Biomechanical analysis and simulation of backward falls with head impact in older adults

This thesis examined the dynamics of backward falls in older adults involving head impact. Time-varying kinematics were extracted from digitizing videos of 11 real-life falls by residents of long-term care. The pelvis always impacted the ground before the head. On average, the head descended 1.2 m, and had a vertical velocity of 1.7 m/s just before it struck the ground. A novel dummy was used to examine how fall mechanics and compliant flooring affect head acceleration. Landing with a curved versus flat torso decreased peak rotational acceleration by 27% (4633 versus 5901 rad/s2). Landing with fixed versus freely rotating hips lowered peak translational accelerations by 36% (101.5 versus 158.7 g) and peak rotational accelerations by 38% (4168 versus 6366 rad/s2). The protective benefit of compliant flooring depended on torso curvature and hip stiffness. These results show that unexplored aspects of fall mechanics strongly influence head impact severity.