What is the primary function of a posterior leaf-spring orthosis?

The primary function of a posterior leaf-spring orthosis is to assist with dorsiflexion. This type of orthosis is designed to provide support during the swing phase of gait, helping to avoid foot drop, which is a condition characterized by difficulty in lifting the front part of the foot. The posterior leaf-spring orthosis has a flexible design that allows some movement while still providing necessary support to the ankle joint, facilitating proper foot positioning during ambulation. This is particularly useful for individuals with certain neurological or muscular conditions affecting dorsiflexion, enabling them to walk more efficiently and with greater safety.

In contrast, assisting with knee extension is not the main purpose of this orthosis; it primarily focuses on the ankle. Providing stability to the ankle is also an ancillary benefit rather than the primary function, as the orthosis is more geared towards aiding movement rather than immobilization. Additionally, supporting hip rotation is outside the intended use of a posterior leaf-spring orthosis, as its design and function are specific to the lower leg and ankle.