Shoehorn-type ankle-foot orthoses: prediction of flexibility.

OBJECTIVE

To predict the factors affecting the flexibility of a shoehorn-type ankle-foot orthosis (AFO) in dorsiflexion and plantarflexion.

DESIGN

Experimental assessment.

INTERVENTIONS: None.

MAIN OUTCOME MEASURES: The dorsiflexion and plantarflexion angles of the ankle joints of the AFOs versus applied force were measured.

RESULTS

The dorsiflexion and plantarflexion angles demonstrated significant negative linear correlations with the height of the AFO (p < .01), the height of the medial wall (p < .05), the height of the lateral wall (p < .01), the width of the narrowest area (p < .001), and the width of the ankle joint area (p < .001). The dorsiflexion angle also demonstrated a significant negative linear correlation with the curvature radius of the lateral trimline (p < .05) and the thickness of the plastic sheet (p < .05). Stepwise multiple regression analysis demonstrated that the width of the ankle joint area, the thickness of plastic sheet, and the height of the lateral wall significantly affected the dorsiflexion and plantarflexion angles (p < .001).

CONCLUSION

The major predictor of flexibility in dorsiflexion and plantarflexion is the width of the ankle joint area, and the second predictor is the thickness of the plastic sheet in dorsiflexion and the height of the lateral wall in plantarflexion.