Orthotics is a medical specialty that focuses on the design and application of orthoses. An orthosis is an externally applied device used to influence the structural and functional characteristics of the neuro-musculo-skeletal systems. Commonly used orthoses for the leg are devices inserted into shoes to support the foot and foot arches, hard and soft braces around the knee to support and protect a knee following injury. For the arm, commonly used orthoses are hard and soft braces for the elbow, forearm and hand.