A need for a more user-centered design in body powered prostheses

Mona Hichert, Dick Plettenburg, Alistair Vardy

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Users of body powered prostheses (BPP) complain about too high operating forces, leading to pain and/or fatigue during or after prosthetic operation. In the worst case nerve and vessel damage can occur [1, 2], leading to nonuse of prostheses. Smit et al. investigated cable forces and displacements required to operate commercially available voluntary closing and voluntary opening hands and hooks [3, 4]. The capacities of prosthetic users to operate these terminal devices remain unknown. Taylor reported in 1954 forces and displacements measured with 50 ‘normal’ subjects for arm flexion (280±24 N; 5.3±1.0 cm), shrug (270±106 N; 5.7±1.5 cm) and arm extension (251±29 N; 5.8±1.7 cm) (mean±SD) [5]. Unfortunately, the measurement procedure is unclear. Moreover, the study reported forces and displacements from isolated movements instead of combinations of movements typically used for BPP operation. Our recent pilot experiments on 10 male subjects (28±2 years old) also without arm defects using a BPP harness revealed average values of 475 N and a peak value of 970 N for one subject. Although these values are higher, it remains unclear if these force levels are sufficient to comfortably operate a BPP, or too low leading to non-use. Importantly, knowing the capacities and limitations of prosthetic users will aid in choosing and redesigning future BPPs to prevent non-use.
Original languageEnglish
Title of host publicationProceedings of the Myoelectric Controls/Powered Prosthetics Symposium, MEC '14
Subtitle of host publicationRedefining the Norm
EditorsWendy Will, Erik Scheme
Place of PublicationFredericton, Canada
PublisherUniversity of New Brunswick
ISBN (Print)978-1-55131-176-0
Publication statusPublished - 2014
EventMyoelectric Controls/Powered Prosthetics Symposium - Fredericton, New Brunswick, Canada
Duration: 19 Aug 201422 Aug 2014


ConferenceMyoelectric Controls/Powered Prosthetics Symposium
Abbreviated titleMEC '14
CityFredericton, New Brunswick

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