Prosthetic History: Becker Hand and Bill McElroy

[Jon Kuniholm]

The Becker Hand is one of the longest-running hand-shape prosthetic products around, and has been well described by Wolf Schweitzer in this post. I have been trying one out, thanks to John Becker, who is still in the family business, and plan to do a more detailed evaluation of this very cool old technology.

As I was doing some patent research, I came across this patent, issued to a Mr. William McElroy, for a hand which I think you'll agree bears a striking resemblance to the Becker hand (externally, at least).

I hadn't heard of McElroy before, but he patented some interesting things, including this hook. Here's the first Becker patent, filed six months after McElroy, and issued to Edward Laherty three years after McElroy's patent. Laherty assigned 49% to Becker.

By 1938, when Becker's second patent was filed, his hand looks very much like the Becker Mechanical Hand that is still sold today.

As with some of the other figures involved in prosthetic arms last century, it would be interesting to understand some of these relationships, beyond the suggestions that we get from patent records.

[Wolf Schweitzer]

Yes, the Imperial contains a mildly cleaned up design of the mechanism, as well as a base plate mounted screw to a second spring to allow for a firmer grip whereas grip strength of the Lock Grip is as is. Otherwise, the case being plastic (and not wood) and thus the single size 8 is the only difference. 

[Jon Kuniholm]

Where did you hear about the Hosmer hand? 

BTW, in looking at those images, I'm wondering if it's possible that the Imperial is simply a Lockgrip with a urethane or other finish on top? The aluminum cover and screws look identical, and I'd swear that I can see the layers of wood in this image.

[Wolf Schweitzer]

I learned that Hosmer who was alleged and rumored to build another mechanical hand with adaptive grips buried their project / product. Also I think the combination of precision / pincer grip, power grip and adaptive grip is quite hard to achieve - and, miraculously the Becker hand does just that. All the same, the Becker mechanism contains technical weirdnesses particularly inasmuch as thumb control is concerned and we started to investigate the issue. Despite that, the hand itself remains a prime product for a price that is impossible to beat. 

After I had asked John Becker to consider building a transparent plastic "phantom" Becker hand, contact broke off and no more mails from him. So I figured that no way around building our own hand in the future where we can actually control and determine materials and appearance ourselves. 

PVC gloves that fit well (to be fitted and then shrunk using a heat pistol) can be ordered from Centri. They have that shape. I have two colors - dark brown and a custom-made red, which looks super. 

For what I use it for - meetings, social events, eating out, driving, .. the Becker hand is perfect even though I will want to get a transparent one one day. So currently, the feature I want to see on top of existing features is to have a relaxed flabby hand. That type of natural motion seems to be a next step. 

Privatized 3D printing and good new ideas probably are the way to go. 

More Becker inside views: 

http://www.swisswuff.ch/tech/?p=934

Eric Ronning model: 

http://www.swisswuff.ch/tech/?p=1132

[Jon Kuniholm]

I just revisited this post, thinking about the Stark Hand, featured in Everyday Edisons (Popular Science, CNN, Announced on Everyday Edisons Season 4). The hand has supposedly been licensed, but as with many announced and hyped prosthetic products, has yet to be made commercially available. One of the problems with bringing out new products in this area is the availability of cheap and capable alternatives like the Becker, coupled with the low level of reimbursement.

Anyway, In reference to Wolf's post below regarding construction, I have the similar Becker Lockgrip Hand, which looks just like the hand in the Becker patent above. The Lockgrip is actually carved out of a composite block of wood, in much the same way as Ohio Willow Wood Legs are, and is covered with deerhide and some kind of sealant. The hide and sealant helps protect and hold together the composite block, and the whole effect of the construction is similar to the way many cedar strip wood boats are made.

While I don't use the Becker hand a lot, I've found it to be great for shooting sports, biking, and other activities where you need to grasp a cylindrical shape, and where the backlock is helpful.

[Jon Kuniholm]

Interesting to note that we HAVE CT scanners, and yet your phantom Becker hand could be the one in the patent above...

[Wolf Schweitzer]

We did a CT scan and here is how a Becker Imperial looks today http://www.swisswuff.ch/tech/?p=348 - From quick analysis of a plastics specialist, he said that the Becker Imperial body was most likely manually cast and plastic foils were used to get the smooth surface, but no injection molding. He said most likely this was a very carefully done manual cast.