Cesarean delivery is associated with lower neonatal mortality among breech pregnancies: a systematic review and meta-analysis of preterm deliveries ≤32 weeks of gestation.

OBJECTIVE: To investigate the association between actual and planned modes of delivery, neonatal mortality, and short-term outcomes among preterm pregnancies ≤32 weeks of gestation. DATA SOURCES: A systematic literature search was conducted in 3 main databases (PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials from inception to November 16, 2022. The protocol was registered in advance in the International Prospective Register of Systematic Reviews (CRD42022377870). STUDY ELIGIBILITY CRITERIA: Eligible studies examined pregnancies ≤32nd gestational week. All infants received active care, and the outcomes were reported separately by different modes of delivery. Singleton and twin pregnancies at vertex and breech presentations were included. Studies that included pregnancies complicated with preeclampsia and abruptio placentae were excluded. Primary outcomes were neonatal mortality and intraventricular hemorrhage. STUDY APPRAISAL AND SYNTHESIS METHODS: Articles were selected by title, abstract, and full text, and disagreements were resolved by consensus. Random effects model-based odds ratios with corresponding 95% confidence intervals were calculated for dichotomous outcomes. Risk Of Bias In Non-randomized Studies - of Interventions-I was used to assess the risk of bias. RESULTS: A total of 19 observational studies were included involving a total of 16,042 preterm infants in this systematic review and meta-analysis. Actual cesarean delivery improves survival (odds ratio, 0.62; 95% confidence interval, 0.42-0.9) and decreases the incidence of intraventricular hemorrhage (odds ratio, 0.70; confidence interval, 0.57-0.85) compared to vaginal delivery. Planned cesarean delivery does not improve the survival of very and extremely preterm infants compared to vaginal delivery (odds ratio, 0.87; 95% confidence interval, 0.53-1.44). Subset analysis found significantly lower odds of death for singleton breech preterm deliveries born by both planned (odds ratio, 0.56; 95% confidence interval, 0.32-0.98) and actual (odds ratio, 0.34; 95% confidence interval, 0.13-0.88) cesarean delivery. CONCLUSION: Cesarean delivery should be the mode of delivery for preterm ≤32 weeks of gestation breech births due to the higher mortality in preterm infants born via vaginal delivery.

Cyclic testing of standalone ALIF versus TLIF in lumbosacral spines of low bone mineral density: an ex vivo biomechanical study.

PURPOSE: Screwed anterior lumbar interbody fusion (SALIF) alleviates the need for supplemental posterior fixation leading to reduction of perioperative morbidity. Specifically, elderly and multimorbid patients would benefit from shorter operative time and faster recovery but tend to have low bone mineral density (BMD). The current study aimed to compare loosening, defined as increase of ROM and NZ, of SALIF versus transforaminal lumbar interbody fusion (TLIF) under cyclic loading in cadaveric spines with reduced BMD. METHODS: Twelve human spines (L4-S2; 6 male 6 female donors; age 70.6 ± 19.6; trabecular BMD of L5 84.2 ± 24.4 mgHA/cm3, range 51-119 mgHA/cm3) were assigned to two groups. SALIF or TLIF were instrumented at L5/S1. Range of motion (ROM) and neutral zone (NZ) were assessed before and after axial cyclic loading (0-1150 N, 2000 cycles, 0.5 Hz) in flexion-extension (Flex-Ext), lateral bending, (LB), axial rotation (AR). RESULTS: ROM of the SALIF specimens increased significantly in all loading directions (p ≤ 0.041), except for left AR (p = 0.053), whereas for TLIF it increased significantly in left LB (p = 0.033) and Flex (p = 0.015). NZ of SALIF showed increase in Flex-Ext and LB, whereas NZ of TLIF did not increase significantly in any motion direction. CONCLUSIONS: Axial compression loading caused loosening of SALIF in Flex-Ext and LB, but not TLIF at L5/S1 in low BMD specimens. Nevertheless, Post-cyclic ROM and NZ of SALIF is comparable to TLIF. This suggests that, neither construct is optimal for the use in patients with reduced BMD.

Atrial Arrhythmia and Bradycardia as a Presentation of Congenital Long QT Syndrome.

We present a term newborn with atrial arrhythmia on the first day of life (DOL). An echocardiogram showed normal structure and normal function; laboratory testing showed normal electrolytes and thyroid function. After initiation of flecainide, the EKG on DOL 2 showed significant and increasing bradycardia with atrial arrhythmia and extremely prolonged QTc interval. Flecainide was stopped and esmolol started. After 6 h of treatment, atrial tachycardia was suppressed, and the rhythm converted to sinus. Genetic testing found variants of unknown significance in the ALPK3 gene and KCNQ1 gene, which has been associated with long QT syndrome (LQTs). LQTs in infants can present as bradycardia, 2:1 AV block, or torsades de pointes. Our review of the literature found only one other case report of atrial arrhythmia in a newborn with congenital LQTs. Diagnosis of LQTs via EKG alone is difficult in neonates since the ST segment and T wave on the first DOL are usually flattened, making correct measurement of the QTc interval difficult. ß-blockers, the first line of treatment for LQTs, are known to shorten QTc intervals and prevent arrhythmia events. As in our patient, ß-blockers may be helpful for atrial arrhythmia prevention in patients with adrenergically mediated atrial tachycardia. In conclusion, atrial arrhythmia with bradycardia can be a presentation of congenital LQTs and be difficult to recognize. For neonates with this presentation with no evidence of myocarditis, congenital heart disease, or significant respiratory illness, genetic congenital LQTs should be highly suspected, especially when associated with low resting heart rates.

Biomechanical Behavior of Injected Cement Spacers versus Traditional Cages in Low-Density Lumbar Spine under Compression Loading.

Background and Objectives: Osteoporosis renders the use of traditional interbody cages potentially dangerous given the high risk of damage in the bone-implant interface. Instead, injected cement spacers can be applied as interbody devices; however, this technique has been mainly used in cervical spine surgery. This study aimed at investigating the biomechanical behavior of cement spacers versus traditional cages in lumbar spine surgery. Materials and Methods: Destructive monotonic axial compression testing was performed on 20 human cadaveric low-density lumbar segments from elderly donors (14 f/6 m, 70.3 ± 12.0 y) treated with either injected cement spacers (n = 10) or traditional cages (n = 10) without posterior instrumentation. Stiffness, failure load and displacement were compared. The effects of bone density, vertebral geometry and spacer contact area were evaluated. Results: Cement spacers demonstrated higher stiffness, significantly smaller displacement (p < 0.001) and a similar failure load compared to traditional cages. In the cage group, stiffness and failure load depended strongly on bone density and vertebral height, whereas failure displacement depended on vertebral anterior height. No such correlations were identified with cement spacers. Conclusions: Cement spacers used in lumbar interbody stabilization provided similar compression strength, significantly smaller failure displacement and a stiffer construct than traditional cages that provided benefits mainly for large and strong vertebrae. Cement stabilization was less sensitive to density and could be more beneficial also for segments with smaller and less dense vertebrae. In contrast to the injection of cement spacers, the optimal insertion of cages into the irregular intervertebral space is challenging and risks damaging bone. Further studies are required to corroborate these findings and the treatment selection thresholds.

Longitudinal CT-based finite element analyses provide objective fracture healing measures in an ovine tibia model.

Measuring the healing status of a bone fracture is important to determine the clinical care a patient receives. Implantable devices can directly and continuously assess the healing status of fracture fixation constructs, while subject-specific virtual biomechanical tests can noninvasively determine callus structural integrity at single time points. Despite their potential for objectification, both methods are not yet integrated into clinical practice with further evidence of their benefits required. This study correlated continuous data from an implantable sensor assessing healing status through implant load monitoring with computer tomography (CT) based longitudinal finite element (FE) simulations in a large animal model. Eight sheep were part of a previous preclinical study utilizing a tibial osteotomy model and equipped with such a sensor. Sensor signal was collected over several months, and CT scans were acquired at six interim time points. For each scan, two FE analyses were performed: a virtual torsional rigidity test of the bone and a model of the bone-implant construct with the sensor. The longitudinal simulation results were compared to the sensor data at corresponding time points and a cohort-specific empirical healing rule was employed. Healing status predicted by both in silico simulations correlated significantly with the sensor data at corresponding time points and correctly identified a delayed and a nonunion in the cohort. The methodology is readily translatable with the potential to be applied to further preclinical or clinical cohorts to find generalizable healing criteria. Virtual mechanical tests can objectively measure fracture healing progressing using longitudinal CT scans.

Homogenized finite element simulations can predict the primary stability of dental implants in human jawbone.

Adequate primary stability is a pre-requisite for the osseointegration and long-term success of dental implants. Primary stability depends essentially on the bone mechanical integrity at the implantation site. Clinically, a qualitative evaluation can be made on medical images, but finite element (FE) simulations can assess the primary stability of a bone-implant construct quantitatively based on high-resolution CT images. However, FE models lack experimental validation on clinically relevant bone anatomy. The aim of this study is to validate such an FE model on human jawbones. Forty-seven bone biopsies were extracted from human cadaveric jawbones. Dental implants of two sizes (Ø3.5 mm and Ø4.0 mm) were inserted and the constructs were subjected to a quasi-static bending-compression loading protocol. Those mechanical tests were replicated with sample-specific non-linear homogenized FE models. Bone was modeled with an elastoplastic constitutive law that included damage. Density-based material properties were mapped based on µCT images of the bone samples. The experimental ultimate load was better predicted by FE (R2 = 0.83) than by peri-implant bone density (R2 = 0.54). Unlike bone density, the simulations were also able to capture the effect of implant diameter. The primary stability of a dental implant in human jawbones can be predicted quantitatively with FE simulations. This method may be used for improving the design and insertion protocols of dental implants.

The biomechanical effect of lumbopelvic distance reduction on reconstruction after total sacrectomy: a comparative finite element analysis of four techniques.

BACKGROUND CONTEXT: Following total sacrectomy, lumbopelvic reconstruction is essential to restore continuity between the lumbar spine and pelvis. However, to achieve long-term clinical stability, bony fusion between the lumbar spine and the pelvic ring is crucial. Reduction of the lumbopelvic distance can promote successful bony fusion. Although many lumbopelvic reconstruction techniques (LPRTs) have been previously analyzed, the biomechanical effect of lumbopelvic distance reduction (LPDR) has not been investigated yet. PURPOSE: To evaluate and compare the biomechanical characteristics of four different LPRTs while considering the effect of LPDR. STUDY DESIGN/SETTING: A comparative finite element (FE) study. METHODS: The FE models following total sacrectomy were developed to analyze four different LPRTs, with and without LPDR. The closed-loop reconstruction (CLR), the sacral-rod reconstruction (SRR), the four-rod reconstruction (FRR), and the improved compound reconstruction (ICR) techniques were analyzed in flexion, extension, lateral bending, and axial rotation. Lumbopelvic stability was assessed through the shift-down displacement and the relative sagittal rotation of L5, while implant safety was evaluated based on the stress state at the bone-implant interface and within the rods. RESULTS: Regardless of LPDR, both the shift-down displacement and relative sagittal rotation of L5 consistently ranked the LPRTs as ICR

Development of an in vitro biofilm model of the human supra-gingival microbiome for Oral microbiome transplantation.

The high prevalence of dental caries and periodontal disease place a significant burden on society, both socially and economically. Recent advances in genomic technologies have linked both diseases to shifts in the oral microbiota - a community of >700 bacterial species that live within the mouth. The development of oral microbiome transplantation draws on the success of fecal microbiome transplantation for the treatment of gut pathologies associated with disease. Many current in vitro oral biofilm models have been developed but do not fully capture the complexity of the oral microbiome which is required for successful OMT. To address this, we developed an in vitro biofilm system that maintained an oral microbiome with 252 species on average over 14 days. Six human plaque samples were grown in 3D printed flow cells on hydroxyapatite discs using artificial saliva medium (ASM). Biofilm composition and growth were monitored by high throughput sequencing and confocal microscopy/SEM, respectively. While a significant drop in bacterial diversity occurred, up to 291 species were maintained in some flow cells over 14 days with 70% viability grown with ASM. This novel in vitro biofilm model represents a marked improvement on existing oral biofilm systems and provides new opportunities to develop oral microbiome transplant therapies.

Beyond the Gut: A Systematic Review and Meta-analysis of Advanced Therapies for Inflammatory Bowel Disease-associated Extraintestinal Manifestations.

BACKGROUND AND AIMS: Extraintestinal manifestations are frequent in patients with inflammatory bowel disease and have a negative impact on quality of life. Currently, however, there is no evidence available to determine which drug should be recommended for these patients beyond anti-tumour necrosis factor [anti-TNF] treatment. We aimed to analyse the frequency of new extraintestinal manifestations and the behaviour of pre-existing extraintestinal manifestations during advanced therapy. METHODS: We conducted a systematic search on November 15, 2022, and enrolled randomized controlled trials, cohorts, and case series reporting the occurrence and behaviour of extraintestinal manifestations in patients with inflammatory bowel disease receiving advanced therapy [non-TNF inhibitor biologicals and JAK inhibitors]. Proportions of new, recurring, worsening, and improving extraintestinal manifestations were calculated with 95% confidence intervals [CIs]. The risk of bias was assessed with the QUIPS tool. RESULTS: Altogether, 61 studies comprising 13,806 patients reported eligible data on extraintestinal manifestations. The overall proportion of new extraintestinal manifestations was 8% [95% CI, 6-12%] during advanced therapy. There was no significant difference between the frequency of new extraintestinal manifestations during vedolizumab and ustekinumab therapy [11%, 95% CI, 8-15% vs 6%, 95% CI, 3-11%, p = 0.166]. The improvement of pre-existing manifestations was comparable between vedolizumab- and ustekinumab-treated patients, except for joint involvement [42%, 95% CI, 32-53% vs 54%, 95% CI, 42-65%, p = 0.029]. CONCLUSION: The proportion of new extraintestinal manifestations was low during advanced therapy. Furthermore, the improvement of pre-existing manifestations was comparable between advanced therapies, except for pre-existing joint manifestations.

On the importance of accurate elasto-plastic material properties in simulating plate osteosynthesis failure.

Background: Plate osteosynthesis is a widely used technique for bone fracture fixation; however, complications such as plate bending remain a significant clinical concern. A better understanding of the failure mechanisms behind plate osteosynthesis is crucial for improving treatment outcomes. This study aimed to develop finite element (FE) models to predict plate bending failure and validate these against in vitro experiments using literature-based and experimentally determined implant material properties. Methods: Plate fixations of seven cadaveric tibia shaft fractures were tested to failure in a biomechanical setup with various implant configurations. FE models of the bone-implant constructs were developed from computed tomography (CT) scans. Elasto-plastic implant material properties were assigned using either literature data or the experimentally derived data. The predictive capability of these two FE modelling approaches was assessed based on the experimental ground truth. Results: The FE simulations provided quantitatively correct prediction of the in vitro cadaveric experiments in terms of construct stiffness [concordance correlation coefficient (CCC) = 0.97, standard error of estimate (SEE) = 23.66, relative standard error (RSE) = 10.3%], yield load (CCC = 0.97, SEE = 41.21N, RSE = 7.7%), and maximum force (CCC = 0.96, SEE = 35.04, RSE = 9.3%), when including the experimentally determined material properties. Literature-based properties led to inferior accuracies for both stiffness (CCC = 0.92, SEE = 27.62, RSE = 19.6%), yield load (CCC = 0.83, SEE = 46.53N, RSE = 21.4%), and maximum force (CCC = 0.86, SEE = 57.71, RSE = 14.4%). Conclusion: The validated FE model allows for accurate prediction of plate osteosynthesis construct behaviour beyond the elastic regime but only when using experimentally determined implant material properties. Literature-based material properties led to inferior predictability. These validated models have the potential to be utilized for assessing the loads leading to plastic deformation in vivo, as well as aiding in preoperative planning and postoperative rehabilitation protocols.

Individual differences in scientists' aesthetic disposition, aesthetic experiences, and aesthetic sensitivity in scientific work.

Introduction: The role of personality in shaping engagement with aesthetics in science has been almost entirely unexplored. Whereas artists and arts settings (e.g., museums) are well-studied from a psychological perspective, the practice of science has often been seen as purely rational or dry. In response, this study presents novel findings on the critical role of scientists' individual differences, which shape their engagement with aesthetics, such as the frequency of their experiences of beauty, wonder, and awe in their scientific work. Methods: Based on a very large and representative four-country study of scientists in the fields of biology and physics (N = 3,092), this study analyzed the associations of Big Five personality traits among scientists with (i) dispositional aesthetics (DPES-awe), (ii) the frequency of aesthetic experiences in scientific work, and (iii) aesthetic sensitivity in science. These survey-weighted OLS regression models included extensive statistical controls for sociodemographic factors. Results: As hypothesized, openness is positively, and neuroticism is negatively linked with dispositional aesthetics, the frequency of aesthetic experiences in scientific work, and aesthetic sensitivity in science. Unexpectedly, agreeableness and conscientiousness (but not extraversion) are highly significant and strong predictors of the three trait and state aesthetic engagement variables. Discussion: The aesthetic engagement and personality framework of this paper is empirically supported and demonstrates the importance of personality types of scientists in the practice of science. The unexpectedly strong association of agreeableness with aesthetic engagement points to the importance of cooperation, collaboration, and communication to maximize scientific creativity.