Lower Limb

A lower limb orthosis is an external device applied or attached to a lower body segment to improve function by controlling motion, providing support through stabilizing gait, reducing pain through transferring load to another area, correcting flexible deformities, and preventing progression of fixed deformities.

Orthosis (or orthotic device) is the medical term for what most people would refer to as a brace or splint.Orthoses generally are named by the body regions that they involve, as demonstrated by the following abbreviations:

• AFO is an ankle-foot orthosis.
• KAFO is a knee-ankle-foot orthosis.
• HKAFO is a hip-knee-ankle-foot orthosis.

An orthosis is classified as a static or dynamic device. A static orthosis is rigid and is used to support the weakened or paralyzed body parts in a particular position. A dynamic orthosis is used to facilitate body motion to allow optimal function. In all orthotic devices, 3 points of pressure are needed for proper control of a joint.

A lower limb orthosis should be used only for specific management of a selected disorder. The orthotic joints should be aligned at the approximate anatomic joints. Most orthoses use a 3-point system to ensure proper positioning of the lower limb inside the orthosis.

The orthosis selected should be simple, lightweight, strong, durable, and cosmetically acceptable. Considerations for orthotic prescription should include the 3-point pressure control system, static or dynamic stabilization, flexible material, and tissue tolerance to compression and shear force. An orthosis can be constructed from metal, plastic, leather, synthetic fabrics, or any combination. Plastic materials, such as thermosetting materials and thermoplastics, are the materials most commonly used in the orthotic industry. Shoes are the important foundation of the lower limb orthosis. Shoes are used to protect and warm the feet, transfer body weight while walking, and reduce pressure or pain through redistributing weight. Shoes should be comfortable and properly fitted. They should be at least 1 cm longer than the longest toe and correspond to the shape of the feet.

An ankle-foot orthosis (AFO) is commonly prescribed for weakness or paralysis of ankle dorsiflexion, plantar flexion, inversion, and eversion. AFOs are used to prevent or correct deformities and reduce weight bearing. The most common material used in fabrication of AFO-s is semi-rigid thermoplastic.