Upper extremity prostheses

I was interested to see what was available in prosthetic devices for upper limb injury, after having visited a prosthesis manufacture workshop in Nairobi in summer 2015, and also since I have an interest in hands.

Prosthesis options:
Passive prosthetics - cosmetically helpful but without significant functional use (some can be reshaped into a pincer grip) http://biomed.brown.edu/Courses/BI108/BI108_2003_Groups/Hand_Transplantation/altern2.html

Functional prosthetics 1 - simple mechanical cable operated - can operate by motion to close the gripping device, which would reopen by an elastic mechanism (e.g. rubber banding).  Limited in those patients with limited movement.  Paired claws and pincers are remarkably functional and offer good visual feedback of what the hand is doing, thus enhancing their use.  Cheaper to produce.



Functional prosthetics 2 - myoelectric - skin-based electrodes sense muscle contraction, and thus enable the device to be controlled.  Devices tend to be heavy, expensive and battery duration can be an issue.   https://www.youtube.com/watch?v=_qUPnnROxvY


Particularly impressive is the variety of grips with the advanced versions of these prostheses:

o    Handshake

o    Power grip

o    Precision grip

o    Mouse grip (e.g. to point and click)

o    Trigger operated device grip

o    Index finger use for PIN number entry

o    Key-holding grip

Notable figures with upper extremity prostheses:

Rick Allen – Def Leppard drummer (RTA amputee)

Aron Ralston – Adventure writer featured in 127 hours film (amputated his own right arm after becoming trapped by a boulder)

Abu Hamza – radical Islamic cleric known for using a pair of hooks (explosives accident)

Matthew Scott - first recipient of a lasting hand transplant, which is still functional more than a decade later (firework explosion).

Blog link 
Great thoughts on prosthetics and exoskeletons
https://forrestbrown.co.uk/news/we-are-all-cyborgs/