For a child's PFFD prosthetic where there is no amputation the fitting is different than what most protheticists are used to working with. Each PFFD case is different. In our case the foot/ankle/tibia/knee are all unaffected. So far (she's almost 3) we've opted for no surgery and to just use a Mosely-type protheses but made of lightweight flexible carbon-fiber.
There are a few key differences we've discovered between the "standard" prosthesis design and a PFFD one including:
a) The prosthetic on the foot is not designed to go into a shoe, but to BE the shoe. The part at the bottom (the skate) is the part that goes into a shoe.
b) The prosthetic needs to allow for growth spurts in length/width of foot
c) Changes in the child's height can be adjusted easily by adding onto the bottom of the lift.
d) The prosthetic is not designed to transfer weight to the skin e.g. to avoid a bone spur or bone end from amputation.
Here is a checklist we use when we get a new prosthesis.
At the casting
- Use a foot plate on the bottom of the foot. The foot plate needs to be the size and shape you'd want for a child's shoe. Our daughter wears wide size shoes.
Update: whether or not to use a footplate depends on the skill of the manufacturer. For devices that are built up from commercial AFOs using a footplate was recommended since there were "sizes" to choose from. However - for custom built fittings - not using the foot plate was recommended. Our othotist/protheticist said "foot plates make it harder to really see what's going on and if you have a good casting you don't need a footplate."
- Cast with the foot at 90 degrees from the leg.
At the fitting
- Check dorsiflexion ankle mobility of the lift. Should allow the ankle to bend the foot 45-60 degrees toward the head (dorsiflexion) to allow for climbing up inclines
- Check plantar flexion ankle mobility of the lift. Should allow the ankle to have the toes point straight down (plantar flexion) (close to 85 degrees back) to allow for jumping.
- Check pliability of the medial/lateral foot part (the part between toes and ankle). When you get shoes they expand. Children's feet grow wider quickly and having that pliability is important for comfort. It also helps in being able to slide the lift on a squirming two-and-a-half year old.
- Check flexibility of the medial/lateral side of lower-leg portion of the lift to allow for ease of sliding on a squirming two-and-a-half year old.
- Check the strength of the ankle hinges - they should not be difficult to bend. The goal of the lift is to provide M/L (medial/lateral) stability and height, not dorsi-plantar flexion support.
- Rock the heel and the toe for proper heel strike and toe-off without a shoe.
- The top strap should be wide to prevent bruising
- A texured rubber sole on the bottom of the skate (e.g. Cat's Paw)
- Add a flexible teflon patch to the side near the ankle to prevent pinching
- Watch for redness