（1） When one or more joints need to be fixed; Such as joint weakness or deformity caused by sequelae of polio.
（2） When a certain deformity needs to be corrected or prevented from further aggravation: for example, congenital clubfoot. Adolescent idiopathic scoliosis, etc.
（3） The purpose is to compensate for the lost function: for example, patients with upper limb paralysis can use the balanced forearm orthosis to facilitate eating and completing some activities of daily life.
（4） Improve walking function; For example, patients with foot droop use plastic ankle-foot orthosis.
（5） For the purpose of reducing and eliminating the weight bearing of limbs: for example, the osteochondral type of femoral head can use the hip abduction and internal rotation orthosis with the weight bearing of the hip.
（6） Used to promote fracture healing: such as various fracture orthoses.
（7） It is used for limb protection after operation.
（8） Use orthosis temporarily while waiting for surgery.
（9） Used to improve the appearance of limbs.