Biomechanics of skull fracture and intracranial injury in young children as a consequence of a low height fall

A challenge for clinicians when presented with a significant head injury in a young child and a postulated fall height is to determine the plausibility of such an injury. Previous authors have aimed to determine the head injuries that can result from a low height fall, however due to a lack of clarity it is difficult to determine a fall height at which certain head injuries including skull fracture and intra cranial injury (ICI) becomes more likely. Biomechanical thresholds aimed at young children exist for skull fracture and adult thresholds for subdural haemorrhage, however they have not been assessed against the injuries seen in a clinical setting. Consequently this study investigated low height falls in a paediatric clinical setting to determine differentiating variables and characteristics in the mechanism of head injury between children with a minor head injury and those with a skull fracture and / or ICI. The primary aim of which was to determine a fall height threshold for skull fracture and / ICI in young children. Following this, biomechanical methods were used to include, the development of an accurate anthropomorphic testing device (ATD) and a finite element model of an infant head, to investigate the differentiating variables and ultimately the clinical fall height threshold. Method A case control study of children ≤ 48 months of age who had a minor head injury and those with a skull fracture and / or ICI, to identify variables and characteristics of falls that influenced injury severity. Children were ascertained from those who attended the University Hospital of Wales Cardiff from a low height fall. The clinical characteristics and biomechanical variables evaluated included the mechanism of injury, surface of impact, site of impact and fall height (taking into consideration height of object and centre of gravity of the child’s body and head mass). Categorical variables were assessed using a Chi Square test and continuous variables using Student t-test or the non parametric equivalent. A modified logistic regression was used to evaluate the likelihood of sustaining a skull fracture and /or ICI based on fall height. Initially to investigate the differentiating variables a biofidelic infant headform was designed via image processing and segmentation of computed tomography (CT) datasets and manufactured using materials with similar properties to the bone and soft tissues of the head. The headform impact response was initially validated against infant cadaver data and then it was subject to tests classed as sub-injurious based on the clinical data collected from the hospital. The headform was dropped at impact angles of 90o, 75o and 60o at three velocities (2.4m/s, 3m/s, 3.4m/s) corresponding to three heights (0.3m, 0.45m, 0.6m), onto four domestic surfaces (carpet, carpet & underlay, laminate and wood) using two skin friction surrogates (latex, polyamide). A Student t-test was used to measure the affect of the coefficient of static friction and a three factorial ANOVA to measure the affect of impact velocity, surface type and angle of impact had on kinematic variables (peak g, HIC, rotational acceleration, change in rotational velocity and duration of impact). Finally to investigate the differentiating variables a finite element (FE) model of an infant head was developed, again through image processing of infant head CT datasets. The FE model consisted of the scalp, sutures, cranial bones, dura membranes, cerebral spinal fluid, bridging veins and the brain and the impact response was also initially validated against infant cadaver data. Post validation a parametric test across four different scenarios (0.3m impact onto the occipital, frontal, vertex and parietal areas of the head) was conducted to assess the affect material properties have on impacted response of the model. Finally the FE was used to assess the affect height (0.3m, 0.6m, 1.2m) and anatomical site of impact have on the impact response of the head, including kinematic variables and material response variables. Results Identified cases included 416 children with a minor head injury and 47 with a skull fracture and / or ICI. The mean fall height for minor head injuries was significantly lower than for a fall causing skull fracture and / or ICI (P<0.001). Utilising the height of centre of gravity of the head, no skull fracture and / or ICI was sustained in children who fell <0.6m (2ft). Skull fractures and / or ICI were more likely in children ≤12 months (P<0.001), following impacts to the temporal/parietal or occipital region of the head (P<0.01), and impacts onto wood (P<0.05). All tests using the biofidelic headform were conducted with impact velocities corresponding to fall heights ≤0.6m, where an increase in impact velocity, increase in surface stiffness and a decrease in impact angle significantly affected both rotational and translation kinematic variables (P<0.05). Peak rotational accelerations at 90 degrees were 11, 363 rad/s2 on wood at an impact velocity corresponding to a height of 0.6m and significantly increased to 16,980 rad/s2 with a 30 degree decrease in impact angle (P<0.001). However head injury criterion (HIC) decreased for wood at impact velocity corresponding to 0.6m from 245 to 121 for a 30degree decrease in impact angle (P<0.001). The parametric test using the finite element model indicated that the skull stiffness has the greatest affect on the dynamic response of the head, an increase in the skull stiffness of 7% increased HIC by 26%. Height and anatomical site of impact affected kinematic and material response variables. The mean value of peak G and HIC at the clinical defined threshold of 0.6m fall height was 85g and 284g, respectively. An increase in fall height to The stiffest parts of the head were the frontal areas and the least stiff were impacts focal to the sutures. Impacts focal to sutures indicated high stress zones on adjacent bones, for example an impact to the vertex indicated high stress zones on the left and right parietal bones. The greatest strain on the connectors used to model the bridging veins was at the most focal impact point, the vertex. For a 1.2m fall the greatest peak stretch ratio for a vertex impact was 1.31. Conclusion A threshold above which skull fracture and / or ICI of 0.6m was proposed. The corresponding mean values for peak g and HIC using the finite element models at a 0.6m fall corresponded well with current biomechanical thresholds for skull fracture, particularly the current National Highway Transport Safety Administration standard. This study highlights the importance of developing threshold specific to young children that are both clinically and biomechanically relevant. A clinical finding was that head injury severity was influence by anatomical site of impact. This was supported by the biomechanical analysis where skull fracture risk and strain on the bridging veins were both influenced by site of impact. The high stress on adjacent bones from a single impact focal to the sutures, suggest the potential for fracture on multiple cranial bones from a single point of impact. Whilst further research is required to validate fracture patterns, it highlights the potential for a bi-parietal fracture from a vertex impact

The Acute Effects of Weighted Vest Protocols on 20-Metre Sprint Performance in Youth Soccer Players

This investigation examined the effects of a warm-up containing weighted vest (WV) sprints on subsequent 20-metre sprint time relative to a control (C) condition in youth soccer players (n=12, mean ± SD age 16 ± 0.60 years, height 175.17 ± 5.92 cm and body mass 61.85 ± 5.88 kg). The main experimental trials consisted of three WV conditions at 10, 20 and 30% of body mass (WV10, WV20 and WV30) and C. Participants were required to complete one 20-metre sprint with each of WV conditions or without additional mass as part of C prior to a 20-metre sprint at 4-, 8- and 12-minutes. A two-way repeated measures ANOVA revealed no significant difference between any of the conditions and rest periods (p = >0.05). The between condition effect sizes for 20-metre sprint times were moderate at 4- and 12-minutes post WV10 (d = -0.86 and -1.15, respectively) and 12-minutes post WV20 (d = -0.84) and WV30 (d = -0.80). Moderate effect sizes were also observed at 4-minutes post WV10 (d = -1.04) and WV20 (d = -0.67) for 10-metre sprint times. These findings demonstrate that WV loading has no significant effect on 20-metre sprint time in youth soccer players. However, there is an opportunity for S&C coaches to implement WV warm-ups of no more than 30% body mass to improve 20-metre sprint times

Health and financial costs of adverse childhood experiences in 28 European countries: a systematic review and meta-analysis

Background Adverse childhood experiences (ACEs) are associated with increased health risks across the life course. We aimed to estimate the annual health and financial burden of ACEs for 28 European countries. Methods In this systematic review and meta-analysis, we searched MEDLINE, CINAHL, PsycINFO, Applied Social Sciences Index and Abstracts, Criminal Justice Databases, and Education Resources Information Center for quantitative studies (published Jan 1, 1990, to Sept 8, 2020) that reported prevalence of ACEs and risks of health outcomes associated with ACEs. Pooled relative risks were calculated for associations between ACEs and harmful alcohol use, smoking, illicit drug use, high body-mass index, depression, anxiety, interpersonal violence, cancer, type 2 diabetes, cardiovascular disease, stroke, and respiratory disease. Country-level ACE prevalence was calculated using available data. Country-level population attributable fractions (PAFs) due to ACEs were generated and applied to 2019 estimates of disability-adjusted life-years. Financial costs (US$in 2019) were estimated using an adapted human capital approach. Findings In most countries, interpersonal violence had the largest PAFs due to ACEs (range 14·7–53·5$0·1 billion (Montenegro) to $129·4 billion (Germany) and were equivalent to between 1·1% (Sweden and Turkey) and 6·0% (Ukraine) of nations’ gross domestic products. Interpretation Availability of ACE data varies widely between countries and country-level estimates cannot be directly compared. However, findings suggest ACEs are associated with major health and financial costs across European countries. The cost of not investing to prevent ACEs must be recognised, particularly as countries look to recover from the COVID-19 pandemic, which interrupted services and education, and potentially increased risk factors for ACEs

Social mobility across the lifecourse and DNA methylation age acceleration in adults in the UK

AbstractDisadvantaged socio-economic position (SEP) is associated with greater biological age, relative to chronological age, measured by DNA methylation (positive ‘age acceleration’, AA). Social mobility has been proposed to ameliorate health inequalities. This study aimed to understand the association of social mobility with positive AA. Diagonal reference modelling and ordinary least square regression techniques were applied to explore social mobility and four measures of age acceleration (first-generation: ‘Horvath’, ‘Hannum’ and second-generation: ‘Phenoage’, DunedinPoAm) in n = 3140 participants of the UK Household Longitudinal Study. Disadvantaged SEP in early life is associated with positive AA for three (Hannum, Phenoage and DunedinPoAm) of the four measures examined while the second generation biomarkers are associated with SEP in adulthood (p &lt; 0.01). Social mobility was associated with AA measured with Hannum only such that compared to no mobility, upward mobility was associated with greater age independently of origin and destination SEP. Compared to continuously advantaged groups, downward mobility was associated with positive Phenoage (1.06y [− 0.03, 2.14]) and DunedinPoAm assessed AA (0.96y [0.24, 1.68]). For these two measures, upward mobility was associated with negative AA (Phenoage, − 0.65y [− 1.30, − 0.002]; DunedinPoAm, − 0.96y [− 1.47, − 0.46]) compared to continually disadvantaged groups. While we find some support for three models of lifecourse epidemiology with early life as a sensitive period, SEP across the lifecourse and social mobility for age acceleration measured with DNA methylation, our findings suggest that disadvantaged SEP across the lifecourse is most consistently associated with positive AA.</jats:p

Application of an indoor air pollution metamodel to a spatially-distributed housing stock

Estimates of population air pollution exposure typically rely on the outdoor component only, and rarely account for populations spending the majority of their time indoors. Housing is an important modifier of air pollution exposure due to outdoor pollution infiltrating indoors, and the removal of indoor-sourced pollution through active or passive ventilation. Here, we describe the application of an indoor air pollution modelling tool to a spatially distributed housing stock model for England and Wales, developed from Energy Performance Certificate (EPC) data and containing information for approximately 11.5 million dwellings. First, we estimate indoor/outdoor (I/O) ratios and total indoor concentrations of outdoor air pollution for PM2.5 and NO2 for all EPC dwellings in London. The potential to estimate concentration from both indoor and outdoor sources is then demonstrated by modelling indoor background CO levels for England and Wales pre- and post-energy efficient adaptation, including heating, cooking, and smoking as internal sources. In London, we predict a median I/O ratio of 0.60 (99% CIs; 0.53–0.73) for outdoor PM2.5 and 0.41 (99%CIs; 0.34–0.59) for outdoor NO2; Pearson correlation analysis indicates a greater spatial modification of PM2.5 exposure by housing (ρ = 0.81) than NO2 (ρ = 0.88). For the demonstrative CO model, concentrations ranged from 0.4–9.9 ppm (99%CIs)(median = 3.0 ppm) in kitchens and 0.3–25.6 ppm (median = 6.4 ppm) in living rooms. Clusters of elevated indoor concentration are found in urban areas due to higher outdoor concentrations and smaller dwellings with reduced ventilation potential, with an estimated 17.6% increase in the number of living rooms and 63% increase in the number of kitchens exceeding recommended exposure levels following retrofit without additional ventilation. The model has the potential to rapidly calculate indoor pollution exposure across large housing stocks and estimate changes to exposure under different pollution or housing policy scenarios

Treatment outcomes 24 months after initiating short, all-oral bedaquiline-containing or injectable-containing rifampicin-resistant tuberculosis treatment regimens in South Africa : a retrospective cohort study

DATA SHARING : The data used for this analysis in the form of deidentified participant data and a data dictionary will be made available after publication. Investigators wishing to access these data will need to have an approved research proposal and complete a data access agreement. All inquiries should be sent to the corresponding author ([email protected] or [email protected]).SUPPLEMENTARY MATERIAL 1 : French translation of the abstract. SUPPLEMENTARY MATERIAL 2 : Appendices.BACKGROUND : There is a need for short and safe all-oral treatment of rifampicin-resistant tuberculosis. We compared outcomes up to 24 months after treatment initiation for patients with rifampicin-resistant tuberculosis in South Africa treated with a short, all-oral bedaquiline-containing regimen (bedaquiline group), or a short, injectable-containing regimen (injectable group). METHODS : Patients with rifampicin-resistant tuberculosis, aged 18 years or older, eligible for a short regimen starting treatment between Jan 1 and Dec 31, 2017, with a bedaquiline-containing or WHO recommended injectable-containing treatment regimen of 9–12 months, registered in the drug-resistant tuberculosis database (EDRWeb), and with known age, sex, HIV status, and national identification number were eligible for study inclusion; patients receiving linezolid, carbapenems, terizidone or cycloserine, delamanid, or para-aminosalicylic acid were excluded. Bedaquiline was given at a dose of 400 mg once daily for two weeks followed by 200 mg three times a week for 22 weeks. To compare regimens, patients were exactly matched on HIV and ART status, previous tuberculosis treatment history, and baseline acid-fast bacilli smear and culture result, while propensity score matched on age, sex, province of treatment, and isoniazid-susceptibility status. We did binomial linear regression to estimate adjusted risk differences (aRD) and 95% CIs for 24-month outcomes, which included: treatment success (ie, cure or treatment completion without evidence of recurrence) versus all other outcomes, survival versus death, disease free survival versus survival with treatment failure or recurrence, and loss to follow-up versus all other outcomes. FINDINGS : Overall, 1387 (14%) of 10152 patients with rifampicin-resistant tuberculosis treated during 2017 met inclusion criteria; 688 in the bedaquiline group and 699 in the injectable group. Four patients (1%) had treatment failure or recurrence, 44 (6%) were lost to follow-up, and 162 (24%) died in the bedaquiline group, compared with 17 (2%), 87 (12%), and 199 (28%), respectively, in the injectable group. In adjusted analyses, treatment success was 14% (95% CI 8–20) higher in the bedaquiline group than in the injectable group (70% vs 57%); loss to follow-up was 4% (1–8) lower in the bedaquiline group (6% vs 12%); and disease-free survival was 2% (0–5) higher in the bedaquiline group (99% vs 97%). The bedaquiline group had 8% (4–11) lower risk of mortality during treatment (17·0% vs 22·4%), but there was no difference in mortality post-treatment. INTERPRETATION : Patients in the bedaquiline group experienced significantly higher rates of treatment success at 24 months. This finding supports the use of short bedaquiline-containing regimens in eligible patients.WHO Global TB Programme.http://www.thelancet.com/infectionhj2023Medical Microbiolog

Assessing uncertainty in housing stock infiltration rates and associated heat loss: English and UK case studies

Strategies to reduce domestic heating loads by minimizing the infiltration of cold air through adventitious openings located in the thermal envelopes of houses are highlighted by the building codes of many countries. Consequent reductions of energy demand and CO2e emission are often unquantified by empirical evidence. Instead, a mean heating season infiltration rate is commonly inferred from an air leakage rate using a simple ratio scaled to account for the physical and environmental properties of a dwelling. The scaling does not take account of the permeability of party walls in conjoined dwellings and so cannot differentiate between the infiltration of unconditioned ambient air that requires heating, and conditioned air from adjacent dwellings that does not. A stochastic method is presented that applies a theoretical model of adventitious infiltration to predict distributions of mean infiltration rates and the associated total heat loss in any stock of dwellings during heating hours. The method is applied to the English and UK housing stocks and provides probability distribution functions of stock infiltration rates and total heat loss during the heating season for two extremes of party wall permeability. The distributions predict that up to 79% of the current English stock could require additional purpose-provided ventilation to limit negative health consequences. National models predict that fewer dwellings are under-ventilated. The distributions are also used to predict that infiltration is responsible for 3–5% of total UK energy demand, 11–15% of UK housing stock energy demand, and 10–14% of UK housing stock carbon emissions