Variability in Body Shape, Superficial Soft Tissue Geometry, and Seatbelt Fit Relative to the Pelvis in Automotive Postures-Methods for Volunteer Data Collection With Open Magnetic Resonance Imaging

Variability in body shape and soft tissue geometry have the potential to affect the body's interaction with automotive safety systems. In this study, we developed a methodology to capture information on body shape, superficial soft tissue geometry, skeletal geometry, and seatbelt fit relative to the skeleton-in automotive postures-using Open Magnetic Resonance Imaging (MRI). Volunteer posture and belt fit were first measured in a vehicle and then reproduced in a custom MRI-safe seat (with an MR-visible seatbelt) placed in an Open MR scanner. Overlapping scans were performed to create registered three-dimensional reconstructions spanning from the thigh to the clavicles. Data were collected with ten volunteers (5 female, 5 male), each in their self-selected driving posture and in a reclined posture. Examination of the MRIs showed that in the males with substantial anterior abdominal adipose tissue, the abdominal adipose tissue tended to overhang the pelvis, narrowing in the region of the Anterior Superior Iliac Spine (ASIS). For the females, the adipose tissue depth around the lower abdomen and pelvis was more uniform, with a more continuous layer superficial to the ASIS. Across the volunteers, the pelvis rotated rearward by an average of 62% of the change in seatback angle during recline. In some cases, the lap belt drew nearer to the pelvis as the volunteer reclined (as the overhanging folds of adipose tissue stretched). In others, the belt-to-pelvis distance increased as the volunteer reclined. These observations highlight the importance of considering both interdemographic and intrademographic variability when developing tools to assess safety system robustness.

Comparison of thoracolumbar spine kinematics and injuries in reclined frontal impact sled tests between mid-size adult female and male PMHS

Disparities in injury tolerance and kinematic response remain understudied despite field data highlighting sex-based differences in injury risk. Furthermore, the automotive industry anticipates occupants will prefer reclined seating in highly automated vehicles. This study aimed to compare thoracolumbar spine kinematics and injuries between mid-size female and male post-mortem human subjects (PMHS) in reclined frontal impacts. Seven adult PMHS (three female, four male) were tested in reclined (50°) 50 km/h frontal impacts. The PMHS were seated on a semi-rigid seat and restrained by a prototype three-point seat belt system designed to mitigate submarining. The 3-D motions of five vertebrae and the pelvis were measured by an optical motion tracking system. Pressure transducers were inserted into intervertebral discs at three locations along the lumbar spine to track timing of lumbar vertebra fractures. Due to variations in the geometry of the pelvis and soft tissue surrounding the pelvis compared to the male subjects, the female subjects could not be positioned in the seat the same as the males, and, as a result, the females and their belt anchors needed to be translated forward in the seat to maintain similar belt geometry relative to the males. The females exhibited similar pre-test spinal curvatures and kinematics to the males. An L1 fracture was observed in one of three female subjects and two of four male subjects, and timing of these fractures were both similar (61 ∼ 65 ms) and close to the time of peak downward seat force. Generally, the female and male subjects exhibited similar kinematic and injury responses in this reclined frontal impact sled test condition.

The Effects of Recline Angle and Restraint Geometry on Lap Belt-Pelvis Interaction for Above-Normal BMI Motor Vehicle Occupants

The interaction of the three-point seat belt with the occupant, particularly the lap belt with the pelvis, is affected by a multitude of intrinsic and extrinsic factors, including the torso recline angle, lap belt angle, and occupant body mass index (BMI). While field data analyses have shown the strong safety benefit for seat belt use regardless of occupant size or crash direction, the term "submarining" historically has been used to describe a scenario in which the lap belt loads the abdominal soft tissue and organs, superior and posterior to the pelvic bone. While contemporary restraint systems work to effectively address the risk of submarining in occupants properly seated and properly belted, scenarios in which the lap belt may not properly engage the load-bearing pelvis remain. These scenarios, including a reclined torso angle or shallow lap belt angle, require further study. In this research study, eight non-injurious seated belt pull tests were conducted on two constrained whole-body cadavers of above-normal BMI (≥ 25 kg/m2) with controlled variation of torso and lap belt-pelvis angles. Test factors affecting belt engagement with the pelvis were identified for each subject. Belt engagement was largely affected by the initial placement of the lap belt. The initial belt placement was affected by the torso angle which influenced the distribution of the abdominal soft tissue. The belt disengagement thresholds differed between subjects due to the inter-subject differences in soft tissue distribution, which affected the lap belt kinematics relative to the pelvis. In addition to improving the understanding of this particular submarining mechanism, this study provides a dataset for future validation of human body model soft tissue deformation response from lap belt loading.

Seat Belt Use in the US by Pregnant Motor Vehicle Occupants

This cross-sectional study assesses patterns of seat belt use among pregnant, nonpregnant, and male occupants.

Development of an Injury Risk Function for the Anterior Pelvis Under Frontal Lap Belt Loading Conditions

Iliac wing fractures due to lap belt loading have been identified in laboratory tests for almost 50 years and an analysis of recent data suggests these injuries are also occurring in the field. With the introduction of highly autonomous vehicles on the horizon, vehicle manufacturers are exploring open cabin concepts that permit reclined postures and separation of the occupant from the knee bolster and instrument panel. This will result in greater reliance on the lap belt and lap belt/pelvis loading to restrain occupants. No injury criteria exist for iliac wing fractures resulting from lap belt loading like that seen in frontal crash conditions. This study tested the tolerance of isolated iliac wings in a controlled lap belt-like loading environment while incorporating the effect of loading angle after analyzing lap belt loading experiments from a previous study. Twenty-two iliac wings were tested; nineteen of them sustained fracture (exact), but the loading input was insufficient to cause fracture in the other three (right censored). The fracture tolerance of the tested specimens ranged widely (1463-8895 N) and averaged 4091 N (SD 2381 N). Injury risk functions were created by fitting Weibull survival models to data that integrated censored and exact failure observations.

Effect of axial compression on stiffness and deformation of human lumbar spine in flexion-extension

OBJECTIVE

The goal of this study was to evaluate the effect of axial compression, employed with a follower-load mechanism, on the response of the lumbar spine in flexion and extension bending. Additional goals include measurement of both the kinetic (stiffness) and kinematic (deformation distribution) responses, evaluating how the responses vary across specimens, and to develop response corridors that can be used to evaluate human body models (HBMs) and anthropomorphic test devices (ATDs).

METHODS

Seven mid-sized male adult lumbar spines (T12-S1) from postmortem human surrogates were tested in subinjurious flexion and extension bending with 0, 900, and 1800 N of superimposed axial compression. Tests were performed in load-control with a 6-DOF robotic test system that applied pure flexion and extension moments to the specimens, and axial compression was directed along the spine's curvature via a follower load mechanism powered by force-controlled linear actuators. Load-deformation response data were captured and used to characterize the kinetic response of the lumbar spine in flexion/extension, and how it varies with axial compression. Individual vertebral kinematics were captured using 3D motion capture and the data was used to illustrate the distribution of bending deformation across each intervertebral joint of the spine, as well has how that distribution changes with axial compression. These response data were used to develop elliptical path-length parameterized response corridors for surrogate biofidelity evaluation.

RESULTS

The lumbar spine was found to be generally stiffer in extension than in flexion, but this difference decreased with increasing axial compression. The lumbar spine exhibited a nonlinear kinetic (moment vs. angle) response in flexion that became more linear and stiffer with the addition of axial compression. In flexion without axial load, the majority of the bending deformation occurred at the L5-S1 joint, whereas in extension, deformation was more evenly distributed across the different intervertebral levels, but the locus of deformation was located in the mid-proximal lumbar at L2-L3.

CONCLUSIONS

The superposition of axial compression in the lumbar spine affects the kinetic and kinematic response of the lumbar spine in flexion and extension. The response data and approach detailed in this study permit better assessment of ATD and HBM biofidelity.

Investigation of factors influencing submarining mitigation with child booster seats

OBJECTIVE

Automobile booster seats are intended to improve belt fit for children that are too large for a harness-style child restraint, but not yet big enough to fit properly in an adult seat belt. Our objective was to prospectively study the relationship between booster seat design and interaction with the seat belt (specifically, submarining risk) for a child occupant using computer simulation of automobile crash events.

METHODS

Frontal-impact simulations were performed with a 6-year-old child human body model. Simplified models of booster seats were developed using an automated process designed to capture key characteristics of booster geometry, stiffness, belt guide construction, and attachment to the vehicle seat. The child model was positioned in a range of postures from upright to slouched. Our main interest was submarining, where the child's pelvis slips under the lap belt and the belt loads into the abdomen (defined based on the motion of the lower lap belt edge relative to the ASIS).

RESULTS

Among the parameters studied, the factors that had the greatest effect on submarining risk were the booster's stiffness and the child's posture. Booster models of a low-stiffness construction (similar to an inflatable booster) nearly always resulted in submarining, regardless of the other design characteristics of the booster. A slouched posture also substantially increased the likelihood of submarining (even for high-stiffness boosters).

CONCLUSIONS

These results suggest that booster seats of a stiffer construction, and booster seats that promote an upright posture may provide a protective benefit compared to softer boosters and boosters that are more likely to result in slouching of the child.

Residual inflammatory risk appeared related to weight, atherogenic lipid profile and biomarkers of inflammation, but not to glycaemic control in type 1 diabetes

Background

Mortality associated with atherosclerotic cardiovascular disease reduces average life expectancy by more than a decade in type 1 diabetes. Systemic inflammation drives atherosclerosis, and the concept of residual inflammatory risk (defined by high-sensitivity C-reactive protein (hsCRP) ≥2 mg/l) poses a potential, new therapeutic target for lowering residual cardiovascular risk in type 1 diabetes. However, the characteristics of individuals with residual inflammatory risk in type 1 diabetes are unknown.

Purpose

Identify differences in relevant demographics, clinical and paraclinical parameters for individuals with residual inflammatory risk as compared to those without in type 1 diabetes.

Methods

Baseline characteristics as stratified for CRP ≥2 mg/l were analysed in 105 patients with type 1 diabetes participating in a previously published clinical trial. The study population was sampled to represent the broad background population struggling with glycaemic control and with a high cardiovascular risk.

Results

Residual inflammatory risk was seen in 39.1% of the study population. Compared to individuals without residual inflammatory risk, individuals with residual inflammatory risk were more frequently women, had increased body weight, body mass index and dual-energy X-ray absorptiometry (DXA)-assessed fat mass and exhibited elevated levels of low-density lipoprotein (LDL), very low-density lipoprotein (VLDL) and total cholesterol as well as triglycerides, interleukin 6 and tumour necrosis factor alpha (Table 1). Glycated haemoglobin, blood pressure and markers of renal function were similar between groups (Table 1).

Conclusion

In the present cohort of individuals with type 1 diabetes, residual inflammatory risk was seen in 39.1% (similar to what is observed outside of type 1 diabetes) and appeared related to overweight/obesity, an atherogenic lipid profile and circulating biomarkers of inflammation but not to glycaemic control, blood pressure or renal function.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): AstraZenecaHerlev Gentofte Hospital

A Review of Finite Element Models of Ligaments in the Foot and Considerations for Practical Application

PURPOSE

Finite element (FE) modeling has been used as a research tool for investigating underlying ligaments biomechanics and orthopedic applications. However, FE models of the ligament in the foot have been developed with various configurations, mainly due to their complex 3D geometry, material properties, and boundary conditions. Therefore, the purpose of this review was to summarize the current state of finite element modeling approaches that have been used in the ?eld of ligament biomechanics, to discuss their applicability to foot ligament modeling in a practical setting, and also to acknowledge current limitations and challenges.

METHODS

A comprehensive literature search was performed. Each article was analyzed in terms of the methods used for: (a) ligament geometry, (b) material property, (c) boundary and loading condition related to its application, and (d) model verification and validation.

RESULTS

Of the reviewed studies, 80% of the studies used simplified representations of ligament geometry, the non-linear mechanical behavior of ligaments was taken into account in only 19.2% of the studies, 33% of included studies did not include any kind of validation of the FE model.

CONCLUSION

Further refinement in the functional modeling of ligaments, the micro-structure level characteristics, nonlinearity, and time-dependent response, may be warranted to ensure the predictive ability of the models.

Methodology to measure seat belt fit in relation to skeletal geometry using an upright open MRI

OBJECTIVE

Poor seat belt fit can result in submarining behavior and injuries to the lower extremity and abdomen. While previous studies have explored seat belt fit relative to skeletal landmarks using palpation, medical imaging remains the gold standard for visualizing and locating skeletal landmarks and soft tissues. The goal of this study was to create a method to image automotive postures and seat belt fit from the pelvis to the clavicle using an Upright Open MRI.

METHODS

The posture and belt fit of 10 volunteers (5M, 5F) were measured in an Acura TLX in each subject's preferred driving posture and a standard reclined posture, and then reproduced in a custom non-ferromagnetic seat replica in the MR scanner with an MRI-visible seat belt. The MRI sequence and coil placement were designed to yield clear visualization of bone, soft tissue borders, and the seat belt markers in separate scans of the pelvis, lumbar, thoracolumbar, and thoracic regions. A process was developed to precisely register the scans, and methods for digitizing spinal and pelvic landmarks were established to quantify belt fit.

CONCLUSIONS

This method creates opportunities to study variation in seat belt fit in different automotive postures, for occupants of different sexes, ages, BMIs, anthropometries, and for pregnant occupants.

Evaluation of a diverse population of morphed human body models for prediction of vehicle occupant crash kinematics

Morphing can be used to alter human body models (HBMs) to represent a diverse population of occupants in car crashes. The mid-sized male SAFER HBM v9 was parametrically morphed to match 22 Post Mortem Human Subjects, loaded in different configurations. Kinetics and kinematics were compared for the morphed and baseline HBMs. In frontal impacts, the morphed HBMs correlated closer with the kinematics of obese subjects, but lower to small females. In lateral impacts HBM responses were too stiff. This study outlines a necessary evaluation of all HBMs that should be morphed to represent the diverse population in vehicle safety evaluations.

Complementing femur model validation with a variability-focused approach

OBJECTIVE

This short communication presents an approach as an objective means to validate that population variability is potentially incorporated into human body models in an accurate way, complementing existing validation techniques based on individual experiment-simulation comparison. This shall provide a further option for the assessment of the quality of large-number statistical simulations with human body models regarding their biofidelic behavior.

METHODS

This population-based approach uses mathematical clustering methods to group similar curves of a combined population of numerical simulation results and experimental curves together. The resulting clusters can be used to assess the biofidelic behavior of numerical simulations, also with characteristics substantially differing from the experimental objects. This developed population-based approach was tested on a reference load case, the dynamic 3-point bending of the femur (Forman et al. 2012).

RESULTS

The clustering approach rendered a distinction into 4 groups of response curves. For this small number, the grouping can be manually assessed as plausible. All experimental, and most numerical responses were grouped into one cluster. Three result curves constitute a cluster of their own, with their meta-data ranking on the margins of the population in at least one of the crucial biomechanical parameters. Such a result can be considered in accordance with the included experimental and anthropometric data.

CONCLUSIONS

The feasibility of using such a cluster analysis without individual comparisons is demonstrated on a small set of results. It is used to judge whether a finite element model including aspects of the variation in a population is in agreement with experimental and anthropometric data. For experiments as the femur bending addressed here, it is of high importance to firstly ensure a gross match of curve shapes between experiments and simulation, i.e., capturing the relevant biomechanical aspects.

Evaluation and Validation of Thorax Model Responses: A Hierarchical Approach to Achieve High Biofidelity for Thoracic Musculoskeletal System

As one of the most frequently occurring injuries, thoracic trauma is a significant public health burden occurring in road traffic crashes, sports accidents, and military events. The biomechanics of the human thorax under impact loading can be investigated by computational finite element (FE) models, which are capable of predicting complex thoracic responses and injury outcomes quantitatively. One of the key challenges for developing a biofidelic FE model involves model evaluation and validation. In this work, the biofidelity of a mid-sized male thorax model has been evaluated and enhanced by a multi-level, hierarchical strategy of validation, focusing on injury characteristics, and model improvement of the thoracic musculoskeletal system. At the component level, the biomechanical responses of several major thoracic load-bearing structures were validated against different relevant experimental cases in the literature, including the thoracic intervertebral joints, costovertebral joints, clavicle, sternum, and costal cartilages. As an example, the thoracic spine was improved by accurate representation of the components, material properties, and ligament failure features at tissue level then validated based on the quasi-static response at the segment level, flexion bending response at the functional spinal unit level, and extension angle of the whole thoracic spine. At ribcage and full thorax levels, the thorax model with validated bony components was evaluated by a series of experimental testing cases. The validation responses were rated above 0.76, as assessed by the CORA evaluation system, indicating the model exhibited overall good biofidelity. At both component and full thorax levels, the model showed good computational stability, and reasonable agreement with the experimental data both qualitatively and quantitatively. It is expected that our validated thorax model can predict thorax behavior with high biofidelity to assess injury risk and investigate injury mechanisms of the thoracic musculoskeletal system in various impact scenarios. The relevant validation cases established in this study shall be directly used for future evaluation of other thorax models, and the validation approach and process presented here may provide an insightful framework toward multi-level validating of human body models.

Obstetric and perinatal risks in 4601 singletons and 884 twins conceived after fresh blastocyst transfers: a Nordic study from the CoNARTaS group

STUDY QUESTION

Are obstetric and perinatal outcomes in pregnancies after fresh blastocyst transfer (BT) comparable with those born after fresh cleavage stage transfer (CT) and spontaneous conception (SC)?

SUMMARY ANSWER

Fresh BT is associated with a higher risk of placental and perinatal complications.

WHAT IS KNOWN ALREADY

BT optimizes the selection of top-quality embryos and increases pregnancy and live birth rates per transfer compared to CT. However, concerns have been raised as extended culture duration may increase obstetric complications and impair perinatal outcomes. Previous studies have shown a higher risk of preterm birth (PTB) among infants born after BT compared with CT. Pregnancies after BT are also prone to a higher risk of same-sex twins after single embryo transfer (SET).

STUDY DESIGN, SIZE, DURATION

A retrospective register-based cohort study used data from Denmark, Norway and Sweden including three cohorts: 56 557 singletons and 16 315 twins born after fresh IVF/ICSI cycles and 2 808 323 SC singletons in Denmark (birth years 1997-2014), Norway (2010-2015) and Sweden (2002-2015). Of the fresh IVF/ICSI singletons, 4601 were born after BT and 51 956 after CT. The twin cohort consisted of 884 fresh IVF/ICSI children born after BT and 15 431 fresh IVF/ICSI children born after CT.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data were obtained from a large Nordic cohort of children born after ART and SC initiated by the Committee of Nordic ART and Safety (CoNARTaS). The CoNARTaS cohort was established by cross-linking National ART-, Medical Birth-, and National Patients Registers using the unique personal identification number, allocated to every citizen in the Nordic countries. Obstetric and perinatal outcomes after BT, CT and SC were compared using logistic regression analysis. For perinatal outcomes, we calculated gestational age based on the date of oocyte pick-up (OPU) and in sensitivity analyses on data from Denmark and Norway, we also calculated gestational age based on the second-trimester ultrasonography (US) scan. Risk of pregnancies with same-sex twins after SET was used as a proxy for risk of monozygotic twins. Adjustments were made for child's sex, birth year, parity (0 or >1), maternal age, body mass index, smoking, educational level, fertilization method (IVF/ICSI), the number of aspirated oocytes, SET and country. Information on educational level and the number of aspirated oocytes was not available for Norway. Children born after frozen embryo transfer were not included. The birth cohorts were restricted according to the year in which BT was introduced in the different countries.

MAIN RESULTS AND THE ROLE OF CHANCE

A higher risk of placenta previa was found in singleton pregnancies after BT compared with CT (adjusted odds ratio [aOR] 2.11 [95% CI 1.76; 2.52]). Singletons born after BT had a higher risk of PTB (aOR 1.14 [95% CI 1.01; 1.29]) compared with CT singletons, when estimated based on OPU. Furthermore, an altered male/female ratio (aOR 1.13 [95% CI 1.06; 1.21]) with more males following BT compared with CT was seen. Risk of same-sex twins after SET was higher after single BT compared with single CT (aOR 1.94 [95% CI 1.42; 2.60]).

LIMITATIONS, REASONS FOR CAUTION

Residual confounding cannot be excluded, in particular related to duration and cause of infertility that we could not adjust for due to lack of reliable data.

WIDER IMPLICATIONS OF THE FINDINGS

Extended embryo culture to the blastocyst stage has the potential to compromise obstetric and perinatal outcomes in fresh cycles. These results are important since an increasing number of IVF/ICSI treatments are performed as BT.

STUDY FUNDING/COMPETING INTEREST(S)

NORDFORSK (project no: 71450). The Research Fund of Rigshospitalet, Copenhagen University Hospital. ReproUnion Collaborative study, co-financed by the European Union, Interreg V ÖKS. Grants from Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (LUA/ALF 70940), Hjalmar Svensson Research Foundation. The Research Council of Norway through its Centres of Excellence funding scheme, project number 262700. None of the authors has any conflicts of interests to declare regarding this study.

TRIAL REGISTRATION NUMBER

ISRCTN11780826.

Sensitivity of scale factor choice on injury response for equal-stress equal-velocity scaling

OBJECTIVE

This study aims to evaluate the assumption of geometric similitude inherent to equal-stress equal-velocity scaling by determining if scale factors created with different anthropometry metrics result in different scaled injury tolerance predictions. This assumption will be evaluated when equal-stress equal-velocity scaling is employed across dissimilar (e.g., 50^th male to small female) and similar (e.g., small female to a reference small female anthropometry) anthropometries.

METHODS

Three average male and three small female lower extremity specimens that were tested in ankle inversion/eversion were selected for scaling analysis. Three additional female specimens were selected as a reference dataset, such that the accuracy of the scaled data could be compared to an independent measured dataset. The failure moments, total height and total weight for these donors were determined from literature. Additional anthropometry metrics (leg length, calcaneus height, and bimalleolar width) were taken from each of their respective CT scans. Scale factors were calculated from these previously determined anthropometric metrics for the six donors selected for scaling analysis by targeting the averaged anthropometry metrics of the reference small female dataset. Equal-stress equal-velocity scaling was applied to the failure moments from literature using different scale factors. The mean predicted failure tolerance and standard deviation for scaled data using different scale factors were compared to one another and to the mean failure tolerance from the reference (unscaled) small female dataset.

RESULTS

When using average male data to predict ankle failure moment for a small female anthropometry, scaled moments were statistically significantly different from measured small female failure moment. Furthermore, scaled failure moments predicted using scale factors based on different anthropometry metrics were found to be significantly different from one another. Conversely, predicted mean failure moment using scaled female data of a similar size to the reference data was not significantly different from measured female failure moment, and the predicted failure moments were not significantly affected by choice of scale factor.

CONCLUSIONS

This study shows that an injury metric predicted with equal-stress equal-velocity scaling is sensitive to choice of scale factor when employing scaling across occupants of dissimilar size and sex. This conclusion suggests error can be introduced into scaled response due to choice of anthropometry metric used to create a scale factor, and therefore, anthropometry metrics used to create scale factors should be justified mechanistically and shown to apply across size and sex before being employed.

Thoracolumbar spine kinematics and injuries in frontal impacts with reclined occupants

OBJECTIVE

Highly automated vehicles may permit alternative seating postures, which could alter occupant kinematics and challenge current restraint designs. One predicted posture is a reclined seated position. While the spine of upright occupants is subjected to flexion during frontal crashes, the orientation of reclined occupants tends to subject the spine to high compressive loads followed by high flexion loads. This study aims to investigate kinematics and mechanisms of loading in the thoracolumbar spine for a reclined seated posture through the use of postmortem human subjects (PMHS).

METHODS

Frontal impact sled tests (50 kph delta-v) were conducted on five adult midsize male PMHS seated with the torso reclined to 50 degrees with respect to the vertical. The PMHS were seated on a semi-rigid seat and restrained by a seat-integrated three-point belt with dual lap-belt pretensioners and a shoulder-belt pretensioner with a 3 kN load-limiter. 3-D kinematic trajectories of five chosen vertebrae, and the pelvis were measured relative to the vehicle buck. Intervertebral pressure transducers were installed at three locations in the lumbar column to detect load timing.

RESULTS

Three PMHS suffered fractures at L1. Combined compression and flexion of the thoracolumbar spine occurred in all tests, but the magnitude of peak flexion varied across the PMHS. During the PMHS' forward excursion, the pelvis rotated anteriorly in two tests and posteriorly in two tests (lap-belt submarining occurred in one). In one test, the pelvis mount interacted with the seat, but did not affect kinematics.

CONCLUSIONS

Anterior rotation of the pelvis caused increased extension of the lumbar spine, which exacerbated lumbar compression in two of the PMHS; the one subject whose pelvis kinematic tracking was lost exhibited similar compression kinematics. Posterior rotation of the pelvis enabled lumbar flexion, which decreased lumbar compression, but lead to lap-belt submarining in one case. Lumbar kinematics for these reclined frontal impacts were sensitive to changes in initial posture of the spine (magnitude of lordosis or kyphosis) and pelvis (pitch angle). To our knowledge, this study is the first to analyze thoracolumbar kinematics and resulting injuries of a reclined seating posture using PMHS.

Kinematics of inboard-leaning occupants in frontal impacts

Objective: Up to one-half of drivers swerve before a crash, which may cause vehicle motions that displace an occupant from a normal seated position. How these altered postures affect occupant restraint in a crash is unknown. The goal of this study was to quantify the effect of an initial inboard lean on occupant kinematics in a frontal impact.Methods: 30 km/h frontal impact tests were performed with three postmortem human subjects (PMHS) seated in a neutral, upright posture and in a 20° inboard-leaning posture identified from simulated swerving tests with human volunteers.Results: In comparison to the upright posture, the inboard-leaning posture increased the initial distance from the D-ring to the belted shoulder by 105-156 mm. In the inboard-leaning tests, the occupant's head displaced 45-70 mm farther forward than in the upright tests and was also located 123-147 mm farther inboard at the time of maximum forward excursion. The peak resultant velocity of the occupant's head relative to the vehicle interior increased 1.40-1.54 m/s in the inboard-leaning tests.Conclusions: The posture-induced increase in the distance between the D-ring and the shoulder permitted the increased maximum forward head displacement and increased maximum head resultant velocity relative to the vehicle interior. Thus, an initial inboard lean in a frontal impact may increase the risk and severity of a head strike to the vehicle interior, and alter the location, timing, and nature of airbag engagement.

Biomechanics of the Human Brain during Dynamic Rotation of the Head

Traumatic brain injuries (TBI) are a substantial societal burden. The development of better technologies and systems to prevent and/or mitigate the severity of brain injury requires an improved understanding of the mechanisms of brain injury, and more specifically, how head impact exposure relates to brain deformation. Biomechanical investigations have used computational models to identify these relations, but more experimental brain deformation data are needed to validate these models and support their conclusions. The objective of this study was to generate a dataset describing in situ human brain motion under rotational loading at impact conditions considered injurious. Six head-neck human post-mortem specimens, unembalmed and never frozen, were instrumented with 24 sonomicrometry crystals embedded throughout the parenchyma that can directly measure dynamic brain motion. Dynamic brain displacement, relative to the skull, was measured for each specimen with four loading severities in the three directions of controlled rotation, for a total of 12 tests per specimen. All testing was completed 42-72 h post-mortem for each specimen. The final dataset contains approximately 5,000 individual point displacement time-histories that can be used to validate computational brain models. Brain motion was direction-dependent, with axial rotation resulting in the largest magnitude of displacement. Displacements were largest in the mid-cerebrum, and the inferior regions of the brain-the cerebellum and brainstem-experienced relatively lower peak displacements. Brain motion was also found to be positively correlated to peak angular velocity, and negatively correlated with angular velocity duration, a finding that has implications related to brain injury risk-assessment methods. This dataset of dynamic human brain motion will form the foundation for the continued development and refinement of computational models of the human brain for predicting TBI.

Submarining sensitivity across varied anthropometry in an autonomous driving system environment

Objective: Self-driving technology will bring novelty in occupant seating choices and vehicle interior design. Thus, vehicle safety systems may be challenged to protect occupants over a wider range of potential postures and seating choices. This study aims to investigate the effects of occupant size, seat recline, and knee bolster position on submarining risk and injury prediction metrics for reclined occupants in frontal crashes.Methods: Frontal crash finite element (FE) simulations were performed with the 3 simplified Global Human Body Model Consortium (GHBMC) occupant models: small female, midsize male, and large male. Additionally, a detailed GHBMC midsize male model was used to compare with selected simplified cases. For each simulation, parameters including seatback recline angle (0.9°, 10.9°, 20.9°, 30.9°) and knee bolster position relative to the occupant (baseline, close, far, and no knee bolster) were varied. Impacts were simulated with the U.S. New Car Assessment Program 56 km/h frontal crash pulse. Occupant kinematics data were extracted from each simulation in a full-factorial sensitivity study to investigate how changes in anthropometry, seating position, and knee bolster position would affect submarining across all simulated cases.Results: Overall, increasing the occupant-to-knee bolster distance resulted in more submarining cases. The threshold for submarining was also affected by the seat recline angle. The lowest threshold observed occurred with 10.9° of recline with the small female model. Submarining was observed at recline angles at and above 20.9° for the midsize male model and 30° for the large male model. The initial lap belt position, pelvis orientation, and their relationship were good predictors of submarining. Increased lumbar flexion moment was observed with increased seat recline angle as well as occupant-to-knee bolster distance. The detailed GHBMC model was more prone to submarining than the simplified model.Conclusions: Submarining may be a major challenge to overcome for reclined occupants, which may become more prevalent with autonomous driving systems. This study shows that the angle of recline, anthropometric variation, and position of the knee bolster affect the risk of submarining. To our knowledge, this is the first study to computationally evaluate the occupant protection implications of seatback recline for multiple body sizes, postures, and positions relative to the vehicle interior.

Cumulative live birth rate prognosis based on the number of aspirated oocytes in previous ART cycles

STUDY QUESTION

Is the number of aspirated oocytes in the first ART cycle associated with the cumulative live birthrates (CLBR) in subsequent cycles?

SUMMARY ANSWER

The number of aspirated oocytes in the first cycle was associated with CLBR in subsequent cycles. Previous treatment response predicts outcome in future cycles.

WHAT IS KNOWN ALREADY

Previous reports have shown a positive association between the number of retrieved oocytes and live birthrate per fresh treatment cycle. This has also been shown for the CLBR in one complete ART-cycle, including possible subsequent frozen-thawed transfers (FER). It has been shown that women with less than five oocytes in the first cycle have poorer outcome within six complete cycles than women with more than 12 oocytes, suggesting that the number of aspirated oocytes in the first cycle may be reproduced in later cycles. However, other studies have shown that an initial low treatment response may be improved with increased gonadotrophin start-dose.

STUDY DESIGN, SIZE, DURATION

The Danish National IVF-registry includes all ART treatments in public and private clinics since 1994. Treatment-cycles were cross-linked with the Medical Birth Registry, identifying treatment-related births and natural conception births. This national cohort study includes all women starting ART treatments with homologous eggs between 2002 and 2011, N = 30 486. Subjects were followed for up to four fresh ART-cycles including subsequent FER-cycles (=four complete cycles), until the first livebirth, or until December 2011.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The CLBR within 1-4 complete ART-cycles were calculated as the proportion of women with a livebirth, out of all women initiating ART-treatment, including drop-outs (no livebirth or no continued treatment within follow-up). In women with one year follow-up from last treatment, multivariate logistic regression analysis assessed impact of retrieved oocytes on CLBR, adjusting results for female age and cause of infertility. Hospital admission due to ovarian hyperstimulation syndrome (OHSS) was reported.

MAIN RESULTS AND THE ROLE OF CHANCE

After one, two and three complete ART-cycles, the CLBRs attributable to ART treatment were 26.4% [95%CI 25.9-26.9], 42.6% [42.0-43.1] and 51.3% [50.7-51.9], respectively. The CLBR attributable to non-ART related conception (natural conception or intrauterine insemination) were 5.3% [5.0-5.6], 8.3% [8.0-8.7] and 10.6% [10.3-11.0], after one, two and three complete cycles. In women without a live birth in the first complete cycle, the number of aspirated oocytes predicted the outcome in the second and third cycle: When compared to women with 0-3 aspirated oocytes in the first cycle, the odds for live birth in the second and third cycle was 1.18 [1.07-1.30] for women with 4-9 aspirated oocytes in the first cycle, 1.41 [1.27-1.57] for women with 10-15 aspirated oocytes and 1.63 [1.42-1.88] for women with more than 15 aspirated oocytes. For women without a livebirth in the first and second cycle, the sum of aspirated oocytes predicted outcome in the third complete cycle. Women with a sum larger than six aspirated oocytes, had marked increased odds ratios for livebirth in the third complete cycle, compared to women with a sum of 0-6 oocytes in the first and second fresh cycle. Incidence of hospital-admission due to OHSS was 1.7% in the first cycle, decreasing to 1.3% and 1.0% in the second and third cycles.

LIMITATIONS, REASONS FOR CAUTION

Although mandatory, there may be treatment-cycles not registered in the IVF-registry. Missing information in number of aspirated oocytes are most likely random losses of information. There were few observations in women with more than 15 aspirated oocytes and these birthrates should be interpreted cautiously. Information on gonadotrophin dose used for stimulation was not available, nor was information on dose adjustments in subsequent cycles.

WIDER IMPLICATIONS OF THE FINDINGS

With these results we can counsel couples returning for fertility treatments, providing an age-stratified revised prognosis for chances of live birth and risk of OHSS, reflecting prior failed attempts and previous ovarian response.

STUDY FUNDING/COMPETING INTEREST(S)

This study was unconditionally funded by Ferring Pharmaceuticals and ReproUnion. The funders had no role in the study design, data collection and interpretation, or decision to submit the work for publication. The authors have no conflicts of interest.

TRIAL REGISTRATION NUMBER

The study was approved by the Danish Data Protection Agency (J.nr. 2012-41-1330).

Automobile injury trends in the contemporary fleet: Belted occupants in frontal collisions

Objective: As vehicle safety technologies and evaluation procedures advance, it is pertinent to periodically evaluate injury trends to identify continuing and emerging priorities for intervention. This study examined detailed injury distributions and injury risk trends in belted occupants in frontal automobile collisions (10 o'clock to 2 o'clock) using NASS-CDS (1998-2015). Methods: Injury distributions were examined by occupant age and vehicle model year (stratified at pre- and post-2009). Logistic regression models were developed to examine the effects of various factors on injury risk (by body region), controlling for delta-V, sex, age, height, body mass index (BMI), vehicle model year (again stratified at 2009). Results: Among other observations, these analyses indicate that newer model year vehicles (model year [MY] 2009 and later) carry less risk of Abbreviated Injury Scale (AIS) 2+ and AIS 3+ injury compared to older model year vehicles, with odds ratios of 0.69 (AIS 2+) and 0.45 (AIS 3+). The largest reductions in risk between newer model year vehicles and older model year vehicles occur in the lower extremities and in the risk of skull fracture. There is no statistically significant change in risk of AIS 3+ rib fracture or sternum injury between model year categories. Females are at greater risk of AIS 2+ and AIS 3+ injury compared to males, with increased risk across most injury types. Conclusions: For belted occupants in frontal collisions, substantial reductions in injury risk have been realized in many body regions in recent years. Risk reduction in the thorax has lagged other body regions, resulting in increasing prevalence among skeletal injuries in newer model year vehicles (especially in the elderly). Injuries also remain common in the arm and hand/wrist for all age ranges studied. These results provide insight into where advances in the field have made gains in occupant protection and what injury types remain to be addressed.

DTL-RnB: Algorithms and Tools for Summarizing the Space of DTL Reconciliations

Phylogenetic tree reconciliation is an important technique for reconstructing the evolutionary histories of species and genes and other dependent entities. Reconciliation is typically performed in a maximum parsimony framework and the number of optimal reconciliations can grow exponentially with the size of the trees, making it difficult to understand the solution space. This paper demonstrates how a small number of reconciliations can be found that collectively contain the most highly supported events in the solution space. While we show that the formal problem is NP-complete, we give a approximation algorithm, experimental results that indicate its effectiveness, and the new DTL-RnB software tool that uses our algorithms to summarize the space of optimal reconciliations (www.cs.hmc.edu/dtlrnb).

Injury risk functions based on population-based finite element model responses: Application to femurs under dynamic three-point bending

OBJECTIVE

The goal of this study was to explore a framework for developing injury risk functions (IRFs) in a bottom-up approach based on responses of parametrically variable finite element (FE) models representing exemplar populations.

METHODS

First, a parametric femur modeling tool was developed and validated using a subject-specific (SS)-FE modeling approach. Second, principal component analysis and regression were used to identify parametric geometric descriptors of the human femur and the distribution of those factors for 3 target occupant sizes (5th, 50th, and 95th percentile males). Third, distributions of material parameters of cortical bone were obtained from the literature for 3 target occupant ages (25, 50, and 75 years) using regression analysis. A Monte Carlo method was then implemented to generate populations of FE models of the femur for target occupants, using a parametric femur modeling tool. Simulations were conducted with each of these models under 3-point dynamic bending. Finally, model-based IRFs were developed using logistic regression analysis, based on the moment at fracture observed in the FE simulation. In total, 100 femur FE models incorporating the variation in the population of interest were generated, and 500,000 moments at fracture were observed (applying 5,000 ultimate strains for each synthesized 100 femur FE models) for each target occupant characteristics.

RESULTS

Using the proposed framework on this study, the model-based IRFs for 3 target male occupant sizes (5th, 50th, and 95th percentiles) and ages (25, 50, and 75 years) were developed. The model-based IRF was located in the 95% confidence interval of the test-based IRF for the range of 15 to 70% injury risks. The 95% confidence interval of the developed IRF was almost in line with the mean curve due to a large number of data points.

CONCLUSIONS

The framework proposed in this study would be beneficial for developing the IRFs in a bottom-up manner, whose range of variabilities is informed by the population-based FE model responses. Specifically, this method mitigates the uncertainties in applying empirical scaling and may improve IRF fidelity when a limited number of experimental specimens are available.

A Novel Method for Quantifying Human In Situ Whole Brain Deformation under Rotational Loading Using Sonomicrometry

Traumatic brain injuries (TBI) are one of the least understood injuries to the body. Finite element (FE) models of the brain have been crucial for understanding concussion and for developing injury mitigation systems; however, the experimental brain deformation data currently used to validate these models are limited. The objective of this study was to develop a methodology for the investigation of in situ three-dimensional brain deformation during pure rotational loading of the head, using sonomicrometry. Sonomicrometry uses ultrasonic pulses to measure the dynamic distances between piezoelectric crystals implanted in any sound-transmitting media. A human cadaveric head-neck specimen was acquired 14 h postmortem and was instrumented with an array of 32 small sonomicrometry crystals embedded in the head: 24 crystals were implanted in the brain, and 8 were fixed to the inner skull. A dynamic rotation was then applied to the head using a closed-loop controlled test device. Four pulses with different severity levels were applied around three orthogonal anatomical axes of rotation. A repeated test of the highest severity rotation was conducted in each axis to assess repeatability. All tests were completed within 56 h postmortem. Overall, the combined experimental and sonomicrometry methods were demonstrated to reliably and repeatedly capture three-dimensional dynamic deformation of an intact human brain. These methods provide a framework for using sonomicrometry to acquire multidimensional experimental data required for FE model development and validation, and will lend insight into the deformations sustained by the brain during impact.

Impact Response Comparison Between Parametric Human Models and Postmortem Human Subjects with a Wide Range of Obesity Levels

OBJECTIVE

Field data analyses have shown that obesity significantly increases the occupant injury risks in motor vehicle crashes, but the injury assessment tools for people with obesity are largely lacking. The objectives of this study were to use a mesh morphing method to rapidly generate parametric finite element models with a wide range of obesity levels and to evaluate their biofidelity against impact tests using postmortem human subjects (PMHS).

METHODS

Frontal crash tests using three PMHS seated in a vehicle rear seat compartment with body mass index (BMI) from 24 to 40 kg/m² were selected. To develop the human models matching the PMHS geometry, statistical models of external body shape, rib cage, pelvis, and femur were applied to predict the target geometry using age, sex, stature, and BMI. A mesh morphing method based on radial basis functions was used to rapidly morph a baseline human model into the target geometry. The model-predicted body excursions and injury measures were compared to the PMHS tests.

RESULTS

Comparisons of occupant kinematics and injury measures between the tests and simulations showed reasonable correlations across the wide range of BMI levels.

CONCLUSIONS

The parametric human models have the capability to account for the obesity effects on the occupant impact responses and injury risks.

Obstetric and neonatal complications in pregnancies conceived after oocyte donation: a systematic review and meta-analysis

BACKGROUND

Approximately 50 000 oocyte donation (OD) treatment cycles are now performed annually in Europe and the US.

OBJECTIVES

To ascertain whether the risk of adverse obstetric and perinatal/neonatal outcomes is higher in pregnancies conceived by OD than in pregnancies conceived by conventional in-vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) or spontaneously.

SEARCH STRATEGY

A systematic search was performed in the PubMed, Cochrane and Embase databases from 1982-2016. Primary outcomes were hypertensive disorders of pregnancy, pre-eclampsia (PE), gestational diabetes mellitus, postpartum haemorrhage, caesarean section, preterm birth, low birthweight and small for gestational age.

SELECTION CRITERIA

Inclusion criteria were original studies including at least five OD pregnancies with a control group of pregnancies conceived by conventional IVF/ICSI or spontaneous conception, and case series with >500 cases reporting one or more of the selected complications. Studies not adjusting for plurality were excluded.

DATA COLLECTION AND ANALYSIS

Thirty-five studies met the inclusion criteria. A random-effects model was used for the meta-analyses.

MAIN RESULTS

For OD pregnancies versus conventional IVF/ICSI pregnancies the risk of PE was adjusted odds ratio (AOR) 2.11 (95% CI, 1.42-3.15) in singleton and AOR 3.31 (95% CI, 1.61-6.80) in multiple pregnancies. The risks of preterm birth and low birthweight in singletons were AOR 1.75 (95% CI, 1.39-2.20) and 1.53 (95% CI, 1.16-2.01), respectively.

CONCLUSIONS

OD conceptions are associated with adverse obstetric and neonatal outcomes. To avoid the additional increase in risk from multiplicity, single-embryo transfer should be the choice of option in OD cycles.

TWEETABLE ABSTRACT

Oocyte donation pregnancies have increased risk of a range of obstetric and neonatal complications.

Academic performance in adolescents born after ART-a nationwide registry-based cohort study

STUDY QUESTION

Is academic performance in adolescents aged 15-16 years and conceived after ART, measured as test scores in ninth grade, comparable to that for spontaneously conceived (SC) adolescents?

SUMMARY ANSWER

ART singletons had a significantly lower mean test score in the adjusted analysis when compared with SC singletons, yet the differences were small and probably not of clinical relevance.

WHAT IS KNOWN ALREADY

Previous studies have shown similar intelligence quotient (IQ) levels in ART and SC children, but only a few have been on adolescents. Academic performance measured with standardized national tests has not previously been explored in a complete national cohort of adolescents conceived after ART.

STUDY DESIGN, SIZE, DURATION

A Danish national registry-based cohort including all 4766 ART adolescents (n = 2836 singletons and n = 1930 twins) born in 1995-1998 were compared with two SC control cohorts: a randomly selected singleton population (n = 5660) and all twins (n = 7064) born from 1995 to 1998 in Denmark. Nine children who died during the follow-up period were excluded from the study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mean test scores on a 7-point-marking scale from -3 to 12 were compared, and adjustments were made for relevant reproductive and socio-demographic covariates including occupational and educational level of the parents.

MAIN RESULTS AND THE ROLE OF CHANCE

The crude mean test score was higher in both ART singletons and ART twins compared with SC adolescents. The crude mean differences were +0.41 (95% CI 0.30-0.53) and +0.45 (95% CI 0.28-0.62) between ART and SC singletons and between ART and SC twins, respectively. However, the adjusted mean overall test score was significantly lower for ART singletons compared with SC singletons (adjusted mean difference -0.15 (95% CI -0.29-(-0.02))). For comparison, the adjusted mean difference was +2.05 (95% CI 1.82-2.28) between the highest and the lowest parental educational level, suggesting that the effect of ART is weak compared with the conventional predictors. The adjusted analyses showed significantly lower mean test scores in mathematics and physics/chemistry for ART singletons compared with SC singletons. Comparing ART twins with SC twins yielded no difference in academic performance in the adjusted analyses. Similar crude and adjusted overall mean test scores were found when comparing ART singletons and ART twins.

LIMITATIONS, REASONS FOR CAUTION

Missing data on educational test scores occurred in 6.6% of adolescents aged 15-16 years for the birth cohorts 1995-1997, where all of the children according to their age should have passed the ninth grade exam at the time of data retrieval. As sensitivity analyses yielded no significant difference in the adjusted risk of having missing test scores between any of the groups, it is unlikely that this should bias our results. Adjustment for body mass index and smoking during pregnancy was not possible.

WIDER IMPLICATIONS OF THE FINDINGS

As our results are based on national data, our findings can be applied to other populations. The findings of this paper suggest that a possible small negative effect of parental subfertility or ART treatment is counterbalanced by the higher educational level in the ART parents.

STUDY FUNDING/COMPETING INTERESTS

The Danish Medical Association in Copenhagen (KMS) funded this study with a scholarship grant. None of the authors had any competing interests.

TRIAL REGISTRATION NO STATISTICS DENMARK

704676.

Blunt impacts to the back: Biomechanical response for model development

The development of advanced injury prediction models requires biomechanical and injury tolerance information for all regions of the body. While numerous studies have investigated injury mechanics of the thorax under frontal impact, there remains a dearth of information on the injury mechanics of the torso under blunt impact to the back. A series of hub-impact tests were performed to the back surface of the mid-thorax of four mid-size male cadavers. Repeated tests were performed to characterize the biomechanical and injury response of the thorax under various impact speeds (1.5m/s, 3m/s and 5.5m/s). Deformation of the chest was recorded with a 59-gage chestband. Subject kinematics were also recorded with a high-speed optoelectronic 3D motion capture system. In the highest-severity tests, peak impact forces ranged from 6.9 to 10.5 kN. The peak change in extension angle measured between the 1st thoracic vertebra and the lumbar spine ranged from 39 to 62°. The most commonly observed injuries were strains of the costovertebral/costotransverse joint complexes, rib fractures, and strains of the interspinous and supraspinous ligaments. The majority of the rib fractures occurred in the rib neck between the costovertebral and costotransverse joints. The prevalence of rib-neck fractures suggests a novel, indirect loading mechanism resulting from bending moments generated in the rib necks caused by motion of the spine. In addition to the injury information, the biomechanical responses quantified here will facilitate the future development and validation of human body models for predicting injury risk during impact to the back.

Large baby syndrome in singletons born after frozen embryo transfer (FET): is it due to maternal factors or the cryotechnique?

STUDY QUESTION

Are singletons born after frozen embryo transfer (FET) at increased risk of being born large for gestational age (LGA) and if so, is this caused by intrinsic maternal factors or related to the freezing/thawing procedures?

SUMMARY ANSWER

Singletons after FET have an increased risk of being born LGA. This cannot solely be explained by intrinsic maternal factors as it was also observed in sibling pairs, where the sibling conceived after FET had an increased risk of LGA compared with the sibling born after Fresh embryo transfer.

WHAT IS KNOWN ALREADY

FET singletons have a higher mean birthweight than singletons born after transfer of fresh embryos, and FET singletons may be at an increased risk of being born LGA.

STUDY DESIGN, SIZE, DURATION

The national register-based controlled cohort study involves two populations of FET singletons. The first population (A: total FET cohort) consisted of all FET singletons (n = 896) compared with singletons born after Fresh embryo transfer (Fresh) (n = 9480) and also with that born after natural conception (NC; n = 4510) in Denmark from 1997 to 2006. The second population (B: Sibling FET cohort) included all sibling pairs, where one singleton was born after FET and the consecutive sibling born after Fresh embryo transfer or vice versa from 1994 to 2008 (n = 666). The sibling cohort included n = 550 children with the sibling combination first child Fresh/second child FET and n = 116 children with the combination first child FET/second child Fresh.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Main outcome measures were LGA defined as birthweight of >2 SD from the population mean (z-score >2) according to Marsáls curves. Macrosomia was defined as birthweight of >4500 g. Crude and adjusted odds ratios (AORs) of LGA and macrosomia were calculated for FET versus Fresh and versus NC singletons in the total FET cohort. Similarly, AOR was calculated for FET versus Fresh in the sibling cohort. Adjustments were made for maternal age, parity, child sex, year of birth and birth order in the sibling analyses. Meta-analyses were performed by pooling our data with the previously published cohort studies on LGA and macrosomia.

MAIN RESULTS AND THE ROLE OF CHANCE

The AORs of LGA (z-score >2) and macrosomia in FET singletons versus singletons conceived after Fresh embryo transfer were 1.34 [95% confidence interval (95% CI) 0.98-1.80] and 1.91 (95% CI 1.40-2.62), respectively. The corresponding risks for FET versus NC singletons were 1.41 (95% CI 1.01-1.98) for LGA and 1.67 (95% CI 1.18-2.37) for macrosomia. The increased risk of LGA and macrosomia in FET singletons was confirmed in the sibling cohort also after adjustment for birth order. Hence, the increased risk of LGA in FET singletons cannot solely be explained by being the second born or by intrinsic maternal factors, but may also partly be related to freezing/thawing procedures per se. In the meta-analysis, the summary effects of LGA and macrosomia in FET versus singletons conceived after Fresh embryo transfer were AOR 1.54 (95% CI 1.31-1.81) and AOR 1.64 (95% CI 1.26-2.12), respectively. The corresponding figures for FET versus NC singletons were for LGA AOR 1.32 (95% CI 1.07-1.61) and macrosomia AOR 1.41 (95% CI 1.11-1.80), respectively.

LIMITATIONS, REASONS FOR CAUTION

Adjustment for body mass index as a possible confounder was not possible. The size of the FET/Fresh sibling cohort was limited; however, the complete sibling cohort was sufficiently powered to explore the risk of LGA. A bias is very unlikely as data coding was based on national registers.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings are consistent with the previous Nordic studies and thus can be generalized to the Nordic countries. The causes for LGA in FET singletons should be further explored.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this project. None of the authors have any conflict of interest to declare.

Abstract OT1-4-03: Phase I study of erlotinib and metformin in triple negative breast cancer

Background: Triple negative breast cancers (TNBC) are enriched for increased phosphorylated EGFR expression and decreased expression of PTEN. We found that combined treatment of metformin and erlotinib induces cell death in a subset of TNBC cell lines with evidence of combined enhanced reduction of EGFR, AKT, S6 and 4EBP1 phosphorylation. Analysis of TNBC cell line alterations led to the hypothesis that loss of PTEN sensitized cells to the drug combination, which was confirmed using isogenic cell line models with and without PTEN expression. The inhibitory effects of combined erlotinib and metformin were confirmed in mouse xenografts of PTEN null TNBC breast cancer cell lines. These data provided a rationale for clinical translation and testing in advanced TNBC patients.

Trial Design: Single institution expanded Phase I design in patients with advanced TNBC. Erlotinib dosing will start and remain at 150 mg. Due to frequent GI upset in patients starting metformin, the dose of metformin will be titrated up to the assigned dose level over 2 weeks. The first metformin dose level will be 850 mg twice daily and will be escalated to its maximum FDA approved dose of 850 mg three times daily. Dose escalation will follow the standard 3 + 3 design. Dose limiting toxicities will be determined during the first 5 weeks of therapy. One metformin dose de-escalation level to 500 mg twice daily is allowed. Cycles will be defined as three weeks of treatment, and response assessments will be performed after every three cycles.

Main Eligibility Criteria:

1. Pathologic diagnosis of TNBC.

2. Measurable or non-measurable disease.

3. At least one prior treatment for metastatic disease.

4. ECOG PS = 0-2.

5. Prior metformin or EGFR targeted therapy.

6. Fasting blood glucose level < 126 mg/dl.

7. Normal renal function.

8. Available archived tumor tissue.

Specific Aims: The primary endpoints are defining the maximum tolerated dose (MTD) of metformin in combination with 150 mg erlotinib, and for the extended phase, determining the potential for clinical benefit by treating 14 patients at the MTD with the goal of rejecting the null hypothesis that the regimen is futile. Clinical benefit is defined as either partial response or lack of progression after 18 weeks of therapy (stable disease). Secondary endpoints include: 1) progression free survival, and 2) pharmacodynamic assessment of the phosphorylation status of AMPK and EGFR from pre- and on-treatment skin biopsies. The exploratory endpoint will be assessment of the status of EGFR, PTEN, LKB1, and 4EBP1 from available patient tumor samples to correlate against treatment response.

Statistical Methods: If one patient meets the primary endpoint, among the 14 patients treated at the MTD, then the regimen will be considered worthy of further investigation.

Target Accrual: 17-20 patients. Four patients accrued as of June 2013. Accrual completion expected June 2015.

Contact: Matthew Maurer, Columbia University Medical Center, mm2058@columbia.edu.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT1-4-03.