Assessment of Thorax Finite Element Model Response for Behind Armor Blunt Trauma Impact Loading Using an Epidemiological Database.

Nonperforating ballistic impacts on thoracic armor can cause blunt injuries, known as behind-armor blunt trauma (BABT). To evaluate the potential for this injury, the back face deformation (BFD) imprinted into a clay backing is measured; however, the link between BFD and potential for injury is uncertain. Computational human body models (HBMs) have the potential to provide an improved understanding of BABT injury risk to inform armor design but require assessment with relevant loading scenarios. In this study, a methodology was developed to apply BABT loading to a computational thorax model, enhanced with refined finite element mesh and high-deformation rate mechanical properties. The model was assessed using an epidemiological BABT survivor database. BABT impact boundary conditions for 10 cases from the database were recreated using experimentally measured deformation for specific armor/projectile combinations, and applied to the thorax model using a novel prescribed displacement methodology. The computational thorax model demonstrated numerical stability under BABT impact conditions. The predicted number of rib fractures, the magnitude of pulmonary contusion, and injury rank, increased with armor BFD, back face velocity, and input energy to the thorax. In three of the 10 cases, the model overpredicted the number of rib fractures, attributed to impact location positional sensitivity and limited details from the database. The integration of an HBM with the BABT loading method predicted rib fractures and injury ranks that were in good agreement with available medical records, providing a potential tool for future armor evaluation and injury assessment.

"Cracking" into the debate about laying hen housing.

Livestock production systems have faced social pressures related to animal welfare; the laying hen industry also has faced changes in governing regulations/policies. This study employs experimental data to evaluate 3 confinement-housing systems: standard cages with no perches, cages with standard perches, and cages with cooled perches. Based on the cost-benefit analysis conducted of revenue less feed costs, operators are expected to have revenue, after covering feed costs, which could contribute to installation and maintenance of standard and/or cooled perches. Thus, egg producers may be able to use caged housing that incorporates perches profitably, depending on the final costs of such a system.

A prospective study of punch biomechanics and cognitive function for amateur boxers.

OBJECTIVE: To evaluate several biomechanical factors of the head during a sparring session and their link to cognitive function. DESIGN: Instrumented Boxing Headgear (IBH) was used for data collection during four 2 min sparring sessions. Neurocognitive assessment was measured using the ImPACT Concussion management software. A baseline neurocognitive test was obtained from each athlete prior to sparring; two additional tests were obtained and compared with the baseline. SETTING: Male and female amateur boxers. PARTICIPANTS: Data were collected from 30 male and 30 female amateur boxers. MAIN OUTCOME MEASUREMENTS: Head accelerations (translational and rotational), injury severity indexes (Head Injury Criteria (HIC) and Gadd Severity Index (GSI)) and cognitive function scores. Results Peak translational and rotational acceleration values were 191 g and 17,156 rad/s(2), respectively, for males and 184 g and 13,113 rad/s(2), respectively, for females. The peak HIC and GSI values for males were 1652 and 2292, respectively, and for females 1079 and 1487, respectively. There was no significant difference in the neurocognitive scores between genders. A decrease was exhibited in the delayed memory postbout scores. All other scores either increased or did not significantly decrease when compared with the baseline. CONCLUSIONS: The majority of impacts experienced by both genders were under the threshold for mild head injury. There was a statistically significant difference between peak translational and rotational acceleration, HIC and GSI when comparing genders. When analysing cognitive functions, there was no statistical difference between genders.

Biomechanics of the head for Olympic boxer punches to the face.

OBJECTIVE: The biomechanics of the head for punches to the jaw and the risk of head injury from translational and rotational acceleration were studied. [figure: see text] METHODS: Seven Olympic boxers from five weight classes delivered 18 straight punches to the frangible face of the Hybrid III dummy. Translational and rotational head acceleration, neck responses, and jaw pressure distribution were measured. High speed video recorded each blow and was used to determine punch velocity. Equilibrium was used to determine punch force, energy transfer, and power. RESULTS: Punch force averaged 3427 (standard deviation (SD) 811) N, hand velocity 9.14 (SD 2.06) m/s, and effective punch mass 2.9 (SD 2.0) kg. Punch force was higher for the heavier weight classes, due primarily to a higher effective mass of the punch. Jaw load was 876 (SD 288) N. The peak translational acceleration was 58 (SD 13) g, rotational acceleration was 6343 (SD 1789) rad/s(2), and neck shear was 994 (SD 318) N. CONCLUSIONS: Olympic boxers deliver straight punches with high impact velocity and energy transfer. The severity of the punch increases with weight class.

A comparison of standard vs. breakaway bases: an analysis of a preventative intervention for softball and baseball foot and ankle injuries.

More than 40 million individuals participate in organized baseball and softball leagues in the United States every year. Unfortunately, it has also been estimated by the Consumer Product Safety Commission that softball and baseball are the two main sports leading to emergency-room visits in the United States. A previous field study has determined that the utilization of breakaway bases has the potential of preventing 96% of sliding injuries, thereby preventing 1.7 million injuries a year in the United States with a savings of $2 billion a year in health care costs. It is the purpose of this study to analyze and compare the potential attenuating capabilities of various types of bases. We found the force at the ankle upon impact when compared to the standard base revealed all breakaway bases reduced the force of impact to a statistically significant level. The force at the foot upon impact when compared to the standard base revealed all breakaway bases reduced the force at variable levels, with the Rogers bases having the only statistically significant reduction. However, the force delivered to the tibia/fibula was increased with the Stay Down and Mag-Net large bases as compared to the standard stationary base. The moments of inversion/eversion and dorsiflexion/plantar flexion upon impact, when compared to the standard base, revealed all safety bases were reduced to a statistically significant level. We conclude breakaway bases reduce the force of impact and moments to a statistically significant level and confirm previous field studies. Though there is a difference among the breakaway bases themselves, they should be used on all fields.

Prevention of commotio cordis in baseball: an evaluation of chest protectors.

BACKGROUND: In a recent study of fatal chest impacts by baseballs, 28% of the children were wearing a chest protector. This study evaluates the effectiveness of chest protectors in reducing the risk of commotio cordis. METHODS: Five commercially available chest protectors were placed on a three-rib structure simulating the chest and impacted at 40, 50, 60, and 70 miles per hour by a standard baseball. Ten repeated tests were conducted on each vest in random order, and on the control (unprotected chest). The viscous response (or viscous criterion [VC]) was used to assess differences in fatality risk. RESULTS: One vest had a statistically lower VC (average, 50.6%, p < 0.05) for all impact speeds. Three averaged 18.7% to 27.7% lower VC, but were significantly different only at higher speeds. One vest had an average 34.2% higher VC, and was significantly higher at 40 to 50 miles per hour (p < 0.05). A method was proposed linking laboratory test results to real-world incidents of ventricular fibrillation. CONCLUSIONS: The majority of commercially available chest protectors fail to provide consistent reductions in commotio cordis risk. Nonetheless, there are benefits from their use in baseball until improved safety equipment is developed and standard tests are established to assess sport equipment effectiveness.

Biomechanical predictor of commotio cordis in high-speed chest impact.

BACKGROUND: Commotio cordis is a term used to describe cases of blunt thoracic impact causing fatality without gross structural damage of the heart and internal organs. Death is attributed to ventricular fibrillation or cardiac arrhythmia aggravated by traumatic apnea. The biomechanical response related to the risk of commotio cordis has not been determined. METHODS: Reanalysis of previously published experimental data was performed to determine which biomechanical parameter predicts the occurrence of commotio cordis. Logistic regression was used to determine the risk for commotio cordis with the level of chest compression, rate of chest deformation, and viscous criterion. RESULTS: By using only cases without serious tissue injury (Abbreviated Injury Scale score < 4), viscous criterion was the best predictor of commotio cordis or ventricular fibrillation (chi2 = 7.69, p = 0.006). It was also the best predictor of heart rupture (chi2 = 13.19,p = 0.0003) and severe cardiac injury with Abbreviated Injury Scale score > or = 4 (chi2 = 25.03, p = 0.0001). CONCLUSION: Based on this in-depth analysis, the viscous criterion is the relevant biomechanical response to assess the risk of commotio cordis and more severe thoracic injury in high-speed blunt impact.

Muscle responses to simulated torque reactions of hand-held power tools.

The aim of this work was to investigate physiological responses to torque reaction forces produced by hand-held power tools used to tighten threaded fasteners. Such tools are used repetitively by workers in many industries and are often associated with upper limb musculoskeletal complaints. The tools considered for stimulation in this study had straight handles and required from 100 to 400 ms to tighten fasteners to a peak torque of 1.0 to 2.5 Nm and from 50 to 150 ms for the torque to decay to zero. A tool stimulator was constructed to apply a programmed torque profile to a handle similar to that of a straight in-line power screwdriver. Wrist flexor and extensor surface EMGs and handle position were recorded as subjects held handles subjected to controlled torque loads that tended to flex the wrist. It was found that: (1) very high EMG values occurred even though torques were of short duration (50 to 600 ms) and the peak torques were low (7-28% of maximum strength); (2) high EMGs in anticipation of torque are directly related to torque build-up rate and peak torque; (3) high peak flexor and extensor EMGs during and following torque onset are related to torque build-up rate and peak torque; (4) minimum time of peak EMGs of 72-87 ms following the onset of torques with 50 ms build-up suggests the contribution of an extensor muscle stretch reflex component; delayed peak for longer build-ups suggests a central control of muscle force in response to torque; (5) angular excursions of handles increase with decreasing torque build-up time and increasing torque magnitude causes increasing eccentric work; (6) the results show that the slow torque build-up times (450 ms) correspond to minimum peak EMGs; and (7) accumulated EMGs increase with increasing torque and torque build-up times. Further studies are needed to evaluate fatigue and musculoskeletal injuries associated with prolonged periods of tool use.

Effect of acute metabolic stress on pituitary-adrenal axis activation in patients with schizophrenia.

OBJECTIVE: Although several lines of evidence suggest that stress plays a role in the course of schizophrenia, studies that have assessed stress-relevant neurobiological measures have not produced consistent results. The authors examined the effects of acute metabolic stress induced by 2-deoxy-D-glucose (2-DG) on pituitary-adrenal axis activation. METHOD: Thirteen patients with schizophrenia and 11 healthy comparison subjects were administered pharmacological doses of 2-DG (40 mg/kg). The subjects' arterial plasma was then assayed for levels of adrenocorticotropic hormone (ACTH) and cortisol. RESULTS: 2-DG induced significant increases in the measured hormones in both groups, and ACTH elevations were significantly greater in patients with schizophrenia than in comparison subjects. CONCLUSIONS: Patients with schizophrenia have an exaggerated ACTH response to acute metabolic stress exposure.

Blunt chest impacts: assessing the relative risk of fatal cardiac injury from various baseballs.

OBJECTIVE: To compare various soft-core baseballs for their ability to reduce the risk of fatal chest-impact injury. DESIGN: This study used a three-rib biomechanical surrogate to quantitatively analyze chest impacts from nine soft-core baseballs and one standard baseball, which served as the control. Impacts were achieved with an air cannon system, with the velocity of impact being 40, 50, and 60 mph. MATERIALS AND METHODS: The deflection of the three-rib structure at the sternum was measured and used to calculate the viscous criterion, which correlates with risk of chest-impact injury. MEASUREMENTS AND MAIN RESULTS: Analysis showed that baseballs with lighter mass had a significantly lower viscous criterion (p < 0.05). Those with a similar mass had no change in the viscous criterion, and the heaviest soft-core baseball had a significantly higher viscous criterion at an impact velocity of 60 mph. CONCLUSION: The results of this study indicate that soft-core baseballs may not differ from a standard baseball with regard to the risk of fatal chest-impact injury while playing baseball. Other techniques, such as preventive coaching, need to be implemented when trying to improve baseball safety.

Intracarpal canal pressures: the role of finger, hand, wrist and forearm position.

OBJECTIVE: The study examined the change in intracarpal canal pressure (ICCP) in relationship to finger, hand, wrist and forearm position. DESIGN: The study was an in vivo measurement of ICCP in seven subjects undergoing a standardized set of manoeuvres that systematically varied finger, hand, wrist, and forearm position. BACKGROUND: It has been known that the ICCP increased with extremes of wrist flexion and extension but the change in pressure in response to radial and ulnar deviation as well as hand and forearm position has not been reported. METHODS: The ICCP was measured using a slit catheter technique; each variation of position was repeated three times with continuous monitoring of ICCP, wrist angulation, and metacarpal-phalangeal joint angulation. RESULTS: The study demonstrated that ICCPs were lowest when the wrist is in a neutral position, the hand relaxed with fingers flexed and the forearm in a semi-pronated position. Wrist extension and flexion resulted in the greatest increase in ICCP followed by forearm pronation and supination. Radial and ulnar deviation also increased the pressure but to a lesser extent. CONCLUSIONS: The findings of this study support the concept that the wrist and forearm should be maintained in a neutral position during vocational and avocational activities in an effort to minimize pressure within the carpal tunnel and thereby reduce the risk of developing carpal-tunnel syndrome. RELEVANCE: It is desirable to know how the ICCP changes in response to change in hand, wrist, and forearm position so that work activities are designed to minimize the pressure within the carpal canal and thus maintain the viability of the median nerve within the carpal canal.

Goal post injuries in soccer. A laboratory and field testing analysis of a preventive intervention.

Soccer is the most popular team sport worldwide, with approximately 40 million amateur participants. Most fatalities in soccer are related to player impact with the goal post. This study focuses on two case reports, a laboratory testing phase, and a pilot field testing phase of preventive equipment that can be used around the goal to prevent injury. Horizontal and vertical impact testing in the laboratory revealed impact force was diminished when the goal post was covered with protective padding (reduction of 31% and 63%) (P < 0.05). These data showed a statistically significant decrease in force at all temperatures. In the pilot field testing phase of the study, 471 games were monitored. Soccer teams participating in youth, teen, and adult soccer leagues were included in this phase of the study. During the 3-year study, there were seven player collisions with padded goal posts, and no injuries were recorded. The use of padded goal posts within the game of soccer has been documented to reduce the possibility of injury, both in the laboratory phase and in the pilot field testing phase.

An analysis and comparison of soccer shin guards.

Worldwide > 40 million amateurs participate in the team sport of soccer. With 647,368 injuries occurring from 1989 through 1992, the risk of injury during the play of soccer is evident. Lower extremity injuries have been found to comprise 13.1% of the total injuries in soccer. To date, a comprehensive evaluation of protective equipment utilized to prevent lower extremity injuries in soccer has been lacking. This study utilized a 5th percentile Hybrid III female dummy to evaluate the effectiveness of shin guards in attenuating the forces which can lead to lower extremity injuries. A pendulum impact apparatus simulated one player being kicked by another. Impacts were delivered to the anterior tibial region of the Hybrid III dummy and peak loads were recorded. Load forces were reduced 41.2-77.1% with the utilization of shin guards. Even at extreme temperatures, the guards were found to be effective in lowering the amount of impact force transferred to the shin region. The results of this study indicate that the use of shin guards will attenuate the force of impact to the tibia and thus reduce the risk of injury.

Reverse Phalen's maneuver as an aid in diagnosing carpal tunnel syndrome.

A reverse Phalen's maneuver involves wrist and finger extension held for 1 minute. We showed that this maneuver results in a significantly higher intracarpal canal hydrostatic pressure as compared to a traditional Phalen's or a modified Phalen's maneuver. Additionally, 31 individuals with complaints of carpal tunnel syndrome symptoms and 20 normal controls were evaluated to see what effect the reverse Phalen's maneuver would have on median sensory latency and amplitude. Both groups demonstrated a prolongation of the median sensory revoked response after 1 minute of this maneuver. The control group had a prolongation of 0.05 ms compared to 0.13 ms in the carpal tunnel syndrome group. The difference between the two groups was significant at a p = 0.05 level. This may add to the sensitivity of conventional screening methods.