Expert Explains Prosthetics Fittings, Types of Amputations
With the recent news coverage of the Olympics and the Paralympics, athletes with amputations are taking a spotlight. We’ve all heard about the amazing accomplishments of Oscar Pistorius, and the Paralympic victories showed us how much athletes who use prosthetics can do.
But what’s the story with amputations? How much do you really know about the abilities of everyday people who use prosthetics?
The Mobillty Project and Mobility Management magazine sat down with Scott Cummings, past president of the American Academy of Orthotists and Prosthetists, a member of the Amputee Coalition’s scientific and medical advisory committee and a certified prosthetist at Next Step O&P in Manchester, N.H., to find out.
TMP: How long before someone with an amputation would be ready to be fitted with a prosthesis?
Cummings: Typically it’s around the time of suture removal, which is about three weeks out (three weeks post-op). The sutures are removed, and the surgeon declares that the person is ready to start the fitting process. The fitting process may take anywhere from a week to three weeks depending on the design of the prosthesis and who’s providing the care. Although there are instances when we fit just a few days after amputation, I think for the most part typical care is provided within that three- to six-week time period.
TMP: Are the prostheses created to be customized to the individual?
Cummings: I mentioned the early fitting prosthesis; that’s typically a noncustom one. They’re prefabricated and then custom fitted to the patient. The fit isn’t as exact as a custom-made prosthesis that’s molded to the shape and the size of the limb by taking a negative impression of the limb. But the new amputee, can’t tolerate full weight bearing because he hasn’t healed up enough. The concept with the custom fitted is there’s a lot of swelling in the residual limb, and the residual limb isn’t going to be full weight bearing so that the fit doesn’t have to be as perfect for the first several weeks. And so, some doctors and prosthetists feel it’s more important to get them up right away and get them walking with something. In that case we use what's called an IPOP—immediate post-op prosthesis or preparatory prosthesis. And that can happen anywhere from the day of amputation to a few weeks later. The customized ones are typically made after that first few weeks. The limb has shrunken down a bit because much of the post-op swelling is gone and the drains have been pulled out; the dressings are reduced. Now we can start seeing the bony anatomy, and we expect the patient to exert more weight bearing on the limb, so we need to go custom.
TMP: Is that something you have to change over the years?
Cummings: Absolutely. The patient will keep changing. Usually somewhere in the first three to six months after we fit a new amputee, we’ll need to replace the socket because they will have changed so much. And at the same time, the requirements on the socket increase. These people are getting more active, more weight bearing, more wearing time, and we expect the fit will need to be better as they progress functionally. So it’s important to maintain a really good fit. If we fit them four weeks post op and we look at them again three to four months later, they’re not the same size and shape. Now they’re thumping around on the prosthesis, and it probably doesn’t fit that great. That’s an indication that it’s time to cast them and refit them. Usually an amputee will change pretty dramatically for the first 18 months or so, and then after that they tend to stabilize. We might do three sockets in the first two years, and then after that, it might be every three years that we replace the socket.
TMP: Do the people who transition to prosthesis continue to use their wheelchair for any reason? Or are they completely converted?
Cummings: I don’t know the exact percentages, but it’s a fair number of people who would continue to use the wheelchair selectively. Many amputees will progress to the point where they don’t need it at all, and they return it to the DME (durable medical equipment) place or give it away, but some people will ambulate in the house and short distances in the community. They might use the wheelchair only for an activity when there’s more walking involved. So it’s not uncommon for that amputee to wheel themselves into a store and then get up and walk around an aisle or two and then get back into the chair and wheel another 100 yards to the other store they want to go in. I will tell you that there’s a difference between the average below-the-knee amputee and the average above-the-knee amputee in the amount of energy expenditure to walk, resulting in the below-the-knee level having a better chance of being ambulatory than the above-the-knee amputees.
TMP: Is that just a balance issue?
Cummings: It’s balance, stability, strength and especially endurance. The amount of energy to walk with an above-the-knee prosthesis far surpasses on average the amount of energy expenditure for the below-the-knee amputee. Consequently, if we were to separate the two groups of amputees, you’d see a different picture. There’d be more of the above-the-knee amputees that decide to utilize a wheelchair than below-the-knee amputees. So it’s not a hard and fast rule, but on average that would be something we’d expect to see.
TMP: Is that something that would improve over time? As they became more comfortable with the prosthesis, would they have more endurance?
Cummings: Yes, absolutely on both levels. If we checked in on them three months after fitting and then again after 12 months, we’d expect both groups, above the knee and below the knee, to improve in their stability, balance, strength and endurance. But there still is a discrepancy between the two groups. We would expect more of the above-the-knee group to use the wheelchair than the below-the-knee group, even though both groups have improved.
TMP: What are the different types of amputations that you typically see?
Cummings:There are three general types. One is congenital, so they’re born that way. Number two is traumatic, and that’s an accident of some sort such as war injuries or motor vehicle accidents. The third type is a disease process, and that could be cancer or it could be diabetes or it could be other circulatory problems as well. Right now, in the U.S., about 50% of all amputations are due to vascular problems. And most of those are related to diabetes. We have an obesity epidemic in this country and with it are projections to have an increase in diabetes-related amputations.
Find out more about amputations and wheelchair use in Mobility Management’s November feature.