ARCCA was asked to analyze injuries that were claimed to have come from an incident where a child suffered a skull fracture when they collided with another, older, child while playing a game. There was a dispute as to whether the child’s injuries could have been prevented if only children of similar age had been allowed on the playfield. ARCCA biomechanics experts were asked to characterize the forces and body motions involved in the collision, and analyze whether the same injuries would still be possible in a collision between two children of similar size and age.

Steps Taken:

ARCCA’s engineering experts designed an experiment to quantify the forces involved in the accident:

  • ARCCA biomechanics experts inspected the location where the accident occurred and documented the condition and dimensions of the playfield.
  • ARCCA experts analyzed medical records and witness statements to determine how the collision occurred.
  • ARCCA biomechanics experts designed a test program to characterize the forces and body motions involved in the collision.
    • Anthropomorphic test devices (ATDs – dummies that mimic the human body and are equipped with sensors) were positioned according to descriptions of the incident.
    • ARCCA’s pendulum test fixture was used to simulate the motion of the two children.
    • In a series of experiments, the ATDs were subjected to controlled collisions while acceleration measurements, force measurements, and high-speed video were recorded.
    • An ARCCA biomechanics expert analyzed the data from the experiment and compared it to published literature on injury criteria.
  • Animators created a video based on the biomechanics experts’ reconstruction of the incident.

Final Findings:

ARCCA biomechanics experts determined that even a collision between two children of the similar age and size could have caused a similar skull fracture to the actual accident. The older, larger child was running at a moderate speed during the accident, and a similar collision with a younger, smaller child but running at a high speed would have produced comparable forces and similar injuries. This was supported by ARCCA’s testing simulating collisions between children of different size moving at different speeds. Thus, restricting play to only children of similar age and size would not have prevented the accident.

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