Biomechanical Response of the Pediatric Ankle

Principal Investigator: John H. Bolte IV, PhD, The Ohio State University

 

Below is an executive summary of this project. Please note that this summary describes results and interpretation that may not be final. Final interpretation of results will be in the peer-reviewed literature.

 

Pediatric volunteer undergoing testing on the Biodex.

 

An increased risk of injury to the leg occurs when a child is placed in a child restraint’s forward-facing position. In a frontal collision, the leg can make contact with the front seatback, causing fairly common and often very serious injuries to the tibial growth plates and ankle joint. Since the pediatric anthropomorphic test device (ATD) has no instrumentation below the knee, it makes it impossible to evaluate the amount of force the leg experiences on impact during frontal collisions. Moreover, because the pediatric ATD does not have a realistic ankle, it is not possible to directly measure these forces to accurately predict injury to the leg.

The aims of this study were to measure the lower extremity anthropometry of 42 children, ages 4 to 12 years, as well as to determine ankle stiffness and the ankle’s range of motion (ROM) in four ways: 1) while standing on one’s toes (plantar flexion), 2) while rotating the foot backward to bring the toes closer to the ankle (dorsiflexion), 3) while rotating the foot so the sole is pointing inward (inversion), and 4) while rotating the foot so that the sole is away from the body (eversion). Seventeen different measurements were taken bilaterally on the foot, ankle, and leg. Using a hand-held goniometer, ROM was measured both actively (flexing) and passively (naturally) in plantar flexion. Ankle stiffness was measured using an Isokinetic Dynamometer in six directions: plantar and dorsiflexion, inversion and eversion in an anatomical position, and inversion and eversion in a relaxed position.

Overall, the study found that younger children have an increased available ROM in all directions measured. Differences did exist between the younger group (ages 4 to 7 years) and the older group (ages 8 to 12 years), especially involving dorsiflexion with both a straight leg and bent knee, as well as actively and passively. The information gained from this study will benefit the automotive industry by helping to produce a more lifelike ankle in both the 6- and 10-year-old ATDs. It also provides beneficial information to the rehabilitation community working with children with gait abnormalities and spasticity disorders.

 

Co-investigator:
Ajit Chaudhari, PhD, The Ohio State University

Student:
Laura Boucher, The Ohio State University

IAB Mentors:
Doug Longhitano, Honda R&D Americas Inc.; Christina Mullen, State Farm Mutual Automobile Insurance Company; Rodney Rudd, National Highway Traffic Safety Administration

About This Center

This Center is made possible through a grant from the National Science Foundation (NSF) which unites CHOP, University of Pennsylvania, and The Ohio State University researchers with R&D leaders in the automotive and insurance industries to translate research findings into tangible innovations in safety technology and public education programs.

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