CHOP and AIAM collaborate to develop more accurate child crash test dummies

Biomechanical Data Collection Informs Latest Advances, Detailed in New Report from The Children's Hospital of Philadelphia and the Association of International Automobile Manufacturers, Inc.

A research report released today by The Children's Hospital of Philadelphia (CHOP) and the Association of International Automobile Manufacturers, Inc. (AIAM) details CHOP's cutting-edge work with academic and industry collaborators to develop more accurate child crash test dummies, called child anthropometric test devices (ATD's).

"These developments fill crucial gaps in knowledge that will allow for innovative restraint products and vehicle designs to help save more children's lives, prevent injuries, and reduce the economic cost of crashes involving child passengers," said Michael J. Stanton, president and CEO of AIAM. "We are honored to provide our support for this critical research report. Child-safety is a top priority for our member companies, and The Children's Hospital of Philadelphia has a long history of leadership on such an important issue."

Experts in pediatric biomechanics at CHOP have studied real-world crashes for more than a decade in order to understand how children's bone structure and soft tissues respond to crash forces differently than fully-developed adults. However, child crash test dummies have essentially been smaller-sized versions of adult dummies, with little consideration for these important differences in body composition -- leaving children more vulnerable to injuries during a crash than adults.

"In order for the auto industry to innovate beyond just 'buckle up' to keep kids safe in crashes, we need better tools, such as accurate child crash test dummies; but we're missing the basic data we need to create those tools," said Kristy Arbogast, Ph.D., director of engineering for CHOP's Center for Injury Research and Prevention. "The research being conducted by biomechanics research centers around the world and here at CHOP delivers the critical data on how children move in a crash and the tolerance of their bodies to injury.  This information is needed to determine how cars can be made safer for children in the future."

The 2010 Child Passenger Safety Issue Report describes research conducted by CHOP and others to improve several body regions in the current child ATD to better represent an actual child's body mechanics: the head and brain, the neck and spine, the abdomen, and the thoracic region (chest and rib cage). These body regions account for the most commonly-seen -- and some of the most serious -- injuries among children involved in car crashes.

Preventing Head and Brain Injury

Brain and skull injuries are the most common type of injury among crash-involved children. Motor vehicle safety systems, including seat belts, air bags, child seats, and occupant compartment padding, are key elements for reducing injuries to the head. However, for children past toddler-age, no accurate model exists to represent a child's developing skull and brain-tissue, which respond differently to impact and crash forces than an adult's or younger child's do. To address this gap, researchers at CHOP and the University of Pennsylvania (UPenn) are working together to develop brain injury criteria for a 6- to 10-year-old child. With these criteria established, an accurate computational model can be developed that mimics the ATD currently available for this age group, to predict the likelihood of brain injury.

Using Bumper Cars to Understand the Pediatric Spine

The cervical spine controls the movement of the head during a crash, and recent research indicates that the spine used in the pediatric ATD may be significantly more rigid than an actual child's spine. Researchers at CHOP recognized the implications of this disparity and partnered with Rowan University, Takata Corporation, and the University of Virginia to devise a unique solution to quantify the motion of a typical adult's and child's spine: bumper cars.

The team measured the "crash" severity in the amusement park ride, then developed a sled test to mimic this experiment in a lab. Subjects were fitted with sensors to track the precise movements of the head, neck and spine during a safe crash force.

"We found that the children's head and spine moved further forward than the adult's, and that the youngest children experienced the most neck flexion," explained Dr. Arbogast. "This leads to more head rotation in children, making it more likely for a child's head to hit the seat, window, or something else in the car during a crash."

These findings form the basis for the development of a more accurate spine for the pediatric dummy, informing industry advancements in restraint and vehicle design to prevent injuries to the head, which remain the most common type of crash injury, and the most deadly.

Preventing "Seat Belt Syndrome"- Abdominal Injuries

Injuries to the abdominal organs are the second most common in crash-injured children, especially in those who are moved into an adult seat belt before they are 4'9" (usually around age 8.) The pediatric ATD's currently used in crash tests do not have the ability to accurately detect injuries to the abdomen.

"It's vital for our crash test dummies to be able to measure the risk of abdominal injury to children in crashes, so that we can protect children from the serious injuries and high healthcare costs associated with this type of injury," explained Dr. Arbogast. "Through collaborative research, we were able to create a prototype of an accurate pediatric abdomen-pelvis for use in the 6-year-old crash test dummy that will help us to better understand how a child's body responds to the belt-loading forces around the abdomen and to develop novel restraint designs to prevent seat belt-related injuries."

Researchers from the University of Virginia, University of Michigan, the Ford Motor Company, Wayne State University and Takata Corporation worked with CHOP researchers to develop an accurate abdominal insert for a child-sized dummy. The researchers used data from real-world crashes; measurements of children's abdomens; animal models; and computational models to create the insert, which is now undergoing tests by the Society of Automotive Engineers (SAE). The goal is to make the pediatric abdomen insert available for broad use in government-mandated crash tests.

Protecting the chest and rib cage

During a frontal crash, the seat belt compresses the chest of the buckled occupant, causing the sternum to compress toward the spine. Therefore, chest-compression is an important area for study during crash tests using ATD's. As with other body regions, no pediatric-specific data was previously available to make sure the compression of the dummies' chest mimics a developing child's. With support from the National Highway Traffic Safety Administration, researchers at CHOP were uniquely positioned to gather accurate chest-compression measurements in pediatric patients who received CPR during treatment in the hospital's emergency department and intensive care unit. After extensive analysis of the force and acceleration withstood by a child's chest during each compression cycle of CPR, researchers compared this data with similar studies done on adults. The research highlights dramatic differences between the ability of the adult and pediatric thorax to resist force. Due to these differences, a child ATD's thorax may not only need to be smaller than the adult ATD's, but also to possess different biomechanical properties.

Understanding Injury to the Lower Extremities: The Legs and Feet

When a child in a forward-facing child restraint is in a motor vehicle crash, the lower extremities are among the most frequently injured. Although not typically life-threatening, these injuries are disabling, costly to treat, and can seriously affect a child and family's long term quality of life. Because their bones are still developing, an injury to the legs can impair growth. Limited data currently exist that can be used to implement an assessment of lower extremity injury risk in the dummies. To close this research gap, biomechanical researchers at CHOP, in collaboration with the School of Veterinary Medicine at the University of Pennsylvania, are implementing a novel approach to develop an age-equivalent animal model for pediatric long bones. These data will serve as the foundation for future research that examines mechanisms of lower extremity injury and explores treatments and countermeasures, impacting the fields of biomechanics, clinical care, and nutrition and bone health.

The future of pediatric crash research

Collection of real-world crash data provides the foundation for biomechanics research efforts to continue. Currently there is no permanent system in place that provides real world data on children in crashes with enough depth and breadth to fuel future advances. CHOP and the National Highway Traffic Safety Administration are conducting pilot research to establish a new child crash surveillance data source, the National Child Occupant Special Study (NCOSS), which will provide the platform for government, industry, and the auto safety research and advocacy communities to continue to advance child passenger safety. More information on NCOSS is available at http://stokes.chop.edu/programs/injury/our_research/nasscop.php.

To download the 2010 Child Passenger Safety Issue Report and for more details on all areas of this research, visit www.chop.edu/injury.

SOURCE The Children's Hospital of Philadelphia