Fabricating the Plastic-in-Leather AFO

By Steve Hill, CO

The AFO fabricated by putting plastic inside layers of leather is becoming very popular. Several central fabrication companies offer their own distinct versions, such as the Arizona AFO® or the Baldwin Boot. But if you want to make your own, here’s how I do it.

Many technicians use molded leather for this type of AFO, which is probably the prettiest way to do it. That way is my first choice when I have plenty of time. Of course, that rarely happens.

While the method I’m going to show you may not be the epitome of the fabricator’s art, it is a fast and efficient way to get the job done. This “down and dirty” method is an excellent alternative to waiting around for molding leather to dry. The details can vary according to your personal taste, but the basics remain.

Applying the first layer of leather
Working from a mold that’s been modified in its full circumference, wrap it entirely in plastic to protect the leather during fabrication. Measure out the leather for the inner layer, first along the length of the foot for the width, then from the top of the cast on the medial side across the bottom of the foot to the top of the lateral side to give you the length. There will be a seam along the front of the cast and one along the back.

A good leather to use would be a soft cream-colored cowhide, but for people who’d rather not kill any more cows, any good leather alternative can be substituted.

Apply the leather to the cast with the finished side down. Staple the leather to itself at each seam, as closely as possible to the shape of the cast. A Y-shaped seam will be required at the heel for an intimate fit.
Remove the leather from the cast and draw a sew line just inside of the staples. Sew the posterior seam as accurately as possible, paying close attention to the “Y” seam at the heel. Trim off the excess material.

Replace the leather on the cast and staple the front to the mold. The edges of the leather should touch each other and completely encompass the mold. Stretch it so that all of the wrinkles have been pulled out and the leather is taut.

Adding the foam pads
Since this type of AFO is usually a total-contact device, you will want to add some foam pads to the parts of the AFO which will be in contact with major bony prominences, to prevent skin breakdown in that area.

I like to heat up a bit of foam and mold it over the lateral ankle and the medial ankle/navicular complex. Also, you can add another foam pad an inch or so from the proximal border to ensure a soft flare. Shape these pads and bevel them accordingly. Once they’re shaped, glue them in place.

Forming the plastic
In preparation for forming the plastic, apply two stockings over the leather-and foam-covered mold. The internal layer of leather acts as an insulator and tends to make the stocking and foam stick to the superheated plastic. Spray the stocking with a release agent to make sure that the plastic doesn’t stick to it. Almost any decent release agent will work.

Vacuum-form the plastic layer as you normally would on any other AFO. The seam should be well anterior and match the seam of the leather beneath. The thickness and type of plastic should reflect the amount of support you hope to accomplish, the weight and the activity level of the patient. I usually use one-eighth-inch thick copolymer.

After the plastic has cooled, remove it from the model. Because you don’t want to harm the leather underneath, cut it off full length, running the cast saw along the edges of the leather. Pull the plastic shell off as carefully as possible to avoid damaging either the leather or the plastic.

Now the plastic can be trimmed and sanded as desired, usually to a low-profile AFO. The only exception is that you’ll cut out the plastic at the heel where the Y-shaped leather seam makes the device unsightly and potentially uncomfortable. Make a foam pad to fit inside of this cutout to help soften the seams and fill some of the gap, for increased comfort and cosmesis.

Gluing the leather
After the plastic was cut off the mold, the leather was probably also cut off. If this is the case, then it’s time to reattach the leather to the mold. Apply a liberal amount of glue only to the area which the plastic covers, and glue the plastic to the mold.

Now measure the mold for another layer of leather, and sew it as you had done the first layer. Again, make sure you’ve got an intimate fit to the mold, and stretch the leather as much as possible. This time, however, invert the leather so that the finished side is out and the seam is facing the cast when you apply it back to the cast.

Using plenty of glue, secure the outside layer of leather to the developing device. Don’t wait for the glue to dry—start pulling and stretching the outside layer onto the mold while the glue is still wet. Work the leather into the nooks and crannies and stretch, stretch, stretch! Once it is tightly in place, staple the edges of the leather to the cast and let the glue dry.

The finishing touches
After the glue has dried, cut the whole works off with a razor blade. Cut full length so that you have plenty of material to work with. To create the proximal flare, roll the inside layer of leather away from the proximal border, and cut the outside layer to the desired flare height. Roll the inside layer back over the top and glue it in place to create a soft flare. Sew this flare along that seam and continue sewing along the entire orthosis at the desired trim lines, taking the width of the tongue into account.

Now you can cut some thin and flexible leather to create the anterior tongue. Sew this tongue into place on whichever side you think the patient will best be able to don and doff the orthosis. The careful and thoughtful addition of either eyelets or Velcro® closures will complete the device.

Contrary to popular belief, adjustments can be made to this orthosis in the same way that adjustments are made to any plastic device: with a heat gun. The plastic beneath the leather usually melts before the leather burns, though, so you should take care when making this or any alteration.

If you have time to wet-mold the leather, you may opt for the traditional method of making a plastic-in-leather AFO. But when time is critical, this glued-and-stretched method should suffice for most applications.

Steve Hill, CO, is secretary of OPTA and CEO of Delphi Ortho, located in Asheville, N.C. and on the Web at www.delphiortho.com.