Allan Grubb CO. (c) Prosthetic Intern; Birgit Gremmen CO. (c) Prosthetic Intern; Chris Hewitt RTPO; Kelowna General Hospital, Kelowna B.C.

We have found a versatile material to address the needs of our patients who require AFO's and HO's. We see a large population of clients with varying degrees of neurological involvement. Two goals that we have explored have been to fit more comfortable AFO's on children with high tone, and to dynamically splint the upper extremity.

Our patients with neurological disorders affecting the upper and lower extremity have benefited from wearing either an AFO with a duraflex liner, or a thumb spica manufactured from the same material.

Patients who present with thumb in palm or adducted thumb have benefited from wearing this type of device as it allow the thumb to be dynamically abducted, yet is soft enough to allow adduction with minimal resistance. The material is extremely durable, hygienic, and only 3 mm thick at its thickest point.

Drawing from the idea of serial casting, the R-Wrap AFO and the Cascade DAFO, we wanted to design an AFO that would provide 360 degrees of control over the ankle and forefoot. The drawback of designs that use a thin plastic fully encompassing the foot is that most parents or caregivers are unable to open the liner with one hand, and position the foot into the brace with the other. The use of the soft, flexible Duraflex inner boot is applied separate from the rigid outer shell. This makes donning the brace, with the foot in the correct position, quite simple.


High-pressure areas are often seen on neurologically involved children wearing conventional AFO's. These area include the:

  • Navicular
  • Posterior calcaneous
  • Base of the fifth metatarsal
  • Medial and lateral malleolus

The pressures generated from bringing a spastic foot into a dorisiflexed and aligned position and maintaining that position, can be tremendous. The modifications to the plaster mold must be generous enough to accommodate the deformity, and the finished product must be padded generously. Strapping to align the ankle and foot must be placed in the correct position to influence the final position. Figure 1 demonstrates a typical spastic plantar flexed foot that will correct with effort. Figure 2 shows a foot that has had previous problems with navicular skin breakdown. This young patient has had multiple surgeries and injections of botox to decrease the developing contractures and deformities.

Figure 1

Figure 2

Other young patients have tried AFO's with little success due to the collapse of the midfoot and posterior displacement of the cal-caneous. See Figure 3 . This patient also displayed lateral displacement of the ankle mortis, making fitting a comfortable AFO very difficult.

Figure 3


  • Clients who have a history of high-pressure areas resulting in skin breakdown or rejection of brace use.
  • Clients who have strong extensor patterns
  • Clients whose caregivers are unable to determine if the foot is properly positioned in the brace
  • Very small children who have few areas to apply corrective forces to maintain the foot a desired position inside the brace.

We have explored ways of reducing shear forces inside the AFO using a flexible inner liner. Introducing a layer between the skin, and the hard thermoplastic shell reduces shear. It is easier to maintain the foot in the desired position, as the material allows us to encompass the foot in a 360-degree wrap.

Figure 4


Our desire was to break the cycle of high tone causing the foot to plantar flex in the brace. The plantar flexion increases the shear forces by moving the foot away from the modified relief areas.


We often use a soft interface material to cushion the areas that are problematic.
Figure 5


Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Instructions for pulling a Duraflex liner:

Duraflex heats quickly at 260F -300F and should be pulled over a bare, warm, moist mold for optimal clarity and working time. After the Duraflex has cooled, it can be trimmed out. A PVA bag is pulled over the liner and cast. Place a cutting strip between the Duraflex and plastic to be used.

A PVA bag is pulled before the outer shell is applied.

Once the outer shell is pulled and has cooled, the outer shell and inner boot can be separated. Final trim lines can then be determined, and the placement of pads and straps can be marked and sent to the technicians for finishing. The boot is first placed on the foot, the boot is clipped into place, and the straps are tightened. The shoe is fit and the patient is stood to assess the alignment. The brace is then removed to assure pressure is applied to the correct area, and that excess pressure is not evident.


Benefits of using Duraflex:

  • Dynamically brace the thumb to abduct but allow controlled adduction movement for children who require grasp function.
  • Bite protection.
  • Easy to clean, hygienic.
  • Very durable.
  • Dynamic in it's function.
  • Comfortable to Wear.
  • Reduction in pressure points.
  • Reduction in bulk.
  • Rigid H. O.

Typical materials used for rigid H.O.'s are low temperature thermoformable materials. Figure 9 . The expected function is to maintain the hand in the desired position, but the usual result is higher than expected pressures, gapping along the web space, and undesirable degrees of hygiene. Note in this picture, the sharp edges along the first metacarpal and the thumb. The patient was seen for an assessment and Duraflex device was manufactured, with the desired results.

Patients who require splinting to prevent biting, benefit from the use of Duraflex, as it is less bulky than conventional plastics, will not deform, and is easy to keep clean. Most maintenance required is to replace straps periodically. This patient was subjected to tethering of the arm to prevent biting before a Duraflex hand splint was built.

Figure 11

This is the same hand after the introduction of a Duraflex hand spint. Figure 12 . The ulnar opening and simple strap design, allow the parents to quickly don the brace and fix the closure. The patient is allowed to move his arm freely, without restriction, and his fingers are protected from injury.

Figure 12


The use of Duraflex as an interface between the skin and the thermoplastic shell of an AFO, and the use of this material as a dynamic hand spint, has shown that the use can benefit both the patient and his immediate caregivers. The product should only be used if the patient has a history of problems with other types of devices, as the cost of the finished product can be substantial.

If your client displays the need for this type of device, the results can be quite beneficial. The use of new materials and ideas, advance our profession, and promote independence to our cliental.