Assessment of pediatric shoulder range of motion and loading response to evaluate the biofidelity of the Large Omni-directional Child (LODC) anthropomorphic test device (ATD) shoulder design.

ABSTRACT

The shoulder girdle complex, through engagement with the seat belt, influences motor vehicle occupant upper body movement during frontal impacts, affecting the movement of the head and spine. The recently developed Large Omni-directional Child (LODC) anthropomorphic test device (ATD) was designed with flexible shoulder girdle structures that capture the unique kinematics in pediatric occupants. However, the LODC shoulder has not been evaluated for biofidelity due to the lack of biomechanical data available on pediatric shoulder responses. This study evaluated quasi-static pediatric shoulder girdle complex responses through non-invasive displacement measurements. These data were obtained to evaluate, and, if necessary, improve the biofidelity of the LODC ATD. Shoulder range of motion and anthropometric measurements were obtained from 25 pediatric volunteers, ages 8-12 years old. Loads were applied bilaterally exclusively to the shoulder complexes in increments of 25 N up to 150 N per shoulder at 90 and 135 degrees of shoulder flexion. Still photos were used to determine shoulder displacement in the sagittal plane from images captured prior to and following the load applications. Data analysis consisted of motion tracking to evaluate the absolute and relative displacement of the right acromion and T1. The displacements for each volunteer were normalized based on the volunteer's shoulder width compared to the shoulder width of the LODC ATD. For the 90° load, the acromion moved relative to T1 an average of 28.1 mm forward and 3.1 mm downward at maximum displacement. For the 135° load, the acromion moved relative to T1 an average of 15.5 mm forward and 42.7 mm upward at maximum displacement. Similar displacements at higher loads indicated that the volunteers achieved their maximum range of motion. The results of this study will be compared to the LODC ATD, assessing the biofidelity of the shoulder complex.