Kinematic Insights Into Older Adult Fall-Related Head Impacts: Boundary Conditions and Injury Risk

Abstract

Objectives

To quantify real-world impact conditions of falls, which cause 50% to 90% of older adult traumatic brain injuries, and reconstruct them using dummy headforms to analyze kinematics and injury outcomes.

Design

Mixed-methods: Observational and experimental.

Setting and Participants

An open-access dataset of 118 videos of head impacts at long-term care facilities was used.

Methods

Videos were analyzed to determine head impact occurrence, and for each video with a head impact, fall characteristics were recorded. Perpendicular view fall videos were analyzed using validated model-based image-matching software to track head impact velocities. From the tracked videos, falls were reconstructed with a Hybrid III headform mounted on an inverted pendulum to capture impact kinematics.

Results

Of the 118 fall videos with head impacts, we tracked 29 videos, finding a normal velocity of 1.76 ± 1.02 m/s and a tangential velocity of 1.27 ± 0.95 m/s. Twenty-three of these impacts were reconstructed, producing peak linear acceleration (PLA) 50.2 ± 36.4 g and peak rotational acceleration (PRA) 2.91 ± 2.16 krad/s². Impacts that occurred against the floor had a 38% higher PLA and a 25% higher PRA compared with wall impacts. Compared with backward and forward falls, lateral falls resulted in 46 and 52 g higher PLA and 3.12 and 4.66 krad/s² higher PRA, respectively.

Conclusions and Implication

Fall direction and impact surface influenced head impact accelerations, with certain fall configurations, such as lateral falls against tile, posing a greater risk for traumatic brain injuries. These findings provide critical insights into the biomechanics of older adult head impact falls and highlight the need for targeted fall prevention strategies, such as interventions that reduce the occurrence of lateral falls. In addition, this work offers foundational data for designing protective equipment, including headgear and energy-absorbing flooring, optimized for these specific kinematics.