Investigator: Eric E. Sabelman, PhD Project Staff: Ruth Yap, MS; Betty S. Troy, MS; Beatrice B. Lee, MS; Marshall J. Keyes, MD; and George Bekey, PhD Project Category: Osteoporosis - 2000 Objective: Over the course of ten years of research at the VA Palo Alto Health Care System Rehabilitation R&D and Geriatrics Research Education and Clinical Centers, we have developed technology for measurement and evaluation of human motion using miniature silicon accelerometers located on a belt at the waist, on eyeglass frames, or elsewhere on the body, combined with a wearable microcomputer. It is desirable to acquire data on motion patterns early in the process of actually falling study actual falls, with the ultimate goal of providing real-time warning of impending falls, particularly falls that could injure an osteoporotic hip joint. A private physician, Dr. Marshall J. Keyes, has patented an active protection device to prevent fractures from falls onto the hip. This device (the "HIPD") incorporates an air bag in a belt, to be inflated during a fall before the wearer's hip contacts the floor. Our knowledge of postural instability and the motion patterns preceding falls could substantially contribute to design of the fall-detection component of the HIPD and to the real-time software necessary to unambiguously detect onset of a fall and trigger inflation of the airbag within the HIPD, without false alarms due to any other abrupt body motions. Dr. Keyes' company, Maven Technologies, is underwriting a small study through PAIRE to acquire accelerometric data during laboratory-induced falls. In particular, upper body motion and consequences of falling differ greatly between falls in which there is forward momentum and those in which the body collapses vertically (Cummings & Nevitt, J Gerontol: Med Sci, 44: M107-111, 1989). Research Plan: As in previous gait and balance tests, subjects wear an eyeglass frame and a belt, each with two 3-axis accelerometers; a data recorder is also on the belt, so that the subject is not tethered to fixed data acquisition equipment. Body movements are videotaped using reflective targets at joints. Floor padding and wrist guards are provided to prevent injury to the subject, a climbing harness arrests motion just above the floor in stationary falls, and a spotter helps catch the subject before he/she hits the floor (we do not need to measure body/floor contact, only the motion pattern preceding impact). We employ several methods for creating controlled stationary lateral falls, using a device similar to other laboratory balance testing apparatus, in which the subject's feet are on a platform, which is abruptly lowered and/ or tilted forward, backward or laterally by releasing an electromagnetic lock. We take data during falls induced at a randomly-selected time while a subject is standing on the platform, and compare the motion patterns to those of abruptly sitting down in a chair, turning in place, stumbling forward while walking, and vertical collapse due to knee buckling. Results: In 1998, a Stanford student, Jamie van Hoften, received independent study credit in Biomechanical Engineering spring quarter and continued during the summer as a VA consultant, testing 5 young able-bodied subjects in lateral, oblique and backward stationary falls. A ME113 class student team was given the assignment of designing an improved tilting platform. During Summer, 1999, another Biomechanical Engineering student, Hsin-Yi Deng, continued testing of 7 subjects in forward, backward and lateral falls, including blindfolded and perturbed initial balance situations. Funding Source: Maven Technologies |
