Evidence Supporting the Regulatory Relationships through a Paracrine Pathway between the Sternum and Pectoral Muscles in Ducks.

Muscles and bones are anatomically closely linked, and they can conduct communication by mechanical and chemical signals. However, the specific regulatory mechanism between the pectoral muscle and sternum in birds was largely unknown. The present study explored the potential relationship between them in ducks. The result of the sections showed that more nuclei in proliferate states were observed in the pectoral muscle fibers attached to the calcified sternum, than those attached to the un-calcified sternum. The RNA-seq identified 328 differentially expressed genes (DEGs) in the sternum between the calcified and un-calcified groups. Gene ontology (GO) showed that the DEGs were mainly enriched in pathways associated with calcification. In addition, DEGs in the muscles between the calcified and un-calcified sternum groups were mainly annotated to signal transduction receptor pathways. The expression patterns of genes encoding for secreted proteins, in bone (CXCL12, BMP7 and CTSK) and muscle (LGI1), were clustered with muscle development (MB) and bone calcification (KCNA1, OSTN, COL9A3, and DCN) related genes, respectively, indicating the regulatory relationships through a paracrine pathway existing between the sternum and pectoral muscles in ducks. Together, we demonstrated that the pectoral muscle development was affected by the sternal ossification states in ducks. The VEGFA, CXCL12, SPP1, NOG, and BMP7 were possibly the key genes to participate in the ossification of the duck sternum. We firstly listed evidence supporting the regulatory relationships through a paracrine pathway between the sternum and pectoral muscles in ducks, which provided scientific data for the study of the synergistic development of bone and skeletal muscle.

Effect of dietary 25-hydroxycholecalciferol on the sternal mass of meat ducks under different vitamin regimens.

Genetic selection and intensive nutrition for increased growth rate in meat-type ducks has resulted in an imbalance between pectorales increment and sternal mass, which is detrimental to productivity and welfare. Reducing body weight and increasing sternal mass probably reverses these adverse effects. Therefore, 2 experiments (Expt.) were conducted to investigate the effects of 25-hydroxycholecalciferol (25-OH-D3), a vitamin D3 metabolites, on sternal mass. In Expt. 1, 512 1-day-old male ducks were randomly assigned to 4 low-nutrient density diets and received following treatments in a 2 × 2 factorial arrangement: (i) NRC or China Agricultural industry standards (NY/T) vitamin premixes and (ii) 0.069 mg/kg 25-HyD in feed or not. At 49 D of age, regardless of 25-OH-D3, NY/T vitamin regimen inhibited bone turnover and consequently increased sternal trabecular bone volume and mineral deposition compared with NRC vitamin premix. Supplementing 25-OH-D3 to NRC but not NY/T vitamin regimen significantly improved sternal microarchitecture and mineral content, which companied by decreased serum bone resorption markers concentration, as well as downregulation of the gene expressions of osteoclast differentiation and activity. In Expt. 2, 256 1-day-old male ducks were fed a standard nutrient density diet contained NRC vitamin premix with 0 or 0.069 mg/kg of 25-OH-D3. Results also showed that 25-OH-D3 treatment significantly improved sternal mineral accumulation and microarchitecture, along with decreasing osteoblast and osteoclast numbers in bone surface, declining serum bone turnover markers levels, and increasing serum Ca concentration. Collectively, these findings indicated that the dietary administration of 25-OH-D3 increased sternal mass in NRC vitamin diet by suppressing bone resorption in 49-day-old meat duck.

Age estimation from ossification of sternum and true ribs using 3D post-mortem CT images in a Japanese population.

Age estimation of cadavers from post-mortem "chest plate" using conventional radiography, which involves radiographic assessment of ossification around the sternum and rib ends, has been evaluated without fruitful results. This study examined the value of images of the chest plate obtained by three-dimensional post-mortem CT for estimation of age at time of death in a Japanese population. Five chest plate ossification scores were evaluated in 320 subjects, including ossification of the first costal cartilage (OF), ossification of the second to seventh costal cartilages at the rib (OR) and sternal (OS) ends, fusion of the manubriosternal joint (FM), and fusion of the xiphisternal joint (FX). OS was found to have the highest correlation with age while FM had no significant correlation. The best composite score for age estimation was the summative score for both sides of the OS and the right side of the OF and FX, for which the coefficient of determination (R2) and the standard error of estimation (SEE) were 0.608 and 12.44 years, respectively, for men and 0.590 and 14.65 years for women. The accuracy of the model was tested in a further 26 male and 24 female subjects, and the accuracy rate within the first SEE was 57.69% and 70.83%, respectively. This rapid and non-invasive method of age estimation in the chest plate area is superior to conventional methods and could be useful for estimation of age at time of death in the Japanese population.

Frontal crash seat belt restraint effectiveness and comfort accessories used by older occupants.

Objective: Around a quarter of older occupants use some type of comfort or orthopedic aftermarket accessory on the vehicle seat while traveling in a vehicle. The aim of this study was to investigate the effect of comfort accessories on the performance of the seat belt restraint system in a frontal crash in terms of potential injury implications for older occupants.Methods: Eight frontal sled tests (43 km/h, 32 g) were carried out on a deceleration sled fitted with a three-point lap-sash seat belt and a front passenger seat from a common Australian passenger car for each test. A 5th percentile Hybrid III anthropometric test device (ATD) was positioned in the seat and measurements were recorded for head center of gravity acceleration, chest acceleration, neck forces and moments and sternal deflection. Tests were carried out in a baseline condition and with seven comfort accessories. Each comfort accessory was inserted between the ATD and vehicle seat as it is intended to be used, with the ATD otherwise positioned as close as possible to the baseline test position.Results: Initial distance between the seat belt anchor and ATD hip was associated with a statistically significant decrease in Head Injury Criterion and increase in sternal deflection. Submarining was related to the ATD torso recline angle and angle of the lap belt from the seat belt anchor.Conclusions: Accessories placed between the seat back and the lumbar region of an occupant have the potential to increase the risk of submarining due to a change in posture and should be avoided if such a change in posture when seated with an accessory is excessive. Sitting on seat cushions resulted in the greatest increase in seat belt anchor to hip distances and hence largest increase in sternal deflection. Given the fragility, frailty and particular importance of chest injuries among older vehicle occupants, further investigation is needed to determine whether these changes in ATD sternal deflection observed with seat cushion use results in injury threshold limits being exceeded and whether pretensioners and load limiters would ameliorate these effects without causing other negative changes in occupant response or kinematics.

In vitro analysis of kinematics and elastostatics of the human rib cage during thoracic spinal movement for the validation of numerical models.

Neither kinematic nor stiffness properties of the rib cage during thoracic spinal motion were investigated in previous studies, while being essential for the accurate validation of numerical models of the whole thorax. The aim of this in vitro study therefore was to quantify the kinematics and elastostatics of the human rib cage under defined boundary conditions. Eight fresh frozen human thoracic spine specimens (C7-L1, median age 55 years, ranging from 40 to 60 years) including entire rib cages were loaded quasi-statically in flexion/extension, lateral bending, and axial rotation using pure moments of 5Nm. Relative motions of ribs, thoracic vertebrae, and sternal structures as well as strains on the ribs were measured using optical motion tracking of 150 reflective markers per specimen, while specimens were loaded displacement-controlled with a constant rate of 1°/s for 3.5 cycles. The third full cycle was used to determine relative angles and strains at full loading of the spine for all motion directions. Largest relative angles were found in the main loading directions with only small motions at the mid-thoracic levels. Highest strains of the intercostal spaces were detected in the anterior section of the lowest fourth of the rib cage, showing compressions and elongations of more than 10% in all spinal motion planes. Elastostatic rib deformation was generally less than 1%. Rib-sternum relative motions exhibited complex motion patterns, overall showing relative angles below 2°. The results indicate that rib cage structures are not macroscopically deformed during spinal motion, but exhibit characteristic reproducible kinematics patterns.

The Effect of Smoking on Sternal Scar Healing: A Prospective Cohort Study.

INTRODUCTION: Cardiothoracic surgery with a median sternotomy is an electing factor for the development of a hypertrophic scar. Hypertrophic scars, characterized by an increased vascularity, often result in aesthetic and functional problems. Smoking, due to its negative effects on vascularization, could therefore have an effect on scar healing. OBJECTIVE: A prospective cohort study was conducted to evaluate the effect of smoking on scar healing after cardiothoracic surgery with a median sternotomy incision. MATERIALS AND METHODS: One hundred patients who underwent cardiac surgery with a median sternotomy were divided into 3 groups: smokers, ex-smokers, and nonsmokers. Erythema values of the scar were measured with a colorimeter on 3 standardized parts of the scar. Scar evaluation was performed at 6 weeks, 3 months, 6 months, and 12 months after surgery. RESULTS: During 1 year, a total of 90 patients were followed after a median sternotomy; 10 patients were lost to follow-up. There were 23 smokers, 52 ex-smokers, and 15 nonsmokers with an overall mean age of 61.5 ± 8.83 years. No significant difference in redness as a parameter for hypertrophic scarring was observed between the 3 groups. Nevertheless, a trend in favor of the smokers was seen, as they developed less hyperemic scars. The caudal part of the scar showed a significantly higher incidence of hypertrophy compared with the middle and cranial part of the scar at all time points. CONCLUSIONS: It is presumed that a large sample size with younger patients is needed to confirm the results herein. Furthermore, more caudally located skin, especially the subxiphoidal part, is prone to hypertrophic scarring and should, for that reason, be avoided in the incision.

Alligator mississippiensis sternal and shoulder girdle mobility increase stride length during high walks.

Crocodilians have played a significant role in evolutionary studies of archosaurs. Given that several major shifts in forelimb function occur within Archosauria, forelimb morphologies of living crocodilians are of particular importance in assessing locomotor evolutionary scenarios. A previous X-ray investigation of walking alligators revealed substantial movement of the shoulder girdle, but as the sternal cartilages do not show up in X-ray, the source of the mobility could not be conclusively determined. Scapulocoracoid movement was interpreted to indicate independent sliding of each coracoid at the sternocoracoid joint; however, rotations of the sternum could also produce similar displacement of the scapulocoracoids. Here, we present new data employing marker-based XROMM (X-ray reconstruction of moving morphology), wherein simultaneous biplanar X-ray video and surgically implanted radio-opaque markers permit precise measurement of the vertebral axis, sternum and coracoid in walking alligators. We found that movements of the sternum and sternocoracoid joint both contribute to shoulder girdle mobility and stride length, and that the sternocoracoid contribution was less than previously estimated. On average, the joint contributions to stride length (measured with reference to a point on the distal radius, thus excluding wrist motion) are as follows: thoracic vertebral rotation 6.2±3.7%, sternal rotation 11.1±2.5%, sternocoracoid joint 10.1±5.2%, glenohumeral joint 40.1±7.8% and elbow 31.1±4.2%. To our knowledge, this is the first evidence of sternal movement relative to the vertebral column (presumably via rib joints) contributing to stride length in tetrapods.

Evaluation of Control Interfaces for Active Trunk Support.

A feasibility study was performed to evaluate the control interfaces for a novel trunk support assistive device (Trunk Drive), namely, joystick, force on sternum, force on feet, and electromyography (EMG) to be used by adult men with Duchene muscular dystrophy. The objective of this paper was to evaluate the performance of the different control interfaces during a discrete position tracking task. We built a one degree of freedom flexion-extension active trunk support device that was tested on 10 healthy men. An experiment, based on the Fitts law, was conducted, whereby subjects were asked to steer a cursor representing the angle of the Trunk Drive into a target that was shown on a graphical user interface, using the above-mentioned control interfaces. The users could operate the Trunk Drive via each of the control interfaces. In general, the joystick and force on sternum were the fastest in movement time (more than 40%) without any significant difference between them, but there was a significant difference between force on sternum on the one hand, and EMG and force on feet on the other. All control interfaces proved to be feasible solutions for controlling an active trunk support, each of which had specific advantages.

A study on the sternum growth and mineralization kinetic of meat duck from 35 to 63 days of age.

The sternum as an important part of the skeleton and not only provides a crucial attachment site for the pectoral muscles and protects internal organs such as the heart and lungs for meat duck, but may also be considered as the primary ventilator in the avian respiratory system. Therefore, this study focuses on the sternum growth and mineralization kinetics of ducks from 35 d to 63 d of age. A total of 72 one-d-old males and 72 females were chosen and fed with the same diet until the age of 9 weeks. The sternum and serum were harvested at 35 d, 42 d, 49 d, 56d, and 63 d of feeding. Results showed that the sternum width rapidly grew from 35 d to 42 d and the value changed little after 42 d, while the keel length and the sternum depth did not significantly change until 49 d age. The sternum defatted weight and density increased assumed to "S" with ducks' age and their plateau in the 56 d. The sternum ash content, calcium (Ca), and phosphate (P) levels increased with duck age, then all three reached a plateau in 49 days. Similarly, serum alkaline phosphatase (ALP) activity was higher in the ducks at both 35 and 42 days, followed by 49 days, and the value was lowered to a minimum on both days 56 and 63. Conversely, serum tartrate resistant acid phosphatase (TRAP) activity substantially increased until 49 days irrespective of duck gender. Results indicate that the dimensions of the sternum were already at the maximum in 49-day-old ducks and the sternum of the ducks rapidly mineralized from 42 d to 49 d of age and achieved a plateau phase after 49-days resulting from the high activity of ALP at the sternum early mineralization.

In-vivo analysis of sternal angle, sternal and sternocostal kinematics in supine humans during breathing.

This paper aims at contributing to the understanding of the combination of in vivo sternum displacement, sternal angle variations and sternocostal joints (SCJ) kinematics of the seven first rib pairs over the inspiratory capacity (IC). Retrospective codified spiral-CT data obtained at total lung capacity (TLC), middle of inspiratory capacity (MIC) and at functional residual capacity (FRC) were used to compute kinematic parameters of the bones and joints of interest in a sample of 12 asymptomatic subjects. 3D models of rib, thoracic vertebra, manubrium and sternum were processed to determine anatomical landmarks (ALs) on each bone. These ALs were used to create local coordinate system and compute spatial transformation of ribs and manubrium relative to sternum, and sternum relative to thoracic vertebra. The rib angular displacements and associated orientation of rotation axes and joint pivot points (JPP), the sternal angle variations and the associated displacement of the sternum relative to vertebra were computed between each breathing pose at the three lung volumes. Results can be summarized as following: (1) sternum cephalic displacement ranged between 17.8 and 19.2mm over the IC; (2) the sternal angle showed a mean variation of 4.4°±2.7° over the IC; (3) ranges of rib rotation relative to sternum decreased gradually with increasing rib level; (4) axes of rotation were similarly oriented at each SCJ; (5) JPP spatial displacements showed less variations at first SCJ compared to levels underneath; (6) linear relation was demonstrated between SCJ ROMs and sternum cephalic displacement over the IC.

Effects of enhancing vitamin D status by 25-hydroxycholecalciferol supplementation, alone or in combination with calcium and phosphorus, on sternum mineralisation and breast meat quality in broilers.

1. The aim of the present study was to examine the effects of improving vitamin D status in broiler diets by supplementary 25-hydroxycholecalciferol (25OHD3), alone or in combination with calcium (Ca) and available phosphorus (aP), on live performance, sternum mineralisation and breast meat quality in broilers. 2. A total of 936 1-d-old Ross 308 broilers were used in the study. After gender determination at the hatchery, chicks from each sex were randomly distributed into three dietary treatments. The following dietary treatments were used in the experiment from hatch to 38 d: (1) A control diet formulated to meet all of the nutrient requirements of broiler chicks according to the management guide; (2) The control diet supplemented with 18.7-15.0 µg/kg of 25OHD3; and (3) The control diet supplemented with 18.7-15.0 µg/kg of 25OHD3 plus Ca + aP. 3. Improvement in vitamin D status by 25OHD3 supplementation, alone or in combination with Ca and aP, had no effect on body weight and feed conversion ratio of broilers. 4. The serum 25OHD3 concentration significantly increased with 25OHD3 and 25OHD3 plus Ca + aP supplementation (P < 0.05), whereas the ionised Ca and Mg concentrations remained unchanged. 5. Sternum absolute weight, ash content and the concentrations of Ca and P significantly increased (P < 0.01) with supplementation of 25OHD3, alone or in combination with Ca + aP. 6. Supplemental 25OHD3, alone or in combination with Ca + aP, slightly increased pH24 (P = 0.05) and decreased (P < 0.01) squeezable water loss in breast meat, whereas it had no significant effect on lightness, yellowness and sarcoplasmic protein solubility. 7. In conclusion, the results suggested that enhancing vitamin D status by 25OHD3 supplementation alone or in combination with Ca + aP may improve sternum structure and mineral accretion. Furthermore, supplemental 25OHD3, even in a nutritionally complete diet, may offer an effective way to improve protein solubility in female broilers.

Procedure to describe clavicular motion.

BACKGROUND: For many years, researchers have attempted to describe shoulder motions by using different mathematical methods. The aim of this study was to describe a procedure to quantify clavicular motion. METHODS: The procedure proposed for the kinematic analysis consists of 4 main processes: 3 transcortical pins in the clavicle, motion capture, obtaining 3-dimensional bone models, and data processing. RESULTS: Clavicular motion by abduction (30° to 150°) and flexion (55° to 165°) were characterized by an increment of retraction of 27° to 33°, elevation of 25° to 28°, and posterior rotation of 14° to 15°, respectively. In circumduction, clavicular movement described an ellipse, which was reflected by retraction and elevation. Kinematic analysis shows that the articular surfaces move by simultaneously rolling and sliding on the convex surface of the sternum for the 3 movements of abduction, flexion, and circumduction. CONCLUSION: The use of 3 body landmarks in the clavicle and the direct measurement of bone allowed description of the osteokinematic and arthrokinematic movement of the clavicle.

Comparisons of bone properties and keel deformities between strains and housing systems in end-of-lay hens.

Susceptibility of caged layers to osteoporosis and cage layer fatigue has generated interest in newer housing systems that favor increased load-bearing activities. However, high incidences of fractures incurred during lay period have been reported in these newer systems. This study is aimed at determining the housing and strain effects on bone properties: dry weight, percentage ash content, cortical density (CBD), cortical thickness (CBT), and keel bone deformities. Tibia, femur, and keel from Hy-Line Brown (HB), Hy-Line Silver Brown (SB), and Barred Plymouth Rock (BR) hens housed in conventional cages (CC), cage-free (CF), and cage-free with range (outdoor access; R) were studied. At 78 wk, 60 hens from each strain and housing system combination were euthanized and bones were excised for analysis. Quantitative computed tomography (QCT) was used to measure CBD and CBT in each bone. Three-dimensional images of keels were generated from software using QCT scans to analyze the deformities. Tibiae CBT was greater (P < 0.01) in BR compared to other two strains. Between housing systems, CBT was greater (P < 0.05) for mid and distal tibia of R and CF compared to CC. Tibiae and femoral cortex were denser (P < 0.05) in BR compared to HB and SB. There was no effect of housing system for femur CBD, but CBD was greater (P < 0.05) for middle and distal tibia of birds housed in R compared to CC. CBD for keel bone was greater (P < 0.05) in CF and R birds compared to CC birds. The housing system did not influence the dry bone weight and ash percentage of tibiae and femur. Each housing system was associated with high prevalence (>90%) of keel deformities and the housing and genotype influenced the type of deformity. These findings indicate that range and cage-free housing may have beneficial impact on tibia and keel bone integrity compared to conventional cages but the improvement may not be sufficient to prevent fractures or deformities of keel.

Combined exposure to big endothelin-1 and mechanical loading in bovine sternal cores promotes osteogenesis.

Increased bone formation resulting from mechanical loading is well documented; however, the interactions of the mechanotransduction pathways are less well understood. Endothelin-1, a ubiquitous autocrine/paracrine signaling molecule promotes osteogenesis in metastatic disease. In the present study, it was hypothesized that exposure to big endothelin-1 (big ET1) and/or mechanical loading would promote osteogenesis in ex vivo trabecular bone cores. In a 2×2 factorial trial of daily mechanical loading (-2000µÎµ, 120cycles daily, "jump" waveform) and big ET1 (25ng/mL), 48 bovine sternal trabecular bone cores were maintained in bioreactor chambers for 23days. The bone cores' response to the treatment stimuli was assessed with percent change in core apparent elastic modulus (ΔEapp), static and dynamic histomorphometry, and prostaglandin E2 (PGE2) secretion. Two-way ANOVA with a post hoc Fisher's LSD test found no significant treatment effects on ΔEapp (p=0.25 and 0.51 for load and big ET1, respectively). The ΔEapp in the "no load + big ET1" (CE, 13±12.2%, p=0.56), "load + no big ET1" (LC, 17±3.9%, p=0.14) and "load + big ET1" (LE, 19±4.2%, p=0.13) treatment groups were not statistically different than the control group (CC, 3.3%±8.6%). Mineralizing surface (MS/BS), mineral apposition (MAR) and bone formation rates (BFR/BS) were significantly greater in LE than CC (p=0.037, 0.0040 and 0.019, respectively). While the histological bone formation markers in LC trended to be greater than CC (p=0.055, 0.11 and 0.074, respectively) there was no difference between CE and CC (p=0.61, 0.50 and 0.72, respectively). Cores in LE and LC had more than 50% greater MS/BS (p=0.037, p=0.055 respectively) and MAR (p=0.0040, p=0.11 respectively) than CC. The BFR/BS was more than two times greater in LE (p=0.019) and LC (p=0.074) than CC. The PGE2 levels were elevated at 8days post-osteotomy in all groups and the treatment groups remained elevated compared to the CC group on days 15, 19 and 23. The data suggest that combined exposure to big ET1 and mechanical loading results in increased osteogenesis as measured in biomechanical, histomorphometric and biochemical responses.

cVEMP morphology changes with recording electrode position, but single motor unit activity remains constant.

Cervical vestibular evoked myogenic potentials (cVEMPs) recorded over the lower quarter of the sternocleidomastoid (SCM) muscle in normal subjects may have opposite polarity to those recorded over the midpoint. It has thus been suggested that vestibular projections to the lower part of SCM might be excitatory rather than inhibitory. We tested the hypothesis that the SCM muscle receives both inhibitory and excitatory vestibular inputs. We recorded cVEMPs in 10 normal subjects with surface electrodes placed at multiple sites along the anterior (sternal) component of the SCM muscle. We compared several reference sites: sternum, ipsilateral and contralateral earlobes, and contralateral wrist. In five subjects, single motor unit responses were recorded at the upper, middle, and lower parts of the SCM muscle using concentric needle electrodes. The surface cVEMP had the typical positive-negative polarity at the midpoint of the SCM muscle. In all subjects, as the recording electrode was moved toward each insertion point, p13 amplitude became smaller and p13 latency increased, then the polarity inverted to a negative-positive waveform (n1-p1). Changing the reference site did not affect reflex polarity. There was a significant short-latency change in activity in 61/63 single motor units, and in each case this was a decrease or gap in firing, indicating an inhibitory reflex. Single motor unit recordings showed that the reflex was inhibitory along the entire SCM muscle. The cVEMP surface waveform inversion near the mastoid and sternal insertion points likely reflects volume conduction of the potential occurring with increasing distance from the motor point.

A morphological approach to detect respiratory phases of seismocardiogram.

This paper presents a new approach to identify the respiratory phases of heart cycles from acceleration signals (i.e., seismocardiogram) recorded from the sternum, in back to front direction. The acceleration signals were recorded simultaneously with a single lead electrocardiogram (ECG), and the respiratory signal (using a chest band strain gauge) from 20 healthy subjects. Two accelerometer-derived respiration (ADR) signals were computed by computing the lower and upper envelope of the accelerometer signal. In the proposed methodology, for each subject a metric so-called, the piecewise total harmonic distortion (THD) was used to identify which one of lower and upper envelopes is the best ADR for detecting respiratory phases. The accuracy of piecewise THD in the selection of the correct envelope of SCG signal as an estimation of ADR is 84.6%. Consequently, respiratory phases of heart cycles were identified using the estimated ADR signals. Results confirm that the proposed envelope detection based ADR technique can detect respiratory phases of heartbeats with the accuracy of above 75%. In other words, using aforementioned methods, THD thresholding and piecewise THD, the capability of ADR signal to detect respiratory phases is increased approximately 14% compared to the lower envelope of the accelerometer (ADRLower) and 4% compared to the upper envelope of accelerometer signal (ADRUpper).

Real-World Rib Fracture Patterns in Frontal Crashes in Different Restraint Conditions.

OBJECTIVE: The purpose of this study was to use the detailed medical injury information in the Crash Injury Research and Engineering Network (CIREN) to evaluate patterns of rib fractures in real-world crash occupants in both belted and unbelted restraint conditions. Fracture patterns binned into rib regional levels were examined to determine normative trends associated with belt use and other possible contributing factors. METHODS: Front row adult occupants with Abbreviated Injury Scale (AIS) 3+ rib fractures, in frontal crashes with a deployed frontal airbag, were selected from the CIREN database. The circumferential location of each rib fracture (with respect to the sternum) was documented using a previously published method (Ritchie et al. 2006) and digital computed tomography scans. Fracture patterns for different crash and occupant parameters (restraint use, involved physical component, occupant kinematics, crash principal direction of force, and occupant age) were compared qualitatively and quantitatively. RESULTS: There were 158 belted and 44 unbelted occupants included in this study. For belted occupants, fractures were mainly located near the path of the shoulder belt, with the majority of fractures occurring on the inboard (with respect to the vehicle) side of the thorax. For unbelted occupants, fractures were approximately symmetric and distributed across both sides of the thorax. There were negligible differences in fracture patterns between occupants with frontal (0°) and near side (330° to 350° for drivers; 10° to 30° for passengers) crash principal directions of force but substantial differences between groups when occupant kinematics (and contacts within the vehicle) were considered. Age also affected fracture pattern, with fractures tending to occur more anteriorly in older occupants and more laterally in younger occupants (both belted and unbelted). CONCLUSIONS: Results of this study confirmed with real-world data that rib fracture patterns in unbelted occupants were more distributed and symmetric across the thorax compared to belted occupants in crashes with a deployed frontal airbag. Other factors, such as occupant kinematics and occupant age, also produced differing patterns of fractures. Normative data on rib fracture patterns in real-world occupants can contribute to understanding injury mechanisms and the role of different causation factors, which can ultimately help prevent fractures and improve vehicle safety.

Biofidelity Corridors for Sternum Kinematics in Low-Speed Side Impacts.

OBJECTIVE: Field data show that side impact car crashes have become responsible for a greater proportion of the fatal crashes compared to frontal crashes, which suggests that the protection gained in frontal impact has not been matched in side impact. One of the reasons is the lack of understanding of the torso injury mechanisms in side impact. In particular, the deformation of the rib cage and how it affects the mechanical loading of the individual ribs have yet to be established. Therefore, the objective of this study was to characterize the ribcage deformation in side impacts by describing the kinematics of the sternum relative to the spine. METHODS: The 3D kinematics of the 1st and of the 5th or 6th thoracic vertebrae and of the sternum were obtained for three Post Mortem Human Subjects (PMHS) impacted laterally by a rigid wall traveling at 15 km/h. The experimental data were processed to express the kinematics of the sternum relative to the spine throughout the impact event. Methods were developed to interpolate the kinematics of the vertebrae for which experimental data were not available. RESULTS: The kinematics of the sternocostal junction for ribs 1 to 6 as well as the orientation of the sternum were expressed in the vertebra coordinate systems defined for each upper thoracic vertebra (T1 to T6). Corridors were designed for the motion of the sternum relative to each vertebra. In the experiments, the sternum moved upward for all rib levels (1 to 6), and away from the spine with an amplitude that increased with the decreasing rib level (from rib 1 to rib 6). None of the differences observed in the kinematics could be correlated to the occurrence of rib fractures. CONCLUSIONS: This study provides both qualitative and quantitative information for the ribcage skeletal kinematics in side impact. This data set provides the information required to better evaluate computational models of the thorax for side impact simulations. The corridors developed in this study provide new biofidelity targets for the impact response of the ribcage. This study contributes to augmenting the state of knowledge of the human chest deformation in side impact to better characterize the rib fracture mechanisms.

Injuries in Full-Scale Vehicle Side Impact Moving Deformable Barrier and Pole Tests Using Postmortem Human Subjects.

OBJECTIVE: To conduct near-side moving deformable barrier (MDB) and pole tests with postmortem human subjects (PMHS) in full-scale modern vehicles, document and score injuries, and examine the potential for angled chest loading in these tests to serve as a data set for dummy biofidelity evaluations and computational modeling. METHODS: Two PMHS (outboard left front and rear seat occupants) for MDB and one PMHS (outboard left front seat occupant) for pole tests were used. Both tests used sedan-type vehicles from same manufacturer with side airbags. Pretest x-ray and computed tomography (CT) images were obtained. Three-point belt-restrained surrogates were positioned in respective outboard seats. Accelerometers were secured to T1, T6, and T12 spines; sternum and pelvis; seat tracks; floor; center of gravity; and MDB. Load cells were used on the pole. Biomechanical data were gathered at 20 kHz. Outboard and inboard high-speed cameras were used for kinematics. X-rays and CT images were taken and autopsy was done following the test. The Abbreviated Injury Scale (AIS) 2005 scoring scheme was used to score injuries. RESULTS: MDB test: male (front seat) and female (rear seat) PMHS occupant demographics: 52 and 57 years, 177 and 166 cm stature, 78 and 65 kg total body mass. Demographics of the PMHS occupant in the pole test: male, 26 years, 179 cm stature, and 84 kg total body mass. Front seat PMHS in MDB test: 6 near-side rib fractures (AIS = 3): 160-265 mm vertically from suprasternal notch and 40-80 mm circumferentially from center of sternum. Left rear seat PMHS responded with multiple bilateral rib fractures: 9 on the near side and 5 on the contralateral side (AIS = 3). One rib fractured twice. On the near and contralateral sides, fractures were 30-210 and 20-105 mm vertically from the suprasternal notch and 90-200 and 55-135 mm circumferentially from the center of sternum. A fracture of the left intertrochanteric crest occurred (AIS = 3). Pole test PMHS had one near-side third rib fracture. Thoracic accelerations of the 2 occupants were different in the MDB test. Though both occupants sustained positive and negative x-accelerations to the sternum, peak magnitudes and relative changes were greater for the rear than the front seat occupant. Magnitudes of the thoracic and sternum accelerations were lower in the pole test. CONCLUSIONS: This is the first study to use PMHS occupants in MDB and pole tests in the same recent model year vehicles with side airbag and head curtain restraints. Injuries to the unilateral thorax for the front seat PMHS in contrast to the bilateral thorax and hip for the rear seat occupant in the MDB test indicate the effects of impact on the seating location and restraint system. Posterolateral locations of fractures to the front seat PMHS are attributed to constrained kinematics of occupant interaction with torso side airbag restraint system. Angled loading to the rear seat occupant from coupled sagittal and coronal accelerations of the sternum representing anterior thorax loading contributed to bilateral fractures. Inward bending initiated by the distal femur complex resulting in adduction of ipsilateral lower extremity resulted in intertrochanteric fracture to the rear seat occupant. These results serve as a data set for evaluating the biofidelity of the WorldSID and federalized side impact dummies and assist in validating human body computational models, which are increasingly used in crashworthiness studies.