Lower limb orthotics

An orthosis is the medical term for what many people call a brace or splint. Lower-limb orthoses are generally named according to the body regions involved:

• AFO: ankle-foot orthosis
• KAFO: knee-ankle-foot orthosis
• HKAFO: hip-knee-ankle-foot orthosis

Static and dynamic orthoses

A static orthosis is relatively rigid and is used to support a weakened or paralyzed body part in a particular position. A dynamic orthosis is designed to facilitate or accommodate motion and support optimal function. Proper control commonly relies on a three-point pressure system.

Design considerations

The selected orthosis should be as simple, lightweight, strong, durable and cosmetically acceptable as the clinical situation allows. Prescription considerations include three-point pressure control, static versus dynamic stabilization, material flexibility and tissue tolerance to compression and shear.

Orthoses may be constructed from metal, plastic, leather, synthetic fabrics or combinations of these materials. Thermoplastics are among the most commonly used materials in contemporary orthotic fabrication.

AFOs

An ankle-foot orthosis is commonly prescribed for weakness or paralysis affecting ankle dorsiflexion, plantar flexion, inversion or eversion. AFOs can help prevent or correct deformity and influence weight bearing. Semi-rigid thermoplastic materials are commonly used in their fabrication.

Shoes matter

Footwear is an important foundation for many lower-limb orthoses. Shoes should be comfortable, properly fitted and appropriate for the orthosis. They should provide sufficient length and accommodate the shape of the foot.