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Development of a Lightweight Powered Lower-limb Prosthesis

(Project D4: Mobility)

Contact Information:

Jim Lipsey, MS, PE (Engineering Project Leader)

j-lipsey@northwestern.edu

Summary

Powered lower-limb prostheses offer great promise to the approximately one million Americans with a lower limb amputation whose ambulation is slower, more asymmetric, less stable, and requires more metabolic energy than that of able-bodied individuals. This is particularly true for older individuals who make up over 90% of persons with a lower limb amputation and who need assistance simply getting out of chairs, off the toilet, and walking the short distances necessary for them to live independently at home.

Older individuals, who are generally smaller and weaker, need powered legs that are strong enough to help them get out of a chair, yet light enough to walk with—and to not tip them off balance during swing-phase.

Recently introduced motorized leg prostheses, designed to augment the abilities of younger, healthier users, are not well suited for elderly individuals. They are too heavy for the limited stability and strength of older individuals. Our recent successful design for a lightweight upper limb prosthesis uses innovative motors and transmissions that have exciting potential for the design of a lightweight lower-limb device.

The objective of this project is to develop a lightweight motorized leg and to evaluate this device in elderly persons with a transfemoral amputation during various ambulation activities.

Target Population

Approximately 90% of the almost one million persons with a lower limb amputation are elderly. Because of the increasing age of the population and incidence of vascular disease, this population is expected to double by 2050. A lightweight powered prosthesis would enable such individuals to maintain independence. Such a device may also be useful for other smaller individuals, including women and children.

This research is supported by the U.S. Department of Education, National Institute on Disability and Rehabilitation Research, grant number H133E130020.