Sternal Morphologic Characteristics of U.S. Military Males by Computed Tomography: Implications for Intraosseous Access

INTRODUCTION

Sternal intraosseous (IO) access has advantages over humeral and tibial access for fluid resuscitation in military medical settings due to superior flow rates and pharmacokinetics. However, the morphology of the young adult manubrial cortical and medullary bone as it relates to IO catheter tips of currently available FDA-approved IO access devices is unclear.

MATERIALS AND METHODS

Computed tomography manubrium images of active duty service members (N = 93) aged 18 to 30 were assessed by radiologists, including manubrial height, width, and cortical thickness, as well as total thickness and medullary thickness at the thickest (superior) and thinnest (inferior) parts of the manubrium. Inference regarding medullary or cortical IO catheter tip placement rates were made for FAST1 (5.5 mm catheter depth) and TALON (4.5 mm catheter depth) sternal IO devices. Data were analyzed using ANOVA, non-parametric, and correlational statistics at P < 0.05.

RESULTS

As inferred from case-specific CT-derived manubrium dimensions and maximal catheter tip penetration depths, both FAST1 and TALON would be placed in the target medullary space on 100% of opportunities if properly applied in the superior manubrium and on 99% of opportunities if properly applied in the inferior manubrium. Age was not significantly related to IO-relevant manubrial dimensions.

CONCLUSIONS

Present findings suggest that both FAST1 and TALON sternal IO catheter tips can be successfully placed into the target medullary bone with high accuracy in male military members aged 18 to 30 who require rapid resuscitation.

Presence of manubrium-sternum joint does not assure sufficient elevation of sternum in Nuss procedure for pectus excavatum patients

BACKGROUND

The manubrium and body of the sternum are connected by the manubrium-sternum joint (MSJ). In performing the Nuss procedure for pectus excavatum patients, the body of the sternum is elevated as the operator flips correction bars upside down. Theoretically, the presence of the MSJ should allow elevation of the sternum body. However, does the MSJ secure sufficient elevation of the sternum? This study aims to elucidate this clinical question.

METHODS

Seventy-four adult pectus excavatum patients with moderate to serious deformity (with Haller Index being equal to or greater than 5) were included in the study. The MSJ was open in all patients. For 29 patients, the sternum was elevated by only bar flipping (Non-Separation Group); for 45 patients, the sternum was horizontally separated after bar flipping (Separation Group). Whether or not additional elevation for Separation Group patients results from the division was observed, and the degree of the additional elevation was evaluated. Furthermore, 74 patients subjectively evaluated postoperative pain and gave scores with a Visual Analog Scale ranging from 0 (no pain) to 10 (intolerable pain). The VAS scores were compared between the two groups.

RESULTS

In the Separation Group, the sternums of all patients achieved additional elevation from sternum separation. The pain scores were lower for the Separation Group than for the Non-Separation Group.

CONCLUSION

Even when the MSJ is present, horizontal separation enhances the elevation of the sternum. Furthermore, horizontal separation of the sternum reduces postoperative pain.

Characterizing thoracic morphology variation to develop representative 3D models for applications in chest trauma

BACKGROUND

Rib fracture(s) occurs in 85% of blunt chest trauma cases. Increasing evidence supports that surgical intervention, particularly for multiple fractures, may improve outcomes. Thoracic morphology diversity across ages and sexes is important to consider in the design and use of surgical intervention devices in chest trauma. However, research on non-average thoracic morphology is lacking.

METHODS

The rib cage was segmented from patient computed tomography (CT) scans to create 3D point clouds. These point clouds were uniformly oriented and chest height, width, and depth were measured. Size categorization was determined by grouping each dimension into small, medium, and large tertiles. From small and large size combinations, subgroups were extracted to develop thoracic 3D models of the rib cage and surrounding soft tissue.

RESULTS

The study population included 141 subjects (48% male) ranging from age 10-80 with ∼20 subjects/age decade. Mean chest volume increased with age by 26% from the age groups 10-20 to 60-70, with 11% of this increase occurring between the youngest groups of 10-20 and 20-30. Across all ages, chest dimensions were ∼10% smaller in females and chest volume was highly variable (SD: ±3936.5 cm3). Representative thoracic models of four males (ages 16, 24, 44, 48) and three females (ages 19, 50, 53) were developed to characterize morphology associated with combinations of small and large chest dimensions.

CONCLUSIONS

The seven models developed cover a broad range of non-average thoracic morphologies and can serve as a basis for informing device design, surgical planning, and injury risk assessments.

Analysis of Factors Influencing Thoracic Deformities after Median Sternotomy in Infants Who Underwent Congenital Cardiac Surgery

Objective. To investigate the incidence of thoracic deformities after median sternotomy in infants who underwent congenital cardiac surgery and determine its influencing factors. Methods. This was a single-center retrospective study. A total of 156 infants who underwent congenital cardiac surgery with median sternotomy in a provincial hospital in China from September 2020 to January 2022 were included. Depending on whether thoracic deformities occurred, the patients were classified into the thoracic deformity group and the no thoracic deformity group. Relevant data were retrieved through an electronic medical record system, and statistical comparisons and analyses were performed. Results. The incidence of postoperative thoracic deformities in this cohort was 10.9%. Sternal pins for auxiliary sternal fixation were used in eighty-nine infants. After analysis, it was found that age at operation (1.9 ± 0.9 vs. 3.7 ± 1.2, $P<0.001$ ) and weight-for-age Z-scores (−2.0 ± 0.7 vs. −1.4 ± 0.7, $P=0.001$ ) of the thoracic deformity group were significantly lower than those of the no thoracic deformity group. In addition, sternal pin use was significantly higher in the no thoracic deformity group than in the thoracic deformity group (61.9% vs. 17.6%, $P=0.001$ ). Univariable analysis showed that age at operation (OR, 4.74; 95% CI, 2.38–9.46; $P<0.001$ ) and weight-for-age Z-scores (OR, 4.40; 95% CI, 1.74–11.12; $P=0.002$ ) were significant risk factors for postoperative thoracic deformity. Using sternal pins for auxiliary sternal fixation was an important protective factor (OR, 7.57; 95% CI, 2.08–27.59; $P=0.003$ ). Conclusions. In this study, 10.9% of infants undergoing congenital cardiac surgery through a median sternotomy developed thoracic deformities after surgery. Younger age at operation and poor nutritional conditions may be risk factors for postoperative thoracic deformity. Sternal pin-assisted fixation has a positive effect on the prevention of thoracic deformities.

Does sternal body shape reflect family relationships? A study on a genealogically documented Central European osteological sample (19th-20th centuries)

In forensic contexts, sternal anatomical varieties represent useful tools for the identification of an individual, either by comparison of ante-mortem and post-mortem data, or by potential comparison of data from biologically related individuals. Sternal body variation is also used to detect the biological affinity of individuals in bioarchaeology. However, no study has been made available to date on the degree to which the overall shape of the sternal body reflects the degree of biological relatedness. We, therefore, analyzed the sternal body shape of 10 individuals with known genealogical data, members of one family over three generations including inbred individuals (19th-20th centuries, Bohemia, Czech Republic), and a control sample of 12 biologically unrelated individuals. First, closely biologically related individuals were compared with unrelated individuals based on 10 variables expressing the morphological characteristics of the sternum, and then all individuals were compared based on Fourier analysis depending on their degree of relationship. The results showed that there is a greater degree of shape similarity in biologically related individuals than in unrelated individuals, and variability decreases with an increasing degree of relatedness. Inbred individuals showed the lowest sternum-shape distances and degree of variability, while unrelated individuals, showed the highest distances and variability. Moreover, in some cases, the documented relationships were also supported by a similar morphology of the ossified and fused xiphoid process. Thus, sternal shape analysis expands the possibilities for individual identification and the detection of the biological affinity of individuals for both the forensic sciences and bioarchaeology.

A high-resolution pediatric female whole-body numerical model with comparison to a male model

Objective. Numerical models are central in designing and testing novel medical devices and in studying how different anatomical changes may affect physiology. Despite the numerous adult models available, there are only a few whole-body pediatric numerical models with significant limitations. In addition, there is a limited representation of both male and female biological sexes in the available pediatric models despite the fact that sex significantly affects body development, especially in a highly dynamic population. As a result, we developed Athena, a realistic female whole-body pediatric numerical model with high-resolution and anatomical detail.Approach. We segmented different body tissues through Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) images of a healthy 3.5 year-old female child using 3D Slicer. We validated the high anatomical accuracy segmentation through two experienced sub-specialty-certified neuro-radiologists and the inter and intra-operator variability of the segmentation results comparing sex differences in organ metrics with physiologic values. Finally, we compared Athena with Martin, a similar male model, showing differences in anatomy, organ metrics, and MRI dosimetric exposure.Main results. We segmented 267 tissue compartments, which included 50 brain tissue labels. The tissue metrics of Athena displayed no deviation from the literature value of healthy children. We show the variability of brain metrics in the male and female models. Finally, we offer an example of computing Specific Absorption Rate and Joule heating in a toddler/preschooler at 7 T MRI.Significance. This study introduces a female realistic high-resolution numerical model using MRI and CT scans of a 3.5 year-old female child, the use of which includes but is not limited to radiofrequency safety studies for medical devices (e.g. an implantable medical device safety in MRI), neurostimulation studies, and radiation dosimetry studies. This model will be open source and available on the Athinoula A. Martinos Center for Biomedical Imaging website.

Hello, world! VIVA+: A human body model lineup to evaluate sex-differences in crash protection

Finite element Human Body Models are increasingly becoming vital tools for injury assessment and are expected to play an important role in virtual vehicle safety testing. With the aim of realizing models to study sex-differences seen in the injury- and fatality-risks from epidemiology, we developed models that represent an average female and an average male. The models were developed with an objective to allow tissue-based skeletal injury assessment, and thus non-skeletal organs and joints were defined with simplified characterizations to enhance computational efficiency and robustness. The model lineup comprises female and male representations of (seated) vehicle occupants and (standing) vulnerable road users, enabling the safety assessment of broader segments of the road user population. In addition, a new workflow utilized in the model development is presented. In this workflow, one model (the seated female) served as the base model while all the other models were generated as closely-linked derivative models, differing only in terms of node coordinates and mass distribution. This approach opens new possibilities to develop and maintain further models as part of the model lineup, representing different types of road users to reflect the ongoing transitions in mobility patterns (like bicyclists and e-scooter users). In this paper, we evaluate the kinetic and kinematic responses of the occupant and standing models to blunt impacts, mainly on the torso, in different directions (front, lateral, and back). The front and lateral impacts to the thorax showed responses comparable to the experiments, while the back impact varied with the location of impact (T1 and T8). Abdomen bar impact showed a stiffer load-deflection response at higher intrusions beyond 40 mm, because of simplified representation of internal organs. The lateral shoulder impact responses were also slightly stiffer, presumably from the simplified shoulder joint definition. This paper is the first in a series describing the development and validation of the new Human Body Model lineup, VIVA+. With the inclusion of an average-sized female model as a standard model in the lineup, we seek to foster an equitable injury evaluation in future virtual safety assessments.

Analysis of pediatric sternal fractures using the Kid's Inpatient Database (KID)

PURPOSE

This study aims to determine if sternal fracture is a predictor of discharge requiring additional care and mortality.

METHODS

Blunt pediatric trauma admissions (<18 years) in the Kid's Inpatient Database (2016) were included in analysis. Weighted incidence of sternal fracture was calculated and adjusted for using survey weight, sampling clusters, and stratum. Regression analysis was used to identify factors associated with poor outcomes.

RESULTS

Annual incidence of sternal fracture in the pediatric blunt trauma population was 0.43 per 100,000. Of 50,076 patients identified, 236 had sternal fractures. The sternal fracture patients were older (median 16 vs 10 years, P < 0.001) and motor vehicle accident was more frequently the mechanism of injury (78% vs 24%, P < 0.001). Common injuries associated with sternal fracture included clavicle fracture (43%), abdominal organ injury (28%), spinal fracture (47%), lung injury (65%), and rib fracture (47%).  Sternal fracture patients were more frequently discharged to receive additional care (22% vs 5%, P < 0.001) and to die of their injuries (3.8% vs 0.9%, P < 0.001). When adjusting for other factors associated with poor outcomes, sternal fracture was not an independent predictor of mortality or discharge to care.

CONCLUSIONS

Sternal fracture is a severe injury in the pediatric population, but it is not independently associated with need for a higher level of care after discharge or mortality.

Comparison of polyetheretherketone cables and stainless steel wires for sternal fixation after median sternotomy

Objective

To compare the sternal fixation effect of a polyetheretherketone (PEEK) cable product and stainless steel wire after median sternotomy.

Methods

A multicentre retrospective clinical trial was conducted in patients that underwent median sternotomy for a range of surgical reasons. The sternum was fixed using PEEK sternal cables in the experimental group and stainless steel wires in the control group. The general patient state, product manoeuvrability, bone and wound healing state and blood test results were evaluated at seven visits during the preoperative, surgical and follow-up periods.

Results

A total of 108 patients (54 in each group) were included in the analysis at the final 180-day follow-up. The sternum was successfully closed using PEEK cables or steel wires in all patients and all healed well. No pathological changes were found on the X-ray imaging. Computed tomography imaging confirmed ideal fracture healing. No significant difference was found between the experimental group and the control group in outcomes.

Conclusion

PEEK cables are easy to implant and show desirable effectiveness in sternal fixation without any observed side-effects.

Predicting pelvis geometry using a morphometric model with overall anthropometric variables

Pelvic fractures have been identified as the second most common AIS2+ injury in motor vehicle crashes, with the highest early mortality rate compared to other orthopaedic injuries. Further, the risk is associated with occupant sex, age, stature and body mass index (BMI). In this study, clinical pelvic CT scans from 132 adults (75 females, 57 males) were extracted from a patient database. The population shape variance in pelvis bone geometry was studied by Sparse Principal Component Analysis (SPCA) and a morphometric model was developed by multivariate linear regression using overall anthropometric variables (sex, age, stature, BMI). In the analysis, SPCA identified 15 principal components (PCs) describing 83.6% of the shape variations. Eight of these were significantly captured (α < 0.05) by the morphometric model, which predicted 29% of the total variance in pelvis geometry. The overall anthropometric variables were significantly related to geometrical features primarily in the inferior-anterior regions while being unable to significantly capture local sacrum features, shape and position of ASIS and lateral tilt of the iliac wings. In conclusion, a new detailed morphometric model of the pelvis bone demonstrated that overall anthropometric variables account for only 29% of the variance in pelvis geometry. Furthermore, variations in the superior-anterior region of the pelvis, with which the lap belt is intended to interact, were not captured. Depending on the scenario, shape variations not captured by overall anthropometry could have important implications for injury prediction in traffic safety analysis.

The pattern of duck sternal ossification and the changes of histological structure and gene expression therein

As the largest single bone, avian sterna are very different from those of mammals in terms of morphology and functions. Moreover, years of artificial selection in poultry led to incomplete sternal ossification at slaughter age, which may cause diseases, sternal injury, and restriction to breast muscle growth. However, in living birds, studies have rarely described the ossification pattern and underlying mechanisms of the sterna. Here, we examined the pattern (timeline, ossification centers, ossification directions, weekly changes of different parts, quantified differences in ossification degree among sexes and parts) and developmental changes (histological structure, gene expression) of postnatal duck sternal ossification. Direct observation and alcian blue and alizarin red staining of whole sterna samples revealed that, duck sterna mainly ossified during 5 to 9 wk old with five ossification centers. These centers and their ossification directions were different from and more complex than the previously studied birds. The weekly changes of sterna and the quantitative analysis of ossification-related traits showed that ossifications in the three parts of duck sterna (sternum body, keel, posterolateral processes) were mutually independent in space and time, meanwhile, the male duck sterna were more late-maturing than the female. The results of hematoxylin-eosin, alcian blue, and toluidine blue stainings and the expression levels of COL2A1, COL10A1, COL1A2, and CTSK together supported that, duck sternal ossification was highly similar to typical endochondral ossification. Furthermore, continuously high expression of MMP13 and SPARC and their significant (P < 0.05) co-expression with COL2A1, COL10A1, COL1A2, and CTSK suggested the importance of MMP13 and SPARC in duck sternal ossification. Taken together, our results may be helpful for the understanding of avian sternal ossification and the improvement of the performance and welfare of poultry from a new perspective.

Morphology and growth of the pediatric lumbar vertebrae

BACKGROUND CONTEXT

The majority of existing literature describing pediatric lumbar vertebral morphology are limited to characterization of the vertebral bodies, pedicles, and spinal canal and no study has described the rates of growth for any lumbar vertebral structure. While it is known that growth of the lumbar vertebrae results in changes in vertebral shape, the dimension ratios used to quantify these shape changes do not represent the 3D morphology of the vertebral structures. Additionally, many of the previous evaluations of growth and shape are purely descriptive and do not investigate sexual dimorphism or variations across vertebral levels.

PURPOSE

This study aims to establish a database of pediatric lumbar vertebra dimension, growth, and shape data for subjects between and ages of 1 and 19 years.

STUDY DESIGN

A retrospective study of computed tomography (CT) data.

METHODS

Retrospective, abdominal, CT scans of 102 skeletally normal pediatric subjects (54 males, 48 females) between the ages of 1 and 19 years were digitally reconstructed and manually segmented. Thirty surface landmark points (LMPs), 30 vertebral measurements, the centroid size, centroid location, and the local orientation were collected for each lumbar vertebra along with the centroid size of the LMPs comprising each subject's full lumbar spine and their intervertebral disc (IVD) heights. Nonparametric statistics were used to compare dimension values across vertebral levels and between sexes. Linear models with age as the independent variable were used to characterize dimension growth for each sex and vertebral level. Age-dependent quadratic equations were fit to LMP distributions resulting from a generalized Procrustes analysis (GPA) of the vertebrae and fixed effects models were used to investigate differences in model coefficients across levels and between sexes.

RESULTS

Intervertebral level dimension differences were observed across all vertebral structures in both sexes while pedicle widths and IVDs heights were the only measurements found to be sexually dimorphic. Dimension growth rates generally varied across vertebral levels and the growth rates of males were typically larger than those of females. Differences between male and female vertebral shapes were also found for all lumbar vertebral structures.

CONCLUSIONS

To the authors' knowledge, this is the first study to report growth rates for the majority of pediatric lumbar vertebral structures and the first to describe the 3D age-dependent shapes of the pediatric lumbar spine and vertebrae. In addition to providing a quantitative database, the dimension, growth, and shape data reported here would have applications in medical device design, surgical planning, surgical training, and biomechanical modeling.

Development, validation, and pilot MRI safety study of a high-resolution, open source, whole body pediatric numerical simulation model

Numerical body models of children are used for designing medical devices, including but not limited to optical imaging, ultrasound, CT, EEG/MEG, and MRI. These models are used in many clinical and neuroscience research applications, such as radiation safety dosimetric studies and source localization. Although several such adult models have been reported, there are few reports of full-body pediatric models, and those described have several limitations. Some, for example, are either morphed from older children or do not have detailed segmentations. Here, we introduce a 29-month-old male whole-body native numerical model, "MARTIN", that includes 28 head and 86 body tissue compartments, segmented directly from the high spatial resolution MRI and CT images. An advanced auto-segmentation tool was used for the deep-brain structures, whereas 3D Slicer was used to segment the non-brain structures and to refine the segmentation for all of the tissue compartments. Our MARTIN model was developed and validated using three separate approaches, through an iterative process, as follows. First, the calculated volumes, weights, and dimensions of selected structures were adjusted and confirmed to be within 6% of the literature values for the 2-3-year-old age-range. Second, all structural segmentations were adjusted and confirmed by two experienced, sub-specialty certified neuro-radiologists, also through an interactive process. Third, an additional validation was performed with a Bloch simulator to create synthetic MR image from our MARTIN model and compare the image contrast of the resulting synthetic image with that of the original MRI data; this resulted in a "structural resemblance" index of 0.97. Finally, we used our model to perform pilot MRI safety simulations of an Active Implantable Medical Device (AIMD) using a commercially available software platform (Sim4Life), incorporating the latest International Standards Organization guidelines. This model will be made available on the Athinoula A. Martinos Center for Biomedical Imaging website.

Effect of internal fixation of the sternum using bioabsorbable pins in small children

OBJECTIVES

A sternal pin can be used to internally fix the reapproximated sternum after midline sternotomy. This paper will evaluate the effectiveness of using a sternal pin in small children by means of a computer tomography scan.

METHODS

Propensity score matching was performed for patients undergoing a first-time median sternotomy from April 2012 to December 2014 with a follow-up computer tomography scan after 6 months. Seventeen matched patients were selected for both the control and the sternal pin groups. The angle of the sternal reflection at the joint surface was measured by computer tomography scan. In addition, the Haller index was measured at each thoracic vertebral level.

RESULTS

The angle of the sternal reflection was more variable in the control group compared with the sternal pin group: the standard deviation was 31.6° for the control group and 10.2° for the sternal pin group (P value = .0009). Seven out of 17 patients in the control group had a negative angle (excavated sternum) compared with 1 out of 17 in the sternal pin group (P = .0391). In the other patients, the angle was 23.9° ± 3.6° in the control group and 10.1 ± 2.8 in the sternal pin group (P = .0061). The Haller index was also more variable in the control group, and it was significantly different from the sternal pin group at the ninth vertebral level (P = .0409).

CONCLUSIONS

The study demonstrated that the use of a sternal pin was associated with decreased variation in the sternal angles and decreased incidence and severity of sternal protrusion and excavation in small children.

Effect of gender on the biodynamic responses to vibration induced by a whole-body vibration training machine

Whole-body vibration training machines are used by both male and female users. However, studies investigating the biodynamic responses to vibration during training have used either mixed-gender subjects or male subjects. No study has investigated the effect of gender on the biodynamic responses under vibration training conditions. The objective of this study is to investigate the effect of gender on the apparent mass and the vibration of the head of standing people during exposure to vibration. A total of 40 subjects (20 females and 20 males) were exposed to vertical vibration at six frequencies in the range 20-45 Hz and vibration acceleration in the range 10.8-20.9 m/s² (peak). The subjects stood on a force platform mounted on the vibrating plate of the machine adopting an upright standing posture with their knees unlocked and their arms straight along their bodies. The vertical acceleration and force at the interface between the vibrating plate and the feet were measured and used to calculate the apparent mass. The accelerations of the head in the x-, y- and z-directions were also measured and used to calculate the transmissibility to the head. The apparent mass of males was found higher than that of females. The transmissibility to the head in all directions was found higher in females than males. The differences in the biodynamic responses between males and females were attributed to the differences in body properties and structure of the two genders. The results of this study imply the need for gender-specific vibration training programmes.

Development and Validation of an Age-Specific Lower Extremity Finite Element Model for Simulating Pedestrian Accidents

The objective of the present study is to develop an age-specific lower extremity finite element model for pedestrian accident simulation. Finite element (FE) models have been used as a versatile tool to simulate and understand the pedestrian injury mechanisms and assess injury risk during crashes. However, current computational models only represent certain ages in the population, the age spectrum of the pedestrian victims is very large, and the geometry of anatomical structures and material property of the lower extremities changes with age for adults, which could affect the injury tolerance, especially in at-risk populations such as the elderly. The effects of age on the material mechanical property of bone and soft tissues of the lower extremities as well as the geometry of the long bone were studied. Then an existing 50th percentile male pedestrian lower extremity model was rebuilt to depict lower extremity morphology for 30- to 70-year-old (YO) individuals. A series of PMHS tests were simulated to validate the biofidelity and stability of the created age-specific models and evaluate the lower extremity response. The development of age-specific lower extremity models will lead to an improved understanding of the pedestrian lower extremity injury mechanisms and injury risk prediction for the whole population in vehicle-pedestrian collision accidents.

Age-related changes in thoracic skeletal geometry of elderly females

OBJECTIVE

Both females and the elderly have been identified as vulnerable populations with increased injury and mortality risk in multiple crash scenarios. Particularly in frontal impacts, older females show higher risk to the chest and thorax than their younger or male counterparts. Thoracic geometry plays a role in this increase, and this study aims to quantify key parts of that geometry in a way that can directly inform human body models that incorporate the concept of person age.

METHODS

Computed tomography scans from 2 female subject groups aged 20-35 and 65-99 were selected from the International Center for Automotive Medicine scan database representing young and old female populations. A model of thoracic skeletal anatomy was built for each subject from independent parametric models of the spine, ribs, and sternum, along with further parametric models of those components' spatial relationships. Parameter values between the 2 groups are directly compared, and average parameter values within each group are used to generate statistically average skeletal geometry for young and old females. In addition to the anatomic measures explicitly used in the parameterization scheme, key measures of rib cage depth and spine curvature are taken from both the underlying subject pool and from the resultant representative geometries.

RESULTS

Statistically significant differences were seen between the young and old groups' spine and rib anatomic components, with no significant differences in local sternal geometry found. Vertebral segments in older females had higher angles relative to their inferior neighbors, providing a quantification of the kyphotic curvature known to be associated with age. Ribs in older females had greater end-to-end span, greater aspect ratio, and reduced out-of-plane deviation, producing an elongated and overall flatter curvature that leads to distal rib ends extending further anteriorly in older individuals. Combined differences in spine curvature and rib geometry led to an 18-mm difference in anterior placement of the sternum between young and old subjects.

CONCLUSIONS

This study provides new geometric data regarding the variability in anthropometry of adult females with age and has utility in advancing the veracity of current human body models. A simplified scaffold representation of underlying 3-dimensional bones within the thorax is presented, and the reported young and old female parameter sets can be used to characterize the anatomic differences expected with age and to both validate and drive morphing algorithms for aged human body models. The modular approach taken allows model parameters to hold inherent and intuitive meaning, offering advantages over more generalized methods such as principal component analysis. Geometry can be assessed on a component level or a whole thorax level, and the parametric representation of thorax shape allows direct comparisons between the current study and other individuals or human body models.

Forensic age estimation by morphometric analysis of the manubrium from 3D MR images

Forensic age estimation research based on skeletal structures focuses on patterns of growth and development using different bones. In this work, our aim was to study growth-related evolution of the manubrium in living adolescents and young adults using magnetic resonance imaging (MRI), which is an image acquisition modality that does not involve ionizing radiation. In a first step, individual manubrium and subject features were correlated with age, which confirmed a statistically significant change of manubrium volume (M_vol:p<0.01, R²¯=0.50) and surface area (M_sur:p<0.01, R²¯=0.53) for the studied age range. Additionally, shapes of the manubria were for the first time investigated using principal component analysis. The decomposition of the data in principal components allowed to analyse the contribution of each component to total shape variation. With 13 principal components, ∼96% of shape variation could be described (M_shp:p<0.01, R²¯=0.60). Multiple linear regression analysis modelled the relationship between the statistically best correlated variables and age. Models including manubrium shape, volume or surface area divided by the height of the subject (Y∼M_shpM_sur/S_h:p<0.01, R²¯=0.71; Y∼M_shpM_vol/S_h:p<0.01, R²¯=0.72) presented a standard error of estimate of two years. In order to estimate the accuracy of these two manubrium-based age estimation models, cross validation experiments predicting age on held-out test sets were performed. Median absolute difference of predicted and known chronological age was 1.18 years for the best performing model (Y∼M_shpM_sur/S_h:p<0.01, R_p²=0.67). In conclusion, despite limitations in determining legal majority age, manubrium morphometry analysis presented statistically significant results for skeletal age estimation, which indicates that this bone structure may be considered as a new candidate in multi-factorial MRI-based age estimation.

Frequency of sternal variations in living individuals

PURPOSE

To evaluate the variations of the sternum and provide the prevalence of sternal foramen and its anatomical relationships.

METHODS

In this retrospective study, 544 subjects ranging in age from 18 to 95 years were evaluated. Sternal variations, prevalence of sternal foramen and its anatomical relationships to mediastinal structures were examined with the axial, sagittal and coronal reformat images of the patients who underwent thoracic computerized tomography.

RESULTS

In 500 subjects, following sternal variations were found: sternal sclerotic band in 120 (24%), sternal cleft in 3 (0.6%), sternal foramen in 26 (5.2%), focal cortical notch and defect in 44 (8.8%) patients. The manubriosternal fusion was partial in 65 (13%) patients and complete in 112 (22.4%) patients. The sternoxiphoid fusion was partial in 201 (40.2%) and complete in 153 (30.6%) patients. There was no xiphoid process in 9 patients (1.8%; 29-51 years; mean age 38 years). Xiphoidal ending types were as follows: single-ended 361 (72.2%), double-ended 125 (25%), and triple-ended xiphoid 5 (1%) patients. The sternal foramen was adjacent to the lung in 13 (2.6%), to the pericardium of heart in 3 (0.6%), and to mediastinal fat in 10 (2%) patients.

CONCLUSION

The sternum is a very critical anatomic structure of the anterior chest wall with several variations that can be confused with pathologic conditions. Radiologists' familiarity with these variations is important for better radiologic evaluation in making differential diagnosis.

What are the differences in injury patterns of young and elderly traffic accident fatalities considering death on scene and death in hospital?

Older traffic participants have higher risks of injury than the population up to 65 years in case of comparable road traffic accidents and further, higher mortality rates at comparable injury severities. Rib fractures as risk factors are currently discussed. However, death on scene is associated with hardly survivable injuries and might not be a matter of neither rib fractures nor age. As 60% of traffic accident fatalities are estimated to die on scene, they are not captured in hospital-based trauma registries and injury patterns remain unknown. Our database comprises 309 road traffic fatalities, autopsied at the Institute of Legal Medicine Munich in 2004 and 2005. Injuries are coded according to Abbreviated Injury Scale, AIS© 2005 update 2008 [1]. Data used for this analysis are age, sex, site of death, site of accident, traffic participation mode, measures of injury severity, and rib fractures. The injury patterns of elderly, aged 65+ years, are compared to the younger ones divided by their site of death. Elderly with death on scene more often show serious thorax injuries and pelvic fractures than the younger. Some hints point towards older fatalities showing less frequently serious abdominal injuries. In hospital, elderly fatalities show lower Injury Severity Scores (ISSs) compared to the younger. The number of rib fractures is significantly higher for the elderly but is not the reason for death. Results show that young and old fatalities have different injury patterns and reveal first hints towards the need to analyze death on scene more in-depth.

Role of testosterone and Y chromosome genes for the masculinization of the human brain

Women with complete androgen insensitivity syndrome (CAIS) have a male (46,XY) karyotype but no functional androgen receptors. Their condition, therefore, offers a unique model for studying testosterone effects on cerebral sex dimorphism. We present MRI data from 16 women with CAIS and 32 male (46,XY) and 32 female (46,XX) controls.

METHODS

FreeSurfer software was employed to measure cortical thickness and subcortical structural volumes. Axonal connections, indexed by fractional anisotropy, (FA) were measured with diffusion tensor imaging, and functional connectivity with resting state fMRI.

RESULTS

Compared to men, CAIS women displayed a "female" pattern by having thicker parietal and occipital cortices, lower FA values in the right corticospinal, superior and inferior longitudinal tracts, and corpus callosum. Their functional connectivity from the amygdala to the medial prefrontal cortex, was stronger and amygdala-connections to the motor cortex weaker than in control men. CAIS and control women also showed stronger posterior cingulate and precuneus connections in the default mode network. Thickness of the motor cortex, the caudate volume, and the FA in the callosal body followed, however, a "male" pattern.

CONCLUSION

Altogether, these data suggest that testosterone modulates the microstructure of somatosensory and visual cortices and their axonal connections to the frontal cortex. Testosterone also influenced functional connections from the amygdala, whereas the motor cortex could, in agreement with our previous reports, be moderated by processes linked to X-chromosome gene dosage. These data raise the question about other genetic factors masculinizing the human brain than the SRY gene and testosterone. Hum Brain Mapp 38:1801-1814, 2017. © 2017 Wiley Periodicals, Inc.

Risk factors for thoracic and spinal deformities following lung resection in neonates, infants, and children

Purpose

We aimed to identify the risk factors for thoracic and spinal deformities following lung resection during childhood and to elucidate whether thoracoscopic surgery reduces the risk of complications after lung resection.

Methods

We retrospectively examined the medical records of all pediatric patients who underwent lung resection for congenital lung disease at our institution between 1989 and 2014.

Results

Seventy-four patients underwent lung resection during the study period and were followed-up. The median age of the patients at the time of surgery was 5 months (range 1 day–13 years), and 22 were neonates. Thoracotomy and thoracoscopy were performed in 25 and 49 patients, respectively. Thoracic or spinal deformities occurred in 28 of the 74 patients (37%). Univariate analyses identified thoracotomy, being a neonate (age: <1 month) at the time of surgery, and being symptomatic at the time of surgery as risk factors for these deformities. However, a multivariate analysis indicated that only thoracotomy and being a neonate were risk factors for deformities.

Conclusions

Thoracoscopic surgery reduced the risk of thoracic and spinal deformities following lung resection in children. We suggest that, where possible, lung resection should be avoided until 2 or 3 months of age.

Wing Shape Variation in the Taxonomic Recognition of Species of Diachlorus Osten-Sacken (Diptera: Tabanidae) from Colombia

We evaluated the directional asymmetry between right and left wings and quantified the intraspecific and interspecific variation of the wing shape of 601 specimens of the genus Diachlorus to determine to what extent the geometrical variation discriminates six species distributed in six protected areas of Colombia. Geometric analyses were performed, integrating Procrustes methods, principal component analyses, cluster analyses, linear and quadratic discriminant analyses, and evaluations of shape changes. In Diachlorus, left and right wings did not present significant asymmetry but a geometrical analysis was allowed for species identification and, in some cases, the origin of the specimens using the variation of wing shape; the best-assigned species was Diachlorus leticia Wilkerson & Fairchild, while the worst was Diachlorus jobbinsi Fairchild, which also had the highest intraspecific variation, while Diachlorus fuscistigma Lutz had the lowest variation. Diachlorus fuscistigma and Diachlorus leucotibialis Wilkerson & Fairchild were the most similar species, while D. leucotibialis and Diachlorus nuneztovari Fairchild & Ortiz were the most disimilar. The specimens with the most different wing shape belonged to Chocó (especially those of D. jobbinsi), the geographically farthest area from the others in the study; however, no correlation was observed between geometric and geographical distances. Linear discriminants were better than nonlinear (quadratic) discriminant analyses in predicting species membership, but the opposite was true for predicting area membership. Based on our data, we hypothesized that other species of Diachlorus could also be discriminated using geometric morphometry of the wing shape.

Image segmentation and registration algorithm to collect thoracic skeleton semilandmarks for characterization of age and sex-based thoracic morphology variation

Thoracic anthropometry variations with age and sex have been reported and likely relate to thoracic injury risk and outcome. The objective of this study was to collect a large volume of homologous semilandmark data from the thoracic skeleton for the purpose of quantifying thoracic morphology variations for males and females of ages 0-100 years. A semi-automated image segmentation and registration algorithm was applied to collect homologous thoracic skeleton semilandmarks from 343 normal computed tomography (CT) scans. Rigid, affine, and symmetric diffeomorphic transformations were used to register semilandmarks from an atlas to homologous locations in the subject-specific coordinate system. Homologous semilandmarks were successfully collected from 92% (7077) of the ribs and 100% (187) of the sternums included in the study. Between 2700 and 11,000 semilandmarks were collected from each rib and sternum and over 55 million total semilandmarks were collected from all subjects. The extensive landmark data collected more fully characterizes thoracic skeleton morphology across ages and sexes. Characterization of thoracic morphology with age and sex may help explain variations in thoracic injury risk and has important implications for vulnerable populations such as pediatrics and the elderly.

Age- and sex-specific thorax finite element model development and simulation

OBJECTIVE

The shape, size, bone density, and cortical thickness of the thoracic skeleton vary significantly with age and sex, which can affect the injury tolerance, especially in at-risk populations such as the elderly. Computational modeling has emerged as a powerful and versatile tool to assess injury risk. However, current computational models only represent certain ages and sexes in the population. The purpose of this study was to morph an existing finite element (FE) model of the thorax to depict thorax morphology for males and females of ages 30 and 70 years old (YO) and to investigate the effect on injury risk.

METHODS

Age- and sex-specific FE models were developed using thin-plate spline interpolation. In order to execute the thin-plate spline interpolation, homologous landmarks on the reference, target, and FE model are required. An image segmentation and registration algorithm was used to collect homologous rib and sternum landmark data from males and females aged 0-100 years. The Generalized Procrustes Analysis was applied to the homologous landmark data to quantify age- and sex-specific isolated shape changes in the thorax. The Global Human Body Models Consortium (GHBMC) 50th percentile male occupant model was morphed to create age- and sex-specific thoracic shape change models (scaled to a 50th percentile male size). To evaluate the thoracic response, 2 loading cases (frontal hub impact and lateral impact) were simulated to assess the importance of geometric and material property changes with age and sex.

RESULTS

Due to the geometric and material property changes with age and sex, there were observed differences in the response of the thorax in both the frontal and lateral impacts. Material property changes alone had little to no effect on the maximum thoracic force or the maximum percent compression. With age, the thorax becomes stiffer due to superior rotation of the ribs, which can result in increased bone strain that can increase the risk of fracture. For the 70-YO models, the simulations predicted a higher number of rib fractures in comparison to the 30-YO models. The male models experienced more superior rotation of the ribs in comparison to the female models, which resulted in a higher number of rib fractures for the males.

CONCLUSION

In this study, age- and sex-specific thoracic models were developed and the biomechanical response was studied using frontal and lateral impact simulations. The development of these age- and sex-specific FE models of the thorax will lead to an improved understanding of the complex relationship between thoracic geometry, age, sex, and injury risk.

Evaluation of morphological changes in the adult skull with age and sex

The morphology of the brain and skull are important in the evaluation of the aging human; however, little is known about how the skull may change with age. The objective of this study was to evaluate the morphological changes of the adult skull using three-dimensional geometric morphometric analysis of thousands of landmarks with the focus on anatomic regions that may be correlated with brain atrophy and head injury. Computed tomography data were collected between ages 20 and 100. Each scan was segmented using thresholding techniques. An atlas image of a 50th percentile skull was registered to each subject scan by computing a series of rigid, affine, and non-linear transformations between atlas space and subject space. Landmarks on the atlas skull were transformed to each subject and partitioned into the inner and outer cranial vault and the cranial fossae. A generalized Procrustes analysis was completed for the landmark sets. The coordinate locations describing the shape of each region were regressed with age to generate a model predicting the landmark location with age. Permutation testing was performed to assess significant changes with age. For the males, all anatomic regions reveal significant changes in shape with age except for the posterior cranial fossa. For the females, only the middle cranial fossa and anterior cranial fossa were found to change significantly in shape. Results of this study are important for understanding the adult skull and how shape changes may pertain to brain atrophy, aging, and injury.