WHO is an acronym for Wrist-Hand Orthosis. A WHO is used for a variety of conditions. It can be used for positioning/stabilization, for range of motion assistance, or to stop a joint from flexing or extending excessively. It can also be used for fracture management. Materials can include canvas, metal, and low temperature thermoplastics. The physician determines use of the device. It may be worn all day or for nighttime use only.