Casting & Fitting

Casting for the Arizona AFO with the STS Casting Sock

The Arizona AFO will offer excellent support and superior comfort for your patients.  For optimum results, use the OHI Casting Kit with the STS Casting Sock and follow these directions.


OHI Casting Kit

Casting Board, Medium Mid-Leg STS Casting Sock (2), Plastic Cutting Strip, Cutting Tube, STS Scissors, Letter Opener (to open cast), Plastic Bag (2), Indelible Pencil

Step 1
step1Place the protective plastic strip over the foot and leg starting just behind the cleavage between the first and second toes, extending proximally over the dorsum of the foot, and over the anterior aspect of the ankle and leg. Hold the strip in place using three or four strips of 1" paper tape.
Step 2

Slip the protective plastic bag over the foot and lower leg.

Step 3

Remove the STS (Synthetic Tubular Sock) material from the pouch. Activate by dipping the roll in room temperature water and by squeezing the roll. Unfold the STS material an inch or two and stretch it open two or three times. Orient the material so the stitched end is lined up with the toes and place the sock over the toes leaving 1" of extra material at the end of the toes to avoid causing digital deformity.

Step 4

Continue to unroll the STS material over the heel and up the leg. Massage the foot and leg area to define anatomical contours, working from distal to proximal to work out the wrinkles. Excessive wrinkling in front of the ankle area can be removed by pulling up on the top front rim to "stretch out" the wrinkles. If desired, add water using a spray bottle to enhance slipperiness and accelerate curing time.

Step 5

With indelible pencil proceed to mark all bony prominences and problem areas as depicted.

A Series of Straight Lines
marking straight

Make this marking to show where you want material removed, which will result in additional support. Usually these areas are under the medial longitudinal arch or under and around the sustentaculum tali area. Our experience is that a met pad works well, so we will build one into your AFO unless you tell us not to.

A Circle With An X in The Middle
marking x

Mark a simple X at the apex of a bony prominence, usually the medial and/or lateral malleolus. Draw a circle around the bone. A 6mm build up will be applied at the X and will be tapered down to the edges of the circle.

A Starburst With A Dot In The Center
marking star

This mark is for a severe prominence. This area will be built up 10mm from the apex and tapered down. This is usually at a prominent navicular or malleolus.

A Circle or Oval With Two Lines In It
marking lines

Use these two parallel lines to mark an area where you can feel a bone, but you do not want a significant build up. It will be built up 3mm.

An Oval With Stitch Marks
marking stitches

This mark is for any scars that are sensitive. The build up will be 5 mm.

Plastic Covered Foam Casting Board (Foam optional and not included in kit)
marking stitches

Take your time while casting.  The better the cast, the better the end result.  If possible, always try to hold the ankle in a subtalar neutral position.  On the work order, be sure to let us know if the ankle joint position is correctable or if it is fused.

While molding the curing STS material, place the patient's foot on the plastic covered foam casting board and maintain the desired position until set (approximately 3 to 5 minutes).

Removal Instructions
marking stitches

Feel the STS material to determine if any portion is uncured and feels soft or tacky. If the material feels soft or tacky, apply more water (with gloved hands) and allow additional time to complete the cure. Using the specifically designed removal scissors/letter openener (or electric cast cutter), with the leg in the horizontal position (toes pointing to the ceiling),cut the material beginning at the top margin, proceeding down to the toes. Keep the cut line over the underlying protective strip.

removalSpread the STS material and carefully remove it from the foot. Having the patient gently wiggle the toes facilitates this process. Remove the plastic liner from the cast and trim top margin to appropriate length with scissors. Place three rubber bands around mold to realign cut margins. Please wait for the cast to dry before shipping.


Click here to view the Arizona AFO™ Work Order.

Click here to view the Arizona AFO™ License Agreement. Please send it along with your cast and your work order.