Orthoses are externally applied devices used to modify the structural and functional characteristics of the neuromusculoskeletal systems; prostheses are externally applied devices used to replace, wholly or in part, an absent or deficient body segment. Included are, e.g. body-powered and externally powered external orthoses, prostheses, orthopaedic footwear. Excluded are endo-prostheses, which are not part of this document.

Orthoses designed to modify the structural and functional characteristics of the neuromusculoskeletal systems of the lower limb; the devices may be custom fabricated or prefabricated; the prefabricated devices may be adjustable or ready to use