  An arm amputation is extremely invalidating since many of our daily tasks
require bi-manual and precise control of hand movements. Perfect hand
prostheses should therefore offer a natural, intuitive and cognitively simple
control over their numerous biomimetic active degrees of freedom. While
efficient polydigital prostheses are commercially available, their control
remains complex to master and offers limited possibilities, especially for high
amputation levels. In this pilot study, we demonstrate the possibility for
upper-arm amputees to intuitively control a polydigital hand prosthesis by
using surface myoelectric activities of residual limb muscles (sEMG) associated
with phantom limb movements, even if these residual arm muscles on which the
phantom activity is measured were not naturally associated with hand movements
before amputation. Using pattern recognition methods, three arm amputees were
able, without training, to initiate 5-8 movements of a robotic hand (including
individual finger movements) by simply mobilizing their phantom limb while the
robotic hand was mimicking the action in real time. This innovative control
approach could offer to numerous upper-limb amputees an access to recent
biomimetic prostheses with multiple controllable joints, without requiring
surgery or complex training; and might deeply change the way the phantom limb
is apprehended by both patients and clinicians.
