An orthopedic prosthesis is an internal or external device that replaces lost parts or functions of the neuroskeletomotor system. In contrast, an orthopedic orthosis is a device that augments a function of the skeletomotor system by controlling motion or altering the shape of body tissue. For example, an arti- cial leg or hand is a prosthesis, whereas a caliper (or brace) is an orthosis. is chapter addresses only orthoses and external orthopedic prostheses; internal orthopedic prostheses, such as articial joints, are a subject on their own.