Search

INTRODUCTION: Brace treatment is common to address radiological dysplasia in infants with developmental dysplasia of the hip (DDH); however, it is unclear whether bracing provides significant benefit above careful observation by ultrasound. If observation alone is non-inferior to bracing for radiological dysplasia, unnecessary treatment may be avoided. Therefore, the purpose of this study is to determine whether observation is non-inferior to bracing for infants with radiological dysplasia. METHODS AND ANALYSIS: This will be a multicentre, global, randomised, non-inferiority trial performed under the auspices of a global prospective registry for infants and children diagnosed with DDH. Patients will be included if they present with radiological dysplasia (centred hip, alpha angle 43-60°, percent femoral head coverage greater than 35% measured on ultrasound) of a clinically stable hip under 3 months old. Patients will be excluded if they present with clinical hip instability, have received prior treatment or have known/suspected neuromuscular, collagen, chromosomal or lower-extremity congenital abnormalities or syndromic-associated hip abnormalities. Patients will be enrolled and randomised to undergo observation alone or brace treatment with a Pavlik harness for a minimum of 6 weeks. Follow-up visits will occur at 6 weeks, 1 year and 2 years post-enrolment. The primary outcome will be the norm-referenced acetabular index measured on the 2-year radiograph with a 3° non-inferiority margin. A total of 514 patients will be included.The study is anticipated to start in April 2024 and end in September 2028.The primary outcome will be compared between arms with a mixed-effects model with a random intercept for study centre, and a single covariate for the treatment group. If the lower bound of the 95% CI lies within 3° of the mean, we will treat this as evidence for non-inferiority. ETHICS AND DISSEMINATION: Ethics approval has been obtained from the lead sites ethics board (University of British Columbia, Childrens and Womens Research Ethics Board). Ethics approval will be obtained from the local ethics committees or institutional review boards at each institution prior to patient enrolment. It is intended that the results of this study shall be published in peer-reviewed journals and presented at suitable conferences. TRIAL REGISTRATION NUMBER: NCT05869851.

Background: In March 2020, Ontario instituted a lockdown to reduce spread of the SARS-CoV-2 virus. Schools, recreational facilities, and nonessential businesses were closed. Restrictions were eased through 3 distinct stages over a 6-month period (March to September 2020). We aimed to determine the impact of each stage of the COVID-19 public health lockdown on the epidemiology of operative pediatric orthopedic trauma. Methods: A retrospective cohort study was performed comparing emergency department (ED) visits for orthopedic injuries and operatively treated orthopedic injuries at a level 1 pediatric trauma centre during each lockdown stage of the pandemic with caseloads during the same date ranges in 2019 (prepandemic). Further analyses were based on patients' demographic characteristics, injury severity, mechanism of injury, and anatomic location of injury. Results: Compared with the prepandemic period, ED visits decreased by 20% (1356 v. 1698, p < 0.001) and operative cases by 29% (262 v. 371, p < 0.001). There was a significant decrease in the number of operative cases per day in stage 1 of the lockdown (1.3 v. 2.0, p < 0.001) and in stage 2 (1.7 v. 3.0; P < 0.001), but there was no significant difference in stage 3 (2.4 v. 2.2, p = 0.35). A significant reduction in the number of playground injuries was seen in stage 1 (1 v. 62, p < 0.001) and stage 2 (6 v. 35, p < 0.001), and there was an increase in the number of self-propelled transit injuries (31 v. 10, p = 0.002) during stage 1. In stage 3, all patient demographic characteristics and all characteristics of operatively treated injuries resumed their prepandemic distributions. Conclusion: Provincial lockdown measures designed to limit the spread of SARS-CoV-2 significantly altered the volume and demographic characteristics of pediatric orthopedic injuries that required operative management. The findings from this study will serve to inform health system planning for future emergency lockdowns. Contexte : En mars 2020, l'Ontario a décrété des mesures de confinement afin de réduire la propagation du virus SRAS-CoV-2. Les écoles, les installations récréatives, et les commerces non essentiels ont dû fermer. Les restrictions ont été par la suite progressivement assouplies en 3 phases distinctes sur une période de 6 mois (de mars à septembre 2020). Notre objectif était de déterminer les répercussions épidémiologiques de chaque phase du confinement imposé par les autorités de santé publique sur la chirurgie orthopédique pédiatrique et traumatologique. Méthodes : Nous avons réalisé une étude de cohorte rétrospective pour comparer le nombre de consultations aux services d'urgence pour des blessures orthopédiques, traitées ou non en salle d'opération, dans des centres de traumatologie pédiatrique de niveau 1 pendant chaque phase de confinement avec le nombre de consultations pendant les mêmes périodes de l'année en 2019 (prépandémie). Nous avons effectué des analyses complémentaires en fonction des caractéristiques démographiques de la patientèle, ainsi que de la gravité, du mécanisme et de la localisation des blessures. Résultats : Comparativement à la période prépandémique, la fréquentation des services d'urgence a diminué de 20% (1356 c. 1698, p < 0,001) et le nombre d'interventions chirurgicales, de 29% (262 c. 371, p < 0,001). Nous avons constaté une baisse significative du nombre d'interventions chirurgicales lors de la phase 1 du confinement (1,3 c. 2,0, p < 0,001), ainsi que lors de la phase 2 (1,7 c. 3,0, p < 0,001), mais aucune différence significative n'a été observée lors de la phase 3 (2,4 c. 2,2, p = 0,35). Par ailleurs, nous avons constaté une baisse significative du nombre de blessures survenues sur des terrains de jeux durant la phase 1 (1 c. 62, p < 0,001) et la phase 2 (6 c. 35, p < 0,001), alors que le nombre de blessures occasionnées par des véhicules automoteurs a augmenté (31 c. 10, p = 0,002) lors de la phase 1. Enfin, lors de la phase 3, tous les paramètres démographiques de la patientèle et toutes les caractéristiques des blessures traitées en salle d'opération sont revenus à leurs valeurs prépandémiques. Conclusion : Les mesures de confinement prises au niveau provincial pour limiter la propagation du virus SRAS-CoV-2 ont significativement modifié le volume et les caractéristiques démographiques des blessures orthopédiques pédiatriques nécessitant une prise en charge chirurgicale. Les résultats de cette étude serviront à améliorer la planification du système de santé en cas de nouveau confinement d'urgence., The COVID-19 pandemic has had an unprecedented impact on health care systems. At its height, governments worldwide implemented various public healdi measures to limit exposure to the virus and to [...]

Traditional practical work for higher education in STEM subjects is under pressure from rising student numbers and a desired increase in active learning. Investing in more buildings and staff is financially challenging, while stretching existing resources affects outcomes, health, and participation. A more pragmatic approach is to embrace a less instrumentalist view of practical work in physical spaces and instead adopt a critical post-humanist approach which mixes both humanity and technology to achieve a sum greater than the parts, not bound by the limits of either. We share the experiences of leading UK exponents of non-traditional laboratories in the four main categories of simulation, virtual laboratories, real-asynchronous, and real-synchronous activities, as well as experts in scaling digital education initiatives for university-wide adoption. We foreshadow opportunities, challenges and potential solutions to increasing the opportunity for active learning by students studying at traditional campuses, via the complementary addition of non-traditional practical work.

Oil-bearing fluid inclusions trapped within authigenic K-feldspar in Late Jurassic reservoirs throughout the UK Atlantic margin are evidence for an early oil migration event from Late Jurassic source rocks in the Faeroe-Shetland Basin. Previous compound-specific isotope studies confirm the hydrocarbon provenance. Temperature-composition-time data show that the Late Jurassic source rocks were oil mature 113 [+ or -] 3.5 Ma (2[sigma]). This new [sup.40][sup.39]Ar Ar authigenic K-feldspar age shows that the Late Jurassic source rocks were oil mature 30-40 m.y. prior to current estimates. doi: 10.1130/G30237.1

Seven localities distributed along a 180-km-long outcrop within the UK sector of the Laurentian margin were sampled, and all showed two phases of authigenic K-feldspar. The first phase was precipitated from a cool fluid of moderate salinity, and the second phase was precipitated from a hotter, more saline fluid.Ar-Ar ages for the two episodes of authigenesis are ca. 470 Ma and ca. 432 Ma. The data can be interpreted to represent two phases of regional-scale fluid migration related to Ordovician arc accretion and Silurian continent-continent convergence, correspond. ing to the Grampian and Scandian episodes of the Caledonian orogeny, respectively. Keywords: authigenic K-feldspar, fluid flow, Caledonian orogeny, Fucoid Beds.

New Lu-Hf garnet growth ages from high-pressure rocks from the structurally lowest terrane (Nevado-Filabride Complex) in the Betic Cordillera of southern Spain indicate early Miocene subduction of continental crust, requiring significant revision of the timing and processes of orogeny in the western part of the Alpine orogenic system. Mafic eclogite and pelitic schist give Lu-Hf ages in the range 18-14 Ma, and fission-track data show that the terrane was exhumed by 12-8 Ma. The overlying terrane (Alpujarride Complex) shows early Tertiary high pressure-temperature metamorphism; this was followed by a thermal event that accompanied rapid crustal extension at 22-18 Ma, leading to the formation of the Alboran Sea backarc basin. The evidence therefore suggests two phases of continental subduction separated by a phase of large-scale intraorogenic extension. The two terranes are now separated by a mid-late Miocene low-angle extensional fault. The timing and paleogeographic setting suggest that the Nevado-Filabride terrane originally was close to the rifted South Iberian margin, and was subducted during westward motion of the extending upper terrane between the converging African and Iberian plates. Keywords: eclogite, geochronology, garnet, subduction, exhumation, Betic Cordillera.

The process of strain localization as rifting proceeds to continental breakup is readily observed along the Oligocene-Recent southern Red Sea rift, yet much of the Red Sea margin in Ethiopia remains unmapped. Rifting initiated above or near a mantle plume, which is marked by the Eo-Oligocene Ethiopia-Yemen flood basalt province. Objectives of this field, remote sensing, and geochronology study are to establish a structural and stratigraphic framework for the southernmost Red Sea passive margin using new and existing [sup.40]Ar/[sup.39]Ar age data along 6 transects. We present new sketch geological maps and cross sections to document the timing of extension in relation to magmatism and its variation along strike. These new data are integrated with plate kinematic, geological, and geophysical data to present a model for evolution of the southern Red Sea margin. Faults commonly marked by eruptive centers initiated between 29 and 26 Ma, coincident with rifting in the Gulf of Aden. The Red Sea rift terminated at 10[degrees]N until linkage of the Main Ethiopian rift and southern Red Sea occurred at ca. 11 Ma. Rifting progressed in three distinct stages; each new phase saw a marked change in the style of volcanism and a narrowing of the locus of extension. Stage 1 rhyolites were emplaced from 29 to 26 Ma in basins bounded by a steep border fault system. Between 25 and 20 Ma, strain localized to narrow zones of basaltic fissural eruptions and minor faulting. Stage 2 faults and eruptive centers are located ~50 km to the east of the border faults, and they comprise flows spanning at least 16-7 Ma. After ca. 7 Ma, the locus of strain again migrated eastward (Stage 3). Strain in Stage 3 was largely accommodated by dike injection. Plate reconstructions predict high stretching factors ([beta] -3) in the southern Red Sea, suggesting that Stages 2 and 3 mark the onset of formation of crust transitional between oceanic and continental. Keywords: passive margin, magmatism, eastern Africa, rift.

Leucite is unique among minerals that have been exploited for K-Ar and At-At dating, in that it exhibits a major phase change at 645-65 [degrees]C, across which Ar diffusion and solubility can be studied. In addition, well-developed twinning occurs only in the low temperature form, offering further opportunity to examine the effects of crystallographic change upon Ar diffusion. Nepheline was studied to compare the effect of its 1-dimensional c-axis oriented lattice channels with the 3-dimensional channels of leucite. The amounts of At introduced into leucite were far higher than those observed in feldspars, allowing its analysis by electron microprobe spot traverses and X-ray maps. This has provided the first high spatial resolution 2-dimensional study of Ar distribution in a K-bearing mineral. Extreme changes in Ar solubility were observed across the leucite phase transition, with Ar solubilities jumping from ~70 ppm (at 1 kbar) in the tetragonal (low-temperature) form to ~750 ppm (at 1 kbar) in the cubic (high-temperature) form. Argon penetration profiles were complex and estimates of the diffusion rates show that they are more rapid than in K-feldspar. In addition, spikes of high Ar concentration were observed in both forms, suggesting extended defects or micro-inclusions formed argon traps in the structure. No concentration changes could be correlated to leucite twin planes, suggesting that twin planes did not act as fast pathways for Ar movement. Nepheline yielded a much lower Ar solubility of 0.15-0.31 ppm at 1 kbar.

Variations of global and regional silicate weathering rates and paleo-ocean circulation patterns are estimated by using radiogenic isotope records, but the effects of changes in provenance are generally ignored. Here sediment provenance has been constrained through the use of Ar-Ar ages for individual detrital minerals from the Labrador Sea, which can be compared directly to the radiogenic isotope compositions from the same core material. Dramatic changes in the radiogenic isotope composition of North Atlantic Deep Water through the Quaternary Period are shown to reflect discrete changes in both sources and weathering processes accompanying Northern Hemisphere glaciation. Changes in the different radiogenic isotope systems reflect the influence of source, physical weathering, and chemical weathering, and not simply changes in the underlying weathering rate or ocean circulation patterns that are typically inferred. Keywords: weathering, isotope geochemistry, radiogenic isotopes, glacial erosion, argon-argon.

Pyritized graptolites from the Welsh Basin (United Kingdom) slate belt acted as rigid bodies during cleavage formation, and epizonal white micas formed within the resulting strain shadows, orthogonal to the principal stress orientation. Although the quantities of mica are small, they are a pure synkinematic mineral and have been dated by [sup.40]Ar-[sup.39]Ar infrared laser microprobe as a means to dating cleavage. Four samples of strain-fringe mica from different hand samples yielded ages ranging from 394.4 [+ or -] 3.1 to 397.8 [+ or -] 1.8 Ma (2[sigma]), with a mean age of 396.1 [+ or -] 1.4 Ma (2[sigma]). By focusing on minerals that are unequivocally synkinematic, this technique provides a novel solution to the problems of isotopically dating slaty cleavage. Previous studies have predominantly relied on dating whole-rock slate samples or separated illite grains by [sup.40]Ar-[sup.39]Ar techniques; problems encountered included (1) separating the effects of isotopic contamination by detrital phases, (2)[sup.39]Ar loss during the irradiation of illite mineral separates, and (3) thermally induced [sup.40]Ar loss in nature from fine-grained minerals. By circumventing these problems, this new method provides the first unequivocal and high-precision age data for Acadian deformation in the well-characterized Welsh Basin slate belt. With such precision, the method may afford geologists the opportunity to track tectonic fronts across orogens and assess the rates of accretion processes in areas that are peripheral to sites of continent-continent collision. Keywords: [sup.40]Ar-[sup.39]Ar laserprobe, low temperature, slate, deformation, geochronology, Acadian.

Three different geochronological techniques (stepwise-heating, laser-ablation [sup.40]Ar/[sup.39]Ar, Rb-Sr microsampling) have been evaluated for dating fault-generated pseudotachylytes sampled along the Periadriatic Fault System (PAF) of the Alps. Because pseudotachylytes are whole-rock systems composed of melt, clast and alteration phases, chemical control from both Ar isotopes (Cl/K, Ca/K ratios) and EMPA analyses is crucial for their discrimination. When applied to stepwise-heating [sup.40]Ar/[sup.39]Ar analyses, this approach yields accurate melt-related ages, even for complex age spectra. The spatial resolution of laser-ablation [sup.40]Ar/[sup.39]Ar analyses is capable of contrasting melt, clast and alteration phases in situ, provided the clasts are not too fine grained, the latter of which results in integrated 'mixed' ages without geological information. Elevated Cl/K and Ca/K ratios were found to be an invaluable indicator for the presence of clast admixture or inherited [sup.40]Ar. Due to incomplete isotopic resetting during frictional melting, Rb-Sr microsampling dating did not furnish geologically meaningful ages. On the basis of isotopic disequilibria among pseudotachylyte matrix phases, and independent Rb-Sr microsampling dating of cogenetic (ultra)mylonites, the concordant [sup.40]Ar/[sup.39]Ar pseudotachylyte ages are interpreted as formation ages. The investigated pseudotachylytes altogether reveal a Cretaceous to Miocene history for the entire PAF, consistent with independent geological evidence. Individual faults, however, consistently reveal narrower intervals of enhanced activity lasting a few million years. Electronic supplementary material to this paper can be obtained by using the Springer LINK server at http://dx.doi.org/10.1007/s00410-002-0381-6

Detrital white micas from a sandstone unit within the Old Red Sandstone of southwest Wales have been analyzed with [sup.40]Ar/[sup.39]Ar ultraviolet and infrared laser microprobes (UVLAMP, IRLAMP) to determine their source region. Single-grain fusion ages determined by the IRLAMP range from 430 [+ or -] 2 to 587 [+ or -] 3 Ma, and intragrain ages determined by the high-spatial-resolution UVLAMP range from 435 [+ or -] 9 to 875 [+ or -] 5 Ma. The UVLAMP technique reveals strong [sup.40]Ar/[sup.39]Ar age zonation preserved within all the analyzed grains, and thus the single-grain fusion [sup.40]Ar/[sup.39]Ar ages determined by the IRLAMP are artifacts of this zonation and represent an average of the old and young ages within each grain. Comparing the observed UVLAMP ages with calculated diffusion profiles for various thermal histories suggests that these detrital micas had a complex polymetamorphic evolution. A thermal event ca. 870 Ma was partly reset by a subsequent thermal event ca. 470 Ma, which is also complicated by Ar loss via a mechanism other than volume diffusion. Such detail as this from detritus allows for a fairly narrowed interpretation of the possible source region, which in this case is the Laurentian Northern and Central Highlands of Scotland. The UVLAMP technique also offers valuable insight into the complexities of dating detrital mineral grains and into the potential for misidentifying source regions and constructing misleading sedimentary, systems, because the ages produced by [sup.40]Ar/[sup.39]Ar dating techniques using either bulk-mineral separates or single-grain fusion will result in average ages from strongly zoned mineral grains. These data represent the first application of the [sup.40]Ar/[sup.39]Ar UVLAMP to detrital minerals and provide insight into the potential for such a technique to investigate the thermal histories of now-eroded mountain belts. Keywords: geochronology, provenance, muscovite, detrital, argon, UVLAMP.

Detailed field and microstructural studies have been combined with high spatial resolution ultraviolet laser [sup.40]Ar/[sup.39]Ar dating of naturally deformed K-feldspar to investigate the direct relationship between deformation-related microstructure and Ar isotope systematics. The sample studied is a ~1,000 Ma Torridonian arkose from Skye, Scotland, that contains detrital feldspars previously metamorphosed at amphibolite-facies conditions ~1,700 Ma. The sample was subsequently deformed ~430 Ma ago during Caledonian orogenesis. The form and distribution of deformation-induced microstructures within three different feldspar clasts has been mapped using atomic number contrast and orientation contrast imaging, at a range of scales, to identify intragrain variations in composition and lattice orientation. These variations have been related to thin section and regional structural data to provide a well-constrained deformation history for the feldspar clasts. One hundred and forty-three in-situ [sup.40]Ar/[sup.39]Ar analyses measured using ultraviolet laser ablation record a range of apparent ages (317-1030 Ma). The K-feldspar showing the least strain records the greatest range of apparent ages from 420-1,030 Ma, with the oldest apparent ages being found close to the centre of the feldspar away from fractures and the detrital grain boundary. The most deformed K-feldspar yields the youngest apparent ages (317-453 Ma) but there is no spatial relationship between apparent age and the detrital grain boundary. Within this feldspar, the oldest apparent ages are recorded from orientation domain boundaries and fracture surfaces where an excess or trapped [sup.40]Ar component resides. Orientation contrast images at a similar scale to the Ar analyses illustrate a significant deformation-related microstructural difference between the feldspars and we conclude that deformation plays a significant role in controlling Ar systematics of feldspars at both the inter- and intragrain scales even at relatively low `bulk' strains. The data show that Ar loss and trapping within the deformed K-feldspars reflects the presence of a deformation-induced population of small diffusion domains in combination with `short-circuit' diffusion along deformation-induced defects. The complex history of microstructures induced in the K-feldspars during their cooling, alteration, erosion and sedimentation do not appear to be as significant as deformation-induced microstructures in controlling the distribution of apparent ages at the grain scale. Keywords Geochronology * Microstructure * Orientation contrast imaging * Skye * Ultra-violet laser microprobe

Purpose: The aim of this study is to evaluate foot deformities and anomalies present in congenital limb deficiencies (CLDs). We sought to define the relationship between the type of limb deficiency and foot posture, patterns of ray deficiencies, and association between tarsal coalition (TC) and ball-and-socket ankle. Materials and Methods: This is a single institution, retrospective radiograph, and medical record review of patients with CLD, comprising congenital femoral deficiency (CFD), tibial hemimelia (TH), and fibular hemimelia (FH) from January 2000 to January 2019. Data extracted included patient demographics, predicted leg length discrepancy, associated deformities and anomalies, and specifics of the foot deformity. Surgical procedures were recorded. Data were reported using descriptive statistics. Fisher's exact test analyses of contingency tables were used for the exploratory components of this study. Results: Eighty-one patients with 97 limb deficiencies were identified (16 - CFD, 18 - TH, and 63 - FH). Isolated CFD was not associated with foot and ankle deformity and TH was associated with an equinocavovarus foot in all limbs. In FH, an equinocavovarus deformity was present in 15/63 (24%) feet, most requiring foot surgery. Of 48 patients with FH and absent rays, two lacked lateral rays, whereas the remainder missed one or more intermediate rays. TC was unrelated to the presence of ball-and-socket ankle. Conclusions: This study demonstrates heterogeneity in the spectrum of foot and ankle deformity in CLD, particularly in FH. Recognition of this phenotypic variation is critical for surgeons to formulate a comprehensive treatment plan and ensure optimal functional outcomes. Level of Evidence: IV. [ABSTRACT FROM AUTHOR]