title: Comparison of body-powered voluntary opening and voluntary closing prehensor for activities of daily life.
abstract: Persons with an upper-limb amputation who use a body-powered prosthesis typically control the prehensor through contralateral shoulder movement, which is transmitted through a Bowden cable. Increased cable tension either opens or closes the prehensor; when tension is released, some passive element, such as a spring, returns the prehensor to the default state (closed or open). In this study, we used the Southampton Hand Assessment Procedure to examine functional differences between these two types of prehensors in 29 nondisabled subjects (who used a body-powered bypass prosthesis) and 2 persons with unilateral transradial amputations (who used a conventional body-powered device). We also administered a survey to determine whether subjects preferred one prehensor or the other for specific tasks, with a long-term goal of assessing whether a prehensor that could switch between both modes would be advantageous. We found that using the voluntary closing prehensor was 1.3 s faster (p = 0.02) than using the voluntary opening prehensor, across tasks, and that there was consensus among subjects on which types of tasks they preferred to do with each prehensor type. Twenty-five subjects wanted a device that could switch between the two modes in order to perform particular tasks.
authors.affiliation: Department of Biomedical Engineering, Northwestern University, Evanston, IL.
authors.forename: Kelsey
authors.initials: K
authors.lastname: Berning
authors.forename: Sarah
authors.initials: S
authors.lastname: Cohick
authors.forename: Reva
authors.initials: R
authors.lastname: Johnson
authors.forename: Laura Ann
authors.initials: LA
authors.lastname: Miller
authors.forename: Jonathon W
authors.initials: JW
authors.lastname: Sensinger
mesh_terms: D000328:Adult; D000368:Aged; D000671:Amputation, Surgical / Q000534:rehabilitation*; D000674:Amputees / Q000534:rehabilitation*; D001186:Artificial Limbs; D005260:Female; D006225:Hand / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D016059:Range of Motion, Articular / Q000502:physiology*; D055815:Young Adult
keywords: amputation; artificial limbs; body-powered prostheses; grasp; outcomes assessment; prehensor; prosthesis 
  design; terminal device; voluntary closing; voluntary opening