Editing Prosthesis (section)

===Body-powered arms===

Current technology allows body-powered arms to weigh around one-half to one-third of what a myoelectric arm does.

====Sockets====
Current body-powered arms contain sockets that are built from hard epoxy or carbon fiber. These sockets or "interfaces" can be made more comfortable by lining them with a softer, compressible foam material that provides padding for the bone prominences. A self-suspending or supra-condylar socket design is useful for those with short to mid-range below elbow absence. Longer limbs may require the use of a locking roll-on type inner liner or more complex harnessing to help augment suspension.

====Wrists====
Wrist units are either screw-on connectors featuring the UNF 1/2-20 thread (USA) or quick-release connector, of which there are different models.

====Voluntary opening and voluntary closing====
Two types of body-powered systems exist, voluntary opening "pull to open" and voluntary closing "pull to close". Virtually all "split hook" prostheses operate with a voluntary opening type system.

More modern "prehensors" called GRIPS utilize voluntary closing systems. The differences are significant. Users of voluntary opening systems rely on elastic bands or springs for gripping force, while users of voluntary closing systems rely on their own body power and energy to create gripping force.

Voluntary closing users can generate prehension forces equivalent to the normal hand, up to or exceeding one hundred pounds. Voluntary closing GRIPS require constant tension to grip, like a human hand, and in that property, they do come closer to matching human hand performance. Voluntary opening split hook users are limited to forces their rubber or springs can generate which usually is below 20 pounds.

====Feedback====
An additional difference exists in the biofeedback created that allows the user to "feel" what is being held. Voluntary opening systems once engaged provide the holding force so that they operate like a passive vice at the end of the arm. No gripping feedback is provided once the hook has closed around the object being held. Voluntary closing systems provide directly [[Proportional Myoelectric Control|proportional control]] and biofeedback so that the user can feel how much force that they are applying.

In 1997, the [[Colombians|Colombian]] Prof. [[Álvaro Ríos Poveda]], a researcher in bionics in [[Latin America]], developed an upper limb and hand prosthesis with [[sensory feedback]]. This technology allows amputee patients to handle prosthetic hand systems in a more natural way.<ref>{{Cite book|last=Rios Poveda|first=Alvaro|url=https://dukespace.lib.duke.edu/dspace/handle/10161/2661|title=Myoelectric Prostheses with Sensorial Feedback|date=2002|publisher=Myoelectric Symposium|isbn=978-1-55131-029-9|language=en-US}}</ref>

A recent study showed that by stimulating the median and ulnar nerves, according to the information provided by the artificial sensors from a hand prosthesis, physiologically appropriate (near-natural) sensory information could be provided to an amputee. This feedback enabled the participant to effectively modulate the grasping force of the prosthesis with no visual or auditory feedback.<ref name="pmid 24500407">{{cite journal|s2cid=206682721 |display-authors=6|last1=Raspopovic |first1=Stanisa |last2=Capogrosso |first2=Marco |last3=Petrini |first3=Francesco Maria |last4=Bonizzato |first4=Marco |last5=Rigosa |first5=Jacopo |last6=Di Pino |first6=Giovanni |last7=Carpaneto |first7=Jacopo |last8=Controzzi |first8=Marco |last9=Boretius |first9=Tim |last10=Fernandez |first10=Eduardo |last11=Granata |first11=Giuseppe |last12=Oddo |first12=Calogero Maria |last13=Citi |first13=Luca |last14=Ciancio |first14=Anna Lisa |last15=Cipriani |first15=Christian |last16=Carrozza |first16=Maria Chiara |last17=Jensen |first17=Winnie |last18=Guglielmelli |first18=Eugenio |last19=Stieglitz |first19=Thomas |last20=Rossini |first20=Paolo Maria |last21=Micera |first21=Silvestro |title=Restoring Natural Sensory Feedback in Real-Time Bidirectional Hand Prostheses |journal=Science Translational Medicine |date=5 February 2014 |volume=6 |issue=222 |pages=222ra19|pmid=24500407 |doi=10.1126/scitranslmed.3006820|url=http://infoscience.epfl.ch/record/198047}}</ref>

In February 2013, researchers from [[École Polytechnique Fédérale de Lausanne]] in Switzerland and the [[Sant'Anna School of Advanced Studies|Scuola Superiore Sant'Anna]] in Italy, implanted electrodes into an amputee's arm, which gave the patient sensory feedback and allowed for real time control of the prosthetic.<ref>[https://www.usatoday.com/story/news/nation/2014/02/05/bionic-hand-amputee-feels/5229665/ "With a new prosthetic, researchers have managed to restore the sense of touch for a Denmark man who lost his left hand nine years ago."], ''USA Today'', February 5, 2014</ref> With wires linked to nerves in his upper arm, the Danish patient was able to handle objects and instantly receive a sense of touch through the special artificial hand that was created by Silvestro Micera and researchers both in Switzerland and Italy.<ref>[http://www.channelnewsasia.com/news/health/artificial-hand-offering/986332.html "Artificial hand offering immediate touch response a success"], ''Channelnewsasia'', February 7, 2014</ref>

In July 2019, this technology was expanded on even further by researchers from the [[University of Utah]], led by Jacob George. The group of researchers implanted electrodes into the patient's arm to map out several sensory precepts. They would then stimulate each electrode to figure out how each sensory precept was triggered, then proceed to map the sensory information onto the prosthetic. This would allow the researchers to get a good approximation of the same kind of information that the patient would receive from their natural hand. Unfortunately, the arm is too expensive for the average user to acquire, however, Jacob mentioned that insurance companies could cover the costs of the prosthetic.<ref>{{Cite web|last=DelViscio|first=Jeffery|title=A Robot Hand Helps Amputees "Feel" Again|url=https://www.scientificamerican.com/article/a-robot-hand-helps-amputees-feel-again/|access-date=2020-06-12|website=Scientific American|language=en}}</ref>

====Terminal devices====
Terminal devices contain a range of hooks, prehensors, hands or other devices.

=====Hooks=====
Voluntary opening split hook systems are simple, convenient, light, robust, versatile and relatively affordable.

A hook does not match a normal human hand for appearance or overall versatility, but its material tolerances can exceed and surpass the normal human hand for mechanical stress (one can even use a hook to slice open boxes or as a hammer whereas the same is not possible with a normal hand), for thermal stability (one can use a hook to grip items from boiling water, to turn meat on a grill, to hold a match until it has burned down completely) and for chemical hazards (as a metal hook withstands acids or lye, and does not react to solvents like a prosthetic glove or human skin).

=====Hands=====
[[File:Myoelectric prosthetic arm.jpg|right|thumb|Actor [[Owen Wilson]] gripping the myoelectric prosthetic arm of a United States Marine]]

Prosthetic hands are available in both voluntary opening and voluntary closing versions and because of their more complex mechanics and cosmetic glove covering require a relatively large activation force, which, depending on the type of harness used, may be uncomfortable.<ref>{{Cite journal
  |vauthors=Smit G, Plettenburg DH | title = Efficiency of Voluntary Closing Hand and Hook Prostheses
  | journal = Prosthetics and Orthotics International
  | volume = 34
  | issue = 4
  | pages = 411–427
  | year = 2010
  | doi = 10.3109/03093646.2010.486390
  | pmid = 20849359| s2cid = 22327910
 | url = http://repository.tudelft.nl/islandora/object/uuid%3A8c18e55f-842a-4a74-9b62-4b7fd23d9756/datastream/OBJ/view
  }}</ref> A recent study by the Delft University of Technology, The Netherlands, showed that the development of mechanical prosthetic hands has been neglected during the past decades. The study showed that the pinch force level of most current mechanical hands is too low for practical use.<ref>{{cite journal|last1=Smit|first1=G|last2=Bongers|first2=RM|last3=Van der Sluis|first3=CK|last4=Plettenburg|first4=DH|title=Efficiency of voluntary opening hand and hook prosthetic devices: 24 years of development?|journal=Journal of Rehabilitation Research and Development|date=2012|volume=49|issue=4|pages=523–534|doi=10.1682/JRRD.2011.07.0125|pmid=22773256}}</ref> The best tested hand was a prosthetic hand developed around 1945. In 2017 however, a research has been started with bionic hands by [[Laura Hruby]] of the [[Medical University of Vienna]].<ref>{{cite magazine |last1=Robitzski |first1=Dan|orig-date=First published 18 April 2017 as "A Spare Hand" |title= Disabled Hands Successfully Replaced with Bionic Prosthetics|magazine=Scientific American |date=May 2017 |volume=316 |issue=5 |page=17 |doi=10.1038/scientificamerican0517-17}}</ref><ref>{{cite journal |last1=Hruby |first1=Laura A. |last2=Sturma |first2=Agnes |last3=Mayer |first3=Johannes A. |last4=Pittermann |first4=Anna |last5=Salminger |first5=Stefan |last6=Aszmann |first6=Oskar C. |title=Algorithm for bionic hand reconstruction in patients with global brachial plexopathies |journal=Journal of Neurosurgery |date=November 2017 |volume=127 |issue=5 |pages=1163–1171 |doi=10.3171/2016.6.JNS16154|pmid=28093018 |s2cid=28143731 }}</ref> A few open-hardware 3-D printable bionic hands have also become available.<ref>[https://bionico.org/mains-low-cost/ 3D bionic hands]</ref> Some companies are also producing robotic hands with integrated forearm, for fitting unto a patient's upper arm<ref>[https://www.theguardian.com/uk-news/2015/jun/16/uk-woman-ride-bike-first-time-worlds-most-lifelike-bionic-hand UK woman can ride bike for first time with 'world's most lifelike bionic hand' ]</ref><ref>[https://www.mirror.co.uk/news/technology-science/technology/revolutionary-1m-bionic-hand-allows-5895366 Bebionic robotic hand]</ref> and in 2020, at the Italian Institute of Technology (IIT), another robotic hand with integrated forearm (Soft Hand Pro) was developed.<ref>[https://www.euronews.com/2020/03/02/a-helping-hand-eu-researchers-develop-bionic-hand-that-imitates-life A helping hand: EU researchers develop bionic hand that imitates life]</ref>

====Commercial providers and materials====
Hosmer and [[Otto Bock]] are major commercial hook providers. Mechanical hands are sold by Hosmer and Otto Bock as well; the Becker Hand is still manufactured by the Becker family. Prosthetic hands may be fitted with standard stock or custom-made cosmetic looking silicone gloves. But regular work gloves may be worn as well. Other terminal devices include the V2P Prehensor, a versatile robust gripper that allows customers to modify aspects of it, Texas Assist Devices (with a whole assortment of tools) and TRS that offers a range of terminal devices for sports. Cable harnesses can be built using aircraft steel cables, ball hinges, and self-lubricating cable sheaths. Some prosthetics have been designed specifically for use in salt water.<ref>{{cite web|last1=Onken|first1=Sarah|title=Dive In|url=http://www.cityviewnc.com/2014/01/06/20010/dive-in|website=cityviewnc.com|access-date=24 August 2015|archive-url=https://web.archive.org/web/20150910011729/http://www.cityviewnc.com/2014/01/06/20010/dive-in|archive-date=10 September 2015|url-status=dead|df=dmy-all}}</ref>