Virtual Reality Training for
Fall Prevention

      David L. Jaffe, MS at the VA Palo Alto Health Care System's Rehabilitation Research and Development Center and David A. Brown, PT, PhD at Northwestern University Medical School's Department of Physical Therapy in Chicago are spearheading a VA funded project involving Virtual Reality (VR) technology in preventing falls. As one of three interventions being investigated in the project, VR is being used to study stepping-over responses in elderly subjects using simulated objects.

      The long-term goal of their work is to investigate techniques to monitor and improve performance in stepping-over obstacles and train more effective movement strategies of elderly individuals at high risk for falling.

      Brown and Jaffe's VR lab employs a color video camera trained on the subject's legs from the side. The computer generates images of rectangular objects of various heights and lengths. The combined image of the legs and virtual objects is presented in a head-mounted display (HMD).

      Subjects wear the HMD as they walk on the treadmill, stepping over the virtual obstacles they see at their feet. The combined leg/obstacle video is analyzed by the computer for intersections of the subject's feet with the virtual obstacles. A collision by the toe on the front edge of the obstacle would indicate that the subject did not lift the foot high enough, while a collision with the heel on the top of the obstacle would indicate the subject did not step far enough. As these collisions are detected, vibro-tactile feedback is applied to the heel or toe of the foot involved in the collision.

      All subjects walking on the treadmill wear an overhead harness to prevent injury in the case of a loss of balance or fall.

      When stepping over obstacles during over-ground walking, young, healthy persons step over higher objects by increasing knee and hip flexion, and when stepping over longer objects they increase stride length. A pilot study verified this same strategy is employed when stepping over the computer-generated obstacles displayed during the treadmill walking.

      In a small group of elderly subjects, the training regimen showed a positive result in that subjects were better able to negotiate an over-ground obstacle course after three training sessions. Jaffe and Brown plan to perform a randomized, controlled study to separate out the nonspecific effects, and have plans to further develop the system so that it can be used in a wide variety of clinical settings and clinical populations.

      Future work on this project may explore simulation techniques with walking aids such as canes and crutches. Other potential areas of research include the study of improvements in fitness and gait through simulation of walking situations for ambulatory nursing home patients and teaching environmental factors and modifications of avoid falls. The system could potentially provide an enjoyable and safe environment for general exercise, a safe setting for "wanderers", or a simulated practice session for way-finding and familiarization of nursing home patients with their facility.

      For more information about the project, contact David L. Jaffe, MS, VA Palo Alto Health Care System, Rehabilitation Research and Development Center; or David A. Brown, PhD, PT, Northwestern University Medical School, Department of Physcial Therapy;