and recycling operations. [ABSTRACT FROM AUTHOR]

Plastics' recycling contributes to society with economic, social and environmental benefits. Therefore, recyclability of a material is an important environmental factor to be considered in the development of new materials, such as nanocomposites. In this study, high impact polystyrene (HIPS) and its nanocomposites with 3 and 5 wt% of Cloisite 20A were processed within four extrusion cycles in a single screw extruder having Maddock mixing section. Changes in nanostructure, in thermal, flow and mechanical properties, and in morphology of neat HIPS and its nanocomposites with reprocessing cycles were investigated. X-Ray diffractograms showed that the basal interplanar distance of clay layers increased at the first extrusion cycle, indicating the formation of nanocomposites with intercalated structure, but remained almost constant along extrusion cycles. The MEV micrographs presented improved distribution and dispersion of clay agglomerates with extrusion cycles. The melt flow index and mechanical properties showed a tendency to increase and reduce or vice-versa along extrusion cycles due to competition between crosslinking and chain scission reactions. Since the degradation mechanisms of neat HIPS and its nanocomposites were similar, the observed differences between them were related to reinforcing and barrier effect of clay, content of agglomerates, and their distribution and dispersion along extrusion cycles. A distinct mechanical behavior was observed only for 5wt% clay nanocomposite due to the high proportion of agglomerates present in this composition. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance allows measurement of proton spin-lattice relaxation times, which reflect the molecular mobility of the sample according to the changes in its chemical structure caused by different mechanisms that can be induced. Nanomaterials and their derivatives are good systems to investigate through NMR relaxometry due to their particular organization and intermolecular interaction. In this study, NMR relaxometry was employed to evaluate UV aging of HIPS nanomaterials formed by the solution method. The results obtained were quite interesting. Regardless of organoclay amount, the aging effect occurred slowly up to 200 h of UV light exposure. However, at 300 h of UV light exposure, competition between chain degradation and chain recombination occurred, and at 400 h the aging effect increased the chain scission. [ABSTRACT FROM AUTHOR]

The disk cover is installed to protect brake disk and calliper and it's removed right before delivering to customers. The temperature of disk cover was measured driving test vehicles(2000cc, diesel) in this study. The highest temperature measured for the driving test(120km/h-braking(0.3G)-stop-120km/h-braking(0.5G)-stop) was 260~270℃ in the upper part of the disk cover and the temperature varied considerably around the disk cover. It can be inferred from this temperature distribution around the cover that the major heat transfer from hot disk to cover was through convection. In other words, the hot air generated by braking friction moved up to the upper part of the disk cover. And only the upper area of the disk cover was melted down during this driving test. The thickness of disk cover was increased to 1.0mm from 0.7mm and 1 paper of masking tape was pasted in the upper region of the disk cover. Then the cover endured the heated air formed by braking friction during the driving test. [ABSTRACT FROM AUTHOR]

A tecnologia dos chamados Compósitos Termoplásticos com Madeira envolve conceitos de compatibilidade e processabilidade e apresenta grandes desafios tecnológicos para a formulação e estabilização da mistura. Devido à baixa estabilidade térmica da celulose, a grande maioria das resinas termoplásticas utilizadas na preparação desses compósitos está restrita às resinas poliolefinicas, estirênicas e ao poli(cloreto de vinila). O Poliestireno de Alto Impacto (HIPS) é um termoplástico bifásico de grande versatilidade de propriedades decorrentes das variações de composição e morfologia das partículas de borracha dispersas na matriz estirênica. Além da sua temperatura relativamente baixa de processamento, estas características tornam o HIPS um termoplástico de grande interesse para aplicações em compósitos com farinha de resíduo de madeira, uma vez que a otimização do balanço de propriedades de rigidez e impacto pode ser alcançada através do controle da morfologia e da formulação do compósito. No presente estudo, "tipos" comerciais de HIPS com diferenças no índice de fluidez e na distribuição do tamanho de partículas foram utilizados na preparação de compósitos termoplásticos com farinha de resíduo de madeira. As propriedades mecânicas dos compósitos obtidos foram discutidas em termos das características morfológicas dos HIPS utilizados e da quantidade de farinha de resíduo de madeira no compósito. Pela simples aplicação da regra das misturas, mostrou-se que devido à baixa densidade do resíduo de madeira, o reforço celulósico poderia ser utilizado eficientemente na substituição de cargas minerais ou fibra de vidro em compósitos termoplásticos com um melhor desempenho em termos de resistência e rigidez específica. A microscopia eletrônica de varredura foi utilizada na análise de superfícies de fratura para ilustrar a dispersão da farinha de madeira na matriz estirênica, a molhabilidade do reforço pela resina e as interações reforço-matriz.The technology of wood-plastics composites includes concepts of compatibility and processability, with important challenges to optimize grade formulations, processing and stabilization of the composite system. Owing to the low thermal stability in wood flour processing, commodities such as polyolefins, styrene and polyvinylchloride represent the large majority of the thermoplastics employed in cellulosic composites. High impact polystyrene (HIPS) is a versatile thermoplastic as a result of variations in composition and morphology of the rubber dispersed phase in the styrenic matrix. In addition to its relatively low processing temperature, such characteristics make HIPS a suitable polymer for wood-plastic composite applications as an optimum stiffness-toughness balance can be achieved by fine control of HIPS morphological parameters and the composite formulation. In the present study, commercial grades of HIPS with different flow index and particle size distribution were used in the preparation of wood-plastic composites. The mechanical properties and the heat distortion temperatures of the composites are discussed in terms of the HIPS characteristics and the filler content in the composite. By simply applying the rule of mixtures, it was shown that owing to their relatively low specific gravity, the wood waste flour might be cost-effective in replacing mineral fillers or glass fibers in plastic composites with a better performance in terms of specific strength and rigidity. Electron microscopy analysis of fractured surfaces was used to illustrate wood flour dispersion, wettability and matrix-filler interactions.

A tenacificação da matriz vítrea de poliestireno (PS) pela adição de borracha polibutadiênica, que tem como conseqüência um aumento de sua resistência ao impacto, origina um polímero com características singulares, o Poliestireno de Alto Impacto (HIPS). Durante a polimerização in situ de estireno em uma solução de borracha, ocorre a formação de cadeias graftizadas de poliestireno no polibutadieno, as quais aumentam a interação interfacial borracha-PS. O HIPS é um material com ampla aplicação na indústria de embalagens e, principalmente, em gabinetes de refrigeradores, a chamada linha branca. O objetivo deste artigo é destacar e discutir as características estruturais e morfológicas do HIPS e a implicação destas na determinação de suas propriedades. Também foram revisadas as técnicas comumente utilizadas na caracterização morfológica e estrutural do HIPS.

Aims: Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients., Methods: A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method)., Results: Mean impingement-free flexion of patients with mixed-type FAI (110° (SD 8°)) and patients with pincer-type FAI (112° (SD 8°)) was significantly (p < 0.001) lower compared to the control group (125° (SD 13°)). The frequency of extra-articular subspine impingement was significantly (p < 0.001) increased in patients with pincer-type FAI (57%) compared to cam-type FAI (22%) in 125° flexion. Bony impingement in maximal flexion was located anterior-inferior at femoral four and five o'clock position in patients with cam-type FAI (63% (10 of 16 hips) and 37% (6 of 10 hips)), and did not involve the cam deformity. The cam deformity did not cause impingement in maximal flexion., Conclusion: Femoral impingement in maximal flexion was located anterior-inferior distal to the cam deformity. This differs to previous studies, a finding which could be important for FAI patients in order to avoid exacerbation of hip pain in deep flexion (e.g. during squats) and for hip arthroscopy (hip-preservation surgery) for planning of bone resection. Hip impingement in flexion has implications for daily activities (e.g. putting on shoes), sports, and sex.Cite this article: Bone Joint Res  2023;12(1):22-32.

Neste trabalho o efeito da adição de 2 a 7% em peso de um copolímero tribloco estireno-b-etileno-co-butileno-b-estireno (SEBS) em uma blenda polipropileno/poliestireno de alto impacto (PP/HIPS) 70:30 foi determinado. As propriedades em tração e impacto, temperatura de amolecimento Vicat e morfologia da blenda PP/HIPS (70:30) em função da concentração de SEBS foram determinadas. As blendas foram processadas em extrusora dupla-rosca contra-rotativa interpenetrante e as amostras moldadas por compressão. Os resultados mostraram que, embora a adição do SEBS tenha promovido um aumento muito leve na resistência tênsil e no módulo elástico, observou-se um expressivo aumento no alongamento na ruptura e na resistência ao impacto das blendas; a temperatura Vicat das blendas foi superior à do HIPS e que a adição do SEBS promoveu uma redução significativa do tamanho de partícula, indicando que o SEBS exerceu um efeito emulsificante e estabilizador na morfologia das blendas investigadas. Resultados otimizados foram obtidos para a composição contendo 5% de SEBS, o que foi atribuido à uma maior compatibilidade entre as fases.

Pyrolysis of high impact polystyrene (HIPS), containing decabromodiphenyl oxide as brominated flame retardant (BFR) with Sb 2 O 3 as a synergist (Br–Sb–HIPS), often leads to high concentrations of toxic brominated organic compounds in the pyrolysis oils which would detrimentally impact the reuse of these pyrolysis oils. In this work, the pyrolysis of Br–Sb–HIPS in the presence of polypropylene (PP) at different blending mass ratios using a fixed bed reactor at 410 °C was performed to investigate what the effect of PP has on the pyrolysis of Br–Sb–HIPS. The thermal decomposition characterization of Br–Sb–HIPS and PP was investigated using thermogravimetry analysis (TGA). The pyrolysis oils were analyzed using Fourier transform infrared spectroscopy (FTIR) and gas chromatography–mass spectrometry (GC–MS). TGA revealed that there was a synergistic interaction between Br–Sb–HIPS and PP during co-pyrolysis process. More wax/oil and less gas were produced and the yields of toluene, ethylbenzene, styrene and many other compounds in the pyrolysis oil reversely increased in the presence of PP. Moreover, PP was found to be effective to reduce bromine in the pyrolysis oil. When 30 wt.% PP was blended into Br–Sb–HIPS, it could reduce the amount of bromine in pyrolysis oil to 38% of the original value. [ABSTRACT FROM AUTHOR]

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The emissions of polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo- p -dioxins and dibenzofurans (PBDD/Fs) and their chlorinated analogues (PCDD/Fs) during the thermal treatment of a high impact polystyrene (HIPS) TV casing were investigated. The halogenated compounds were analyzed in the original material and in the gases emitted during its treatment at temperatures between 50 °C and 250 °C. DecaBDE was the primary PBDE in the TV casing, which also contained high levels of PBDFs (ppm range). At the lower treatment temperatures, non-modified PBDEs evaporated from the samples. Conversely, at 200 °C or above, debromination reactions led to the formation of additional tri- through nonaBDE. The formation of new PBDD/Fs was also detected in the gas phase when the plastic was heated to 200 °C or 250 °C, with higher yields of furans than dioxins. This appreciably increased the toxic equivalent (TEQ) levels of the gas phase relative to those seen in the untreated sample. In all cases, the levels and TEQ contributions from PCDD/Fs were negligible compared to those for brominated analogues. [ABSTRACT FROM AUTHOR]

This work investigates the effect of kinetic factors and the surface chemistry of the particles on the dispersion and distribution of clays in heterogeneous system containing polystyrene (PS) and polybutadiene (PB). It was carried out in 2 stages. In the first stage, an isothermal system without copolymer was investigated; that involved simple blends of the mentioned homopolymers, of commercially-modified clays, and of styrene (St) as solvent. In these soft blends, phase demixing was not spontaneous observed, but was induced by centrifugation. After demixing, the composition of the isolated phases was determined by calcination/infrared spectroscopy (FTIR); and in some phases, the clay dispersion was analyzed by X-ray diffraction (XRD). In the second stage, in situ and nitroxide-mediated polymerizations of the St-containing blends were carried out. The incorporation of the organo-clay particles into the different phases and morphology of the rubbery particles of the resulting high-impact polystyrenes (HIPS's), were observed by transmission electronic microscopy, TEM. The distribution of silicates between the phases was analyzed by calcination/FTIR. In all the samples (i.e., in those of simple blends and in those with polymerization), the clay was mainly incorporated into the PB-rich phase, due to the high affinity between PB and the clay modifiers. In the case of the soft blends, demixing was prevented by the increased stability introduced by the clay; and several mechanisms were proposed to explain such behavior. In the case of the synthesized HIPS's, their thermal resistances were increased by the presence of the modified clays and by increasing the degree of dispersion of the clay in the polymer. [ABSTRACT FROM AUTHOR]

This article describes a novel wearable robot (WR) intended to assist hip and knee flexion/ extension through series elastic actuators (SEAs). A nonanthropomorphic (NA) design was pursued to improve ergonomics while optimizing dynamic properties through a smart distribution of swinging masses. Once the anthropomorphism constraint is relaxed, the number of possible architectures becomes very high, and a methodology must be defined to point out the best options. To this purpose, a design methodology, which includes a novel approach to kinematic synthesis, topology selection, and morphological optimization, is also presented. The advantages offered by the novel architecture are demonstrated both theoretically and experimentally. In particular, the results show a low reflected inertia on the user's body, a high backdrivability, and an intrinsic tolerance to misalignments. Such advantages make the proposed robot a promising platform for the development of assistive and rehabilitation systems. [ABSTRACT FROM AUTHOR]

Aims: Leg length discrepancy (LLD) is a common pre- and postoperative issue in total hip arthroplasty (THA) patients. The conventional technique for measuring LLD has historically been on a non-weightbearing anteroposterior pelvic radiograph; however, this does not capture many potential sources of LLD. The aim of this study was to determine if long-limb EOS radiology can provide a more reproducible and holistic measurement of LLD., Methods: In all, 93 patients who underwent a THA received a standardized preoperative EOS scan, anteroposterior (AP) radiograph, and clinical LLD assessment. Overall, 13 measurements were taken along both anatomical and functional axes and measured twice by an orthopaedic fellow and surgical planning engineer to calculate intraoperator reproducibility and correlations between measurements., Results: Strong correlations were observed for all EOS measurements (r s > 0.9). The strongest correlation with AP radiograph (inter-teardrop line) was observed for functional-ASIS-to-floor (functional) (r s = 0.57), much weaker than the correlations between EOS measurements. ASIS-to-ankle measurements exhibited a high correlation to other linear measurements and the highest ICC (r s = 0.97). Using anterior superior iliac spine (ASIS)-to-ankle, 33% of patients had an absolute LLD of greater than 10 mm, which was statistically different from the inter-teardrop LLD measurement (p < 0.005)., Discussion: We found that the conventional measurement of LLD on AP pelvic radiograph does not correlate well with long leg measurements and may not provide a true appreciation of LLD. ASIS-to-ankle demonstrated improved detection of potential LLD than other EOS and radiograph measurements. Full length, functional imaging methods may become the new gold standard to measure LLD.Cite this article: Bone Jt Open  2022;3(12):960-968.

Aims: This study aimed to investigate the estimated change in primary and revision arthroplasty rate in the Netherlands and Denmark for hips, knees, and shoulders during the COVID-19 pandemic in 2020 (COVID-period). Additional points of focus included the comparison of patient characteristics and hospital type (2019 vs COVID-period), and the estimated loss of quality-adjusted life years (QALYs) and impact on waiting lists., Methods: All hip, knee, and shoulder arthroplasties (2014 to 2020) from the Dutch Arthroplasty Register, and hip and knee arthroplasties from the Danish Hip and Knee Arthroplasty Registries, were included. The expected number of arthroplasties per month in 2020 was estimated using Poisson regression, taking into account changes in age and sex distribution of the general Dutch/Danish population over time, calculating observed/expected (O/E) ratios. Country-specific proportions of patient characteristics and hospital type were calculated per indication category (osteoarthritis/other elective/acute). Waiting list outcomes including QALYs were estimated by modelling virtual waiting lists including 0%, 5% and 10% extra capacity., Results: During COVID-period, fewer arthroplasties were performed than expected (Netherlands: 20%; Denmark: 5%), with the lowest O/E in April. In the Netherlands, more acute indications were prioritized, resulting in more American Society of Anesthesiologists grade III to IV patients receiving surgery. In both countries, no other patient prioritization was present. Relatively more arthroplasties were performed in private hospitals. There were no clinically relevant differences in revision arthroplasties between pre-COVID and COVID-period. Estimated total health loss depending on extra capacity ranged from: 19,800 to 29,400 QALYs (Netherlands): 1,700 to 2,400 QALYs (Denmark). With no extra capacity it will take > 30 years to deplete the waiting lists., Conclusion: The COVID-19 pandemic had an enormous negative effect on arthroplasty rates, but more in the Netherlands than Denmark. In the Netherlands, hip and shoulder patients with acute indications were prioritized. Private hospitals filled in part of the capacity gap. QALY loss due to postponed arthroplasty surgeries is considerable.Cite this article: Bone Jt Open  2022;3(12):977-990.

Background Femoral neck fractures are common injuries. Although many studies have compared two-hole dynamic hip screw (DHS) versus multiple cannulated cancellous screw (CCS) fixation for undisplaced intracapsular fractured neck of femurs (NOF), there is no consensus on which surgical technique results in better outcomes. The aim of our study was to compare DHS and CCS for undisplaced NOFs. The primary outcomes were reoperation and mortality rates at one year postoperatively. Methodology A retrospective analysis was performed involving all patients who underwent fixation with DHS/CCS for an undisplaced intracapsular NOF at our hospital between January 2016 and December 2020. All patients had a minimum follow-up time greater than one year. All patients underwent a standardised NOF protocol. Patients either underwent DHS or CCS fixation according to surgeon preference, and there was no randomisation to either group. Results A total of 41 patients underwent fixation with DHS compared to 32 who underwent CCS. The reoperation rate at one year was 9.8% in the DHS group compared to 6.3% in the CCS group. This difference was not statistically significant (p = 0.588). The one-year mortality rate was similar between groups at 22.0% and 21.9% in the DHS group and the CCS group, respectively (p = 0.994). Registrar-level surgeons performed 80.5% of DHS compared to 59.4% of CCS, and consultant surgeons performed 4.9% of DHS compared to 25% of CCS. Conclusions There was no significant difference in revision rates or complications seen between CCS and DHS. A significantly higher percentage of CCS fixations were performed by consultant-grade surgeons at our hospital compared to DHS. This study provides further data on the choice of fixation method for intracapsular fractures. It also reports on the grade of the operating surgeon at our unit, which may be a factor in the quality of fixation and ultimately reoperation rates., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Cullen et al.)

Aims: The preventive effects of bisphosphonates on articular cartilage in non-arthritic joints are unclear. This study aimed to investigate the effects of oral bisphosphonates on the rate of joint space narrowing in the non-arthritic hip., Methods: We retrospectively reviewed standing whole-leg radiographs from patients who underwent knee arthroplasties from 2012 to 2020 at our institute. Patients with previous hip surgery, Kellgren-Lawrence grade ≥ II hip osteoarthritis, hip dysplasia, or rheumatoid arthritis were excluded. The rate of hip joint space narrowing was measured in 398 patients (796 hips), and the effects of the use of bisphosphonates were examined using the multivariate regression model and the propensity score matching (1:2) model., Results: A total of 45 of 398 (11.3%) eligible patients were taking an oral bisphosphonate at the time of knee surgery, with a mean age of 75.8 years (SD 6.2) in bisphosphonate users and 75.7 years (SD 6.8) in non-users. The mean joint space narrowing rate was 0.04 mm/year (SD 0.11) in bisphosphonate users and 0.12 mm/year (SD 0.25) in non-users (p < 0.001). In the multivariate model, age (standardized coefficient = 0.0867, p = 0.016) and the use of a bisphosphonate (standardized coefficient = -0.182, p < 0.001) were associated with the joint space narrowing rate. After successfully matching 43 bisphosphonate users and 86 non-users, the joint narrowing rate was smaller in bisphosphonate users (p < 0.001)., Conclusion: The use of bisphosphonates is associated with decreased joint degeneration in non-arthritic hips after knee arthroplasty. Bisphosphonates slow joint degeneration, thus maintaining the thickness of joint cartilage in the normal joint or during the early phase of osteoarthritis.Cite this article: Bone Joint Res  2022;11(11):826-834.

Aims: Although CT is considered the benchmark to measure femoral version, 3D biplanar radiography (hipEOS) has recently emerged as a possible alternative with reduced exposure to ionizing radiation and shorter examination time. The aim of our study was to evaluate femoral stem version in postoperative total hip arthroplasty (THA) patients and compare the accuracy of hipEOS to CT. We hypothesize that there will be no significant difference in calculated femoral stem version measurements between the two imaging methods., Methods: In this study, 45 patients who underwent THA between February 2016 and February 2020 and had both a postoperative CT and EOS scan were included for evaluation. A fellowship-trained musculoskeletal radiologist and radiological technician measured femoral version for CT and 3D EOS, respectively. Comparison of values for each imaging modality were assessed for statistical significance., Results: Comparison of the mean postoperative femoral stem version measurements between CT and 3D hipEOS showed no significant difference (p = 0.862). In addition, the two version measurements were strongly correlated ( r = 0.95; p < 0.001), and the mean paired difference in postoperative femoral version for CT scan and 3D biplanar radiography was -0.09° (95% confidence interval -1.09 to 0.91). Only three stem measurements (6.7%) were considered outliers with a > 5° difference., Conclusion: Our study supports the use of low-dose biplanar radiography for the postoperative assessment of femoral stem version after THA, demonstrating high correlation with CT. We found no significant difference for postoperative femoral version when comparing CT to 3D EOS. We believe 3D EOS is a reliable option to measure postoperative femoral version given its advantages of lower radiation dosage and shorter examination time.Cite this article: Bone Joint J  2022;104-B(11):1196-1201.

Aims: Pelvic discontinuity is a rare but increasingly common complication of total hip arthroplasty (THA). This single-centre study evaluated the performance of custom-made triflange acetabular components in acetabular reconstruction with pelvic discontinuity by determining: 1) revision and overall implant survival rates; 2) discontinuity healing rate; and 3) Harris Hip Score (HHS)., Methods: Retrospectively collected data of 38 patients (39 hips) with pelvic discontinuity treated with revision THA using a custom-made triflange acetabular component were analyzed. Minimum follow-up was two years (mean 5.1 years (2 to 11))., Results: There were eight subsequent surgical interventions. Two failures (5%) of the triflange acetabular components were both revised because of deep infection. There were seven (18%) patients with dislocation, and five (13%) of these were treated with a constraint liner. One patient had a debridement, antibiotics, and implant retention (DAIR) procedure. In 34 (92%) hips the custom-made triflange component was considered stable, with a healed pelvic discontinuity with no aseptic loosening at midterm follow-up. Mean HHS was 80.5 (48 to 96)., Conclusion: The performance of the custom triflange implant in this study is encouraging, with high rates of discontinuity healing and osteointegration of the acetabular implant with no aseptic loosening at midterm follow-up. However, complications are not uncommon, particularly instability which we successfully addressed with constrained liners.Cite this article: Bone Jt Open  2022;3(11):867-876.

Aims: Hip dysplasia (HD) leads to premature osteoarthritis. Timely detection and correction of HD has been shown to improve pain, functional status, and hip longevity. Several time-consuming radiological measurements are currently used to confirm HD. An artificial intelligence (AI) software named HIPPO automatically locates anatomical landmarks on anteroposterior pelvis radiographs and performs the needed measurements. The primary aim of this study was to assess the reliability of this tool as compared to multi-reader evaluation in clinically proven cases of adult HD. The secondary aims were to assess the time savings achieved and evaluate inter-reader assessment., Methods: A consecutive preoperative sample of 130 HD patients (256 hips) was used. This cohort included 82.3% females (n = 107) and 17.7% males (n = 23) with median patient age of 28.6 years (interquartile range (IQR) 22.5 to 37.2). Three trained readers' measurements were compared to AI outputs of lateral centre-edge angle (LCEA), caput-collum-diaphyseal (CCD) angle, pelvic obliquity, Tönnis angle, Sharp's angle, and femoral head coverage. Intraclass correlation coefficients (ICC) and Bland-Altman analyses were obtained., Results: Among 256 hips with AI outputs, all six hip AI measurements were successfully obtained. The AI-reader correlations were generally good (ICC 0.60 to 0.74) to excellent (ICC > 0.75). There was lower agreement for CCD angle measurement. Most widely used measurements for HD diagnosis (LCEA and Tönnis angle) demonstrated good to excellent inter-method reliability (ICC 0.71 to 0.86 and 0.82 to 0.90, respectively). The median reading time for the three readers and AI was 212 (IQR 197 to 230), 131 (IQR 126 to 147), 734 (IQR 690 to 786), and 41 (IQR 38 to 44) seconds, respectively., Conclusion: This study showed that AI-based software demonstrated reliable radiological assessment of patients with HD with significant interpretation-related time savings.Cite this article: Bone Jt Open  2022;3(11):877-884.