Skip to Content

Evaluation of a Novel Body-powered Prehensor

(Project R1: manipulation)

Contact Information:

Laura Miller, CP. PhD (Prosthetist)
lamiller@northwestern.edu

Summary

Expectations for control of upper limb prostheses are high because of the standard established by able-bodied dexterity. Despite a cultural fascination with robotic prostheses, active users often prefer body-powered prostheses in which shoulder movement is translated into prosthesis movement via Bowden cables. These devices are simpler, lighter, more rugged, and provide inherent proprioceptive and force feedback. Body-powered prehensors (split-hooks and other non-anthropomorphically shaped terminal devices) are considered more functional than body-powered hands.

Unfortunately, users must choose between the two types of currently available prehensors: voluntary open (VO) devices, in which the user exerts force to open the device, and voluntary close (VC) devices, in which the user actively closes the device. VO devices provide a weak grasp force of only a few pounds, but are easy to use. VC devices enable the user to apply large grasp forces but require the user to constantly exert force to hold an object.

With previous funding from NIDRR, we have developed a prehensor with an innovative yet simple manual switching system that enables a user to operate the device in either VO or VC mode. This VO/VC device can be used in the VO mode for manipulating light objects, and can easily be switched to VC mode to provide a high grasp force, when needed.
The objective of this research project is to evaluate the clinical utility of a VO/VC device by objectively quantifying usage of this device by individuals in their home environments.

Target Population

The primary target population for this research project is persons with upper limb amputations. This population comprises many thousands of people in the United States, including many combat-injured military service personnel, who are overwhelmingly young and active.

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