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The hypothesis that local hypoxia and chlorophyll concentration are spatially tethered to local, sediment-driven nutrient release was examined in a small, nutrient-impacted estuary in the Southern Gulf of St. Lawrence, Canada. Sediment reactor core samples were taken at 10 locations between 0.25 and 100% of the estuary area in spring and fall (2019) and used to estimate nitrogen and phosphate flux. Sediment organic matter, carbonate, percent nitrogen, percent carbon, δ13C, and δ15N were measured from the reactor core stations. Oxygen was recorded continually using oxygen loggers while chlorophyll and salinity were measured bi-weekly. A hydrodynamic model was used to determine water renewal time at each station. The most severe eutrophication effects were in the upper one-fifth of the estuary. There were strong local relationships between sediment biogeochemistry, hypoxia, and chlorophyll metrics but not with water renewal time. Internal nutrient loading represented 65% and 69% of total N loading, and 98% and 89% of total P loading to the estuary in June and September, respectively. Sediment nitrogen flux was highly predictable from a range of local sediment variables that reflect either nutrient content, or organic carbon enrichment in general. Percent nitrogen and percent carbon were highly correlated but sediment P flux was poorly predicted from sediment parameters examined. The highest correlations were with percent nitrogen and percent carbon. These results indicate that incorporating internal nutrient loading into nutrient monitoring programs is a critical next step to improve predictive capacity for eutrophication endpoints and to mitigate nutrient effects., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Objective: Automated driving systems (ADS) are actively being deployed within the driving fleet. ADS are designed to safely navigate roadways, which entails an expectation of encountering varying degrees of potential conflict with other road users. The ADS design and evaluation process benefits from estimating injury severity probabilities for collisions that may occur. Current regression models in the literature are typically bespoke analyses involving targeted principal directions of force (PDOFs) and occupant positions. It is preferable to rely on injury severity models derived from a single source to provide a continuous function of risk for all planar collisions, while also accounting for specific vehicle and occupant characteristics. The novel feature of the proposed models is continuous, parametric injury risk surfaces that encompass the full spectrum of available United States field data. Methods: We used years 2001-2015 of the National Automotive Sampling System, Crashworthiness Data System (NASS-CDS) and years 2017-2019 of the Crash Investigation Sampling System (CISS) to estimate injury risk at the maximum abbreviated injury scale (MAIS) 3 and higher (3+) and 5 and higher (5+) levels for all adult occupants traveling in 2002 or newer passenger vehicles which were less than 10 years old at the time of the crash. The models account for occupant, vehicle, and crash characteristics. Interactions with vulnerable road users (e.g., pedestrian, bicyclist) were not considered. Results: We present statistical models suitable to predict injury in all non-rollover crashes at the maximum MAIS3+ and 5+ levels, and show that these models can be comparable to similar single scenario (e.g., frontal) crash models. We discuss challenges with imputing missing field data, and discuss handling of covariates that may not be known at the time of the crash. Conclusions: Collision severity assessment is a vital component of the ADS design process. We developed a novel injury risk function that can assess occupant injury risks across the spectrum of foreseeable planar collisions. These models can provide insight on potential outcomes of counterfactual simulations, injury risk and crashworthiness considerations for human driven vehicles, and provide an evaluation tool that can be applied in ADS safety impact evaluation.

The relationship between laboratory and on-field performance of football helmets was assessed for 31 football helmet models selected from those worn by players in the 2015-2019 National Football League (NFL) seasons. Linear impactor tests were conducted with helmets placed on an instrumented Hybrid III head and neck assembly mounted on a sliding table. Based on impacts to each helmet at six impact locations and three velocities, a helmet performance score (HPS) was calculated using a linear combination of the head injury criterion (HIC) and the diffuse axonal multi-axis general evaluation (DAMAGE). To determine the on-field performance of helmets, helmet model usage, player participation, and incident concussion data were collected from the five NFL seasons and used to calculate helmet model-specific concussion rates. Comparison of laboratory HPS to the helmet model-specific concussion rates on a per play basis showed a positive correlation (r 2  = 0.61, p < 0.001) between laboratory and on-field performance of helmet models, indicating that helmets which exhibited reduced impact severity in the laboratory tests were also generally associated with lower concussion rates on-field. Further analysis showed that NFL-prohibited helmet models exhibited a significantly higher odds of concussion (OR 1.24; 95% CI 1.04-1.47; p = 0.017) relative to other helmet models.

Consideration of position-specific features of the NFL concussion environment could enable improved risk mitigation through the design of position-specific helmets to improve self-protection as well as protection for the other player with whom the contact occurs. The purpose of this paper is to quantify position-specific features of scenarios resulting in concussions to NFL players, and the players they contact, by reviewing all game footage (broadcast and non-broadcast) over 4 seasons. Position-specific features were documented for 647 concussions in which a primary exposure could be visualized, including impact source, helmet impact location, activity, and the other player with whom the contact occurred. Findings include the over-representation of helmet-to-ground impacts to the rear of the quarterback's helmet, the high frequency of impacts to the side (upper) location of both concussed players and the players they contacted regardless of position, and distinct differences in the circumstances of concussions to cornerbacks and safeties. The study shows that some features of concussion scenarios are common to all positions, but several position-specific features exist and can inform the design of position-specific helmets for NFL players.

Background: Concussions in American football remain a high priority of sports injury prevention programs. Detailed video review provides important information on causation, the outcomes of rule changes, and guidance on future injury prevention strategies., Purpose: Documentation of concussions sustained in National Football League games played during the 2015-2016 and 2016-2017 seasons, including consideration of video views unavailable to the public., Study Design: Descriptive epidemiology study., Methods: All reported concussions were reviewed with all available video footage. Standardized terminology and associated definitions were developed to describe and categorize the details of each concussion., Results: Cornerbacks sustained the most concussions, followed by wide receivers, then linebackers and offensive linemen. Half (50%) of concussions occurred during a passing play, 28% during a rushing play, and 21% on a punt or kickoff. Tackling was found to be the most common activity of concussed players, with the side of the helmet the most common helmet impact location. The distribution of helmet impact source-the object that contacted the concussed player's helmet-differed from studies of earlier seasons, with a higher proportion of helmet-to-body impacts (particularly shoulder) and helmet-to-ground impacts and with a lower proportion of helmet-to-helmet impacts. Helmet-to-ground concussive impacts were notable for the high prevalence of impacts to the back of the helmet and their frequency during passing plays., Conclusion: Concussion causation scenarios in the National Football League have changed over time., Clinical Relevance: The results of this study suggest the need for expanded evaluation of concussion countermeasures beyond solely helmet-to-helmet test systems, including consideration of impacts with the ground and with the body of the opposing player. It also suggests the possibility of position-specific countermeasures as part of an ongoing effort to improve safety.

Previous studies on neck muscle strength and motion have assumed or imposed varying constraints on the heads and bodies of the subjects. In this study, we asked 20 subjects to vigorously shake their heads 5-10 times in a completely unconstrained manner. The kinematics and kinetics of the head and neck were measured from video analysis and instrumentation mounted inside the mouth. Subjects shook their heads at self-selected tempos ranging from 1.9-4.7 Hz over a 20-91° range of motion. The motion of each subject's head could be approximated by a fixed center of rotation that was typically located in the midcervical spine, but varied widely among subjects. Significant differences between men and women were observed. Peak head accelerations were low (4.3 ± 1.1 g and 250 ± 103 rad/s2 for men, 3.0 ± 0.9 g and 182 ± 58 rad/s2 for women) and estimated peak generated neck moments at C7/T1 were comparable to values reported in isometric neck strength studies (47 ± 14 N·m in extension and 22 ± 9 N·m in flexion for men, 25 ± 8 N·m in extension and 9 ± 7 N·m in flexion for women).

In this study we asked whether asymmetries related to handedness in right-handers (n=10) and left-handers (n=10) could influence hemispheric motor facilitation when the preferred or less-preferred hand is engaged in haptic sensing. Transcranial magnetic stimulation (TMS) was used to assess corticomotor excitability when young participants performed a precision grip under two conditions, i.e., with or without a haptic sensing component. In the grip condition participants were required to grasp a 5-mm thick plate between thumb and index fingers, whereas in the haptic condition they performed the same action but were also required to make judgements about the plate's thickness, i.e., either thin (5 mm) or thick (10 mm). Analysis of task-related variations in motor evoked potentials (MEP) amplitude recorded in hand muscles revealed a significant task×hand/hemisphere interaction only in the group of right-handers when the left hand/right hemisphere was engaged in haptic sensing as opposed to simply gripping. Collectively, these results are congruent with other TMS reports describing a greater degree of hemispheric asymmetry in right-handers, who are typically more strongly lateralised than left-handers. Our results with regard to a rightward hemispheric asymmetry for MEP facilitation with haptic sensing are also congruent with the predominant role ascribed to the right sensorimotor cortex in the processing of proprioceptive information.

Previous epidemiological studies of rollover crashes have focused primarily on serious and fatal injuries in general, while rollover crash testing has focused almost exclusively on cervical spine injury. The purpose of this study was to examine and compare the risk factors for cervical spine, head, serious, and fatal injury in real world rollover crashes. Rollover crashes from 1995-2008 in the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) were investigated. A large data set of 6015 raw cases (2.5 million weighted) was generated. Nonparametric univariate analyses, univariate logistic regression, and multivariate logistic regression were conducted. Complete or partial ejection, a lack of seatbelt use, a greater number of roof inversions, and older occupant age significantly increased the risk of all types of injuries studied (p<0.05). Far side seating position increased the risk of fatal, head, and cervical spine injury (p<0.05), but not serious injury in general. Higher BMI was associated with an increased risk of fatal, serious, and cervical spine injury (p<0.05), but not head injury. Greater roof crush was associated with a higher rate of fatal and cervical spine injury (p<0.05). Vehicle type, occupant height, and occupant gender had inconsistent and generally non-significant effects on injury. This study demonstrates both common and unique risk factors for different types of injuries in rollover crashes., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Ejection greatly increases the risk of injury and fatality in a rollover crash. The purpose of this study was to determine the crash, vehicle, and occupant characteristics that affect the risk of ejection in rollovers. Information from real world rollover crashes occurring from 2000 - 2010 was obtained from the National Automotive Sampling System (NASS) in order to analyze the effect of the following parameters on ejection risk: seatbelt use, rollover severity, vehicle type, seating position, roof crush, side curtain airbag deployment, glazing type, and occupant age, gender, and size. Seatbelt use was found to reduce the risk of partial ejection and virtually eliminate the risk of complete ejection. For belted occupants, the risk of partial ejection risk was significantly increased in rollover crashes involving more roof inversions, light trucks and vans (LTVs), and larger occupants. For unbelted occupants, the risk of complete ejection was significantly increased in rollover crashes involving more roof inversions, LTVs, far side occupants, and higher levels of roof crush. Roof crush was not a significant predictor of ejection after normalizing for rollover severity. Curtain airbag deployment was associated with reduced rates of partial and complete ejection, but the effect was not statistically significant, perhaps due to the small sample size (n = 89 raw cases with curtain deployments). A much greater proportion of occupants who were ejected in spite of curtain airbag deployment passed through the sunroof and other portals as opposed to the adjacent side window compared to occupants who were ejected in rollovers without a curtain airbag deployment. The primary factors that reduce ejection risk in rollover crashes are, in generally decreasing order of importance: seatbelt use, fewer roof inversions, passenger car body type, curtain airbag deployment, near side seating position, and small occupant size.

The purpose of this study was to document head and neck loading in a group of ordinary people engaged in non-injurious everyday and more vigorous physical activities. Twenty (20) volunteers that were representative of the general population were subjected to seven test scenarios: a soccer ball impact to the forehead, a self-imposed hand strike to the forehead, vigorous head shaking, plopping down in a chair, jumping off a step, a seated drop onto the buttocks, and a vertical drop while seated supine in a chair. Some scenarios involved prescribed and well-controlled stimuli, while others allowed the volunteers to perform common activities at a self-selected level of intensity. Head accelerations up to 31 g and 2888 rad/s(2) and neck loads up to 268 N in posterior shear, 526 N in compression, and 36 Nm in extension were recorded. Most head and neck injury criteria predicted a low risk of injury in all activities. However, rotational head accelerations and Neck Injury Criterion (NIC) values were much higher than some proposed tolerance limits in a large number of tests, all of which were non-injurious. The data from this study help us to establish an envelope of head and neck loading that is commonly encountered and presents a minimal risk of injury.

The most important factor in predicting the risk of injury or death in a frontal crash is the crash severity, which is expressed as the velocity change, or delta-V, experienced by the vehicle during the crash. The National Automotive Sampling System (NASS) is the largest database in the world linking injury outcomes with delta-Vs, which are obtained from field reconstructions. The accuracy of these reconstructions was assessed by analyzing 228 NASS cases involving single event frontal crashes in which the vehicle's frontal delta-V was also measured directly by an onboard event data recorder (EDR). Compared to the EDR measurements, the delta-V values in NASS averaged 19% lower with a standard deviation of 8.6 kph. The effect of this error on injury and fatality risk calculations was investigated using NASS data from 1997 - 2006 for frontal crashes with a known delta-V. Injury and fatality risk functions were calculated by curve fitting the distributions of the delta-V values associated with injury and fatality incidence normalized by the fitted crash exposure distribution. Individual delta-V values were linearly scaled to correct for the bias error, and the delta-V distributions were corrected for scatter error using a numerical deconvolution technique. Correcting for delta-V bias error shifted the calculated risk curves to the right and correcting for delta-V scatter error shifted the curves back to the left, but to a lesser extent. The effects of occupant age, gender, and belt use on injury and fatality risk were substantial.

For this study, a comprehensive analysis was performed to assess the influence of body mass index on thoracic injury potential. The data for this study were obtained from the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) database for years 1993-2005. Obese occupants had a 26 and 33% higher risk of AIS > or = 2 and AIS > or = 3 thoracic injury when compared to lean occupants. The increased risk of AIS > or = 3 injury due to obesity was slightly higher for older occupants, but the influence of age was greater than that of obesity. The increase in injury potential was higher for unbelted obese occupants than unbelted. Non-parametric and parametric risk curves were developed to estimate the risk of thoracic injury based on occupant BMI, belt use and delta-V. Overall, increase in thoracic injury risk due to obesity is more prominent in males and older occupants and for occupants sustaining AIS > or = 3 thoracic injuries.

The increase in upper extremity injuries in automobile collisions, because of the widespread implantation of airbags, has lead to a better understanding of forearm injury criteria. Risk functions for upper extremity injury that can be used in instrumented upper extremities would be useful. This paper presents a risk function for forearm injury for the 50th percentile male based on bending fracture moment data gathered from previous studies. The data was scaled using two scaling factors, one for orientation and one for mass, and the Weibull survival analysis model was then used to develop the risk function. It was determined that a 25% risk of injury corresponds to an 82 Nm bending load, a 50% risk of injury corresponds to a 100 Nm bending load, and a 75% risk of injury corresponds to a 117 Nm bending load. It is believed the risk function can be used with an instrumented upper extremity during vehicle testing.

The increase in upper extremity injuries in automobile collisions, because of the widespread implantation of airbags, has lead to an increased focus in humerus injury criteria. Risk functions for upper extremity injury that can be used in instrumented upper extremities would be useful. This paper presents a risk function for humerus injury for the 50th percentile male based on bending fracture moment data gathered from previous studies. The data was scaled using two scaling factors, one for mass and one for rate, and the Weibull survival analysis model was then used to develop the risk function. It was determined that a 25% risk of injury corresponds to a 214 Nm bending load, a 50% risk of injury corresponds to a 257 Nm bending load, and a 75% risk of injury corresponds to a 296 Nm bending load. It is believed the risk function can be used with an instrumented upper extremity during vehicle testing.

Head injury is typically predicted using linear or rotational acceleration-based injury criteria. In many cases, the linear components of head acceleration can be determined more easily than the rotational components. Peak rotational head acceleration (apeak) can be calculated from the peak linear head acceleration (apeak) by assuming a value for the effective radius of rotation (r) of the head (apeak = apeak / r). Empirical values for the effective radius of rotation were calculated using linear and angular head acceleration data from 20 human volunteers subjected to a wide variety of test scenarios, including a soccer ball impact to the forehead, a voluntary hand strike to the forehead, voluntary shaking of the head, plopping down in a chair, and a vertical drop while seated supine in a chair. In addition, values for the effective radius of rotation of the head were calculated for American football, boxing, and frontal and rear end automotive impacts using data from the literature. The range of values for the effective radius of rotation of the head for each activity was characterized statistically by calculating median, middle 50%, and middle 95% values from the cumulative distribution. Median values for the effective radius of rotation of the head ranged from 84 mm for boxing to 376 mm for voluntary hand strikes to the forehead. It is important to note that the concept of an effective radius of rotation of the head is simply a convenient method for expressing an empirical relationship between peak linear and peak rotational head acceleration, and does not represent an accurate model of the kinematics of the head. In most of the activities studied, the head kinematics were complex, and the center of gravity of the head did not rotate at a constant radius about a fixed point.

The purpose of this study is to develop injury risk functions that predict zygoma fracture based on baseball type and impact velocity. Zygoma fracture strength data from published experiments were mapped with the force exerted by a baseball on the orbit as a function of ball velocity. Using a normal distribution, zygoma fracture risk functions were developed. Experimental evaluation of these risk functions was performed using six human cadaver tests and two baseballs of different stiffness values. High speed video measured the baseball impact velocity. Post test analysis of the cadaver skulls was performed using CT imaging including three-dimensional reconstruction as well as autopsy. The developed injury risk functions accurately identify the risk of zygoma fracture as a result of baseball impact. The experimental results validated the zygoma risk functions at the lower and upper levels. The injuries observed in the post test analysis included fractures of the zygomatic arch, frontal process and the maxilla, zygoma suture, with combinations of these creating comminuted, tripod fractures of the zygoma. Tests with a softer baseball did result in injury but these had fewer resulting zygoma bone fragments and occurred at velocities 50% higher than the major league ball.

Dysplasia of the renal and cervical arteries are well known, but dysplasia of the superior mesenteric artery (SMA) is less frequent and has specific presentation. There have been few reports on the different types of presentations. We report a series of 38 cases and present the characteristic features together with a comparison with data in the literature. These non-atheromatous non-inflammatory lesions of the arterial wall occurred either in a context of fibromuscular disease which cause is unknown (30/38 patients) or in patients with genetic disease such as neurofibromatosis (3/38) or Ehlers-Danlos disease (5/38). The fibromuscular disease presented three aspects with specific characteristics. a) stenosing lesions found predominantly in women with a different morphology than in the other localization (usually associated): irregular diffuse stenosis discovered in patients with hypertension, or ischemic digestive symptoms (6/14 patients). b) Aneurysms, also found predominantly in women, but less frequently associated with other dysplasias. These aneurysms were generally sacciform. Unlike data in the literature, our series only included rupture in 1/8 cases. The aneurysm was discovered during the exploration of abdominal pain or hypertension. c) The third type of fibromuscular disease concerned dissections which were observed in the male population, (except one case of segmental dysplasia), and presented with signs of digestive ischemia in the other seven patients, four in an emergency context requiring immediate treatment. Two genetic diseases were observed. a) Neurofibromatosis led to dysplasia analogous to fibromuscular disease, but with abnormal nerve formations in the wall. For the three cases observed, one involved only the visceral arteries and the two others thoraco-abdominal coarctation. b) We had five patients with Ehlers-Danlos syndrome, with dysplasia of the superior mesenteric artery. For three there was a fusiform dilatation and in one small aneurysms along the arterial trunk, which only required surveillance. There was only one aneurysm which required treatment by resection and venous graft. In these young patients, revascularization was generally achieved with autologous material and the prognosis was favorable. Embolization was successful in treating the sacciform aneurysm in one patient. In conclusion, dysplasia of the superior mesenteric artery has a specific presentation which must be recognized to enable diagnosis of this not uncommon condition in young subjects (even children) who often present with an acute abdomen requiring urgent treatment.

By incorporating material and geometrical properties into a model of the human thorax one can develop an injury criterion that is a function of stress and strain of the material and not a function of the global response of the thorax. Previous research on the mechanical properties of ribs has focused on a limited set of specific ribs. For this study a total of 52 rib specimens were removed from four cadaver subjects. Variation in peak moment by thoracic region was significant (p < 0.01) with average values of 2, 2.9 and 3.9 N-m for the anterior, lateral and posterior regions respectively. Two geometrical properties, radius of gyration and distance from the neutral axis, showed significant variation by region (p < 0.0001) as well as by rib level (p = < 0.01, 0.05). The results of this study can be used to update current models of the human thorax to account for the variation in strength and geometrical properties throughout the rib cage. Accounting for the variation in rib properties by region will improve injury predictive measures and, therefore, the ability to design systems to prevent thoracic injury.

The purpose of this study was to develop injury risk functions for dynamic bending of the human femur in the lateral-to-medial and posterior-to-anterior loading directions. A total of 45 experiments were performed on human cadaver femurs using a dynamic three-point drop test setup. An impactor of 9.8 kg was dropped from 2.2 m for an impact velocity of 5 m/s. Five-axis load cells measured the impactor and support loads, while an in situ strain gage measured the failure strain and subsequent strain rate. All 45 tests resulted in mid-shaft femur fractures with comminuted wedge and oblique fractures as the most common fracture patterns. In the lateral-to-medial bending tests the reaction loads were 4180 +/- 764 N, and the impactor loads were 4780 +/- 792 N. In the posterior-to-anterior bending tests the reaction loads were 3780 +/- 930 N, and the impactor loads were 4310 +/- 1040 N. The difference between the sum of the reaction forces and the applied load is due to inertial effects. The reaction loads were used to estimate the mid-shaft bending moments at failure since there was insufficient data to include the inertial effects in the calculations. The resulting moments are conservative estimates (lower bounds) of the mid-shaft bending moments at failure and are appropriate for use in the assessment of knee restraints and pedestrian impacts with ATD measurements. Regression analysis was used to identify significant parameters, and parametric survival analysis was used to estimate risk functions. Femur cross-sectional area, area moment of inertia (I), maximum distance to the neutral axis (c), I/c, occupant gender, and occupant mass are shown to be significant predictors of fracture tolerance, while no significant difference is shown for loading direction, bone mineral density, leg aspect and age. Risk functions are presented for femur cross-sectional area and I/c as they offer the highest correlation to peak bending moment. The risk function that utilizes the most highly correlated (R2 = 0.82) and significant (p = 0.0001) variable, cross-sectional area, predicts a 50 percent risk of femur fracture of 240 Nm, 395 Nm, and 562 Nm for equivalent cross-sectional area of the 5(th) percentile female, 50(th) percentile male, and 95(th) percentile male respectively.

This paper presents the results of dynamic material tests and computational modeling that elucidate the effects of regional rib mechanical properties on thoracic fracture patterns. First, a total of 80 experiments were performed using small cortical bone samples from 23 separate locations on the rib cages of four cadavers (2 male, 2 female). Each specimen was subjected to dynamic three-point bending resulting in an average strain rate of 5 +/- 1.5 strain/s. Test coupon modeling was used to verify the test setup. Regional variation was defined by location as anterior, lateral, or posterior as well as by rib level 1 through 12. The specimen stiffness and ultimate stress and strain were analyzed by location and rib level. Second, these material properties were incorporated into a human body computational model. The rib cage was partitioned into anterior, lateral, and posterior segments and the material properties were varied by location using an elastic-plastic material model. A total of 12 simulations with a rigid impactor were performed including 2 separate material assumptions, original and modified rib properties for regional variations, 3 separate impactor velocities, and 2 directions, anterior and lateral. The data from the material tests for all subjects indicate a statistically significant increase in the average stiffness and average ultimate stress for the cortical bone specimens located in the lateral (11.9 GPa modulus, 153.5 MPa ultimate stress) portion of the ribs versus the anterior (7.51 GPa, 116.7 MPa) and posterior (10.7 GPa, 127.7 MPa) rib locations. In addition, the stiffness, ultimate stress, and ultimate strain for all subjects are significantly different by rib level with each variable generally increasing with increasing rib number. The results from the computational modeling for both frontal and lateral impacts illustrate that the location and number of rib fractures are altered by the inclusion of rib material properties that vary by region.

Over 2.4 million eye injuries occur each year in the US, with over 30,000 patients left blind as a result of the trauma. The majority of these injuries occur in automobile crashes, military operations and sporting activities. This paper presents a nonlinear finite element model of the eye and the results of 22 experiments using human eyes to validate for globe rupture injury prediction. The model of the human eye consists of the cornea, sclera, lens, ciliary body, zonules, aqueous humor and vitreous body. Lagrangian membrane elements are used for the cornea and sclera, Lagrangian bricks for the lens, ciliary, and zonules, and Eulerian brick elements comprise the aqueous and vitreous. Nonlinear, isotropic material properties of the sclera and cornea were gathered from uniaxial tensile strip tests performed up to rupture. Dynamic modeling was performed using LS-Dyna. Experimental validation tests consisted of 22 tests using three scenarios: impacts from foam particles, BB's, and baseballs onto fresh eyes used within 24 hours postmortem. The energies of the projectiles were chosen so as to provide both globe rupture and no rupture tests. Displacements of the eye were recorded using high speed color video at 7100 frames per second. The matched simulations predicted rupture of the eye when rupture was seen in the BB and baseball tests, and closely predicted displacements of the eye for the foam tests. Globe rupture has previously been shown to occur at peak stresses of 9.4 MPa using the material properties included in the model. Because of dynamic effects and improvements in boundary conditions resulting from a more realistic modeling of the fluid in the anterior and posterior chambers, the stresses can be much higher than those previously predicted, with the globe remaining intact. The model is empirically verified to predict globe rupture for stresses in the corneoscleral shell exceeding 23 MPa, and local dynamic pressures exceeding 2.1 MPa. The model can be used as a predictive aid to reduce the burden of eye injury, and can serve as a validated model to predict globe rupture.

Surgical management of hypogastric artery aneurysm is associated with high morbidity due to hemorrhage and ischemia. Occlusion by embolization is an attractive alternative treatment. Between 1991 and 1995, we used Gianturco coils to embolize 17 hypogastric aneurysms in 14 patients. All patients were men with a mean age of 77 years. Ten patients had previously undergone aortic repair. Complete occlusion of the aneurysm was achieved in 16 cases but placement of an iliac stent was required in 1 case. Embolization failed in one case involving rupture of a large aneurysm. No complications were observed. Moderate buttock claudication was noted after bilateral embolization in three cases. Embolization of hypogastric artery aneurysm using coils resolves the long-term problems associated with surgical ligation. Extensive aneurysm of the origin to the bifurcation is the main indication for nonresective treatment but embolization can also be a useful alternative to open surgery for high-risk patients. Availability of stent grafts may extend the indication for endovascular treatment.

Post-irradiation axillo-subclavian arteriopathy can develop 6 months to 20 years after radiotherapy. Incidence estimated from duplex scan screening is about 30%, half of the cases having no hemodynamic significance. In our experience, asymptomatic lesions are the most common. Nevertheless, we have observed since 1978, 38 symptomatic patients including 23 with either acute ischemia (8 patients), or chronic ischemia (15 patients) requiring revascularization. We used an endovascular approach in 8 and open surgery in 15. A bypass graft was performed in 13 patients, using a vein (8 patients) rather than a prosthesis (5 patients), implanted in healthy territory, proximally or in the common carotid (11 patients) or the proximal subclavian (2 patients), and distally in the axillary artery (5 patients) or the brachial artery (8 patients). One venous bypass became occluded postoperatively. The other bypasses remained patent during follow-up of over 10 years. There of the five prosthetic bypassess gradually failed without recurrence of critical ischemia. Other revascularization procedures included endarterectomy and thrombectomy. In the long term, functional prognosis mainly depended on the frequently associated involvement of the plexus in the post-irradiation changes, which, together with the revascularization procedure, also required neurolysis in 11 patients, two omental covers and a free musculocutaneous transfer in 9 patients.

The purpose of this retrospective, single-institution study was to analyze the results of endovascular treatment of iliac aneurysm using covered stents. Since January 1, 1996, a total of 34 iliac aneurysms have been treated with covered endovascular stents. The series included 9 isolated aneurysms, 29 aneurysms following repair of aortic aneurysm, and 3 false anastomotic aneurysms. The mean diameter of aneurysm was 42 mm (range, 21 to 120 mm). The aneurysm was either symptomatic or complicated in 11 cases. Three procedures were carried out under emergency conditions after acute rupture. Stent deployment was successful in 33 cases (technical success rate, 97.6%). Exclusion of the aneurysm was obtained in all cases with one (n = 26) or two overlapping (n = 7) covered stents. Mean procedure duration was 45 min (range, 25 to 75 min). The internal iliac artery was patent in 28 cases, but patency was preserved in only 4 cases. In the remaining 24 cases the internal iliac artery was excluded either preoperatively by embolization using Gianturco coils (n = 15) or intraoperatively by placement of the stent (n = 9). Endovascular treatment of iliac aneurysm with covered stents achieves good short- and middle-term results but usually requires exclusion of the internal iliac artery.

The objectives of this study were to examine the morphology, restenosis, dilatation, and possible complications of polyester collagen impregnated carotid patches. Between March 1994 and January 1995, 207 patients (56 females and 151 males) undergoing 221 carotid endarterectomies (CE) with a collagen-impregnated knitted polyester patch were enrolled in a European prospective multicenter study. Patches were used for arteries deemed to be smaller than usual by visual inspection. General anesthesia was used in 201 procedures (91%), and a shunt was used in 76 procedures (34.4%). One hundred fourteen CE (51.6%) were checked by a perioperative arteriography or angioscopy. The diameter of the internal carotid artery (ICA) and carotid bulb (CB) were measured by duplex scan both preoperatively and every 6 months during follow-up. The main end point was carotid occlusion or restenosis, defined as a stenosis of 50% or more according to NASCET criteria. Carotid polyester-impregnated patches appear to be reliable. The patch was easy to cut and suture, and hemostasis was obtained immediately. No rupture occurred. However, the higher restenosis rate in women may restrict the use of polyester patch to men.

Five inflammatory aortopathies were disclosed 3 to 16 years after inaugural giant cell arteritis. Three patients were symptomatic: one aneurysm of the subrenal abdominal aorta discovered at work-up for an inferior arteriopathy, one thoraco-abdominal aneurysm with a "fissuration" episode, one calcified thoraco-abdominal aortopathy suggesting dissection. In these three cases, there was a severe inflammatory syndrome with asthenia, fever, elevated erythrocyte sedimentation rate and a large inflammatory crown around the aortopathy. In the two asymptomatic cases, the diagnosis was made during the follow-up of Horton's disease, in one patient with active disease, the other late after the initial episode. Two aneurysms required surgical cure, with resection-prosthesis of the thoraco-abdominal aneurysm and revascularization of the digestive and renal arteries. In the 4 active cases, corticosteroid therapy cured the inflammatory process both on the basis of laboratory results and the involution of the periaortic crown and, in one case, the total regression of ureteral compression causing pyeloureteral dilatation on the left. The diagnosis of giant cell arteritis was confirmed histologically in the two operated cases. Extra-cervical localizations of aortic aneurysm of dissection in patients with giant cell arteritis is not a fortuitous coincidence but an association as demonstrated by the Mayo Clinic epidemiology. On the basis of these reported cases and data in the literature, the practical conclusions are: in case of aorta involvement, particularly with inflammation in subjects under 50, giant cell arteritis should be entertained as a possible diagnosis; in patients with giant cell arteritis, follow-up should include yearly thoracic radiograms to search for thoracic aorta involvement and Doppler and ultrasound explorations to identify any abdomino-iliac lesions. This protocol is required to avoid the life-threatening complications of dissection or rupture of an aortic aneurysm.

Type 1 neurofibromatosis (NF1) is the most frequently observed phacomatosis, but involvement of arterial trunks is uncommon. Expression depends on the localization and is not easily related to the causal condition. Seven patients with type 1 neurofibromatosis developed vascular manifestations (table I) disclosed by hypertension (n = 2) digestive angina (n = 1), arterial rupture (n = 1) and aneurysm of the subrenal aorta (n = 1). The diagnosis of NF1 was clear in 5 cases; in 2 cases, the diagnosis could only be established on the basis of pathology findings demonstrating dysplasia of the media with voluminous periadventitial hypertrophic nerves (table II). All the large arteries can be involved in NF1. A complete vascular work-up is needed to identify multiple arterial localizations as found in two of our cases. Thoraco-abdominal stenosis was observed in 5 cases leading, in 2 cases, to coarctation with a hemodynamic and functional impact requiring aortic revascularization. The most frequently observed localization involves the renal arteries: 3 of our patient had occlusive lesions of the renal arteries and in 2, aneurysms were observed. Three of our patients (including 2 of the preceding), had major occlusion of digestive arteries. Three other cases revealed an aneurysm of inflammatory subrenal aorta, a rupture of the iliac into the inferior vena cava and a rupture covered by a subclavian aneurysm. The indication for surgery depends on the arterial signs of associated complications (5 of our cases). In one case surgery was indicated to prevent rupture of a splenic artery aneurysm and an aneurysm of the subrenal abdominal aorta. Two cases were treated by exclusion (ilio-cava fistula) or excision (splenic aneurysm); renal or digestive revascularization was performed with arterial or venous autografts in young patients (3 cases). One extensive abdominal coarctation was repaired with a PTFE graft as were the subclavian and subrenal aorta aneurysms. One patient with an ilio-cava fistula died from collapsus. Long-term results of the revascularizations are satisfactory with good control of the hypertension and total regression of the digestive angina. Fibrodysplasia of the renal or digestive media occurring alone or thoraco-abdominal coarctation should suggest NF1 and lead to a complete work-up to identify other arterial localizations. Patients should be followed regularly to prevent complications which in case of rupture can be life-threatening.

Popliteal venous aneurysms are uncommon. We reviewed 101 cases reported in the literature and our series of 11 operated cases to study the nosology and therapeutic indications. In our series, there were 7 cases of unique dystrophic aneurysms, 4 cases involving locoregional angiodysplasia: 3 cases with venous hemodynamics and 1 case with arteriovenous flow. Pulmonary embolism developed in 2 cases. Ultrasonography provided the diagnosis. A sacciform aneurysm was found in 10 cases and a fusiform aneurysm in 1 case. Venous repair was performed in all cases: 9 endoaneurysmal sutures, 1 interposition of the medial gastrocnemius vein, and 1 PTFE graft. Permeability was confirmed in all cases with no recurrent embolism. These cases and the histological correlations describe the nosology of dysplastic venous aneurysms which should be distinguished from dystrophic ectasia of incompetent veins which is not associated with pulmonary embolism. Indeed, pulmonary embolism is the most common complication revealing venous aneurysms (table I). Doppler ultrasonography can provide early diagnosis before such complications develop. Surgery is required for emergency cure in case of pulmonary embolism and is warranted for preventive cure, generally by endoaneurysmorraphic repair allowing venous permeability without the risk of iterative embolism.

During a 6-year period six patients had combined revascularizations for an abdominal aortic aneurysm and a high-grade (> 80%) stenosis of either the superior mesenteric artery (N = 14) and/or a renal artery (N = 60 including 6 bilateral revascularizations). Revascularizations of a visceral artery were done more often with a bypass graft (N = 61) than by endarterectomy (N = 6), reimplantation (N = 4) or endovascular technique (N = 3). Fifty patients had concomitant repair of the aorta and of the visceral artery, and ten had a staged repair, favored in-high risk patients and in cases of multiple visceral artery revascularizations. Four patients (7.5%) died (2 myocardial infarctions and 2 multisystem organ failure) and twelve (20%) had a non-fatal complication in the postoperative period. Survival was 91% at one year and 81% at 5 years. Our experience emphasizes the option of a staged approach in these high-risk patients, with the availability of extra-anatomic reconstruction, and the limited value of endovascular revascularization of the visceral arteries.

Study Aim: Endovascular surgery can be proposed as an alternative to infrainguinal conventional surgery in critical ischemia. The aim of this study was to report the latest results of our series of 186 patients., Materials and Methods: One hundred and eighty-six patients (100 women and 86 men; mean age 74.5 +/- 13 years) were treated for pain during rest (31.5%), gangrene (58%), or ischemic ulcer (10.5%). The lesions were unilateral (n = 172) or bilateral (n = 14). Two hundred eighty-seven target lesions were treated: for stenosis (n = 168) or occlusion (n = 119): of superficial femoral artery (31.7%), popliteal artery (40%) or tibial arteries (28.3%)., Results: Technical success was achieved in 81% (15% amputations). The in-hospital mortality rate was 6.5%. The cumulative patency rate was 61 +/- 3% at 12 months, and 52 +/- 6% at 48 months. The limb salvage rate was 87 +/- 3% at 12 months and 82 +/- 4% at 48 months. Thirteen potential factors of patency were analyzed: the only predictive factors affecting patency were occlusion versus stenosis, and the use of atherectomy (Log rank test: P < 0.001 and P < 0.0001)., Conclusion: Despite a risk of technical failure and of mid-term restenosis, endovascular surgery for critical ischemia provides a fair long-term limb salvage rate.

Concomitant discovery of long-standing arteriovenous fistula (AVF) and proximal dilatation is commonplace whereas the disclosure of proximal arterial dilatation several years after closure of AVF is much more surprising and less often described. The goal of this study was to call attention to this late complication, to evaluate its prevalence, and to describe the mechanism and outcome after treatment. Six new observations were added to 11 cases already published in the literature. Most AVF were located in the popliteal or superficial femoral arteries. The mean duration of these AVF was 20 years and 7 months. The mean delay between closure of AVF and the discovery of arterial dilatation was 9 years and 8 months. One patient required emergency operation for rupture. Another patient sustained embolism. All patients were treated by exclusion-bypass. Six years after operation for arterial dilatation, one patient had to be reoperated on for impending rupture of an aortic aneurysm. These facts lead us to advocate 1) closure of all AVF, even when iatrogenic, whenever present for 45 days or longer, 2) careful observation of all patients after operation for long-standing AVF, 3) operation on all patients with arterial dilatation secondary to AVF, and 4) life-long surveillance of the proximal arteries of these patients.

The authors report the case of a 34-year old woman with no previous cardiovascular disease who was admitted to hospital for acute ischaemia of the right arm due to embolism, preceded by two episodes of pain and tingling of the left arm related to subacute ischaemia. After right embolectomy, with no possibility of controlateral disobliteration an effective anticoagulation, no cardiac source of embolism could be found; However, transoesophageal echography showed a large mobile thrombus in the aortic arch implanted just before the origin of the left subclavian artery. The only explanation for embolism to the right arm was a retro-oesophageal subclavian artery which was confirmed by scanner. Doppler and arteriography. These investigations, however, did not allow visualisation of the aortic thrombus. In view of the risk of recurrent embolism, a thrombectomy was performed without cardiopulmonary bypass, associated with correction of the vascular abnormality with no complications. This case shows that oesophageal echography is a useful investigation in the work up of acute arterial obstruction in young patients with no cardiac disease.

Emboligenic aortopathies are defined as lesions of the aortic wall leading to the production of thromboatheromatous material which can migrate in fragments or entirely. Emboligenic aortopathy can occur in all parts of the aorta. Localized lesions are rare and usually involve the subrenal abdominal aorta or the isthma. Diffuse lesions involving several segments of the aorta are encountered more often. There are three anatomic types of lesions: ulcerated plaques, atheromatous ulcerations, an evrysmal disease of the aorta. Therapeutic indications depend on: 1) clinical presentation: fibrinocruoric emboli, distal microemboli, disseminated cholesterol emboli; 2) the unique or multiple nature of the emboli; 3) the anatomic lesion; 4) localization.

Diabetic arteriopathy is a specific entity as it associates macro-angiopathy ischemia factor and micro-angiopathy leading to peripheral neuropathy. This association leads to specific clinical manifestations dues to interplay of ischemic and infectious phenomena. Diffuse occlusive lesions predominate distally with mediacalcosis. Wider surgical indications for revascularization of distal vessels of the leg, the ankle and the foot have reduced the number and extent of amputation. Long-term permeability after salvage surgery is identical to that in non-diabetic patients as shown by our series of 695 distal revascularizations. Endovascular techniques with or without stents or recanalization are alternatives which may be indicated in case of short occlusions or trophic disorders contraindicating surgery. Associating stents with conventional surgery may also be indicated in diabetic patients. One final progress in reducing the number of amputations has been provided by free-transfer micro-surgery techniques which allow both vascular supply and coverage of distal tissue loss.

An unusual case of nondysplastic saccular aneurysm associated with elongation of the extracranial internal carotid artery is reported. The artery was normal except for a punch-hole defect in the media, which distinguished it from true fibromuscular dysplasia. Although neurologic symptoms and treatment were not specific, this case is interesting in that the exact cause of the aneurysm remains unknown.

Between January 1, 1979, and December 31, 1988, 149 infrapopliteal polytetrafluoroethylene (PTFE) bypasses were performed in 145 patients with chronic, critical, limb-threatening ischemia. These operations represented 27.9% of 534 infrapopliteal bypasses performed during the same period. There were 92 males and 53 females. Mean age was 71.8 +/- 12.3 years. Signs and symptoms of critical ischemia were gangrene, ulceration, and isolated rest pain in 101 (69%), 23 (15.3%), and 25 (16.7%) cases, respectively. A composite (PTFE-saphenous vein) graft was used in 53 (35%) cases. In 96 prosthetic bypasses the distal anastomosis was performed using vein patch angioplasty in 65 (44%) cases and directly in 31 (21%). The in-hospital mortality rate was 3.3%. Patency, limb salvage, and patient survival rates were plotted according to the actuarial method and the curves obtained were compared using the log-rank test. Actuarial survival rates were 68% +/- 5% and 57% +/- 7% at 3 and 5 years, respectively. Primary patency and lower limb salvage rates were 41% +/- 5% and 68% +/- 6% at 3 years and 35% +/- 9% and 65% +/- 10% at 5 years, respectively. There was no statistically significant difference noted in primary patency rates at 3 years according to the type of bypass (composite or all-prosthetic: 36% vs. 44%), the type of distal anastomosis (direct or vein patch angioplasty: 43% vs. 45%), the site of distal anastomosis (upper or lower half of the leg: 38% vs. 46%), lateral or medial placement of the bypass (39% vs. 43%), or according to whether or not it was a repeat operation (40% vs. 44%). In conclusion, patency rates using infrapopliteal PTFE bypasses are low. Certain technical approaches, although they do not seem to improve patency, definitely increase the feasibility of bypass and in our opinion decrease the risk of early failure in unfavorable anatomic settings. The limb salvage rates following infrapopliteal PTFE and composite bypass are encouraging and justify the use of routine distal revascularization, even in the absence of autogenous vein graft.

Whether or not to operate an asymptomatic aneurysm of the aorta in a patient over 80 years of age is a question increasingly facing the surgeon: longer life span (about 7 years), aneurysm discovered on a sonogram or scan ordered for digestive, urologic or pelvic disorders. This discussion is based on a personal retrospective series of 800 patients who underwent elective operation for non-ruptured aneurysms of the subrenal abdominal aorta between January 1985 and June 1990. For the 732 patients under 80, mortality was 1.9% and for the 68 patients over 80, it was 8.8%, emphasising that in this group survival at 6 months was reduced by 10%. The operative risk, as for younger subjects, results from coronary risk (reversible ischaemia), the quality of the heart muscle (ejection fraction < 35%), respiratory and renal function. Increased age raises mortality when one of these factors is severely jeopardized but associated lesions, such as digestive disorders or arterial lesions (severe occlusion of the downstream vessels, occlusion of the mesenteric and hypogastric arteries increases the risk of acute ischaemia of a limb or the intestine), should also be taken into consideration. Indications for operation should be discussed in light of these factors in patients at risk (large aneurysm > 60 mm or increasing in size, "images" suggesting risk of rupture: bleb or bubble ectasia, flotting mural thrombus, "digitiform" lysis of a mural thrombus, rupture of the calcified shell or covered rupture). When there is a high risk of lesion and the operative risk prohibits conventional surgery, other procedures can be discussed: axillo-bifemoral bypass with exclusion of the iliac and secondary embolization or subrenal exclusion, substitution with an endoaortic prosthesis allowing wider indications.

Lower limb arterial disease in diabetics resembles that in non diabetics. However, some important differences include the vessels involved and the extent of the involvement. In the diabetic, the arteries most frequently involved are those below the knee. Arterial occlusions are bilateral, multisegmental, and involve unusual vessels such as the internal iliac artery, the deep femoral artery, the small branches and the collateral circulation. Arterial disease in the diabetic appears at a younger age, advances more rapidly, is more diffuse, and is almost as common in women as in men. Interaction of arterial disease, neuropathy and infection produces a wide away of clinical findings, including callus formation, foot ulcers, cellulitis, osteomyelitis and patchy areas of gangrene. Foot abscess and cellulitis require emergency debridement and drainage. Arterial reconstruction, including endovascular procedures, lessen the rate of amputation, allow partial foot amputation, and prevent from recurrent foot ulcer. Soft tissue repair, and especially fasciocutaneous flaps or musculocutaneous flaps, provide the means to heal most of the patients without infection, and avoid below-knee amputation.