Requirements for prosthetic arms in context of chronic overuse and strain symptoms and carpal tunnel syndrome [analysis]

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.

A very detailed list of problems and tips for CTS [link] caught my eye as I found it matched my own experience really well. I took some time to re-sort that list under aspects of prosthetic arm usage.


Avoid manual tasks and use prosthetic arm / hand instead

Problem Avoid Use prosthetic for these tasks
1. Try your best to avoid activities requiring excessive up-and-down and side-to-side movements of the wrist as much as possible. Make it a healthy habit to be concerned what force your applying against your wrists and you'll go a long way in preventing or recovering from carpal tunnel syndrome. Tasks such as hard scrubbing. Sandpapering. Chipping large chunks of wood. Chiseling. Tasks such as hard scrubbing. Sandpapering. chipping large chunks of wood.
2. Refrain from doing activities that put direct pressure over the
heel of the hand (just below your palm), like push-ups from example.
If you do push-ups, try using your fists instead of your palms.
Hard pushes. Hard pushes.
3. Avoid activities requiring forceful repetitive grasping, such as using garden cutters. If you absolutely must use one, use well-cushioned gloves and if possible, tools with padded handles. If you do a lot of work similar to this, it's best that you purchase some tools that easy to use and have padded grips or handles. Repetitive forceful grasps such as garden cutting, vacuum cleaning, heavy lifting or such. If there is no other way use protective gloves, possibly padded. Forceful grasps for straining repetitive tasks such as garden cutting, raking, shoveling, vacuum cleaning, heavy lifting and such.
4. Avoid activities involving the use of power tools that cause significant vibration. Power tool usage that cause significant vibrations. Use prosthetic for supporting and handling of power tools that cause significant vibrations.
5. If you are shopping, take the moment to grab a shopping cart, even if you don't have that many groceries to buy. Carrying basket with sound hand. Carrying shopping basket or push cart.
6. Avoid asserting concentrated weight or force on your joints, like carrying things with small thin handles. Instead use a box forcing you to use both hands or find a way to create a bigger handle so you can grip it easier. Carrying thin handles or carrying items on thin strings. Carrying heavy items with strings or thin handles.
7. If your dominant hand is the one with CTS, work on strengthening your other hand with weights, exercises and stretches regularly. Start using this hand whenever you can save yourself from using your dominant one. Avoid task: using dominant / sound hand for weights and exercises. Use prosthetic for every single task it can be possibly used for, even if slightly more clumsy or slower at first. Ease and proficieny will follow. Including and in particular heavy lifts, exercises, weights.
8. Always consult your doctor if you are experiencing numbness or tingling to accurately determine the cause of such discomfort and rule out a more serious problem. Avoid solving numbness or tingling problems yourself. Immediately consult doctor. Prosthetic setup: in particular, a custom made shoulder anchor point is important. The doctor should prescribe the extensive works on this, and the prosthetic technician should have a look at this very thoroughly.

Train new behavior

Problem Train
9. Reduce the intensity of muscle tension when your grasping things. Most people hold their pens and pencils unnecessarily hard. Minimize as much as you can the applied force by practicing minimum grip. Train: relaxed and well centered manipulations with minimal pressure and flexion or extension of the wrist.
10. Shake your hands and wrists rapidly to increase comfort and reduce tension. Train: shaking hand and wrist rapidly to increase comfort.
11. If your task requires only one hand, try switching hands now and then giving the other one a good rest even if your not as efficient. Train: particularly for strong grip, strong push or pull weighted, for seriously repetitive and vibration-loaded tasks, switch hands, that is, alternatively or predominantly use the prosthetic arm. That is what you *need* the prosthetic arm for.
12. When you're working on something, try to avoid having your hands too far or too close from your body Train: postural symmetry.
13. Most people have the habit of using one hand when it comes to pouring or holding drinks. Next time your drinking from a bottle, cup or pouring out drinks, practice holding with two hands. Instead of applying all the weight on one wrist, it's now 2 times lighter and less stressful. Train: left / right hand / prosthetic load balancing.
14. When driving 5-speed cars, try using the force of your arm to switch gears instead of your hand and wrist. Better yet, drive an automatic vehicle if you own one. Train: repetitive manipulations that can be made from whole arm rather than wrist motion need to be made from whole arm motion. Such as gear shifting, steering the car, and so on.
15. Make it a habit to take 5-10 mini breaks to stretch and walk around at least every hour when working at the computer. Train: mini breaks.


  • 16. Applying heat to the area you feel the carpal tunnel helps relax the aching muscles and reduces soreness. Find a heating pad or if you don't have one, find a water bottle and fill it with hot water, then put it on the area.
  • 17. Applying cold to the area you feel the carpal tunnel helps to lessen the swelling and pain. Put an ice pack or let the area run under cold water for a few minutes or let your wrists hover above a ice pack when your typing.
  • 18. Be gentle with your body. After a hard workout or long hours of doing a repetitive task, take a long well deserved rest. If you can't possibly afford to take a rest, slow down or try working on an easier task.
  • 19. For minor temporary pain relief, briefly soak the area you feel the pain in cold or ice water. Recommended that you only do this if you absolutely have to finish a task.

General posture, task completion and general training, setup and equipment

  • 20. If you're using tools, make sure the handles and grips are not too small or too big. Big handles will mean more weight to stress, too small handles will mean concentrated stress from the weight.
  • 21. If you have a job or hobby that requires you to type a lot, adjust the level of your chair so the keyboard is level with your forearms. This will save you from flexing your wrists when your typing
  • 22. Wearing tight watchbands or jewelry and garments with tight elastic sleeves can irritate your wrists, try and wear something lose and more comfortable.
  • 23. Next time your hand feel that burning, sore, tingly or numb sensation, relax some of the tension by massaging in a circular motion starting from the finger tips and continuing all the way down to the base of the palm.
  • 24. Try using your legs and arms instead of your wrists when your lifting heavy objects, like changing a tire or lifting grocery bags. Your legs alone can easily take on more weight and stress than your arms and wrists combined.
  • 25. Don't be afraid to ask for help when your moving heavy objects, like lifting furniture around when your cleaning the house.
  • 26. If you have Carpal Tunnel and live with a family, let them know you have it and tell them it's vital to your health and recovery that they help or try to do all the heavy work around the house. Don't just shake out the pain and deny that it is there.
  • 27. Meditation and relaxation loosen up stress on your muscles. The more relaxation you provide to your wrists and body, the less inflamed your area will be. Pop in meditation music or pray and take deep slow breaths and visualize yourself in paradise. Your mind is very powerful and research has proven that expectations of yourself and your belief of recovering from problems and diseases influence how fast you will recover.
  • 28. Avoid sitting or standing in the same position all day, move around or change your position if you must continue working on that task.
  • 29. Invest in a high quality jell pad, the smoothness and texture of the pads you chose will have a large influence on the amount of stress will be caused on your wrists.
  • 30. A great way to exercise and strengthen your hand again is to find a good tennis ball and for a few minutes squeeze it in your palm over and over again. After you are done, take a 5 minute break before you start do anything again.
  • 31. If you're doing regular weight lifting, when your doing tasks with your wrist like curls, or bench press, keep your wrists from folding back wards. This will also give your arm the full workout instead of using the wrist. If you can't stop your wrist from folding back wards, then try gearing down on the weights onto something lighter and easier.
  • 32. Avoid resting your wrists or area that has CTS on hard surfaces for long periods of time. If you rest your wrists on a surface, make sure you're using a soft support like a jell pad or pillow.
  • 33. Use a spare pillow for your wrist when your sleeping. When you're sleeping you could unintentionally move your wrists under your body's weight.
  • 34. If your job is being a clerk, you could be at a special risk. The problem with this job is that most of the counters you will be using to type will require you to stand. Unfortunately virtually all of these counter levels are not high enough for proper wrist form. Ask politely your supervisor your concern for CTS and if he can find a way to adjust the desk for not only you but other employees.
  • 35. When your typing on the keyboard and clicking the mouse, make sure that your tapping the keys as lightly as possible and sitting up straight in your chair. There has been cases where people develop a disease separate but similar to CTS in the thumbs because they click too much, too hard or too fast with the mouse.
  • 36. If your use the computer a lot, take the time to learn all the shortcuts keys. Almost any program has them, especially ones created by Microsoft like Word, Excel or PowerPoint. Master the shortcuts and you'll save yourself a lot of time and stress put on your hands.
  • 37. Never write on a pad or book support in your lap. Your hands are too close to your body and your wrist will likely be bending in a dangerous form. Take the moment to find a good table to write on.
  • 38. When your brushing your teeth, instead of using just the wrists to force the brush against your teeth, tighten your cheeks a little. This will help get the force you want to clean your teeth so you don't have to grip the brush as tight, careful not to ruin ur brush!
  • 39. When your using the computer, practice keep your feet flat on the ground. This will help you keep your body, shoulders and arms straight and your wrists a safe distance from the keyboard.
  • 40. Buy a headset for your cell phone and house phone. Most phones today have a speaker phone option, so use it! You are putting stress on your wrist just by simple holding the phone. Taking a break to talk on the phone is also a great way to relax your hands, and keeping in touch with your friends!
  • 41. When your using a chair, it's best to use one that has long, wide and padded arm supports.
  • 42. Work on big tables with plenty of room. This prevents you from working in cramped areas especially if it's your office. Most likely you will have a pile of stuff that steals up the space you require to sit, type or work properly.
  • 43. When your on the computer, keep the mouse close to the keyboard. This will stop you from having to stretching across the desk and keep your body and shoulders straight.
  • 44. If your painting or drawing, keep your wrist above the surface and let your fingers and arm to the work.
  • 45. A good way to see if your wrists are in a healthy posture is by checking if you took a ruler and lined it up from the middle of your fingers to base of your wrists and check if it lines up and continues up your arm.

General health care and treatment approach

  • 46. If you are overweight, make a commitment to lose weight and improve your blood flow. Exercise daily and eat healthy will go a long way in controlling weight. This can help you prevent carpal tunnel syndrome or help you recover faster from it.
  • 47. Medicine's like Ibuprofen, Motrin Advil and Tylenol can not give you permant treatment or cures but can only provide atemporary pain relief from your symptoms.
  • 48. If your using a splint, it is important that you don't strap it on so tight that it starts to cut off blood circulation. If it feels even more numb when you use a splint then you know its too tight. Same with those balancing bands, they might not work for you, if you feel that something is hurting you more than helping stop using it.
  • 49. Surgery should be the last resort when you're thinking up treatments for your CTS. Surgery is risky, can cost an arm and a leg and will keep you from moving your hands at all for weeks if it is successful.
  • 50. By simply drinking enough water (8 cups/day) alone, does wonders preventing and recovering from CTS. Having a good water source in your body is critical for your muscles and connective tissues to go back healthy function and condition. A great book I highly recommend to get is "Your Body's Many Cries For Water" by Dr. F. Batmanghelidg, MD.
  • 51. Cut down on your amount of alcohol, coffee and smoking as much as possible. If you have CTS or want to prevent your chances of getting it, simply cut down on unhealthy habits and activities. The amount of alcohol and smoking you do will also effect the speed of your recovery.
  • 52. Make sure your getting plenty of Vitamin E. This helps improve blood circulation & protects blood vessels from being damaged. Also make sure you are using lots of Glucosamine, MSM and Emu Oil. These 3 are the key ingredients in recovering from many RSI's.

Conclusion -requirements for prosthetic arm

It is obvious that these considerations must play a major role for prosthetic equipment.

Most prosthetic component manufacturers entirely ignore these requirements. Any prosthetic part that Otto Bock sells is not built for heavy "usage" [1]. It is interesting to note that Otto Bock engineers consider "safety of the patient" as related to not using their prosthetic too much. I cannot say that this perception plays out in every day life. Not even close. Much rather, really using the prosthetic arm for practically everything thinkable is what makes my remaining (real) hand and therefore me as a user safe.

Overusing a prosthetic may cause it to break, and as these are industry parts, they can be replaced by a simple order and replace process. If I damage my remaining hand however, problems can be hard or impossible to treat and consequences can be expensive. Insurances and employers alike should have an interest in this as well. The impact that evaluation, choice and build of a prosthetic has on mid term to long term problems and costs is not to be underestimated. Now, one does not at all have top buy fragile items with ridiculous warranty terms such as Otto Bock's stuff. There really are other components that are a lot better to buy and use.

Also, the burden on socket manufacturing is rather extensive. All excessive loading will be transmitted through the socket to the stump - and the more I can actually use my prosthetic arm for moderate and heavy weights and tasks, the more likely I can protect my remaining hand from chronic overuse. So you really want a large surface of the stump to fit very tightly and well, and the socket should be very light and stiff. I find silicone liners with a pin lock ideal. With a very proficient prosthetic arm that can be used for heavy and repetitive stuff comes huge relief.

With that, I highly doubt that osseointegration is able to provide the type of relief that a prosthetic arm would have to sustain. Osseointegration definitely will fail under "extreme" torsion, "extreme" push and pull weights, under full immersion in dirty toilets or pools, over chemical, hot items and hazardous stuff. Because if you can't do these with your prosthetic arm, those are the activities that may eventually kill your real hand.

So here is the list of requirements for a prosthetic arm:

  • Sweat proof - in a sense that a socket keeps a firm mount point despite dripping sweat (Problem 5, 6).
  • Very firm socket mount so weights can be pulled (Problem 5, 6).
  • Torsion and rotation proof, push and pull proof, with a relatively high maximum force still to be tolerated.
  • Vibration proof - in a sense that prosthetic components hold up to mechanical vibration (Problem 4) such as power tools or lawn mowers.
  • Shock proof - in a sense of bangs and hits, usage as hammer, to hold a hammer, and for forceful blows (Problem 2).
  • Shoulder anchor point of cable operated prosthesis should not compress nerves (Problem 8). Alternatively, other anchor points are acceptable (such as ThoughWare PRX' systems) as long as no important nerves or vessels are compressed.
  • Sports proof, extreme usage proof, extremely robust (Problems 1, 2, 3).
  • Safe for water, chemicals and biohazards (Problem 1 - scrubbing).

So the very activities that companies like Otto Bock use to argue a void of warranty - exactly these are your most significant way to use the prosthetic arm for. To just sit and look purrty is not to be considered an achievement.


[1] From prosthetic hand product description "8K20 / 8K21 / 8K22 / 8K23": Die hier beschriebenen Otto Bock Prothesenpassteile wurden für Alltagsaktivitäten entwickelt und dürfen nicht für außergewöhnliche Tätigkeiten wie z.B. für Extremsportarten (Freiklettern, Paragleiten, etc.) eingesetzt werden. Sorgfältige Behandlung der Passteile und ihrer Komponenten erhöhen nicht nur deren Lebenserwartung, sondern dienen vor allem der Sicherheit des Patienten. Sollten Passteile extremen Belastungen ausgesetzt worden sein (z. B. durch Sturz), müssen diese umgehend von einem Orthopädie-Techniker auf Schäden überprüft werden. Ansprechpartner ist der zuständige Orthopädie-Techniker, der die Prothese ggf. an den Otto Bock-Service weiterleitet.

Cite this article:
Wolf Schweitzer: - Requirements for prosthetic arms in context of chronic overuse and strain symptoms and carpal tunnel syndrome [analysis]; published 10/11/2011, 00:50; URL:

BibTeX: @MISC{schweitzer_wolf_1685687710, author = {Wolf Schweitzer}, title = {{ - Requirements for prosthetic arms in context of chronic overuse and strain symptoms and carpal tunnel syndrome [analysis]}}, month = {November}, year = {2011}, url = {} }