Tiny AFOs: Bracing for Premature Babies

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By Morgan Stanfield

When you see the tiny bootie in the palm of Ken Kane's hand, it's not surprising to learn that he went to college to be a toymaker. The sole of the wee lacer doesn't begin to span the width of the six-footer's big palm, and he might—might—be able to wedge his pinky finger inside it without it getting stuck. When you handle the little item, though, you see that the bootie isn't doll footwear; it's intended for the tiniest of human feet, and those feet have clubfoot.

Kane, CO, didn't actually get the job at Playskool he was hoping for when he got a bachelor's degree in plastics in 1984. Instead, three weeks after hanging up his cap and gown, he was offered a job as an orthotist. He thrived in his new career, became certified, and worked in a variety of facilities. About ten years ago, he was working in his current position at the University of California San Francisco Hospital when he was sent to fit a new baby with a pair of straight-last shoes and a Denis Browne Bar.

"I walked in, and that child weighed one pound, one ounce," Kane recalls. "The smallest straight-last shoes that I know of are triple zeroes, which were approximately 15 times too big." The preemie, born 15 weeks early, set Kane on an inventing process that has culminated in the creation of the teeny device he holds in his hand, a brace the UCSF staff has dubbed the "Tiny AFO."

Big Problems with Tiny Feet

Ken Kane, CO. Photographs courtesy of Ken Kane.

The Tiny AFOs Kane makes actually come in several forms. Some are actually KAFOs, and others are femur-fracture splints for very fragile babies who were born vaginally. They commonly take the place of plaster casts on infants whose legs, Kane says, "are so small that doctors can't even put a long leg cast on them...and preemies like that grow so quickly that you'd be changing the cast every three days anyway—and then you'd have to think about how you were going to get the cast off. How could you use a saw?" For children this size, he adds, even custom Mitchell Braces are too big.

The advantages of the meticulously engineered Tiny AFOs are myriad. First, they offer effective correction soon after birth, before ingrained problems solidify. Second, they're flexible and well-padded enough not to chafe or squeeze an infant's delicate legs. Third, they're amenable to the world of incubators and diapers, being as easy to clean as the toys they resemble, freshening up with new laces and a dunk in household soap and water whenever necessary. Finally, they can last much longer than other methods.

"We normally go through about three sets of these on a baby," Kane explains. "For the really, really small preemies, the least amount of time I got one to last was ten days, and the child had more than doubled his weight in that time. After we get through that initial stage, they can last upwards of three months. After that point, they can either go into Ponseti casting, straight-last shoes, or Mitchell Braces." Kane adds that his braces can also be modified in a variety of ways. If you want to use a Denis Browne Bar, for example, you can just Velcro a little bar to the bottom of the brace.

Inventing in Miniature

Developing the Tiny AFOs took years. "We figured out that we should make a two-part plaster cast that you can take apart," Kane recalls. "It has a posterior shell and an anterior shell on top of that. You make the posterior shell, let it harden up, and then cast the anterior shell on top."

The brace itself is also in two parts. "You make a little light interior shell out of a material called Aliplast 10 X-Firm Density," Kane explains. "It's a heat-moldable material that can just be drape-molded under the posterior shell. Then the anterior shell slides right in, so really you're making a removable cast, or a fracture brace without a joint. Without the interior shell, the children move around inside." The two-part nature of the brace means that nurses can check the wearer's skin and parents can take off the brace in an emergency, but it's not so tempting to remove that they have compliance problems.


Making Your Own

Kane's team makes Tiny AFOs for about nine patients per year, and he's happy to share his method with colleagues.

Steps for Making Tiny AFOs

  1. Prepare the baby, the parent if applicable, and your workspace. The room should be a comfortable temperature, not overly lit, and with "not too many beeping things," Kane says. It helps if the baby is sleepy and has recently been fed.
  2. Make a basic pattern for the plaster strips and cut them to shape, making enough for four layers on both the posterior and anterior shells.
  3. Place the seamed stockinette on the baby's leg.
  4. Position the child. Prone position is best; on the side is second best. If the child is in the hospital and absolutely cannot be held still, he or she can be medicated if necessary, but normally it's possible to work around this.
  5. Measure the leg. "I really couldn't make these without the orthometry form [shown on pg. 44]," Kane says. "I use the calcaneus as the anterior landmark and the knee center for the heights, lengths, and circumferences."
  6. Wet the plaster in lukewarm water—never hot water, which can burn thin skin.
  7. Have your team hold the leg in the corrected position while placing the plaster, planning to place the posterior splint, let it set, then lay a piece of stockinette over it and run the anterior shell over that. Kane explains, "Have one member of your team hold the patient's foot, one person hold the knee, and one person hold the upper femur.... With both my hands, I'm trying to hold on to the calcaneus and the forefoot. My colleague is trying to hold the material onto the femur and into the popliteal. Now, while the plaster is still wet, we are trying to manipulate the leg into as neutral a position as possible. We only move it until we feel slight resistance—maybe five or six degrees."
  8. Remove the plaster and cast the positive model as usual, using the quarter-inch steel rod for a mandrel.
  9. Modify the positive model while referring to the measurement form, using the Trautman, Dremel, or dental tools. "It's just like doing a regular KAFO or AFO. You still have to do the same build ups to make sure you're not putting pressure on bony prominences," Kane says.
  10. Make a pattern for the liner and cut the Aliplast 10 X-Firm to shape. Heat the Aliplast 10 X-Firm, use the perforating wheel to perforate it all over, then place it on the positive model. Kane explains, "If you perforate the material once you've heated it in the oven, you can pull the pattern onto the model and it won't wrinkle because it has hundreds of little vent holes.... The tiny holes also make it stick to the model, and when you put the hot plastic on it, it also adheres itself to that."
  11. Heat and drape-mold the polyethylene or copolyethylene onto the form.
  12. Trim any excess material using the Xacto knife or scalpel. Kane trims the foot plate to just past the ends of the toes. "Everybody wants to know how to tell when the brace is getting too tight, so I make the foot pieces so that as soon as the big toe gets to the edge of the plastic, they can know it's time for a new brace," he says.
  13. Use the hole punch to create holes for laces and, if the child is in a relatively hot environment, to punch a hole in the bottom of the heel cup and a few on the foot, calf, and thigh for venting and drainage. "The first time we tried this, I used a drill press to put some little vent holes in one, and the drill caught and just ripped it all apart," Kane cautions. "I bought a soldering iron to poke holes through it, and that left a little sharp edge on the hole. Finally, I went back to the same hole punch that I made the lace holes with, and it didn't leave an edge."
  14. Insert the laces. Kane says that Velcro straps are "useless" for this application. "You have to individually glue the little pieces of hook on the AFO because if you use sticky-back on the polyethylene, it comes right off the first time the nurses pull on it to look at the skin. Velcro also sticks to everything in the incubator, so you end up with the baby stuck to the blankets." Kane adds that laces also encourage compliance. "Hopefully, everybody has had a pair of shoes, and you know never to pull on their laces so hard that it macerates the skin, but you also don't leave them loose," he says. Laces also give what Kane calls "a huge mechanical advantage" because they give consistent pressure from top to bottom.

Working with Parents

Working with the baby's parents is an essential part of the process, especially if the baby is healthy enough not to be in an intensive care nursery. When possible, Kane prefers to fit the child with both parents present, and to cast the baby in the mother's arms. For those castings, he brings a cute sample of the finished brace and gives the parents a choice of copoly colors to help soften any fears that their baby will be stuck in a leather-and-metal torture device.

Orthometry Form

Kane says that making Tiny AFOs simply isn't possible without using a measurement form, and this goes for replacement braces as well. "We tried putting four or five socks on a model that we had already done, but it was out of proportion.... And you can't put it on a computer and add an inch to the entire model, then ten days later do it again. What we learned is that when they become too tight, we have to do it over, and trying to save time doesn't work."

If the child's right foot is being cast, have the parent cradle the child with his head on the parent's right shoulder, exposing the right leg to you. Or, expose the child's back aspect by holding the baby as if he was breastfeeding. During fitting, if the baby is going home with the brace, have each parent don and doff the brace about three times. "The parents get comfortable really quickly," Kane says. "It's just like diaper changes or a Pavlik harness—the first time Mom might be pretty upset because she can't figure out which way the thing goes, but by the third try, she's a pro." Kane also explains cleaning at this point, and tells parents that the splint can easily be removed in an emergency. "I also tell them they can call me any time and every single day if they need to," Kane says.

Kane concludes that once you get the hang of making Tiny AFOs, they can take as little as 15 minutes to cast, and that you'll feel comfortable fabricating them after making six or so.

However, after nine years of making Tiny AFOs and other items for miniature backs, hips, legs, and even arms, he still has a challenge that he says he hopes The O&P EDGE's clinician readers can help him with.

"I've never figured out how to do this for hands," he says. "Can you imagine trying to do a splint on a two-pound preemie that has a contracture of the thumb? I can put little splints on the arms, but the fingers are so tiny—the little fingernails are like a pinhead, that's how small they are."


Editor's note: If you'd like to offer suggestions, e-mail Kane at

Morgan Stanfield can be reached at