Effects of Firefighter Helmets on Cervical Intervertebral Kinematics: An OpenSim-Based Biomechanical Study

Abstract

AbstractWearing head-mounted devices for prolonged time in occupational settings is one of the leading causes of neck pain. In the case of firefighters, the helmets are designed to provide protection against both fire and impact, making it heavier, thereby increasing the risk of neck pain and musculoskeletal injuries. In this study, we evaluated user adaptability and chances of injury with two different firefighter helmet designs, US-style helmet with a comparatively higher center of mass (COM), and European-style helmet with higher mass, based on cervical intervertebral kinematics. We collected motion data of 18 male and 18 female firefighters while performing static and dynamic flexion-extension and lateral bending with and without the helmets and measured the helmets’ inertial properties. Musculoskeletal simulations were performed by applying the motion data and helmet inertial properties to a modified OpenSim full-body model to calculate cervical intervertebral kinematics. It was found that the US-style helmet, although lighter in weight, significantly increased the maximum neck and intervertebral angles during static flexion, and lateral bending and decreased static and dynamic maximum extension angles. In addition, both helmets affected cervical lordosis, which could potentially increase the risks of musculoskeletal disorders during long-term usage or firefighting operations. This study revealed that the higher lever arm of the helmet COM and moment of inertia about the axis of rotation, especially in the case of US-style helmets, is the reason for variations in neck kinematics. A low-profile helmet design (lower COM) would improve the safety and musculoskeletal health of the firefighters.