Differences in long-term medical consequences depending on impact direction involving passenger cars

Risk of permanent medical impairment after road traffic crashes: A systematic review

PURPOSE

To systematically review the risk of permanent disability related to road traffic injuries (RTIs) and to determine the implications for future research regarding permanent impairment following road traffic crashes.

METHODS

We conducted this systematic review according to the preferred reporting items for systematic reviews and meta-analysis statement. An extended search of the literature was carried out in 4 major electronic databases for scientific research papers published from January 1980 to February 2020. Two teams include 2 reviewers each, screened independently the titles/abstracts, and after that, reviewed the full text of the included studies. The quality of the studies was assessed using the strengthening the reporting of observational studies in epidemiology (STROBE) checklist. A third reviewer was assessed any discrepancy and all data of included studies were extracted. Finally, the data were systematically analyzed, and the related data were interpreted.

RESULTS

Five out of 16 studies were evaluated as high-quality according to the STROBE checklist. Fifteen studies ranked the initial injuries according to the abbreviated injury scale 2005. Five studies reported the total risk of permanent medical impairment following RTIs which varied from 2% to 23% for car occupants and 2.8% to 46% for cyclists. Seven studies reported the risk of permanent medical impairment of the different body regions. Eleven studies stated the most common body region to develop permanent impairment, of which 6 studies demonstrated that injuries of the cervical spine and neck were at the highest risk of becoming permanent injured.

CONCLUSION

The finding of this review revealed the necessity of providing a globally validated method to evaluate permanent medical impairment following RTIs across the world. This would facilitate decision-making about traffic injuries and efficient management to reduce the financial and psychological burdens for individuals and communities.

Health status and quality of life among road users with permanent medical impairment several years after the crash

OBJECTIVE

Improvements in road infrastructure and vehicle safety have been achieved in many countries during the last decades. As the number of fatalities have dropped, the consequences of non-fatal injuries have been brought into focus. Therefore, the objective was to investigate self-reported health status and health-related quality of life several years after the crash for road-users that sustained injuries resulting in permanent medical impairment (PMI).

METHODS

A self-administered questionnaire using instruments to measure if health, health-related quality of life and physical activity had been affected by the crash, were used. The injured road-users were identified from insurance policy holders of the Folksam Insurance Group. The response rate was 29%, a total of 2078 responses were received from the 7174 road-users with PMI that received the questionnaire.

RESULTS

In total 85% were still suffering from the injuries several years after the crash (8-18 year after the crash). Furthermore, road-users with injuries to the spine were having highest pain intensity. Older road-users had poorer self-reported health status than younger road-users. Although, younger road-users had the greatest change in physical activity when comparing before and after the crash. Before the crash in total 63% were physically active while only 34% after the crash. The higher the PMI the higher it affected health several years after the crash.

CONCLUSIONS

The Swedish definition of serious injury, an injury leading to PMI, was found to correlate with self-reported health loss; 85% of the injured road-users reported that they still had remaining symptoms several years after the accident. The injured body region leading to PMI after an accident can vary from the body regions reported to cause long-term health loss. It was found that the higher the degree of PMI the higher the health loss. Sustaining a PMI regardless severity and injured body region has the same effects on general health for men and women. Sustaining a PMI will both lower the health-related quality of life and physical activity after the crash compared to before.

Minimal Aortic Injury: Mechanisms, Imaging Manifestations, Natural History, and Management

Over the last 2 decades, increased depiction of minimal aortic injury (MAI) in the evaluation of patients who have sustained trauma has mirrored the increased utilization and improved resolution of multidetector CT. MAI represents a mild form of blunt traumatic aortic injury (BTAI) that usually resolves or stabilizes with pharmacologic management. The traditional imaging manifestation of MAI is a subcentimeter round, triangular, or linear aortic filling defect attached to an aortic wall, representing a small intimal flap or thrombus consistent with grade I injury according to the Society for Vascular Surgery (SVS). Small intramural hematoma (SVS grade II injury) without external aortic contour deformity is included in the MAI spectrum in several BTAI classifications on the basis of its favorable outcome. Although higher SVS grades of injury generally call for endovascular repair, there is growing literature supporting conservative management for small pseudoaneurysms (SVS grade III) and large intimal flaps (>1 cm, unclassified by the SVS), hinting toward possible future inclusion of these entities in the MAI spectrum. Injury progression of MAI is rare, with endovascular aortic repair reserved for these patients as well as patients for whom medical treatment cannot be implemented. No consensus on the predetermined frequency and duration of multidetector CT follow-up exists, but it is common practice to perform a repeat CT examination shortly after the initial diagnosis. The authors review the evolving definition, pathophysiology, and natural history of MAI, present the primary and secondary imaging findings and diagnostic pitfalls, and discuss the current management options for MAI. Online DICOM image stacks are available for this article. ^©RSNA, 2020.

Types and site distributions of intestinal injuries in seat belt syndrome

OBJECTIVE

Intestinal injuries in seat belt syndrome are relatively uncommon but can be potentially lethal due to accompanying peritonitis and hemorrhaging. It can be difficult to identify the exact injury sites of the intestine as multiple areas are often damaged and massive intraperitoneal hemorrhaging may make it challenging to determine causal bleeding points of mesenteric injuries. This study aimed to clarify the incidence and distribution of intestinal injuries in seat belt syndrome.

METHODS

We retrospectively reviewed the clinical records of 25 patients who underwent laparotomy for suspected intestinal injuries due to seat belt syndrome during a frontal impact. The incidence and distribution of the sites of intestinal injuries, as well as associated injuries, were investigated. Intestinal injuries were divided into bowel and mesenteric injuries. Additionally, bowel injuries were classified into two types: perforation and non-perforation (seromuscular tears/intramural hematomas). Regarding the injured sites, the small intestine was divided into the following three parts: (1) the ligament of Treitz (100-cm distal from the ligament [proximal jejunum]), (2) the ileocecal valve (100-cm proximal from the valve [distal ileum]), and (3) the intermediate area between those two regions (jejunoileal junction).

RESULTS

In total, there were 64 major injuries among 25 patients requiring surgical intervention: 34 bowel injuries (20 perforations and 14 non-perforations) and 30 mesenteric injuries. Significantly more bowel perforations occurred in the small intestine (1 [interquartile range (IQR), 0-1]) than in the large intestine (0 [IQR, 0-0]) (p = 0.003). Similarly, significantly more mesenteric injuries occurred in the small intestine (1 [IQR, 0-1.25]) than in the large intestine (0 [IQR, 0-0]) (p < 0.001). Specific sites of the mesenteric injuries in the small intestine included the jejunoileal junction (0 [IQR, 0-1]) and distal ileum (0 [IQR, 0-1]); the jejunoileal junction was significantly more vulnerable than the proximal jejunum (0 [IQR, 0-0]) (p = 0.015).

CONCLUSIONS

In patients with seat belt syndrome, the small intestine was more vulnerable to perforation and mesenteric injury than the large intestine. Additionally, for mesenteric injuries, the jejunoileal junction was more likely to be damaged than the proximal jejunum.

Sickness absence, disability pension and permanent medical impairment among 64 000 injured car occupants of working ages: A two-year prospective cohort study

OBJECTIVE

There is a lack of knowledge regarding sickness absence (SA) and disability pension (DP) as consequences of road traffic injuries, and on the association between DP and permanent medical impairment (PMI). Therefore, the aim of this study was to investigate SA, DP, and PMI among injured passenger car occupants two years after a crash, and how they are associated, accounting for sociodemographics, crash-related factors, and previous SA/DP.

METHODS

This prospective cohort study included 64 007 injured car occupants aged 17-62 years at the time of a crash occurring in 2001-2013, involving a car insured at Folksam Insurance Group in Sweden. Information on sociodemographics, crash-related factors, SA (in SA spells >14 days) and DP status at inclusion and at two-year follow-up, and PMI assessed by the insurance company was used. PMI grades were categorized as 1-4, 5-9, 10-19, or >19%. Logistic regression was performed to calculate odds ratios (OR) with 95% confidence intervals (CI) for DP at follow-up and for PMI, respectively.

RESULTS

At the time of the crash 13% were already on SA or DP. At follow-up two years after the crash, 6% among those not already on SA/DP at the time of the crash were on SA and 2% on DP. Furthermore, 8% of the total cohort had a determined PMI. Among those not already on DP at the crash, 3% with no PMI had DP at follow-up. This proportion was higher the higher PMI grade. Among individuals without already ongoing DP at the crash date, 10% of those with a PMI 1-4 ha d DP, compared to 76% among PMI ≥ 20. Already ongoing SA at the time of the crash (OR = 39.16, 95% CI 34.89-43.95) and PMI grade (PMI ≥ 5 OR = 27.44, 95% CI 23.88-31.52, reference group PMI 0) were found to be associated with DP at two years after crash. The factor most strongly associated with PMI was the model year of the car. The older the car, the higher the risk of PMI (Model year ≤ 1990 OR = 3.36, 95% CI 2.67-4.23, reference group model year 2006-2010). An association with the same direction was also found between the model year of the car and DP at follow-up.

CONCLUSIONS

The association between PMI grade and DP status at follow-up among occupants not on DP at the crash date indicates that both could be used to measure long-term consequences of road traffic injury. In this cohort, already ongoing SA at the crash date was associated with DP at the two-year follow-up, emphasizing the importance of accounting for this factor in future research.

Pattern Recognition: A Mechanism-based Approach to Injury Detection after Motor Vehicle Collisions

Motor vehicle collisions cause substantial mortality, morbidity, and expense worldwide. Certain types of injuries are more likely to result from frontal versus side-impact collisions, and knowledge of these specific patterns and why they occur aids in accurate and efficient diagnosis of traumatic injuries. Although the proper use of seat belts decreases crash-related mortality during frontal impact, certain injury patterns to the torso are directly attributed to restraint use. The spectrum of seat belt-related injuries ranges from mild skin and soft-tissue contusions to traumatic bowel injuries and unstable spine injuries that require surgery. Impact with the steering wheel or windshield during a frontal crash can cause characteristic injuries to the head, neck, torso, and distal upper extremity. Steering wheel deformity is an independent predictor of serious thoracic and abdominal injury among front-seat passengers. Impact of a flexed knee with the dashboard during a frontal collision can cause knee, thigh, and hip injuries. Distal lower extremity injuries are encountered frequently when the floorboard is driven into the foot. Lateral impact crashes often result in traumatic brain, thoracic, abdominal, and pelvic injuries, which are more often fatal to occupants on the side of the impact. The specific mechanism-based injury patterns are reviewed to establish a structured systematic search pattern that enables the radiologist to identify traumatic injuries with greater accuracy and speed, thereby improving the care of patients who experience acute trauma. ^©RSNA, 2019 See discussion on this article by Ballard and Mellnick .

Market penetration of intersection AEB: Characterizing avoided and residual straight crossing path accidents

Car occupants account for one third of all junction fatalities in the European Union. Driver warning can reduce intersection accidents by up to 50 percent; adding Autonomous Emergency Braking (AEB) delivers a reduction of up to 70 percent. However, these findings are based on an assumed 100 percent equipment rate, which may take decades to achieve. Our study investigates the relationship between intersection AEB market penetration rates and avoidance of accidents and injuries in order to guide implementation strategies. Additionally, residual accident characteristics (impact configurations and severity) are analyzed to provide a basis for future in-crash protection requirements. We determined which accidents would have been avoided through the use of an Intersection AEB system with different sensor field-of-views (180° and 120°) by means of re-simulating the pre-crash phase of 792 straight crossing path (SCP) car-to-car accidents recorded in the German In-Depth Accident Study (GIDAS) and the associated Pre-Crash Matrix (PCM). Intersection AEB was activated when neither of the conflict opponents could avoid the crash through reasonable braking or steering reactions. For not-avoided accidents, we used the Kudlich-Slibar rigid body impulse model to calculate the change of velocity during the impact as a measure of impact severity and the principal direction of force. Accident avoidance over market penetration is not linear but exponential, with higher gains at low penetration rates and lower gains at higher rates. A wide field-of-view sensor (180°) substantially increased accident avoidance and injury mitigation rates compared to a 120° field-of-view sensor. For a 180° field-of-view sensor at 100 percent market penetration, about 80 percent of the accidents and 90 percent of the MAIS2 + F injuries could be avoided. For the remaining accidents, AEB intervention rarely affected side of impact. The median change of velocity (delta-V) of the remaining crashes reduces only marginally at low penetration rates but this reduction increases with higher penetration rates. With 100 percent market penetration, one quarter of the vehicles still involved in straight crossing path accidents will sustain a delta-V higher than 17 km/h. Intersection AEB is very effective. Enabling a fast initial implementation of systems with wide field-of-view sensor(s) and ensuring a high market penetration over the longer term is essential to achieve high crash avoidance and injury mitigation rates over time. The standards for in-crash protection must be high to mitigate injury in the unavoidable, residual accidents.

Opportunities for crash and injury reduction: A multiharm approach for crash data analysis

OBJECTIVE

A multiharm approach for analyzing crash and injury data was developed for the ultimate purpose of getting a richer picture of motor vehicle crash outcomes for identifying research opportunities in crash safety.

METHODS

Methods were illustrated using a retrospective analysis of 69,597 occupant cases from NASS CDS from 2005 to 2015. Occupant cases were analyzed by frequency and severity of outcome: fatality, injury by Abbreviated Injury Scale (AIS), number of cases, attributable fatality, disability, and injury costs. Comparative analysis variables included precrash scenario, impact type, and injured body region.

RESULTS

Crash and injury prevention opportunities vary depending on the search parameters. For example, occupants in rear-end crash scenarios were more frequent than in any other precrash configuration, yet there were significantly more fatalities and serious injury cases in control loss, road departure, and opposite direction crashes. Fatality is most frequently associated with head and thorax injury, and disability is primarily associated with extremity injury. Costs attributed to specific body regions are more evenly distributed, dominated by injuries to the head, thorax, and extremities but with contributions from all body regions. Though AIS 3+ can be used as a single measure of harm, an analysis based on multiple measures of harm gives a much more detailed picture of the risk presented by a particular injury or set of crash conditions.

CONCLUSIONS

The developed methods represent a new approach to crash data mining that is expected to be useful for the identification of research priorities and opportunities for reduction of crashes and injuries. As the pace of crash safety improvement accelerates with innovations in both active and passive safety, these techniques for combining outcome measures for insights beyond fatality and serious injury will be increasingly valuable.

Real-world adjustments of driver seat and head restraint in Saab 9-3 vehicles

OBJECTIVE

Whiplash-associated disorder (WAD), commonly denoted whiplash injury, is a worldwide problem. These injuries occur at relatively low changes of velocity (typically <25 km/h) in impacts from all directions. Rear impacts, however, are the most common in the injury statistics. Females have a 1.5-3 times higher risk of whiplash injury than males.  Improved seat design is the prevailing means of increasing the protection of whiplash injury for occupants in rear impacts. Since 1997, more advanced whiplash protection systems have been introduced on the market, the Saab Active Head Restraint (SAHR) being one of the most prominent. The SAHR-which is height adjustable-is mounted to a pressure plate in the seatback by means of a spring-resisted link mechanism.  Nevertheless, studies have shown that seats equipped with reactive head restraints (such as the SAHR) have a very high injury-reducing effect for males (∼60-70%) but very low or no reduction effect for females. One influencing factor could be the position of the head restraint relative to the head, because a number of studies have reported that adjustable head restraints often are incorrectly positioned by drivers.  The aim was to investigate how female and male Saab drivers adjust the seat in the car they drive the most.

METHODS

The seated positions of drivers in stationary conditions have been investigated in a total of 76 volunteers (34 females, 42 males) who participated in the study. Inclusion criteria incorporated driving a Saab 9-3 on a regularly basis.

RESULTS

The majority of the volunteers (89%) adjusted the head restraint to any of the 3 uppermost positions and as many as 59% in the top position.  The average vertical distance between the top of the head and the top of the head restraint (offset) increase linearly with increasing statures, from an average of -26 mm (head below the head restraint) for small females to an average of 82 mm (head above the head restraint) for large males. On average, the offset was 23 mm for females, which is within a satisfactory range and in accordance with recommendations; the corresponding value for males was 72 mm.  The backset tended to be shorter among female volunteers (on average 27 mm) compared to the male volunteers (on average 44 mm). Moreover, the backset tended to increase with increasing statures.

CONCLUSIONS

Incorrect adjustment of the head restraint cannot explain the large differences found between the sexes in the effectiveness of the SAHR system.

A review of the revised Functional Capacity Index as a predictor of 12 month outcomes following injury

The measurement of functional outcomes following severe trauma has been widely recognised as a priority for countries with developed trauma systems. In this respect, the Functional Capacity Index (FCI), a multi-attribute index which has been incorporated into the most recent Abbreviated Injury Scale (AIS) dictionary, is potentially attractive as it offers 12-month functional outcome predictions for patients captured by existing AIS-coded datasets. This review paper outlines the development, construction and validation of the predictive form of the FCI (termed the pFCI), the modifications made which produced the currently available 'revised' pFCI, and the extent to which the revised pFCI has been validated and used. The original pFCI performed poorly in validation studies. The revised pFCI does not address many of the identified limitations of the original version, and despite the ready availability of a truncated version in the AIS dictionary, it has only been used in a handful of studies since its introduction several years ago. Additionally, there is little evidence for its validity. It is suggested that the pFCI should be better validated, whether in the narrow population group of young, healthy individuals for which it was developed, or in the wider population of severely injured patients. Methods for accounting for the presence of multiple injures (of which two have currently been used) should also be evaluated. Many factors other than anatomical injury are known to affect functional outcomes following trauma. However, it is intuitive that any model which attempts to predict the ongoing morbidity burden in a trauma population should consider the effects of the injuries sustained. Although the revised pFCI potentially offers a low-cost assessment of likely functional limitations resulting from anatomical injury, it must be more rigorously evaluated before more comprehensive predictive tools can be developed from it.

Opportunities and limitations for intersection collision intervention-A study of real world 'left turn across path' accidents

Turning across the path of oncoming vehicle accidents are frequent and dangerous. To date not many car manufacturers have introduced Automated Emergency Braking (AEB) systems addressing this type of conflict situation, but it is foreseeable that these scenarios will be part of the Euro NCAP 2020 rating. Nine out of ten collisions are caused by the driver of the turning vehicle. An AEB system evaluating the ego and conflict vehicle driver's possibilities to avoid a pending crash by either braking or steering was specified for application in various constellations of vehicle collisions. In virtual simulation, AEB system parameters were varied, covering parameters that are relevant for driver comfort such as longitudinal and lateral acceleration (to define avoidance possibilities), expected steering maneuvers to avoid conflict, and intervention response characteristics (brake delay and ramp up) to assess the safety benefit. The reference simulation showed a potential of the AEB system in the turning vehicle to avoid approximately half of the collisions. An AEB system of the straight going vehicle was less effective. The effectiveness of the turning vehicle's AEB system increases if spatial limitations for the collision-avoidance steering maneuver are known. Such information could be provided by sensors detecting free space in or around the road environment or geographical information shared via vehicle to cloud communication. AEB interventions rarely result in collision avoidance for turning vehicles with speeds above 40km/h or for straight going vehicles with speeds above 60km/h. State of the art field-of-views of forward looking sensing systems designed for AEB rear-end interventions are capable of addressing turning across path situations.

A Female Ligamentous Cervical Spine Finite Element Model Validated for Physiological Loads

Mathematical cervical spine models allow for studying of impact loading that can cause whiplash associated disorders (WAD). However, existing models only cover the male anthropometry, despite the female population being at a higher risk of sustaining WAD in automotive rear-end impacts. The aim of this study is to develop and validate a ligamentous cervical spine intended for biomechanical research on the effect of automotive impacts. A female model has the potential to aid the design of better protection systems as well as improve understanding of injury mechanisms causing WAD. A finite element (FE) mesh was created from surface data of the cervical vertebrae of a 26-year old female (stature 167 cm, weight 59 kg). Soft tissues were generated from the skeletal geometry and anatomical literature descriptions. Ligaments were modeled with nonlinear elastic orthotropic membrane elements, intervertebral disks as composites of nonlinear elastic bulk elements, and orthotropic anulus fibrosus fiber layers, while cortical and trabecular bones were modeled as isotropic plastic-elastic. The model has geometrical features representative of the female cervical spine-the largest average difference compared with published anthropometric female data was the vertebral body depth being 3.4% shorter for the model. The majority the cervical segments compare well with respect to biomechanical data at physiological loads, with the best match for flexion-extension loads and less biofidelity for axial rotation. An average female FE ligamentous cervical spine model was developed and validated with respect to physiological loading. In flexion-extension simulations with the developed female model and an existing average male cervical spine model, a greater range of motion (ROM) was found in the female model.