PFFD Prosthosis

This is a checklist we've been developing over the years as we've grown into new devices and even in talking with other families. I hope it is helpful for anyone who might use a Prosthosis for PFFD.


A prosthosis is a combination of a orthosis and a prosthesis. We call it a "lift." Our child is now much older than the 6 years old when the picture was taken, but you can see the progression up to that time.

A majority of orthopaedic surgeons, all physiatrists, and all CPO's recommended a Moseley-type prosthosis. When we started this internet website there were very few people who had heard of this kind of device (although in recent years it has become much more common). This page is to record our thoughts as well as have a checklist of sorts so we can refer to it for future work.

The early versions (25 months to about age 4.5) were made entirely of carbon fiber/nylon/resin and were extremely light. No pediatric components. They were made by Noel Chlaudek of Des Moines and his work was amazing.

At 4 years we moved cities and also switched to prosthetic components. Because of insurance billing codes that meant that costs went from about $1500 per lift (orthotic codes) to about $5000-$6000 per lift (prosthetic billing codes).

Overall Results:
We've been very happy with the results. Our child runs, jumps, rides bikes w/out training wheels, roller-blades, walks a mile to school each day, etc.

Below is a video of bilking at about age 5.

If you can't see it, there is a copy here:

Over the years we've noticed there are certain things that need to happen in order for each prosthosis to work well. Keeping to these standards avoids things like skin changes, device failure, and or unwieldy systems.

We've worked with quite a few different prosthetic and/or orthotic providers over the last 9 years. In some cases we switched because we moved to a different part of the country, in other cases we switched because the CPO moved away, and in some cases the provider was not great with PFFD designs/casting/etc. Some have used 100% carbon fiber (CF) + laminate, others all laminate. Some have used nylon hinges, some have used metal hinges. This has given us a wide range of experience in working with different casting techniques, materials, providers, insurance companies, etc.

So, for both us and others if you find it useful, below is our checklist that we use


1. When casting it is critical that the cast be made with the foot exactly perpendicular to the lower leg. This is important for good hinge placement. (more on this later). Sometimes the CP will call in a CPO or a CO to make the cast in the same way that a cast would be made for an AFO (ankle foot orthotic). We once had a CP think in terms of a socket and angled the foot downward, didn't use a foot plate, and tried to have the weight supported on the skin instead of the bones. Disaster. The resulting prosthetic (not a prosthosis) caused bruising and pain and was ultimately rejected/returned.

2. Blue marks on the inside of the cast at casting time making sure the bony prominences (e.g. ankle) are taken into account.

3. Make sure measurment of the size of the unaffected foot is done.

4. Discuss componentry to be used. Pediatric vs non-pediatric, type of foot, size of foot, split toe (sandals) vs non-split toe, etc.

5. Make a cutout of the PFFD foot and leave it with the provider. Every time we've ever had a cast made they
focus on the heel, ankle, calf, etc but at the toes just leave it undefined. Leaving a record of the PFFD foot means that
when they get ready to form the toe section they have a model.


1. Distance from big toe to front of orthotic portion 2.5 to 3 cm at most. Curves around, close to small toes. The PFFD foot might be smaller than the unaffected foot.

This means that we have room for growth, but also is not so long that it will impede walking/turning, and will fit inside
snow pants.

2. Dorsal View: Top of lift is parallel to bottom of lift and pilon. In the image below
you can see a failed manufacturing. The stick is parallel to the top of the lift, but shows how the bottom is about 17 degrees off the center line.

The consequence of the top not parallel to the bottom is that the hinges will fail frequently and over time the carbon-fiber/laminate where the hinges attach will rip apart. We've gone from the nylon hinges in a lift lasting 6 months to the hinges lift failing every week with only this difference in vertical alignment.

3. Side view (Medial View): upper part is directly above and parallel to pilon. This helps with hinge alignment (see part 8 below)

3.5 Top View. There is a lot of medial and lateral pressure - the lift should wrap around the lower leg to avoid pinching the skin, digging into the leg, etc, but not so far as to cause a problem getting it on/off.

4. Padding inside orthotic portion. If the provider says "some redness and bruising is normal at first" know that this view is not shared by effective professionals with an orthotic certification nor is it borne out by our experience with a well made lift. We have found that with a well-made prosthosis there should be no redness that doesn't disappear after 5 minutes at most. Similarly to how you get redness on knees that disappears when crossing/uncrossing them. Expect to take 30 minutes to make sure that the fit is good. If the provider says "we try to put as little padding as possible with an AFO so it can fit well in side a shoe" then that's an indication that they fail to understand there is extra carbon inside the device to withstand the extra forces and flexibility of the device is limited.

5. Liner: Liner wraps up and over part of foot. Length should be based on the PFFD foot, NOT the unaffected foot as the PFFD foot is smaller. In the image below the foot was about 18.5 cm long.

6. Cats paw or pad underneath toe of orthotic portion to assist with climbing.

7. Liner: Velcro attached to both shell and liner to hold liner down. Failure to do this results in the liner flopping around when walking. I actually an Othotist once said "we want as little padding as possible because of how it will fit in the shoe." Note to Orthotists, the AFO part does NOT go in a shoe.

8. Hinges: connecting calf support to foot should be parallel with the main axis and perpendicular to plane of foot (no rotation across transverse axis) In the image below the lift on the left worked extremely well for months. Although the picture just says "caused skin changes" other issues that occur are failure of hinges, stiffness of motion, and failure of the carbon-fiber/laminate area. In the picture below the lift on the left lasted until our child started to outgrow it (nearly a year), but if the hinges are not well aligned like the lift on the right, the lift hinges can fail within weeks. We've even had a CPO try metal hinges but they did not match requirement #8 and so instead of the metal hinges failing, the Laminate/Carbon section failed.

9. Prosthetic foot should be the same size of the unaffected foot. This is very important for developing gait, stability, not to mention dancing/jumping/roller-blading/biking and buying one size pair of shoes at a time.

10. Walking in bare feet should be ok

11. Bring to first fitting several pairs of shoes to make sure they fit. If in cold area bring snow-boots.