Study Examines Plantarflexion Resistance in Commonly Used AFOs

BOSTON — Joseph Whiteside, CO presented findings documenting plantarflexion resistance in a variety of commonly prescribed ankle-foot-orthoses (AFOs) at the American Orthotic and Prosthetic Association National Assembly here.

The study, originally published in the Journal of Prosthetics and Orthotics, was conducted to address the need for quantified data relating to plantarflexion resistance in commonly used AFOs.

The researchers used a leg model with the knee at 90° and a free-motion ankle joint to test plantarflexion resistance in a number of AFOs. Measurements of the devices were taken using a digital goniometer and load was measured using a digital tensiometer. The two test parameters included resting at 90° and then loading to 10º plantarflexion and resting at 10° dorsiflexion and loading to 10º plantarflexion. Categories that were tested included plantarflexion stop, plantarflexion resist and non-ambulatory devices.

Based on the test results, the researchers determined that the AFO’s provided magnitude of resistance increased with plantarflexion and that these tests would be useful for determining sagittal plane plantarflexion resistance in AFO selection. They also concluded that the ability to adjust dorsiflexion angle increased the magnitude of resistance.

“I think this is something that we can all appreciate as clinicians,” Whiteside said. “Having an adjustable system and enabling the capability of the patient to increase the dorsiflexion angle and have a positive response, especially in those patients who need more plantarflexion resistance, would be [beneficial].”

Whiteside also noted that pressure relief AFOs (PRAFO) were comparable or exceeded the plantarflexion resistance of many of the tested custom and prefabricated ambulatory AFOs.

“The aluminum strut [in the PRAFO] differentiates itself from other devices on the market, and the ability to use something like this, not only for traditional use and use for off-loading positioning, but using it as a functional AFO is a nice option,” Whiteside said. “It is affordable and has the adaptability and accessibility and ankle to offset that plantarflexion positioning during gait.”

For more information:

Whiteside, J. Plantarflexion resistance of selected ankle-foot orthoses. Presented at the American Orthotic & Prosthetic Association National Assembly 2012. Sept. 6-9, Boston.

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