A First Step Toward a Family of Morphed Human Body Models Enabling Prediction of Population Injury Outcomes

The injury risk in a vehicle crash can depend on occupant specific factors. Virtual crash testing using finite element human body models (HBMs) to represent occupant variability can enable the development of vehicles with improved safety for all occupants. In this study, it was investigated how many HBMs of different sizes that are needed to represent a population crash outcome through a metamodel. Rib fracture risk was used as an example occupant injury outcome. Morphed HBMs representing variability in sex, height, and weight within defined population ranges were used to calculate population variability in rib fracture risk in a frontal and a side crash. Two regression methods, regularized linear regression with second-order terms and Gaussian process regression (GPR), were used to metamodel rib fracture risk due to occupant variability. By studying metamodel predictive performance as a function of training data, it was found that constructing GPR metamodels using 25 individuals of each sex appears sufficient to model the population rib fracture risk outcome in a general crash scenario. Further, by utilizing the known outcomes in the two crashes, an optimization method selected individuals representative for population outcomes across both crash scenarios. The optimization results showed that 5-7 individuals of each sex were sufficient to create predictive GPR metamodels. The optimization method can be extended for more crashes and vehicles, which can be used to identify a family of HBMs that are generally representative of population injury outcomes in future work.

Hot Air Balloon Fatalities in New Mexico: The Forensic Pathology Experience

INTRODUCTION

Albuquerque New Mexico is the "hot air balloon capital of the world," with balloons flying throughout the year and during the Albuquerque International Balloon Fiesta. The medical literature regarding morbidity and mortality in hot air balloon accidents is relatively scarce.

METHODS

A series of fatal, hot air balloon accidents were identified by querying and analyzing the databases of the Office of the Medical Investigator in New Mexico from 1972 to 2021.

RESULTS

Twenty-one lethal cases from 11 hot air balloon accidents were evaluated. Fifty-seven percent of decedents were male, the age range was 29 to 74 years, and all the decedents were White. Causes of death were certified as multiple injuries (52.4%), blunt trauma (42.9%), and electrocution (4.76%). The manner of death was accidental in all cases. Most common autopsy findings were rib fractures (100%), pelvic fractures (81.8%), and subarachnoid hemorrhage (72.7%). October was the month with the most accidents (63.63%), the most common cause was the pilot's failure to maintain clearance from obstacles (14.3%), and the most frequent collision was with power lines (63.6%).

CONCLUSIONS

Hot air balloon fatalities are rare, and the patterns of injury resemble those seen in free falls from significant heights with extensive blunt trauma.

Comparison of small female PMHS thoracic responses to scaled response corridors in a frontal hub impact

OBJECTIVE

The purpose of this study was to generate biomechanical response corridors of the small female thorax during a frontal hub impact and evaluate scaled corridors that have been used to assess biofidelity of small female anthropomorphic test devices (ATDs) and human body models (HBMs).

METHODS

Three small female postmortem human subjects (PMHS) were tested under identical conditions, in which the thorax was impacted using a 14.0 kg pneumatic impactor at an impact velocity of 4.3 m/s. Impact forces to PMHS thoraces were measured using a load cell installed behind a circular impactor face with a 15.2 cm diameter. Thoracic deflections were quantified using a chestband positioned at mid-sternum. Strain gages installed on the ribs and sternum identified fracture timing. Biomechanical response corridors (force-deflection) were generated and compared to scaled small female thoracic corridors using a traditional scaling method (TSM) and rib response-based scaling method (RRSM). A BioRank System Score (BRSS) was used to quantify differences between the small female PMHS data and both scaled corridors.

RESULTS

Coefficients of variation from the three small female PMHS responses were less than 2% for peak force and 7% for peak deflection. Overall, the scaled corridor means determined from the TSM and RRSM were less than two standard deviations away from the mean small female PMHS corridors (BRSS < 2.0). The RRSM resulted in smaller deviation (BRSS = 1.1) from the PMHS corridors than the TSM (BRSS = 1.7), suggesting the RRSM is an appropriate scaling method.

CONCLUSIONS

New small female PMHS force-deflection data are provided in this study. Scaled corridors from the TSM, which have been used to optimize current safety tools, were comparable to the small female PMHS corridors. The RRSM, which has the great benefit of using rib structural properties instead of requiring whole PMHS data, resulted in better agreement with the small female PMHS data than the TSM and deserves further investigation to identify scaling factors for other population demographics.

Factors affecting the numerical response and fracture location of the GHBMC M50 rib in dynamic anterior-posterior loading

Rib fractures are common traumatic injuries, with links to increased morbidity and mortality. Finite element ribs from human body models have struggled to predict the force-displacement response, force and displacement at fracture, and the fracture location for isolated rib tests. In the current study, the sensitivity of a human body model rib with updated anisotropic and asymmetric material models to changes in boundary conditions, material properties, and geometry was investigated systematically to quantify contributions to response. The updated material models using uncalibrated average material properties from literature improved the force-displacement response of the model, whereas the cross-sectional geometry was the only parameter to effect fracture location. The resulting uncalibrated model with improved material models and cross-sectional geometry closely predicted experimental average force-displacement response and fracture location.

Obese Occupant Response in Reclined and Upright Seated Postures in Frontal Impacts

The American population is getting heavier and automated vehicles will accommodate unconventional postures. While studies replicating mid-size and upright fore-aft seated occupants are numerous, experiments with post-mortem human subjects (PMHS) with obese and reclined occupants are sparse. The objective of this study was to compare the kinematics of the head-neck, torso and pelvis, and document injuries and injury patterns in frontal impacts. Six PMHS with a mean body mass index of 38.2 ± 5.3 kg/m2 were equally divided between upright and reclined groups (seatback: 23°, 45°), restrained by a three-point integrated belt, positioned on a semi-rigid seat, and exposed to low and moderate velocities (15, 32 km/h). Data included belt loads, spinal accelerations, kinematics, and injuries from x-rays, computed tomography, and necropsy. At 15 km/h speed, no significant difference in the occupant kinematics and evidence of orthopedic failure was observed. At 32 km/h speed, the primary difference between the cohorts was significantly larger Z displacements in the reclined occupant at the head (190 ± 32 mm, vs. 105 ± 33 mm p < 0.05) and femur (52 ± 18 mm vs. 30 ± 10 mm, p < 0.05). All the moderate-speed tests produced at least one thorax injury. Rib fractures were scattered around the circumference of the rib-cage in the upright, while they were primarily concentrated on the anterior aspect of the rib-cage in two reclined specimens. Although MAIS was the same in both groups, the reclined specimens had more bi-cortical rib fractures, suggesting the potential for pneumothorax. While not statistical, these results suggest enhanced injuries with reclined obese occupants. These results could serve as a data set for validating the response of restrained obese anthropometric test device (ATDs) and computational human body models.

Analysis of Thoracic Aorta Injury in 27 Road Traffic Accident Deaths

OBJECTIVES

To analyze the characteristics of thoracic aorta injury in road traffic accidents, to provide data reference for forensic identification.

METHODS

The data of 27 traffic accident death cases with thoracic aorta injury were analyzed according to relevant parameters including sex, age, mode of transportation, and thoracic aorta injury.

RESULTS

Aortic injury in traffic accidents was significantly more in males than females, and 74.1% cases were in the age range of 31-70 years. The most common mode of transportation was the motorcycle, followed by electric bike, most of which crashed with trucks. Most cases were accompanied by rib fractures and lung injuries. Thoracic aorta injury was the most common in ascending aorta, followed by aortic arch and thoracic aorta. Ascending aorta injury was most likely to occur in the range of 0-<1.6 cm from the aortic valve, while it was rare over 2.6 cm. Taking the aortic valve as the reference, the most common locations of injury were the anterior semilunar valve, followed by the right posterior semilunar valve and the left posterior semilunar valve. Thoracic aortic rupture occurred in 63.0% cases, and intima and media lacerations only occurred in 37.0% cases. A few deceased had aortic diseases.

CONCLUSIONS

The proximal part of the ascending aorta is prone to be injured because of the large external force of traffic accidents. The medical examiner should carefully examine the aortic injury in traffic accident deaths, and evaluate the relationship between the injury and the disease according to the condition and degree of aortic injury.

Costal cartilage fractures in blunt polytrauma patients - a prospective clinical and radiological follow-up study

Purpose

To assess the healing of costal cartilage fractures (CCFX) in patients with blunt polytrauma with follow-up imaging and clinical examination. Effect on physical performance and quality of life (QoL) was also evaluated.

Methods

The study group comprised twenty-one patients with diagnosed CCFX in trauma CT. All the patients underwent MRI, ultrasound, ultra-low-dose CT examinations, and clinical status control. The patients completed QoL questionnaires. Two radiologists evaluated the images regarding fracture union, dislocation, calcifications, and persistent edema at fracture site. An attending trauma surgeon clinically examined the patients, with emphasis on focal tenderness and ribcage mobility. Trauma registry data were accessed to evaluate injury severity and outcome.

Results

The patients were imaged at an average of 34.1 months (median 36, range 15.8–57.7) after the initial trauma. In 15 patients (71.4%), CCFX were considered stable on imaging. Cartilage calcifications were seen on healed fracture sites in all the patients. The fracture dislocation had increased in 5 patients (23.8%), and 1 patient (4.8%) showed signs of a non-stable union. Four patients (19.0%) reported persistent symptoms from CCFX.

Conclusion

Non-union in CCFX is uncommon but may lead to decreased stability and discomfort. Both clinical and radiological examinations play an important part in the post-traumatic evaluation of CCFX. CT and MRI visualize the healing process, while dynamic ultrasound may reveal instability. No significant difference in QoL was detected between patients with radiologically healed and non-healed CCFX. Post-traumatic disability was mostly due to other non-thoracic injuries.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10140-022-02066-w.

Cardiopulmonary Resuscitation Induced Posterior Rib Fractures in Nontraumatic Pediatric Deaths

ABSTRACT

Posterior rib fractures are considered suspicious for nonaccidental injury when observed in infants without significant trauma history or underlying bone disease. The biomechanical mechanism postulated for causing posterior rib fractures is anterior/posterior compression of the chest with posterior levering of the rib head over the transverse process of the vertebra creating a focal area of stress. The recommended "2-thumb" cardiopulmonary resuscitation method involves the administrator placing both thumbs on the sternum of the patient, encircling the chest with the hands, and placing the finger tips lateral to the spine. From this position, the administrator compresses the chest in an anterior/posterior direction by pressing on the sternum. Theoretically, the 2-thumb method should focus all force on the sternum while the back is supported by the fingers limiting posterior levering of the ribs and reducing the risk of posterior rib fractures. However, posterior rib fractures have been found during the autopsy of infants who received 2-thumb cardiopulmonary resuscitation, had no traumatic history, had a nontraumatic cause of death, and had no indication of underlying bone disease. This case study series presents the demographics, birth histories, circumstances surrounding death, and autopsy findings of four such medical examiner cases.

Multimodal analgesia reduces opioid requirements in trauma patients with rib fractures

BACKGROUND

Rib fractures are common in trauma patients and are associated with significant morbidity and mortality. Adequate analgesia is essential to avoid the complications associated with rib fractures. Opioids are frequently used for analgesia in these patients. This study compared the effect of a multimodal pain regimen (MMPR) on inpatient opioid use and outpatient opioid prescribing practices in adult trauma patients with rib fractures.

STUDY DESIGN

A pre-post cohort study of adult trauma patients with rib fractures was conducted at a Level I trauma center before (PRE) and after (POST) implementation of an MMPR. Patients on long-acting opioids before admission and those on continuous opioid infusions were excluded. Primary outcomes were oral opioid administration during the first 5 days of hospitalization and opioids prescribed at discharge. Opioid data were converted to morphine milligram equivalents (MMEs).

RESULTS

Six hundred fifty-three patients met inclusion criteria (323 PRE, 330 POST). There was a significant reduction in the daily MME during the second through fifth days of hospitalization; and the average inpatient MME over the first five inpatient days (23 MME PRE vs. 17 MME POST, p = 0.0087). There was a significant reduction in the total outpatient MME prescribed upon discharge (322 MME PRE vs. 225 MME POST, p = 0.006).

CONCLUSION

The implementation of an MMPR in patients with rib fractures resulted in significant reduction in inpatient opioid consumption and was associated with a reduction in the quantity of opiates prescribed at discharge.

LEVEL OF EVIDENCE

Therapeutic/Care Management; level IV.

Analysis of Pedestrian Fractures in Collisions Between Small Cars and Pedestrians Based on Surveillance Videos

OBJECTIVE

To discuss the collision relationship and the cause of the fracture caused by traffic accidents in which the front of a small car collides with the side of a pedestrian while braking.

METHODS

The surveillance videos of 42 traffic accidents involving the front of a small car colliding with the side of a pedestrian while braking were collected. By analyzing the surveillance videos and the paths, the speed of the collision, the relationship between the vehicle and the pedestrian upon collision, and the movement trajectory of the human body were clearly identified. The type and severity of the injuries were also determined through autopsy. The characteristics of the human injuries and vehicle paths were analyzed according to the collision speed (<40 km/h, 40-60 km/h, 60-90 km/h), and the correlations between the fracture and the height of the pedestrian, the height of the hood and the length of the hood were discussed.

RESULTS

When a small car hits the side of a pedestrian, the front bumper first hits the lower limbs of the pedestrian, and then, the human body falls to the side of the vehicle, causing a secondary collision with the hood and front windshield; thus, the pedestrian is thrown at a speed similar to the speed of the vehicle, finally falling to the ground and sliding forward a certain distance. (1) When V is less than 40 km/h (n = 10), the pedestrian's head did not collide with the windshield, and the fatal injuries were caused by the individual striking the ground. (2) When V is greater than 40 km/h (n = 32), the majority (97%) of cases showed collision with the windshield. (3) When 40 to 60 km/h (n = 16), the pedestrian's head collided with the windshield, which can cause fatal injuries, and pelvic fractures and rib fractures occurred in 56.25% of patients. (4) When V is less than 60 km/h (n = 26), the ratio of the height of the pedestrian to the height of the hood was significantly smaller in the pelvic fracture group than in the nonpelvic fracture group (P < 0.01). (5) When 60 to 90 km/h (n = 16), there were holes in the windshield, and the pedestrians experienced severe head injuries, with cervical spine fracture occurring in 37.5% of patients, pelvic fractures occurring in 43.75% of patients, and rib fractures occurring in 31.25% of patients.

CONCLUSIONS

When V is less than 40 km/h, the vehicle does not cause severe injuries in pedestrians; when V is greater than 40 km/h, the collisions of the pedestrian's head with the windshield lead to severe head injuries and the accident can cause severe pelvic and rib fractures; when V is greater than 60 km/h, the collisions of the pedestrian's head with the windshield can cause cervical spine fracture in addition to head injuries. The occurrence of human injuries is related to not only the vehicle speed but also factors such as the height of the pedestrian, the height of the hood and the length of the hood.

Vomiting-induced costal cartilage fracture: a case report

The use of ultrasonography as a first line imaging test in cases of possible costal cartilage fracture can be pivotal. In this case report, we present the case of a patient with a suspected atraumatic vomiting-induced costal cartilage fracture. The costal cartilage fracture was non-displaced and incomplete, thus not visible in a Computed Tomography scan. When Ultrasound imaging was employed at the area of tenderness, soft tissue edema and hematoma around the cartilage were visualized. High level of suspicion for a cartilage fracture in this case revealed a subtle osseous injury.

The effect of skeletal muscle area and attenuation in patients with sternum fracture due to blunt chest trauma

OBJECTIVE

This study aims to retrospectively investigate the imaging features of patients with sternum fracture (SF) and concomitant organ injuries. We also aimed to evaluate the potential prognostic effect of skeletal muscle area (TMA) and muscle attenuation (MuA) values.

PATIENTS AND METHODS

Computed tomography (CT) images of patients with SF were re-evaluated by two observers (Observer-1 and 2). Observer-3 has measured TMA and MuA values. Observer-1 has repeated the measurements blindly to the first measurement results to evaluate the inter-observer agreement. The length of hospital stay, death, hemiplegia, or quadriplegia were investigated from the archives. Mann-Whitney U-test or Student's t-test was used to investigate the relationship between linear variables. The intraclass correlation coefficient (ICC) score was used to evaluate the interobserver agreement. Logistic regression analysis was used to estimate the relative effect of variables by calculating unadjusted odds ratios (ORs) for categorical outcomes.

RESULTS

Sixty-five patients had SF and 53 patients had SF and concomitant organ injuries. The most common injuries accompanying SF were rib fracture (73.58%) and lung contusion (60.38%). Manubrium fracture was the most common fracture location (52.3%), and 18 patients (27.7%) had displaced SF. Eight patients (15.1%) were discharged with plegia and five (9.4%) died. Hemothorax, displaced SF and decreased MuA were predictors of prolonged hospital stay, and the presence of cardiac contusion, displaced SF, hemothorax, and vertebra body fracture were independent factors for death.

CONCLUSIONS

The presence of a displaced SF and decreased MuA value are important prognostic factors in patients with SF.

Elderly trauma associated with high-risk recreational activity: A population-based study, United States, 2010 through 2016

BACKGROUND

Understanding trends in prevalence and etiology is critical to public health strategies for prevention and management of injury related to high-risk recreation in elderly Americans.

METHODS

The National Emergency Department Sample from 2010 through 2016 was queried for patients with a principal diagnosis of trauma (ICD-9 codes 800.0-959.9) and who were 55 years and older. High-risk recreation was determined from e-codes a priori. Primary outcome measures were mortality and total hospital charges.

RESULTS

Of the 29,491,352 patient cohort, 458,599 (1.56%) engaged in high-risk activity, including those age 85 and older. High-risk cases were younger (median age 61 vs 70) and majority male (71.87% vs 39.24%). The most frequent activities were pedal cycling (45.81%), motorcycling (29.08%), and off-road vehicles (9.13%). Brain injuries (8.82% vs 3.88%), rib/sternal fractures (13.35% vs 3.53%), and cardiopulmonary injury (5.25% vs 0.57%) were more common among high-risk cases. Mortality (0.75% vs 0.40%) and total median hospital charges ($3,360 vs $2,312) were also higher for high-risk admissions, where the odds of mortality increased exponentially per year of age (odds ratio, 1.06; 99.5% CI, 1.05-1.08). High-risk recreation was associated with more than $1 billion in total hospital charges and more than 100 deaths among elderly Americans per year.

CONCLUSION

Morbidity, mortality, and resource utilization due to high-risk recreation extend into the ninth decade of life. The patterns of injury described here offer opportunities for targeted injury prevention education to minimize risk among this growing segment of the United States population.

Potential effect of pre-activated muscles under a far-side lateral impact

OBJECTIVE

The goal of this study is to evaluate the potential effect of muscle pre-activation under a lateral impact scenario, in this case focusing on a far-side impact, using an Active Human Body Model.

METHODS

In total fourteen simulations were run, out of these, twelve were computed with an Active Human Body Model and two with a passive one. The models were subjected to a far-side impact scenario reaching up to 14 g's. Two different pre-crash scenarios were analyzed with the Active Human Body Model: (1) constant velocity, and (2) braking deceleration. During the pre-crash phase a lambda control based on the muscle length computed the muscle activation. Since there is no available data concerning the neuromuscular strategy of the occupants subjected to high accelerations, six different control strategies were analyzed during the in-crash phase. Besides, rib fracture and brain injury risk were analyzed, since they are the two most relevant body regions in this simplified far-side crash scenario.

RESULTS

The pre-activation of the muscles showed an effect on both the occupant kinematics and estimated injury risks. Depending on the considered muscle strategy, the head lateral excursion varied up to 75 mm, specifically for the scenario with constant velocity. Moreover, the rib fracture probability and the brain injury indicator revealed higher injury risks for the passive Human Body Model. When applying the constant velocity during pre-crash, the fracture probability for two or more ribs ranged from 9.91 to 46.06% for the Active Human Body Model, whereas it reached 84.3% for the passive model. The brain injury indicator was reduced by about 10% when using the active model compared to the passive one.

CONCLUSIONS

The numerical results show that the pre-activation of the muscles affects the kinematic and injury outcomes in car crashes. In this study, six muscular control strategies have been proposed. The two muscular controls that may be most realistic are: constant activation after the in-crash phase starts, by trying to hold the position prior to the crash, or no stimulation, by not responding to the upcoming in-crash event.

[Negative Pressure Wound Therapy as a Treatment Option for Extensive Post-Trauma Subcutaneous Emphysema]

Subcutaneous emphysema can be a secondary complication of chest trauma or one of the complications of ruptured bullae in advanced chronic obstructive pulmonary disease. Massive subcutaneous emphysema impairs the respiratory mechanics and affects the venous returns of the head and neck. It can lead to respiratory insufficiency with the need for mechanical ventilation. The treatment should focus on the primary pathology. Nonetheless, in patients with subcutaneous emphysema as the only but serious symptom, the treatment can zero in solely on this complication. The standard procedure consists in the insertion of chest drain which does not necessarily have to lead to successful treatment results. The authors present a case study of a 77-year-old man with major comorbidities, with extensive subcutaneous emphysema after blunt chest wall trauma, in which respiratory insufficiency developed. The chest drain was ineffective. The solution was to apply subfascial negative pressure therapy infraclavicularly to the area of the pectoral muscle, which made the subcutaneous emphysema almost immediately subside and which substantially improved the clinical condition of the patient. Local negative pressure therapy can be used as the method of choice for treating massive subcutaneous emphysema in patients, in whom the standardised treatment by chest drain with active suction mechanism failed and the lung is expanded in the pleural cavity, and for whom surgery is far too risky. Key words: negative pressure wound therapy, subcutaneous emphysema, rib fracture.

SURGICAL STABILIZATION OF MULTIPLE RIB FRACTURES AND MULTIPLE LONG BONE FRACTURES OF LOWER EXTREMITIES IN POLYTRAUMA PATIENTS

Objectives - determine the impact of rib osteosynthesis on the incidence of complications development and mortality in patients with multiple rib fractures and multiple long bone fractures of lower extremities. A prospective controlled trial was conducted from June 2015 to December 2019, and included adult patients with polytrauma, Injury Severity Score (ISS) ≥18p, multiple long bone fractures of lower extremities, one of which is the femur, and multiple rib fractures. All included patients were divided into two groups: in Group I - 17 patients who underwent surgical stabilization of rib fractures, Group II - 24 included patients treated without rib osteosynthesis. There were no significant statistic differences between patients of Group I and Group II in demographics, mechanism of injury, severity of trauma, and overall patient status. All patients had high rates of injury severity for ISS (37.8±7.9 vs. 36.9±8.6, p=0.863), New Injury Severity Score (NISS) (39.5±9.2 vs. 38.5±7.6, p=0.759) and Glasgow Coma Scale (GCS) (8.2±3.5 vs. 8.7±3.8, p=0.896).The time between trauma and rib osteosynthesis in Group I was 3.4±1.7 days. The period from trauma to definitive long bone osteosynthesis was 6.9±3.2 days in Group I and 9.4±3.8 days in Group II (p=0.039). Patients of Group I compared with Group II had a lower incidence of Acute Respiratory Distress Syndrome (ARDS) (23.5% vs. 54.2%, p=0.049) and pneumonia (29.4% vs. 62,5%, p= 0.038), shorter terms of Mechanical Ventilation (MV) (11.6±9.4 vs. 18.9±9.9, p=0.001), Length Of Stay in Intensive Care Unit (LOS ICU) (15.3±10.2 vs. 22.1±10.8, p=0.003) and Hospital Length Of Stay (HLOS) (36.9±15.8 vs. 44.3±17.4, p=0.001). Use of the rib osteosynthesis in patients with severe polytrauma, multiple rib and long bone of lower extremity fractures is more effective tactic comparing to non-surgical rib fracture treatment, it allows to reduce the incidence of ARDS and pneumonia, decreases the duration of MV, LOS ICU and HLOS.

[Diaphragmatic Injury Due to Blunt Trauma Diagnosed by a Diagnostic Thoracoscopy;Report of a Case]

We performed an exploratory thoracoscopy for a suspected diaphragm injury caused by a blunt-force chest trauma. A male patient in his fifties involved in a traffic accident and was transported by ambulance to our hospital. Upon arrival, his vital signs were stable, however, he was diagnosed as having fractures of the right tibia and fibula, multiple rib fractures and a slight right hemothorax. The limb fracture was treated by emergency surgery and the chest trauma was managed by chest drainage. Since injury of the diaphragm by fragment of the right 10th rib was suspected with chest computed tomography(CT), an exploratory thoracoscopy was performed after orthopedic surgery, and a laceration of the diaphragm without herniation was successfully closed.

[Early Sternum Fixation with a Locking Plate for Traumatic Sternal Fracture]

An 86-year-old man fell from a farm trolley and presented with chest bruising. Chest computed tomography showed a hemopneumothorax, multiple right rib fractures, and a sternal fracture at the sternal angle. Although he was treated with a chest tube for drainage and external fixation, a flail chest and severe pain continued. We performed a locked plate fixation of the sternal fracture on the 6th day of hospitalization. The postoperative course was favorable and the patient's flail chest improved. In cases of fracture of the sternum, minimally invasive locked plate sternal fixation may lead to early recovery.

A Novel Approach to Scaling Age-, Sex-, and Body Size-Dependent Thoracic Responses using Structural Properties of Human Ribs

Thoracic injuries are frequently observed in motor vehicle crashes, and rib fractures are the most common of those injuries. Thoracic response targets have previously been developed from data obtained from post-mortem human subject (PMHS) tests in frontal loading conditions, most commonly of mid-size males. Traditional scaling methods are employed to identify differences in thoracic response for various demographic groups, but it is often unknown if these applications are appropriate, especially considering the limited number of tested PMHS from which those scaling factors originate. Therefore, the objective of this study was to establish a new scaling approach for generating age-, sex-, and body size- dependent thoracic responses utilizing structural properties of human ribs from direct testing of various demographics. One-hundred forty-seven human ribs (140 adult; 7 pediatric) from 132 individuals (76 male; 52 female; 4 pediatric) ranging in age from 6 to 99 years were included in this study. Ribs were tested at 2 m/s to failure in a frontal impact scenario. Force and displacement for individual ribs were used to develop new scaling factors, with a traditional mid-size biomechanical target as a baseline response. This novel use of a large, varied dataset of dynamic whole rib responses offers vast possibilities to utilize existing biomechanical data in creative ways to reduce thoracic injuries in diverse vehicle occupants.

[Surgery for Flail Chest with Titanium Plates after Cardiopulmonary Resuscitation;Report of a Case]

A 74-year-old woman was admitted for the management of nausea with hyponatremia. On the 19th day of hospitalization, the patient developed cardiac arrest and needed cardiopulmonary resuscitation (CPR). CPR was successful but the patient developed multiple rib fractures with flail chest by CPR. Because of persistent dyspnea, surgery for fixing of the fractured ribs was performed using 4 titanium plates, with prompt improvement of the flail chest after the operation.

Quantification of Skeletal and Soft Tissue Contributions to Thoracic Response in a Dynamic Frontal Loading Scenario

Thoracic injuries continue to be a major health concern in motor vehicle crashes. Previous thoracic research has focused on 50^th percentile males and utilized scaling techniques to apply results to different demographics. Individual rib testing offers the advantage of capturing demographic differences; however, understanding of rib properties in the context of the intact thorax is lacking. Therefore, the objective of this study was to obtain the data necessary to develop a transfer function between individual rib and thoracic response. A series of non-injurious frontal impacts were conducted on six PMHS, creating a loading environment commensurate to previously published individual rib testing. Each PMHS was tested in four tissue states: intact, intact with upper limbs removed, denuded, and eviscerated. Following eviscerated thoracic testing, eight individual mid-level ribs from each PMHS were removed and loaded to failure. A simplified model in which ribs of each thorax are treated as parallel springs was utilized to evaluate the ability of individual rib response data to predict each subject's eviscerated thoracic response. On average across subjects, denuded thoraces retained 89% and eviscerated thoraces retained 46% of intact force. Similarly, denuded thoraces retained 70% and eviscerated thoraces retained 30% of intact stiffness. The rib model did not adequately predict eviscerated thoracic response but provided a better understanding of the influence of connective tissue on a rib's behavior with-in the thorax. Results of this study could be used in conjunction with the database of individual rib test results to improve thoracic response targets and help assess biofidelity of current anthropomorphic test devices.

Sources of Variability in Structural Bending Response of Pediatric and Adult Human Ribs in Dynamic Frontal Impacts

Despite safety advances, thoracic injuries in motor vehicle crashes remain a significant source of morbidity and mortality, and rib fractures are the most prevalent of thoracic injuries. The objective of this study was to explore sources of variation in rib structural properties in order to identify sources of differential risk of rib fracture between vehicle occupants. A hierarchical model was employed to quantify the effects of demographic differences and rib geometry on structural properties including stiffness, force, displacement, and energy at failure and yield. Three-hundred forty-seven mid-level ribs from 182 individual anatomical donors were dynamically (~2 m/s) tested to failure in a simplified bending scenario mimicking a frontal thoracic impact. Individuals ranged in age from 4 - 108 years (mean 53 ± 23 years) and included 59 females and 123 males of diverse body sizes. Age, sex, body size, aBMD, whole rib geometry and cross-sectional geometry were explored as predictors of rib structural properties. Measures of cross-sectional rib size (Tt.Ar), bone quantity (Ct.Ar), and bone distribution (Z) generally explained more variation than any other predictors, and were further improved when normalized by rib length (e.g., robustness and WBSI). Cortical thickness (Ct.Th) was not found to be a useful predictor. Rib level predictors performed better than individual level predictors. These findings moderately explain differential risk for rib fracture and with additional exploration of the rib's role in thoracic response, may be able contribute to ATD and HBM development and alterations in addition to improvements to thoracic injury criteria and scaling methods.

Extruded talus treated with reimplantation and primary tibiotalocalcaneal arthrodesis

Extruded talus is a rare serious result from a high-energy injury to a supinated and plantar flexed foot. Treatment remains controversial with a lack of congruent evidence for talar reimplantation. A 34-year-old woman was involved in a road traffic accident at 40 mph. Imaging revealed a left talus extruded anterolaterally with a talar neck fracture. Additional injuries included right acetabular fracture, transverse process fractures and rib fractures, which were treated conservatively. The talus was reimplanted and the talar neck fixed with a cortical screw. A hindfoot nail was used to fuse the calcaneus, talus and tibia. Follow-up at two years showed solid tibiotalocalcaneal fusion, with no evidence of avascular development, and the patient was fully weight bearing without pain. We believe this is the first published case of successful primary tibiotalocalcaneal fusion for extruded talus injuries.

[Thoracic inestability fixed with bioabsorbable screws and plates]

BACKGROUND

Flail chest is managed with mechanical ventilation or inhaloteraphy and analgesia. Little has been published on the use of bioabsorbable material and its evolution in flail chest fixation.

METHODS

This is a descriptive study of patients with unstable chest undergoing fixation with bioabsorbable plates and screws in a period from February 2009 to December 2011.

RESULTS

We report 18 cases, aged 33-74 years (mean 53), three with bilateral involvement; rib fixation was performed between 1-21 days of the accident (mean 1.5). They started walking the next day in 14 cases; postoperative stay was four days (range 3-14). The heart rate of patients prior to surgery was 90 per minute (range 82-100) and lowered to 84 after fixation (range 82-92), preoperative respiratory rate was 26 per minute (range 22-28) and below 22 per minute (range 20 to 26) in postoperative period.

CONCLUSIONS

The use of bioabsorbable material for osteosynthesis of costal fractures did not show side effects in our period of study.

Responses and Injuries to PMHS in Side-Facing and Oblique Seats in Horizontal Longitudinal Sled Tests per FAA Emergency Landing Conditions

The objective of the present exploratory study is to understand occupant responses in oblique and side-facing seats in the aviation environment, which are increasingly installed in modern aircrafts. Sled tests were conducted using intact Post Mortem Human Surrogates (PMHS) seated in custom seats approximating standard aircraft geometry. End conditions were selected to represent candidate aviation seat and restraint configurations. Three-dimensional head center-of-gravity linear accelerations, head angular velocities, and linear accelerations of the T1, T6, and T12 spinous processes, and sacrum were obtained. Three-dimensional kinematics relative to the seat were obtained from retroreflective targets attached to the head, T1, T6, T12, and sacrum. All specimens sustained spinal injuries, although variations existed by vertebral level. While the tension mechanism was associated with cervical spine injuries, complex distraction-coupled with bending and tension was attributed to thoracolumbar spine injuries. Skeletal fractures to the ribcage were attributed to compression induced by the restraint from the seatbelt, the presence of the armrest, and/or severe motions of the unconstrained torso. Pelvic injuries were also attributed to restraint offered by the lap belt on the accelerating torso-pelvis complex in the absence of the armrest. Lower extremity injuries occurred due to the unconstrained motion (flailing mechanism). These results serve as an initial dataset to understand the kinematics of different body regions, injuries and patterns, and potential injury mechanisms describing PMHS responses in the aviation environment.

Skeletal Aspects of Non-Accidental Injury

Inflicted non-accidental skeletal injuries form a small but important part of the spectrum of child abuse, with the majority of skeletal injuries occurring in children under 2 years of age. Radiology plays a vital role in the detection and evaluation of these skeletal injuries. A thorough detailed radiological evaluation should be undertaken to investigate a child appropriately for a suspected inflicted non-accidental injury to accurately detect and possibly date any injuries and also to exclude normal variants of growth that may mimic fractures. In some cases, the survey may diagnose an underlying metabolic or genetic disorder of the bone that may predispose the child to fracturing. While radiology plays an important role in the dating of injuries, the dating of fractures from radiological appearances is difficult and imprecise. Any fracture may be the result of an inflicted injury or accidental event. Therefore, it is important that all fractures identified are correlated with any relevant clinical history. Certain injuries, such as rib and metaphyseal fractures, require a more specific method of causation and therefore carry a higher degree of suspicion of being the result of an inflicted injury compared with other fracture types, which are relatively non-specific in their mechanisms of causation, such as skull and clavicular fractures. In all cases, correlation with clinical history is mandatory.

[Traumatic changes of intrathoracic organs due to external mechanical cardiopulmonary resuscitation. Case reports]

External mechanical resuscitation systems were developed for continuous and effective chest compression with the goal to increase the probability of spontaneous blood circulation renew. We describe results of four autopsy cases, where the external mechanical resuscitation by system Lucas (n=3) and AutoPulse (n=1) was performed prior to death. In all the cases were found traumatic changes which are commonly described in various studies such as skin abrasions on the chest, multiple rib fractures, fracture of the sternum and hematoma in the mediastinum or pericardium. In addition to these usual traumatic changes accompanying mechanical cardiopulmonary resuscitation we have observed injuries of intrathoracic organs, mainly the contusions of the heart and contusions and laceration of the lungs. In addition to these changes were in one case, associated with prolonged AutoPulse resuscitation, found ruptures of intima of the right common carotid artery. These injuries, with few exceptions, are not commonly described even over much wider number of examined persons. Injuries of the abdominal organs in connection with mechanical resuscitation, as described in a few case reports, were not present. However in one case there was found contusion of myocardium due to the external resuscitation by the Lucas system with clinical manifestation of sudden coronary incident even though the cause of death was massive thrombotic embolism to pulmonary arteries. All reported cases were similar in the relatively long-lasting mechanic cardiopulmonary resuscitation and prolonged time of dying of the patients.

KEYWORDS

cardiopulmonary resuscitation - Lucas - AutoPulse - intrathoracic injury.

Association between treatment with brachytherapy vs whole-breast irradiation and subsequent mastectomy, complications, and survival among older women with invasive breast cancer

CONTEXT

Brachytherapy is a radiation treatment that uses an implanted radioactive source. In recent years, use of breast brachytherapy after lumpectomy for early breast cancer has increased substantially despite a lack of randomized trial data comparing its effectiveness with standard whole-breast irradiation (WBI). Because results of long-term randomized trials will not be reported for years, detailed analysis of clinical outcomes in a nonrandomized setting is warranted.

OBJECTIVE

To compare the likelihood of breast preservation, complications, and survival for brachytherapy vs WBI among a nationwide cohort of older women with breast cancer with fee-for-service Medicare.

DESIGN

Retrospective population-based cohort study of 92,735 women aged 67 years or older with incident invasive breast cancer, diagnosed between 2003 and 2007 and followed up through 2008. After lumpectomy 6952 patients were treated with brachytherapy vs 85,783 with WBI.

MAIN OUTCOME MEASURES

Cumulative incidence and adjusted risk of subsequent mastectomy (an indicator of failure to preserve the breast) and death were compared using the log-rank test and proportional hazards models. Odds of postoperative infectious and noninfectious complications within 1 year were compared using the χ(2) test and logistic models. Cumulative incidences of long-term complications were compared using the log-rank test.

RESULTS

Five-year incidence of subsequent mastectomy was higher in women treated with brachytherapy (3.95%; 95% CI, 3.19%-4.88%) vs WBI (2.18%; 95% CI, 2.04%-2.33%; P < .001) and persisted after multivariate adjustment (hazard ratio [HR], 2.19; 95% CI, 1.84-2.61, P < .001). Brachytherapy was associated with more frequent infectious (16.20%; 95% CI, 15.34%-17.08% vs 10.33%; 95% CI, 10.13%-10.53%; P < .001; adjusted odds ratio [OR], 1.76; 1.64-1.88) and noninfectious (16.25%; 95% CI, 15.39%-17.14% vs 9.00%; 95% CI, 8.81%-9.19%; P < .001; adjusted OR, 2.03; 95% CI, 1.89-2.17) postoperative complications; and higher 5-year incidence of breast pain (14.55%, 95% CI, 13.39%-15.80% vs 11.92%; 95% CI, 11.63%-12.21%), fat necrosis (8.26%; 95% CI, 7.27-9.38 vs 4.05%; 95% CI, 3.87%-4.24%), and rib fracture (4.53%; 95% CI, 3.63%-5.64% vs 3.62%; 95% CI, 3.44%-3.82%; P ≤ .01 for all). Five-year overall survival was 87.66% (95% CI, 85.94%-89.18%) in patients treated with brachytherapy vs 87.04% (95% CI, 86.69%-87.39%) in patients treated with WBI (adjusted HR, 0.94; 95% CI, 0.84-1.05; P = .26).

CONCLUSION

In a cohort of older women with breast cancer, treatment with brachytherapy compared with WBI was associated worse with long-term breast preservation and increased complications but no difference in survival.

Predicting rib fracture risk with whole-body finite element models: development and preliminary evaluation of a probabilistic analytical framework

This study sought to develop a strain-based probabilistic method to predict rib fracture risk with whole-body finite element (FE) models, and to describe a method to combine the results with collision exposure information to predict injury risk and potential intervention effectiveness in the field. An age-adjusted ultimate strain distribution was used to estimate local rib fracture probabilities within an FE model. These local probabilities were combined to predict injury risk and severity within the whole ribcage. The ultimate strain distribution was developed from a literature dataset of 133 tests. Frontal collision simulations were performed with the THUMS (Total HUman Model for Safety) model with four levels of delta-V and two restraints: a standard 3-point belt and a progressive 3.5-7 kN force-limited, pretensioned (FL+PT) belt. The results of three simulations (29 km/h standard, 48 km/h standard, and 48 km/h FL+PT) were compared to matched cadaver sled tests. The numbers of fractures predicted for the comparison cases were consistent with those observed experimentally. Combining these results with field exposure informantion (ΔV, NASS-CDS 1992-2002) suggests a 8.9% probability of incurring AIS3+ rib fractures for a 60 year-old restrained by a standard belt in a tow-away frontal collision with this restraint, vehicle, and occupant configuration, compared to 4.6% for the FL+PT belt. This is the first study to describe a probabilistic framework to predict rib fracture risk based on strains observed in human-body FE models. Using this analytical framework, future efforts may incorporate additional subject or collision factors for multi-variable probabilistic injury prediction.

Frailty and injury causation

PURPOSE

: The current study will attempt to elucidate whether frailty has a role in motor vehicle crash injury causation.

METHODS

: The association between frailty and injury was studied among Crash Injury Research Engineering Network (CIREN) cases. The baseline "physical functioning" (PF) score of the SF-36 was used as a marker of frailty (i.e., PF score <75). Frailty associations with ISS and occupant, vehicular and crash factors were explored. Frailty association with delta V was analyzed among injured (i.e., brain, rib, or femur) belted occupants in frontal crashes to establish whether frailty confers a different risk of each particular injury.

RESULTS

: Frailty occurred in 13.7 % of the cohort (n=1,747). Median (q1-q3) ISS was 14.0 (10-22) among the frail and 17.0 (10-24) among the non frail (p=0.40). Frailty was significantly associated with advanced age, male gender, the presence of co-morbidities, extreme BMIs, frontal and near-side crashes and delta V < 45 km/h. Seat belt use and ISS<16 were not associated with frailty. Multiple linear regressions, adjusting for age, gender and BMI revealed a negative association between frailty and log delta V (coefficient -0.188, p=0.04) among those with rib fractures but not among those with brain injuries or femur fractures.

CONCLUSION

: PF score, a marker of frailty, is associated with similar ISS and lower delta V and is independently linked to lower delta V thresholds for some injuries (i.e. rib fractures) but not for others (i.e. brain injuries and femur fractures). These associations suggest a potential role of frailty in injury causation.

Response of the human torso to lateral and oblique constant-velocity impacts

The objective of this study was to provide new biomechanical response data for the thorax with lateral and oblique loading, so as to support the development of safety systems for side impact protection that would offer the level of protection that has been achieved in frontal impact. Three male human cadavers were successively impacted by an impactor system delivering a constant velocity impact from the left and the right sides at three levels (shoulder, upper chest and mid-chest). Different impact directions were also chosen for each side: lateral, +15° posterolateral, -15° anterolateral. One subject was impacted at 1, 3 and 6 m/s whereas the other two subjects were impacted at 3 m/s only. A total of nineteen tests was performed. The impact force and the chest lateral deflection were measured using respectively a standard data acquisition system and also an optoelectronic stereophotogrammetric system (OSS). After each test, attempts were made to detect rib fractures by palpation, and a necropsy of the torso was performed after the tests series to document the injuries produced by all the tests. Overall, the peak impact force increased from the lowest impact level (mid-chest) to the highest (shoulder) and was found to be rate-sensitive. The force-deflection relationship was non linear for the shoulder impacts (stiffness increased with increasing deflection) whereas stiffness was nearly constant for the mid- and upper-chest impacts. The anterolateral impacts to the mid- and upper-chest generated more rib fractures than the other impact directions.

Age thresholds for increased mortality of predominant crash induced thoracic injuries

The growing elderly population in the United States presents medical, engineering, and legislative challenges in trauma management and prevention. Thoracic injury incidence, morbidity, and mortality increase with age. This study utilized receiver-operator characteristic analysis to identify the quantitative age thresholds associated with increased mortality in common isolated types of thoracic injuries from motor vehicle crashes (MVCs).The subject pool consisted of patients with a single AIS 3+ thorax injury and no injury greater than AIS 2 in any other body region. A logistic regression algorithm was performed for each injury to estimate an age threshold that maximally discriminates between survivors and fatalities. The c-index describing discrimination of the model and odds ratio describing the increased mortality risk associated with being older than the age threshold were computed.Twelve leading thoracic injuries were included in the study: unilateral and bilateral pulmonary contusion (AIS 3/4), hemo/pneumothorax, rib fractures with and without hemo/pneumothorax (AIS 3/4), bilateral flail chest, and thoracic penetrating injury with hemo/pneumothorax. Results are consistent with the traditional age threshold of 55, but were injury-specific. Pulmonary contusions had lower age thresholds compared to rib fractures. Higher severity pulmonary contusions and rib fractures had lower age thresholds compared to lower severity injuries.This study presents the first quantitatively estimated mortality age thresholds for common isolated thoracic injuries. This data provides information on the ideal 'threshold' beyond which age becomes an important factor to patient survival. Results of the current study and future work could lead to improvements in automotive safety design and regulation, automated crash notification, and hospital treatment for the elderly.