Properly fitting your prosthetic foot to a shoe is as important when you are replacing your shoes as it was the first time your prosthetist tightened the laces into place.
"Yesterday, my leg worked fine, but today it doesn't work at all!"
At some point or another, all prosthetists hear this frustrated lament. And having heard it before, we know that the most likely culprit is a new, different shoe. Properly fitting your prosthetic foot to a shoe is as important when you are replacing your shoes as it was the first time your prosthetist tightened the laces into place.
The foot and shoe act as the foundation of your prosthetic limb. If they don't complement each other, the prosthesis cannot function to its fullest potential. Only when the foot and the shoe complement each other does the full benefit of alignment and socket fit become available.
There are three major areas to consider when fitting a prosthetic foot to a shoe length, heel height, and foot volume. Ideally, the prosthetic foot should fill the shoe with only 1/2 to 1/4" extra space at the toe, just like the anatomical foot. Although this makes the foot more difficult to slip into the shoe, it results in less sliding and movement between the foot and shoe. Less slippage here means a more stable limb overall.
Prosthetic feet are sized using centimeters, a standard established by European manufacturers. Adult foot sizes typically range from about 22 to 30 cm (Refer to the foot conversion chart).
Proper measurement of the foot starts with the shoe. Use a metric tape and measure the inside of the shoe from toe to heel. This measurement is rounded down to the next lower centimeter size. For very pointy shoe styles, it is sometimes necessary to go even one more centimeter lower. The second consideration, heel height, is a measurement of how much higher the heel is positioned in relation to the forefoot. It is calculated by measuring the amount of soling under the heel area of the shoe, and subtracting the amount of soling under the forefoot. Matching the heel height of your foot to the heel height of your shoe can be critical to the action of your prosthesis. If the heel height of the shoe is 3/8" (a typical tennis shoe), and a 3/4" heel rise foot is placed in it (the typical foot for a man's dress shoe), you will notice that the leg leans backwards and is impossible to walk in easily.
Generally, it is a good idea to select a certain shoe heel rise, and stick with it. But this is not always desirable or even possible. Amputees who wish to wear multiple heel rises should bring their shoes to the prosthetist and discuss their needs prior to starting the next leg. Often by ordering a single higher heeled foot, the practitioner can accommodate a small range of shoe heels (typically a 1/2" range) by creating heel wedges for the lower heeled shoes.
Finally, the foot should fill the forefoot of the shoe snugly so that when the shoe is squeezed side to side a small pocket of material pulls away from the top of the foot. If the shoe is too tight, the foot may not be able to function appropriately. If the shoe is too loose, the prosthesis will seem unstable and sloppy.
Since most manufacturers make feet in a single average width, you can ensure a better shoe fit by choosing footwear that has laces or Velcro closures to accommodate the varying foot widths. Although convenient, slip-on shoes provide little support and tend to become even more stretched with time.
In cases where there is significant difference in volume between the two feet (such as when an AFO is on the sound side), purchasing mismatched shoes may be your best bet. One Seattle-based store chain, Nordstroms, sells mismatched shoes for a slightly higher than standard price.
There will always be those situations in which the ideal is difficult, if not impossible, to achieve. But keep in mind the goals, exercise your creativity, and soon you will be expertly sizing up your own prosthetic foot.
About the Author
Cindy J. Clinton, CP, has been a staff prosthetist since 1991 at the M+IND Corporation, manufacturer of the Seattle Foot. She received her BS in prosthetics and orthotics at the University of Washington in 1986, and was ABC certified in prosthetics in 1988. She earned five years of private clinical experience in Iowa and Washington before assuming her present position with M+IND.