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Dick's Page

ctaaa

 

I spend a lot of time at the keyboard, writing both text and software programs. As a result, I developed severe pain in my wrists and became very worried about carpal tunnel and similar problems. My solution was to redesign my keyboard/mouse system and, for me at least, this has eliminated the problem at the source. You are welcome to use the procedures outlined below to see if my solution will also be effective in your particular situation.

I also recommend taking frequent breaks from the keyboard. Get up every so often and stretch or go for an occasional walk. This not only helps me relax while working, it actually improves my writing.

A better mouse Some definitions: CTS and RSI In the beginning ... The mouse that roared The solution that works for me Why other approaches help, but don't eliminate CTS The time interval factor How to build your own CTS-proof computer system.

 

A better mouse

I really do think I have invented a better mouse. What I have done is connect two different products -- a conventional mouse and a standard trackball mouse -- in a particular way that eliminates the specific motion that is the basic cause of Carpal Tunnel Syndrome or CTS.

Like many others who use computer keyboards a lot, I had developed a full-blown set of CTS problems, particularly with my right wrist. Several things helped this condition, including an ergonomic keyboard with a wrist support, and switching from a regular (Microsoft) mouse to a (Logitech) trackball. I also added a pad next to the trackball so that I would be using the trackball with my wrist held horizontally instead of being bent upwards.

While these measures helped, the CTS condition only improved slightly. When I added my "invention" to these measures, the condition was completely reversed and (hallelujah) I was cured. The pain I felt while using the computer stopped immediately, and the lingering soreness in my wrist was gone within a few days -- even though I continue to use the computer as heavily as before. I assume that this is not a unique case and that my invention could also cure a very large number of people who use computers and experience CTS problems.

 

Some definitions: CTS and RSI

These definitions are often used interchangeably and incorrectly.

RSI -- repetitive strain injury. This is a general description of a host of problems, including carpal tunnel problems.

CTS -- carpal tunnel syndrome. This is a diagnosis of a particular injury, common but not unique to the combination of a keyboard and a mouse or other "pointing device."

 

In the beginning ...

There were typewriters, of course, that people used for decades. While repetitive strain injuries (RSI) were probably a problem in the old typing pool, nobody cared much if "Miss Jones" had a sore back. CTS does not occur in large numbers with typewriters because this condition is a product of the computer and specifically the mouse. In short, just typing is not the culprit or the main cause of CTS.

Pushing buttons doesn't cause CTS either. If it did, people who uses calculators, push-button phones, or point-of-sale terminals a lot would be afflicted with CTS, and they aren't.

 

The mouse that roared

Blame the mouse. The click-and-drag motion of the mouse is the specific action that I believe is the root cause of CTS. Whether this idea is correct or not, removing this specific action from the operation of the computer ends CTS problems. At least it did for me.

Try this:

Press down on the desk with your index finger.

Rub your finger left and right an inch or two, bending your wrist.

If you do this a hundred times or so, your carpal tunnel will probably become inflamed and you will not be able to do this any more without some pain in your wrist. Continue, and the situation will get worse.

Your wrist is not designed to do this. It is not designed to bend a lot while the fingers are being pressed and the ligaments are in compression. This is precisely the action that takes place when a person clicks the mouse button and, while holding the button down, moves the mouse. The click-and-drag is the precise action that causes CTS.

If you could use the mouse without bending your wrist or holding down the button while you move the mouse, this particular problem would not occur. (You may get other RSI stuff, but not CTS). This is why wrist braces that keep the wrist from bending while you use the mouse, and other gadgets that keep the wrist immobilized are often used as cures for CTS problems. My invention eliminates the specific action that causes CTS in the first place, while letting you use the cursor as freely as before.

 

A solution that works for me

The permanent fix for CTS is to avoid bending the wrist while the fingers are in tension. I do this by separating these two functions and assigning them to separate hands.

The right hand controls the cursor position with a trackball. The buttons on the trackball are not used at all. I can move this hand all I want because the wrist is relaxed and the fingers are not in tension. It's fairly easy to move a trackball around without bending the wrist or tensing the fingers.

The left hand controls the buttons. I can push, click, or hold buttons all day long with my left hand because I'm not trying to move the wrist at the same time. Only the fingers wiggle while the wrist is motionless, and this causes no problem at all.

As it turns out, it's very easy to move the cursor with one hand and push a button with the other. Click-and-drag and the drag-and-drop motions of the cursor while using two hands instead of one are quite easy to master, and actually feel perfectly normal. The dominant hand with the trackball can position the cursor precisely with no effort.

Although I used a trackball for positioning the cursor, I could have just as easily used a conventional mouse for this action. The critical factor is to not press and hold any buttons with the same hand that is positioning the cursor.

(I may have thought of this because of playing the guitar. One hand "thinks" and plays, while the other hand pushes down the strings at the right places. So a two-handed computer mouse seemed quite reasonable -- like a two-handed guitar.)

 

Why other approaches help, but don't eliminate CTS

Just using the trackball instead of the conventional mouse doesn't solve the CTS problem. Pressing the buttons on the trackball while rolling the ball around to position the cursor is the same basic motion that causes CTS in the first place. Even if the wrist is held still, pressing the thumb or forefinger down while wiggling the other fingers to position the trackball is overload for the carpal tunnel. There's simply too much stuff going on in a small space, and the area becomes inflamed.

The scratched systems that replace the mouse with a pressure-sensitive pad are also repeating the same motion that causes CTS. The "finger mouse" button that's imbedded in some keyboards may help, but the finger using the button is still held down while the wrist is tensed. This is not the same action as pressing a key briefly, as in typing.

 

The time interval factor

I'm not sure why normal handwriting does not cause CTS. Perhaps it does (writer's cramp?) but not in large numbers. I believe that the time interval during which the carpal tunnel is stressed may be a critical factor. In handwriting, the fingers are in tension while the wrist is being bent, but the motion and consequently the tension are constantly fluctuating over time. With the mouse, the pressure is constant and of comparatively long duration. If this "time interval" theory were correct, it would explain why handwriting and many other tasks do not cause CTS, while click-and-drag functions of the mouse or trackball would. This would also suggest that the scratched systems and "finger mouse" replacements are not a solution either.

 

How to build your own CTS-proof computer system

You may be able to combine a trackball and a regular mouse to your computer at the same time, using USB connectors. If your computer can accept two mouse inputs via USB connectors, then using a regular mouse and trackball in parallel may work for you. I now use the standard mouse that came with the computer as a clicker only, and position this at the left side of the keyboard. I also use a Logitech Trackball (Marble Mouse) on the right side of the keyboard and use this for positioning the cursor only. By positioning with my right hand and clicking with the left I am able to eliminate the click-and-drag motion that had caused my RSI problems.

Depending on your computer, this dual mouse setup may not work entirely correctly. If so, you will have to go to more direct approach. Before I was using a computer that allowed dual mouse inputs, I sacrificed a commercial trackball and a mouse to create my two-handed mouse system. I wired the buttons on a regular mouse in parallel with the main buttons on the trackball. Fortunately, the mouse button switches in the trackball I used are open circuit, so that I could just parallel these with a second set of buttons. In practice, any trackball or mouse could be used as the main pointing device to position the cursor, with any other simple switches added.

If you are familiar with computer circuits and are handy with a soldering iron, you should be able to create your own version of this system by modifying a conventional track ball and mouse. If you aren't handy with electronic stuff, get a knowledgeable friend to help. A wrong solder connection can definitely short out your computer and fry things -- so be careful.

If you do follow my recommendations and create your own modified system, drop me a note and let me know how this solution works.

 

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