Investigator: Eric E. Sabelman, PhD

Project Staff: David L. Jaffe, MS and Alan K. Nakahara, MS

Summary: Accurately assessing balance and mobility impairment is important for diagnosing and reducing risk of falls, formulating individualized therapies, and monitoring patients' progress. Improvements in technology have made it possible for a wearable motion analysis system to be much faster, lighter and more capable than previous versions. This proposal supports building and testing several sets of newly-designed post-second generation equipment, developing software for extracting clinically useful information from its data, and technology transfer to a commercial partner for further development via a Co-operative R&D Agreement (CRADA).

Objectives: Accurately assessing balance and mobility impairment is important for diagnosing and reducing risk of falls, formulating individualized therapies, and monitoring patients' progress. This project supports: (1) building and testing several sets of newly-designed post-second ("2+") generation equipment, (2) developing software for extracting clinically useful information from its data, (3) comparing results with those obtained using the earlier version, and (4) enlisting support of a commercial partner in further development via a Co-operative R&D Agreement (CRADA). A design/development approach to bringing the accelerometry system up-to-date is essential to commercialization of the methodology.

Background: Under Merit Review project, Upper Body Motion Analysis for Amelioration of Falls in the Elderly (E601), we created a wearable instrument with wide potential as a diagnostic and therapeutic tool, and tested subjects as they performed 65 standardized activities, including standing, reaching, bending, walking and simulated activities of daily living. Algorithms were developed using accelerometric data directly, rather than calculating velocity or position. A continuation, Reliability and Validity of Accelerometric Gait & Balance Diagnosis, is underway, comparing accelerometry to laboratory-based motion analysis, in a large population of normal fit and deconditioned older subjects. However, this research-oriented project does not provide for comparison of alternative wearable computers, for developing software to make full use of the system's new capabilities, nor for testing of the advanced system by potential commercial manufacturers and distributors.

Significance: Reducing the number and severity of fall-related injuries, and increasing the mobility and independence of older veterans are the ultimate goals of this research. VA gerontologists, physiatrists, and therapists concerned with improving veterans' gait and balance have expressed need for better methods for identifying individuals at risk for falls and for monitoring efficacy of interventions. The technology has commercial possibilities in clinical diagnosis of fall risk of patients in nursing homes and hospitals, and has potential uses in athletic and occupational injury prevention and rehabilitation. Accelerometry overcomes deficiencies of current laboratory and qualitative mobility diagnosis using cutting-edge technology, and as such is appropriate to the Rehabilitation R&D Service mission.

Status: We are continuing development of accelerometric body motion analysis by means of the following pre-commercialization activities:

1. "2+"-generation construction and testing - The wearable version is being designed, but has not yet been fabricated. A functional desktop version has been constructed, for testing using the methods for the first system (sensor drift, sensitivity to misalignment, etc.). The desktop version is being upgraded with the newest components and will be tested for functionality. After verification of the upgraded desktop version, a wearable version will be constructed and tested using the same methods as the first system. Alternative methods of sensor and computer mounting on the body are under study, particularly battery pack placement, to accommodate users with special needs. Results from normal subjects will be compared to the first generation database and to conventional measures (force platform, goniometry, qualitative gait and balance score). A multi-link simulator will be built so that complex body motions like sit-to-stand can be reproduced without artifacts due to human subjects.

2. Software adaptation - Software for extracting sway angle, time to completion, etc., from standard tasks is currently being written and will be installed in the new system. Programs using the new system's capabilities (real-time alarms, interaction with therapist, etc.) are included in general in the command structure of the wearable CPU; specific command menus will be written when subject testing is begun.

3. System replication - Two additional sets of "2+"-generation equipment will be assembled after successful construction and functional testing of wearable unit. Training literature and videotapes will be updated to reflect changes from the first generation. The second system will be given to the Technology Transfer Section for demonstration to selected users and manufacturers. The third system will be available to a CRADA partner for pre-production trials and modifications.

4. Technology transfer - Palo Alto Rehabilitation R&D has contacted over 50 companies in the fields of industrial motion/vibration and physical therapy/diagnostic equipment. We also plan to contact companies in the new field of wearable computers, who typically need non-military markets for their products. A CRADA has yet to be negotiated with a company. Contact has been made to discuss the possibility of a licensing agreement with a representative of Silicon Designs, Inc., which has expressed an interest in a device similar to ours that has the capability of user control.

Related Work: Reliability and Validity of Accelerometric Gait

Funding Source: VA RR&D Merit Review - Project E2182DA (SAB0024)