William Charles Walker

Simulating the Mechanics of Human Falls

Several estimates indicate that over 10,000 people 65 and older die annually from fallrelated injuries, making falls the leading cause of injury-related death for this age group. At present, no standard test or devices exists that can be used to simulate human falls, which makes research to undertand the mechanics of falls very difficult. To address the need for a test method and protocol for studying falls, a project was initiated to develop a device that simulates human falls and the resulting hip-floor impact. The device is designed to approximate the kinematics and kinetics of a fall event, and is configured to accept full-scale physical models of the hip, femur, fat and tissue. Key outputs of the test device include the force vs. time profile exerted on the ball of the hip during impact with the floor, the force exerted on the end (knee joint) of the femur, deformation of the hip model vs. time, and the velocity of the hip at impact. Simulations and preliminary tests with the prototype configured for an average-sized person indicate the device is capable of accurately simulating a fall and the resulting hip-floor impact. Peak force exerted on the ball of the hip during impact is similar to values from simulations and to those reported from previous studies. Preliminary tests on protective garments does reveal a significant reduction in the force exerted on the hip during fall.