My New Leg

Well, the second step of getting a prosthesis is actually called “casting,” but it usually does involve a lot of plaster. Dara (my friend and photographer for this project) and I arrived at the prosthetics shop a few minutes early and waited in the front office.

When Wayne was ready, he showed us into a fitting room and we chatted about my leg for a few minutes. I hadn’t seen him in a few years — since he made my current leg and did a big favor for one of my kids — so we caught up on what I’d been doing and discussed what I’m looking for in a new leg. Wayne’s fitting rooms are pretty standard — chairs, a set of parallel bars to hold while walking with a mirror at the end, and coated with the light dusting of plaster that seems permeate everything in prosthetics shops. This fitting room also had a set of stairs ascending and a ramp descending, with handrails, so people can practice walking on stairs and slopes.

Prosthetists have a few ways of “examining” their patients and diagnosing progress and problems during clinical visits. One is to watch the amputee doff and don (remove and put on, respectively) their prosthesis. This can provide important clues about whether the prosthesis is fitting properly and whether the amputee is having trouble getting their leg on all the way. Another is to read the amputee’s skin, looking for redness or irritation that may hint at too much pressure, friction, or an otherwise problematic fit. One of the most important methods is simply watching the amputee walk and observing their gait (people often associate gait with horses, but it’s used to refer to the manner of walking for people, too). Prosthetists are skilled at on-the-spot gait analysis and can see if the prosthesis is aligned (positioned) correctly by watching their patient walk.

I unlocked and removed my prosthesis and rolled off the silicone liner that pads my stump inside the carbon fiber socket, and described my recent issues with the socket’s fit as Wayne inspected the skin on my stump. My stump is pretty beat up after so many years of being encased in silicone, but I don’t have any major problems currently.

I also mentioned the issue of my foot bottoming out when I put much weight on it, and he suggested the idea of putting a foam rubber wedge inside the heel of the foot to at least prevent the clack-scratch sound made when the heel compresses.

Then we started the actual casting process, the first step in creating a socket to custom fit my stump for my new leg. There are a variety of ways to do this, using plaster, inflatable air bladders, CAD-CAM, or some combination thereof. The latter has been mentioned often in the field in the past few years, but has yet to be adopted very widely. Prosthetists are notoriously pragmatic and slow to adopt technologies unless they offer a discernible benefit in terms of patient care or cost savings. Wayne has told me that CAD-CAM socket technology was originally developed for use in developing countries where there is a lack of skilled prosthetists and a need to produce large volumes of prostheses quickly. But in America, CAD-CAM systems are prohibitively expensive for most businesses and reduce the level of tactility valued by prosthetists when using plaster. Wayne, like most prosthetists, continues to use the traditional plaster method.

First, he had me roll on the silicone liner that pads my stump inside the socket and then pulled a plastic bag over the liner to protect it from the plaster.

Then he pulled a one-ply prosthetic sock over my stump and had me bend my knee at a 10 degree angle and hold the sock in place while he marked me up. Prosthetic socks come in various thicknesses — one, three, and five-ply — and are used to adjust the fit of the prosthesis throughout the day. In this case, Wayne used a one-ply sock as a canvas so he could use a grease pencil to mark the landmarks and features of my knee and stump.

When he was done marking me up, he dunked a roll of plaster of Paris into warm water, squeezed it out, and started to wrap the plaster bandage around my stump. We chatted as he wrapped 2 rolls of the plaster. Wayne dipped his fingers in the water and smoothed the cast out as the plaster began to set, using his thumbs to make sure the cast fit closely, especially along the flat surfaces on the sides of my tibia and around my knee.

After the plaster had hardened sufficiently, he had me straighten my knee and gently pulled the sock and cast off my stump. The grease pencil markings had transfered from the sock to the inside of the cast, which would assist him later when shaping the plaster positive for the check socket.

We were done with the casting! Wayne asked me to surf the web, shop around for a few feet I’d like to try out, and email him my selection so he could order them.

If you want to learn more, read a detailed description of the casting process in the chapter about clinical communication, “There’s No Language for This…”, in my Ph.D. dissertation about the prosthetics field, Performing Able-Bodiedness: amputees and prosthetics in America.