Head kinematics of human subjects during laboratory-induced ladder falls to the ground

Introduction: Fall-induced traumatic brain injury (TBI) is considered one of the most serious occupational injuries in construction. Given the frequency of falls from ladders, knowledge of head kinematics during ladder falls to the ground may help inform any potential improvement to construction safety helmet design and improve their protection against head injury. Therefore, the goal of this descriptive study was to measure head kinematics during laboratory-induced ladder falls to the ground. Method: Eighteen young adults wearing a hockey helmet simulated construction tasks that challenged their balance while standing on stepladders and an extension ladder with their feet at heights up to 1.8 m above padding covering the ground. Falls onto the padding occurred spontaneously or were induced by an investigator nudging the ladder to simulate ladder movement resulting from the ground shifting. Optoelectronic motion capture was used to capture head kinematics up to the instant immediately before head impact. Results: Of 115 total falls, 15 involved head impact with the padding and were analyzed. Head impact during all 15 of these falls occurred on the back of the head. Immediately before impact with the padding, head vertical velocity ranged from 0.42 to 3.88 m/s and head angular velocity about a medial–lateral axis ranged from 60.1 to 1215.5 deg/s. Conclusions: These data can be used with computer simulations or headform impact testing to estimate true head impact kinematics, or to inform future versions of construction safety helmet testing standards. Practical applications: This is the first study we are aware of to capture head kinematics of human subjects during ladder falls to the ground. These results have the potential to inform future versions of construction safety helmet testing standards and contribute to improved helmet design for protection against fall-induced head injury.