Finally got a little spare time so I thought I'd post a follow up and get some closure on this. About a month ago I got my new prosthetic leg and it's wonderful. It fits just about perfectly, nice and snug and very positive. My old prosthetic doesn't fit nearly as well and I just couldn't pad it with enough socks to make it fit properly and still get it on. I could hold my leg out and shake it and my prosthetic would rattle back and forth, my stump was like a clapper in a bell.
My old prosthetic also has a rigid ankle. The foot form in it is made of carbon fiber and shaped with cantilever springs in the heel and toe so there is some overall springiness and the ability to provide for a reasonably natural rollover from heel to toe as you walk, but the rigid ankle means that I am standing on my toes when I get up from a chair, and also when I try to squat down and pick up something from the ground. Very unbalancing!
My new prosthetic has a hydraulic ankle with a range of motion that is slightly less than what a human ankle usually has, with two adjustable valves to control how quickly the ankle flexes forward and backward. Of course there are also numerous adjustments to control the direction and attitude of the basic foot, so it can be adjusted for (literally!) toe-in or -out, pitch, yaw, and roll. I am knock kneed and so my lower leg points outward, these adjustments allow for the prosthetic to be adjusted to my physiology. Once tuned and adjusted, my new leg feels really natural. The one thing it lacks is any springiness.
(An aside to the technical folks: my old prosthetic was a spring system with no damping; my new one is a damped system with no springiness, a superior system would be a spring-and-dashpot system with springiness and damping, such as that on a car with springs and shock absorbers. But I digress...)
My old prosthetic requires that I wear on a 6mm thick gel sleeve (it has a cloth outer layer to prevent stretching) with a barb on the end that mechanically latches into the base of the socket. To take off my socket I have to press in a button to release the barbed end. It is simple and quick and I still use it at night when I need to get up and use the restroom. I can put it on in the dark in just a few seconds and for the few steps it takes to make it to the head it is fine.
My new prosthetic is held on by air pressure. I wear a 4mm gel sleeve (no cloth outer layer) on my stump. My prosthetic has a carbon fiber outer socket, a semi-clear soft vinyl inner liner, and sandwiched between the two is a black gel sleeve. I wear a cloth sock of the proper thickness over the gel leg sleeve so that there is about a 2" band of gel exposed at the top, and when I step into the socket I just roll up the black outer sleeve and press it onto the gel leg sleeve to form an air tight seal. There is a simple push button air valve on the side of the socket; when I stand up any residual air is forced out of the valve. To take off the socket I have to roll down the black sleeve to break the seal and then press the button to equalize the pressure. It is a VERY secure method of attachment.
I wore my new leg for three days with no problems. Then I took it off on day four and unrolled the gel sleeve and poured about a half cup of bodily fluid and lots of bits of skin out of it. All the callous that I had built up on the end of my stump had softened and come off, and I had a raw spot about the size of a coffee cup. I put some antibiotic on it and dressed it and since it was a Friday I had to wait until Monday to call my prostheticist. Meanwhile I got the walker back out and spent the next ten days confined to getting around the house in my rolling office chair and using the walker to get to the restroom.
My prostheticist told me that apparently what had happened was that there was a small unfilled void at the bottom of the socket and while I was up and walking I had squeezed all the air out, but when I sat down and took the weight off my stump had pulled back a little bit and the end had formed a near perfect vacuum. This literally sucked the fluid out of my stump and peeled off the hardest and least flexible skin on the end. A hickey you don't want to get!
Once I was able to wear a prosthetic again I used my old one until I could get in for a refit of my new one earlier this week. My guy tweaked a few rub spots (a little heating and reforming of the soft vinyl inner layer took care of that) and also put a wad of lamb's wool down into the base of the socket. It fills the void and even when compressed it traps enough air to keep from forming too high a vacuum. I also learned not to dangle my leg or let it hang, and to hit the air valve to let air pressure in the base when I sit down. I can feel the pressure change when I do that; I need to learn what the new sensations mean when wearing my new prosthetic.
I have been wearing my new leg for almost a week now and have been up and working with no problems so I think that obstacle is overcome. Now that I am mobile again I can get back to meeting with contractors, etc to get going on building our new shop.
Old prosthetic on left, new on right. Note button latch on left, air valve on right.
Three layer construction. carbon fiber outer, vinyl inner, gel sleeve between
Sleeve for old prosthetic. Note barb on end.
Gel sleeve I wear for new prosthetic
Here I am wearing new prosthetic
Here is the ankle with all its adjustments
