April, 2019: Are there roles for passive prosthetic hands and tools?
Maat B et al Passive prosthetic hands and tools: A literature review. Prosthet Orthot Int. 2018 Feb;42(1):66-74.
Dutch investigators performed a literature review on passive prosthetic hands and tools. Using standard search strategies and literature databases, they found 38 articles for inclusion. Seventeen were based on user studies (n=2367), and three were based on author experience in fitting and evaluating prostheses (n=7847). The remaining articles were reviews, descriptions of specific prostheses, or evaluations of prosthetic appearance.
The authors first address the issue of terminology, which has been non-specific, overlapping, or both. and therefore confusing. They provide a new classification system by dividing the devices into either prosthetic hands or prosthetic tools, and then subdividing these groups into static and adjustable. Static prostheses have no moving parts. With an adjustable prosthesis, users can reposition the fingers or wrist with their sound hand or by pushing the prosthesis against a solid object.
Across ten studies, one-third of subjects used a passive hand prosthesis. Conventional thought has been that recent amputees and children start with a passive device and then transition to an active prosthesis. On review, however, many older people and long-standing amputees use passive hand prostheses after having tried active devices. Motivation to use a passive hand prosthesis centers around appearance and comfort, and the device may mostly be used on social occasions for enhanced self-confidence and self-image.
Several studies note that there is a great overestimation of the physical disability of people with an upper limb amputation and that approximately 90% of activities of daily living can be performed using the sound hand, and the other 10% require only minimal extra effort. The authors speculate that the push for active prostheses might relate to an overestimation of physical impairment caused by a unilateral hand amputation and/or that people other than the amputee have interests and expectations of their own, which might be a personal interest or a financial driver.
Future research on passive prosthetic hands should focus on improving comfort and reducing weight of passive hand prostheses such that the user can wear it comfortably, forget about it, and pass unnoticed.
Papers on passive prosthetic tools center on driving, sports, and musical instruments. Tools are commercially available for playing hockey, tennis, golf, and baseball and for bowling, fishing, skiing, paddling, shooting, weight lifting, and photography. Tools for holding a drumstick, violin bow, or guitar pick are also available. In many instances amputees may not know about the adaptive devices and unnecessarily give up their vocation or avocation. A steering wheel knob is the most frequent driving aide and can be used by the normal hand or by either a passive hand prosthesis or a tool. For tools to be maximally helpful, issues regarding further development include secure suspension, durability, suitable weight, and simplicity. Prosthetic tools are typically task specific, whereas a passive adjustable prosthetic hand can grasp a wide range of objects.
The authors recommend that future improvements not focus on functionality since passive prosthetic hands offer limited although adequate assistance for most activities of daily living. Rather research should focus on improved appearance, comfort, and control.
COMMENT: I found the paper enlightening. Those of us with two highly functional hands naturally want everybody else to have a working pair as well, but perhaps our help is misguided in directing amputees toward active prostheses which can be rather complicated, cumbersome, and heavy. The authors suggest, having reviewed the available literature, that an amputee may feel otherwise and would rather manage without a prosthesis at all or favor one that improves appearance more than function. Also, we should be aware of available passive prosthetic tools that can help amputees succeed at what are normally bimanual activities. FREE FULL TEXT