National Physical Therapy Examination (NPTE) Practice Exam 2026 - Free NPTE Practice Questions and Study Guide

The primary purpose of a spiral ankle-foot orthosis is to address medial or lateral instability of the ankle. This type of orthosis is designed to provide stability and support to the ankle joint, especially in cases where there is a risk of ankle sprains or instability due to injury or weakness in the surrounding musculature.

By encasing the foot and ankle in a supportive spiral design, the orthosis helps to restrict excessive movement that could lead to further injury while allowing for some range of motion necessary for functional activities. This balance of support and mobility is vital for individuals recovering from ankle injuries or for those with congenital or acquired conditions leading to instability.

The other choices relate to specific movements of the ankle that may not be the primary rationale for using this orthosis. For instance, while limiting plantarflexion or dorsiflexion might be necessary for certain patients, the main objective of a spiral ankle-foot orthosis is more focused on providing overall stability to prevent lateral or medial instability rather than solely restricting specific movements. Increasing plantarflexion would also not align with the primary function, as the orthosis aims to stabilize rather than enhance a particular motion.