An externally-powered prosthesis mechanism usable with persons with amputations
at or proximal to the level of the metacarpophalangeal joint, as well as persons
with high-level amputations. The prosthesis mechanism includes a grasping mechanism
including a mechanically operable finger member and a mechanically operable thumb
member kinematically linked to the finger member such that the grasping mechanism
is disposed in respective opened and closed configurations when the finger member
is respectively moved away from and toward the thumb member. The prosthesis mechanism
further includes a drive system extending tangentially with respect to the grasping
mechanism and including a motor operatively connected to drive at least one planetary
gear stage, which is operatively connected to drive the grasping mechanism to the
opened configuration when the motor is driven in a first direction and further
drive the grasping mechanism to the closed configuration when the motor is driven
in a second opposite direction.
