Prostheses in the context of limb loss are usually prescribed by medical doctors. Prosthetic arms and hands are prostheses and thus - stay with me here - prescription items.
Of course you can just buy parts for prosthetic arms yourself and after a doctor or prosthetic technician have made some provisions I see no limitations in where you buy rubbers or cables, batteries or gloves.
But some basic decisions - for example, what type of prosthesis, or what specific problems a patient may have and that the prosthetist must know about - are always medical. And it can make sense to treat prostheses as medical specialties for two specific reasons:
- Two professions - doctors and prosthetic technicians - as well as retailers tagging along seem to look as the art of making and the business of selling prosthetic arms as somewhat unique to their professions. They somehow seem to assume they are the only ones that can do it. With that assumption, however, comes responsibility. It may be a wise idea to remind professionals of these responsibilities. Conversely, if some doctor or prosthetic technician's work causes permanent damage to your remaining arm due to intentionally deceitful counseling, they make themselves liable to all kinds of charges - criminal or civil.
- Medical education provides rules and decision strategies. If one is to accept a professional basis also for prosthetic arms, then these rules and decision strategies will hold firmly. The first and foremost rule of medical treatment is "PRIMUM NIL NOCERE". That is Latin and it means, that you should most importantly not damage your patient, whatever you do. A second far more pragmatic aspect of medical education is that nowadays, education is a compulsory part of certified professions. In other words, no doctor or prosthetic technician can go there and claim they did not know. In a reverse twist, anyone who prescribes or builds prostheses that do not conform to a pain saving and overuse preventing lifestyle is - by definition - obviously not to be seen as a medical professional.
The ramifications are intriguing.
For many arm amputees, chronic overuse, carpal tunnel syndrome and a painful numb overused remaining hand are relevant, serious, often irreversible and somewhat determining conditions after a few years. The reason, almost exclusively, is that prosthetic arms and usage of these is not taught, administered and checked correctly.
Instead, fatal mistakes are made. Prosthetic technicians then recommend myoelectric arms usually because these are by far the most profitable for them. Also, users tend to be less active with these prostheses and instead continue to overuse their remaining arm, and so they do not damage or even wreck them that much.
However, overuse of the remaining limb is not at all treated with myoelectric arms. Myoelectric or "bionic"arms do not allow for the amount and extent of load balancing of the type of activities that cause chronic overuse in the first place (read below, really).
This is obvious, to start off with. You need a special customized body powered arm to really live life and allow your overused remaining hand to survive. You want to stay away from regular strap type harnesses and ill fitted sockets [such as prize-winning Jonathan Naber's IPT - designed to compress and damage nerves, designed to damage stumps, something that has you better off not wearing a prosthesis at all - - at best to be worn for short amount of time if at all]. And you really want to definitely stay away from heavy anchor type dead weights such as myoelectric arms, as that technology has nowadays taken on a dynamics on its own that is everything else but healthy for the user [link: vicious cycle]. That much, to be frank, is painfully obvious. If that is not obvious to you already now, it may make sense to check my previously visualized usage examples [links: hedge cutting, vacuum cleaner, toilet cleaning, some more ADL activities of daily living, and a lot of other ADL activities of daily living]. None of these can be successfully carried out with a myoelectric arm. The fact of myoelectric arms being useless for real life also was illustrated, last but not the least, at a recent Otto Bock Michelangelo hand demonstration in Zuerich that had the Otto Bock artist chew on cables using his mouth (sic!) rather than using his Michelangelo arm prosthetic when setting up his demonstration computer [link]. Also, my body powered arm weighs 1/3 to 1/2 of a myo arm. That makes a big difference.
Chronic overuse requires true professional doctors and prosthetic technicians - to manage, to prevent and to babysit. And whatever activities a prosthetic arm has to deliver to avoid chronic overuse in your remaining hand (nerve compression and carpal tunnel problems) will necessarily have an impact on what a prosthetic arm will have to look like.