Mechanisms of abdominal organ injury in seat belt-restrained children.

BACKGROUND: Previous research has identified key predictors of elevated abdominal injury risk in seat belt-restrained child vehicle occupants; however these data cannot be used to isolate specific mechanisms or sources of injury to suggest strategies for prevention. METHODS: Using a large child-focused crash surveillance system, cases of seat belt-restrained children who sustained an internal abdominal injury in a frontal crash were studied using standard crash investigation protocols. A second group of cases of restrained children in similar crashes without abdominal injury was investigated. Medical, crash, and child characteristics of each case were analyzed in the context of known biomechanics of abdominal injury to determine the mechanisms of injury and associated kinematics. RESULTS: Review of 21 cases of abdominal injury identified belt loading directly over the injured organ as the most common mechanism of injury. Three unique kinematic patterns were identified that varied by the initial position of the lap belt and kinematics of the upper torso. Sixty percent of the drivers and 90% of the other child occupants in these crashes sustained either no or minor injury. In the 16 no abdominal injury cases, all but one sustained external bruising to their abdomen and contact injury to the head and face. CONCLUSIONS: This evaluation of crashes in which belted children did and did not sustain abdominal injuries revealed key characteristics about their mechanism. In this data set, belt compression directly on the abdomen, manifested by improper initial placement of the seat belt, poor child posture, or misuse of the shoulder belt, resulted in abdominal injury in low-severity crashes in which other occupants sustained little injury. The cases pointed to control of torso excursion by consistent use of the shoulder belt and suggested that technologies such as lap belt pretensioners or belt-positioning booster seats might be a possible strategy, among others, for prevention.

Field investigation of child restraints in side impact crashes.

OBJECTIVE: Various test procedures have been suggested for assessing the protection afforded by child restraints (CRS) in lateral collisions. Analyses of real world crashes can be used to identify relevant characteristics of the child, restraint, collision, and injury mechanisms that should be incorporated into the design of the test procedures as well as in the design of related ATDs and injury metrics. The objective of this work is to use in-depth crash investigations of children restrained in CRS in side impacts to elucidate specific sources and mechanisms of injuries and explore the role of crash severity variables such as magnitude and location of intrusion and specific impact angle. METHODS: Real world crashes involving children restrained in forward facing CRS in side impacts were analyzed from Partners for Child Passenger Safety, an on-going child specific crash surveillance system in which insurance claims are used to identify cases. In-depth crash investigations using standardized protocols were used to calculate the crash severity and determine the mechanisms and sources of the injuries sustained. RESULTS: Cases of 32 children restrained in CRS in 30 side impact crashes were examined. Twenty-five percent sustained AIS 2+ injuries. The most common injuries sustained by children restrained in CRS in side impact crashes were to the face, head, and lower extremity. Characteristics of the crashes that appeared related to injury were intrusion that entered the child's occupant space or caused an interior part of the vehicle to enter the child's occupant space, forward component of the crash, and the rotation of the CRS, restrained by a seat belt, towards the side of the impact. CONCLUSIONS: The ability to assess the injury potential in a laboratory setting for the body regions of common injury, the head, face, and lower extremity, must be explored. Characteristics of a regulatory-based test procedure to assess injury risk should include a frontal component to the crash and intrusion into the occupant's seating position. Design enhancements of the CRS should address rotation during lateral impacts. These results provide guidance to current efforts to design and regulate these restraints for the safety of child passengers in side impacts.

Differential risk of injury in child occupants by passenger car classification.

In the United States, passenger cars are the most common passenger vehicle, yet they vary widely in size and crashworthiness. Using data collected from a population-based sample of crashes in State Farm-insured vehicles, we quantified the risk of injury to child occupants by passenger car size and classification. Injury risk is predicted by vehicle weight; however, there is an increased risk in both Large vs. Luxury and Sports vs. Small cars, despite similar average vehicle weights in both comparisons. Parents who are purchasing passenger cars should strongly consider the size of the vehicle and its crashworthiness.

Performance evaluation of child safety seats in far-side lateral sled tests at varying speeds.

Protection of children in Child Safety Seats (CSS) in side impact crashes has been a topic of recent studies. The objective of this study was to evaluate the performance of CSS in far-side impacts through a series of sled tests conducted at varying test speeds. Forty eight sled tests were conducted at three speeds (24 km/h, 29 km/h and 36 km/h), under two different CSS attachment conditions (LATCH and seat belt attached), using rear facing and forward facing CSS from four different manufacturers. Analyses were conducted to examine head retention within the CSS, velocity of the head as it passes an imaginary plane (cross over into other occupant space or door), lateral trajectory of the head and knee; head, chest and pelvis accelerations; neck and lumbar loads and moments. In addition to these parameters, the CSS were visually inspected for structural integrity after each test. Results from these sled tests highlighted the differential performance of CSS in far-side impacts. During the tests, all CSS experienced significant lateral movement irrespective of attachment type. In rear facing CSS tests, one of the designs failed as the seat disengaged from its base. In forward facing CSS tests, it was observed that the seat belt attached CSS experienced less rotational motion than the LATCH attached CSS. ATD head retention within the seat was not achieved with either CSS attachments at any speed. The findings from this study augment the current efforts to define regulatory sled setup procedure for far-side impact crashes involving children in CSS, which currently does not exist and will eventually further the protection of children in automobiles.

Risk of injury to child passengers in compact extended-cab pickup trucks.

CONTEXT: An increasing number of compact pickup trucks can accommodate restrained rear occupants. Rear seats in these pickup trucks are exempt from regulatory safety testing though their relative safety has not been determined. OBJECTIVES: To evaluate the risk of injury to children in compact extended-cab pickup trucks compared with children in other vehicles and to determine if any unique hazards exist. DESIGN: Cross-sectional study of children aged 15 years or younger in crashes of insured vehicles, with data collected via insurance claim records and a telephone survey. SETTING AND PARTICIPANTS: Probability sample of 7192 multirow vehicles involved in crashes, with 11 335 child occupants, in 3 large US regions from December 1, 1998, to November 30, 2000. MAIN OUTCOME MEASURE: Relative risk of injury, defined as concussions and more serious brain injuries, spinal cord injuries, internal organ injuries, extremity fractures, and facial lacerations, estimated by odds ratios (ORs) adjusting for age, restraint use, point of impact, vehicle weight, and crash severity. RESULTS: Injuries were reported for 1356 children, representing 1.6% of the population. Children in compact extended-cab pickup trucks were at greater risk of injury than children in other vehicles (adjusted OR, 2.96; 95% confidence interval [CI], 1.68-5.21). Children in the rear seats of compact pickup trucks were at substantially greater risk of injury than rear-seated children in other vehicles (adjusted OR, 4.75; 95% CI, 2.39-9.43). Children seated in the front seat of compact extended-cab pickup trucks were at greater risk of injury than children in the front seats of other vehicles, but this risk was not statistically significant (adjusted OR, 1.70; 95% CI, 0.78-3.69). CONCLUSIONS: Children in compact extended-cab pickup trucks are not as safe as children in other vehicles, primarily due to the increased relative risk of injury in the back seat. For families with another choice of vehicle, clinicians should advise parents against transporting children in compact pickup trucks. The current exemption for regulatory testing for occupant protection in the rear seats of compact pickup trucks should be reconsidered.

The role of restraint and seat position in pediatric facial fractures.

BACKGROUND: Recently, head and brain injuries were identified as consequences of the inappropriate use of seat belts by children. The proposed mechanism of these injuries might also place a child at risk for facial fracture. METHODS: A probability sample of children under age 16 involved in crashes were enrolled in an ongoing crash surveillance system (1998-2001) that links insurance claims data to telephone survey and crash investigation data (unweighted, n = 12,659; weighted, n = 131,717). Incidence of facial fracture was estimated and a series of cases were examined using in-depth crash investigation to identify the mechanisms of these injuries, specifically, the role of seating position and restraint use in the mechanism of injury. RESULTS: Ninety-two children suffered a fracture of the facial bones (0.07% of all children in crashes). Among restrained children with facial fractures (n = 68), those inappropriately restrained were at a 1.6-fold higher risk (95% confidence interval, 1.2-2.1; p = 0.001) of significant injury than those appropriately restrained for their age. The in-depth investigations revealed that excessive head excursion resulting from suboptimal torso restraint caused facial impact, which resulted in the facial injuries described. CONCLUSION: The potential for disfigurement associated with these facial injuries may resonate strongly with parents, and prevention of disfigurement may provide additional motivation for proper restraint, in particular, booster seats and rear seat location, for this pediatric population.