Upper Limb Prosthetic Terminal Devices: Hands Versus Hooks

No one would argue that the human hand is the most complex and challenging structure of the human anatomy to replace and restore. The hand is an extremely complex structure which moves with a precision and dexterity that has long challenged the minds of researchers in medicine and engineering. Beyond its kine­ matic capabilities, the hand is also one of the most intricate sensory mechanisms of the human body—with unequaled proprioceptive and sensory feedback capabilities. With this in mind, it is easy to understand why prosthetic terminal devices today (hand and/or hook) offer very little in the way of true functional restora­ tion to individuals with upper limb defi­ ciencies. This is not meant to be critical of past devel­ opments, but puts into proper perspective the complexities and challenges of duplicating the human hand. Further emphasis of this is found in a commentary by Murphy in which he stated, "Though engineers and prosthetists have made substantial contributions, they need perspective and humility to inspire and guide the very long, sustained efforts required to re­ place even a few of the roles of the hand." This challenge will doubtlessly keep researchers in prosthetics, and now those involved in ro­ botics, busy with the task of trying to duplicate the kinematic and sensory capabilities of the human hand for years to come.