Plantarflexion Resistance of Selected Ankle-Foot Orthoses: A Pilot Study of Commonly Prescribed Prefabricated and Custom-Molded Alternatives

Very little objective data have been published regarding the control offered by specific ankle-foot orthosis designs, despite their widespread clinical application. In addition, the proliferation of custom designs and prefabricated variants in recent years has made it increasingly difficult to judge the effectiveness of a particular ankle-foot orthosis before completion of the fitting. A review of the literature showed that no definitive method for measuring load deflection characteristics of orthoses has been established to date. For this pilot study, we investigated the use of a simple digital tensiometer to objectively quantify the plantarflexion resistance supplied at the forefoot for a variety of common orthoses. In the study, the tested orthoses fell into three distinct groupings based on the average static resistance to plantarflexion. These data suggest that nonambulatory orthoses can be readily identified by the minimal plantarflexion resistance offered, whereas ambulatory devices can be classified as those offering moderate plantarflexion resistance versus those that function as a plantarflexion stop. This grouping according to biomechanical performance in the sagittal plane may have clinical significance and therefore may be useful in determining what specific ankle-foot orthosis should be prescribed.