Abstract
An active protection device (in contrast to passive padding) has been proposed to prevent fracture from falling onto the hip, a major cause of morbidity and mortality in the elderly. Such devices require nearly-infallible algorithms for real-time motion analysis, activating only if a fall is likely to cause hip injury, while excluding false alarms due to any other abrupt motion. Upper body motion is likely to differ between falls with forward momentum and those in which the body collapses vertically and laterally (J Gerontol: Med Sci, 44:M107-111,1989). In a preliminary study, we examined stationary falls by young able-bodied subjects standing on a platform held level by an electromagnet. When the magnet was turned off at a randomly selected time, the platform tilted forward, backward or laterally. Mattresses and a climbing harness prevented impact on the floor. Motion patterns during the first 0.5 seconds of falling were compared to quickly sitting down, turning in place, stumbling while walking, and vertical collapse due to knee buckling.