There are a lot of theories about how people learn. For example, some educators believe that there are three different modes of learning: auditory, visual, and kinesthetic. Basically, you learn either by hearing, seeing, or doing. While I believe that people use each of these learning techniques at different times and to varying degrees, I think most technicians absorb technical data best through kinesthetics. We love to touch and manipulate things, and we need to have a visceral understanding of technical information. Of course, we learn subjects like anatomy and diagnostics through auditory or visual input like everyone else, but when it comes to technical skills, we want to touch stuff!
So when the Orthotic & Prosthetic Technological Association (OPTA) board of directors sat down to build this year’s technical education program for the 2010 American Orthotic & Prosthetic Association (AOPA) National Assembly (OPTA co-sponsored the tech ed. program), we decided to include hands-on workshops. The program was scheduled to be seven hours long. This sounds like a long time when you first sit down with a blank sheet of paper. In reality, however, it really isn’t an adequate amount of time to transmit enough information to make the trip worthwhile for most technicians. So how were we going to make sure the information we provided to those who did attend was valuable? If high-quality technical programming is the goal, then kinesthetics is the method of choice! The questions that remained were “What do we do?” and “How in the world do we do it?”
Brad Mattear, MA, CFo, of O&P1 fame, answered the “What?” question for us. In some of our conversations, board members discussed thermoforming over foam models for AFOs. Five years ago, most technicians had never done this, but now it is becoming common practice. The problem with thermoforming over foam models is that there are a lot of different techniques being used—some science, some voodoo, but nothing conclusive that we could share with the world. We saw this as an opportunity not only to teach, but also to do what technicians do best—share.
We achieved the “How?” by assembling a working lab and testing a few of the more popular methods to figure out which one or ones had the most merit.
The hardest part of developing a hands-on education program is actually doing it! If this had happened in my lab, or any other lab for that matter, it would have been a piece of cake. I mean, we would have had to clean up a bit and maybe rent some chairs, but we would have had everything we needed and know right where everything was. A hotel conference room is a whole different story—no oven, no vacuum station, no scissors, nothing. We had to assemble everything! Granted, it would have to be a stripped down version of a lab, but we needed to have everything there, which meant we had to pack up and ship all of our equipment and tools across the country, reassemble everything, and make it work. We knew we wouldn’t have 220-volt electrical systems, dust collection, or even running water. Fortunately, this wasn’t our first traveling rodeo. Most OPTA board members have years of experience doing hands-on programming all over the country. Surprisingly, it almost always works. This was no exception.
This year’s technical education program was special because it was the first time we really focused on learning from each other rather than just imparting information. The subject of thermoforming over foam models is so new and mysterious that none of us has all the answers; in fact, we barely have any of the answers! So we didn’t just want to preach from the front of the room—we wanted the attendees on their feet, talking with one another and sharing. It is through this type of interaction that we learn the most.
The program began with a great presentation on lab safety by Don Pierson, CO, CPed, of Arizona AFO, Mesa, and then, to make sure we covered all our bases, Peter Panuncialman, president of Windy City Fabricators, Chicago, Illinois, gave an overview of various prosthetic fabrication techniques. We then moved on to the main lecture. To make sure we all developed an understanding of the physics behind thermoforming over a foam model, we asked Gary Bedard, CO, FAAOP, from Becker Orthopedic, Troy, Michigan, to explain exactly what we were up against. He took the complex science of thermoforming and distilled it into a very useful set of parameters.
Once the lecture was over, it was time to get down to business. We were glad to be able to pull in the talents of Jim Williams and Ed Fry. Jim is the go-to technical guy from SPS, Alpharetta, Georgia, and co-owner of Peaster & Williams Central Fab, Cumming, Georgia; Ed is a team leader at Hanger Prosthetics & Orthotics’ Orlando, Florida, fabrication site, where he pulls plastic on foam models all day every day, so they have both developed some very workable techniques for getting this done. Last but not least, I scoured the web to find a technique that was popular yet seemed like it would be an unlikely answer to the problem at hand.
Education In Action
The object of this exercise was to end up with a conclusive technique for thermoforming over a foam model, so we had five exact copies of a scanned mold cut from the same four-pound foam. (Three were for use; two were cut as extras, just in case.) Then we cut five sheets of the plastic from a single sheet of 3/16-inch polypropylene. The sheets were cut in the same direction and in the same size. Participants heated the material to the same temperature and applied the same vacuum force to all the pulls. The only thing that changed was the set-up—each pull used a slightly different set-up technique and a different interface.
The first was pulled with a single pantyhose covered with a PVA bag. The bag was then perforated to allow vacuum to flow through it. This technique was first described to me several years ago and is very fast to set up. You need to be careful to smooth out the PVA bag, which can sometimes be difficult because, as most of you know, those things aren’t designed to go around an AFO mold. All in all, it worked well. The surface wasn’t as nice as what we would traditionally expect, but considering the makeshift nature of our lab, most would have called it a success.
The second process was even more simplistic: one moistened layer of cotton stockinette followed by one moistened layer of Nyglass stockinette. The finish was pretty smooth, and it worked quite well. I don’t know if the glass content has any effect, or if it is just the surface texture that imparts a smooth surface, but either way, it left a finish most technicians would characterize as acceptable.
The third process was one I have known about for years and have been skeptical about for almost as long. It involves applying two pantyhose to the mold and then spraying the outer hose with a generous coat of 77 spray glue. A healthy coat of talcum powder is then applied over that. While I have used this technique for years to keep small areas of stockinette from sticking in a pull, such as over a Tamarack joint or a pad, the idea of using this for a large area sounds improbable. Needless to say, this was the only real failure of the three techniques tried that day. The stockinette welded to the plastic and could not be removed. While this provides a consistent surface texture, it is very rough and will absorb whatever fluids it comes in contact with. Not good.
After each of these pulls, we cut off the finished part and measured them to see if there was any obvious discrepancy with the supplied mold shape, and there was. The downside of pulling over a foam model is the obvious difference in the cooling rate of the inner and outer aspects of the material. We have known for years that slowing down the cooling rate of the inside of the plastic causes the plastic to curl in. This happens when we pull over a foam liner and was obvious in all of the finished products. Each exhibited a similar rate of part instability once de-molded. While we did find several successful techniques for achieving a smooth inner surface, we clearly don’t have all the answers yet.
All in all, we discovered two things. First, we need to do a lot more research about this emerging technology, and second, we as technicians need a lot more opportunities to gather and share ideas. Both of these discoveries exemplify the challenges that our changing profession faces. As with every challenge we have encountered, I am certain that both will be met.
Also published in the December 2010 edition of the O&P Edge. © 2010 O&P Edge